National Park Service

U.S. Department of the Interior

Natural Resource Stewardship and Science

Landbird Population Trends for Seven Great Lakes 

Network National Parks

Natural Resource Report NPS/GLKN/NRR—2015/1091
ON THE COVER

Chestnut-sided Warbler (Setophaga pensylvanica) by William H. Majoros/Wikimedia Commons. Conducting point counts in 

forest, field, and river, NPS photos/T. Gostomski.
Landbird Population Trends for Seven Great Lakes 

Network National Parks

Natural Resource Report NPS/GLKN/NRR—2015/1091

Alexander T. Egan1, Ted Gostomski2and Leonard C. Ferrington, Jr.1

1University of Minnesota

219 Hodson Hall

1980 Folwell Avenue

St. Paul, Minnesota 55108

2National Park Service

Great Lakes Inventory and Monitoring Network

2800 Lakeshore Drive East

Ashland, Wisconsin 54806

November 2015

U.S. Department of the Interior

National Park Service

Natural Resource Stewardship and Science 

Fort Collins, Colorado
ii

The National Park Service, Natural Resource Stewardship and Science office in Fort Collins, 

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This report is available in digital format from the Great Lakes Network website 

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report in a format optimized for screen readers, please email irma@nps.gov.

Please cite this publication as:

Egan, A. T., T. Gostomski and L. C. Ferrington, Jr. 2015. Landbird population trends for seven Great 

Lakes Network national parks. Natural Resource Report NPS/GLKN/NRR—2015/1091. National 

Park Service, Fort Collins, Colorado.

NPS 920/130696, November 2015
iii

Contents

Page

Figures..................................................................................................................................................vii

Tables...................................................................................................................................................vii

Appendices............................................................................................................................................ix

Executive Summary..............................................................................................................................xi

Acknowledgments...............................................................................................................................xiii

List of Terms and Acronyms ..............................................................................................................xiii

Introduction............................................................................................................................................1

Methods..................................................................................................................................................5

Spatial and Temporal Allocation of Samples.................................................................................5

Point Count Methods, Park Objectives, and Data Arrangement ....................................................5

Apostle Islands National Lakeshore ..........................................................................................6

Grand Portage National Monument...........................................................................................7

Indiana Dunes National Lakeshore ...........................................................................................7

Isle Royale National Park..........................................................................................................8

Saint Croix National Scenic Riverway......................................................................................9

Sleeping Bear Dunes National Lakeshore...............................................................................11

Voyageurs National Park.........................................................................................................12

Analytical Methods ......................................................................................................................13

Trend analyses.........................................................................................................................13

Density and detectability .........................................................................................................14

Guilds ......................................................................................................................................15

Results..................................................................................................................................................17

Trend Analyses.............................................................................................................................17

Apostle Islands National Lakeshore ........................................................................................17

Grand Portage National Monument.........................................................................................18

Indiana Dunes National Lakeshore .........................................................................................19

Isle Royale National Park........................................................................................................20

St. Croix National Scenic Riverway........................................................................................20
iv

Contents (continued)

Page

Sleeping Bear Dunes National Lakeshore...............................................................................22

Voyageurs National Park.........................................................................................................22

Density and Detectability .............................................................................................................23

Grand Portage National Monument.........................................................................................24

St. Croix National Scenic Riverway........................................................................................25

Sleeping Bear Dunes National Lakeshore...............................................................................25

Voyageurs National Park.........................................................................................................25

Guilds ...........................................................................................................................................25

Apostle Islands National Lakeshore ........................................................................................26

Grand Portage National Monument.........................................................................................26

Indiana Dunes National Lakeshore .........................................................................................27

Isle Royale National Park........................................................................................................27

St. Croix National Scenic Riverway........................................................................................27

Sleeping Bear Dunes National Lakeshore...............................................................................27

Voyageurs National Park.........................................................................................................27

Discussion............................................................................................................................................31

Observational Regression Trends.................................................................................................31

Density and Detectability .............................................................................................................32

Guilds ...........................................................................................................................................33

Park-specific Conclusions............................................................................................................34

Apostle Islands National Lakeshore ........................................................................................34

Grand Portage National Monument.........................................................................................34

Indiana Dunes National Lakeshore .........................................................................................35

Isle Royale National Park........................................................................................................35

St. Croix National Scenic Riverway........................................................................................36

Sleeping Bear Dunes National Lakeshore...............................................................................37

Voyageurs National Park.........................................................................................................38

Conclusions..........................................................................................................................................43
v

Contents (continued)

Page

Management Recommendations..........................................................................................................45

Quality Control.............................................................................................................................45

Reporting ......................................................................................................................................45

Improved Analyses.......................................................................................................................45

Survey Effort ................................................................................................................................46

Literature Cited ....................................................................................................................................47

vii

Figures

Page

Figure 1. Locations of the nine national park units in the Great Lakes Inventory and 

Monitoring Network. .............................................................................................................................1

Figure 2. Locations of ten breeding bird survey routes at Apostle Islands National 

Lakeshore (Wisconsin), 1995–2009. .....................................................................................................6

Figure 3. Breeding bird survey points are distributed at ≥250 m intervals along the 13.7 

km portage trail at Grand Portage National Monument (Minnesota). ...................................................7

Figure 4. Location of breeding bird survey points at Indiana Dunes National Lakeshore 

(Indiana).................................................................................................................................................8

Figure 5. Locations of eight breeding bird survey routes at Isle Royale National Park 

(Michigan)..............................................................................................................................................9

Figure 6. Six breeding bird survey river routes at St. Croix National Scenic Riverway 

(Wisconsin/Minnesota). .......................................................................................................................10

Figure 7. Locations of 41 breeding bird survey points at Sleeping Bear Dunes National 

Lakeshore (Michigan)..........................................................................................................................12

Figure 8. Locations of 80 breeding bird survey points (nine routes) at Voyageurs 

National Park (Minnesota)...................................................................................................................13

Figure 9. Proportional and mean categorization of distances to birds recorded at Grand 

Portage (GRPO), Sleeping Bear Dunes (SLBE), Voyageurs (VOYA), and St. Croix 

Riverway (SACN)................................................................................................................................24

Tables

Page

Table 1. Year of establishment and number of points for breeding bird surveys at Great 

Lakes Network parks. ............................................................................................................................2

Table 2. Regression trends (average proportional change per year) for species observed 

during 10-minute point counts at Apostle Islands National Lakeshore, 1995–2009 ...........................17

Table 3. Regression trends (average proportional change per year) for species observed 

during 10-minute point counts at Grand Portage National Monument, 2000–2014............................18

Table 4. Regression trends (average proportional change per year) for species observed 

during 3-minute roadside point counts at Indiana Dunes National Lakeshore, 1993–2013. ...............19

Table 5. Regression trends (average proportional change per year) for species observed 

during 5-minute point counts at Isle Royale National Park, 1996–2013.............................................20
viii

Tables (continued)

Page

Table 6. Regression trends (average proportional change per year) for species observed 

during 3-minute point counts at St. Croix National Scenic Riverway, 1998–2014.............................21

Table 7. Regression trends (average proportional change per year) for species with 

significant increases or declines during 3-minute stationary point counts at St. Croix 

National Scenic Riverway, 2005–2014................................................................................................22

Table 8. Regression trends (average proportional change per year) for species observed 

during 10-minute point counts at Sleeping Bear Dunes National Lakeshore, 2004–2006 

and 2009–2013.....................................................................................................................................22

Table 9. Regression trends (average proportional change per year) for species observed 

during 10-minute point counts at Voyageurs National Park, 1997–2013............................................23

Table 10. Trends for combined species within guilds at Apostle Islands National 

Lakeshore and St. Croix National Scenic Riverway............................................................................26

Table 11. Trends for combined species within guilds at Isle Royale National Park, 

Voyageurs National Park, and Grand Portage National Monument....................................................28

Table 12. Trends for combined species within guilds at Sleeping Bear Dunes National 

Lakeshore and Indiana Dunes National Lakeshore..............................................................................29
ix

Appendices

Page

Appendix A: Route Completion Details..............................................................................................55

Appendix B: Regression Analysis Details...........................................................................................61

Appendix C: Distance Analysis Details...............................................................................................81

Appendix D: Taxonomic Species List ...............................................................................................101

xi

Executive Summary

In recent decades, bird surveys in western Great Lakes national park units have documented avian 

communities for scientific, management, and interpretive purposes. Surveys targeted landbirds, 

particularly passerines and woodpeckers, during the peak of breeding season when detectability of 

birds is greatest due to territorial singing. The Great Lakes Network office has developed standard 

methods, which most parks have adopted, making data relatively comparable across the region. 

Seven of the nine Network parks have datasets spanning greater than five years that are analyzed in 

this report.

Data are collected by experienced observers annually in June, during early to mid-morning hours, in 

good weather conditions, at pre-selected points on hiking trails, roads, and, in one park, along rivers. 

Data from the counts are used to document the species assemblage and population changes over time. 

Analyses utilized regressions to focus on the trajectory of bird populations over time. Both empirical 

and density-estimate models were employed to determine the most reliable trends for species in each 

park where sufficient data were available. Empirical models use log-transformed observations from 

annual surveys. Density models use distance measurements to estimate the proportion of birds that 

were present but not detected; the estimates are often improved by including covariates such as 

weather data. Only one park had habitat association data available. Guilds of species assemblages 

were also analyzed, including migration strategy, habitat preference, and diet and foraging substrate. 

When compared to patterns among individual species, guild analyses can simplify complex avian 

community compositions and indicate how habitats may be influencing them.

Overall, there was little consistency in significant avian population trends across parks, although 

most species either corresponded to broader regional trends or had no clear pattern. Individual parks, 

each protected for unique ecological landscapes, often support avian communities that are distinctive 

in their particular mix of species and abundances. Within parks, trend models were very similar, 

indicating that observational techniques are adequate for most analytical purposes. However, 

distance-based density estimates gave a more statistically refined estimate of population trends and 

should be used for long-term analyses.

Two species showed strong increasing trends across Network parks (American Robin and Redwinged Blackbird), and another five species exhibited weaker increases (Northern Flicker, Alder 

Flycatcher, Red-breasted Nuthatch, Common Yellowthroat and Yellow-rumped Warbler). Only three 

species had strong declining trends across parks (American Crow, Chestnut-sided Warbler and 

Evening Grosbeak). The remainder of species is more appropriately considered on a park-by-park 

basis using local expertise. Individual results and discussion are presented for each park so findings 

can be incorporated into specific planning and management decisions.

Birds with a substantial proportion of fruit in their summer diet showed a general decline across 

parks. Declining frugivore populations indicate a possible change or decline in berry-producing 

plants in the region. Two guilds that included generally increasing species were wetland occupants 

and bark foragers. Otherwise there were no clear patterns within guilds; most notably there is no 

obvious cause for concern regarding Neotropical migrants, a group that has received a great deal of 
xii

attention in recent decades due to concerns of population stressors during migration and on wintering 

grounds.

It appears that most survey objectives are being accomplished in Network parks, but there are 

inconsistencies. However, the potential exists to improve both the surveys themselves and the 

methods of data management, the latter lending itself to finer levels of analyses. Some form of post 

hoc habitat designation for each survey point would add substantially to analyses and should be 

coordinated through the Network office for consistency. The most important recommendation is for 

greater quality control in data management, including use of standardized data entry and a strategy 

for double-checking all entries. This report is a benchmark for comparing avian communities in the 

protected park landscapes to those in habitats more directly impacted by human activities.
xiii

Acknowledgments

Thanks to Seth Stapleton, post-doctoral fellow at the University of Minnesota, for advice on using 

Distance software, and to Joshua Schmidt at the NPS Central Alaska Network for comments on 

Distance analyses. We thank the many park staff, contractors, agency partners, and volunteers who 

spent their very early mornings conducting the counts. We appreciate the comments provided by 

three reviewers, which made important improvements to the manuscript.

List of Terms and Acronyms

APIS Apostle Islands National Lakeshore (Wisconsin)

BBS Breeding bird survey

GLKN Great Lakes Inventory and Monitoring Network

GRPO Grand Portage National Monument (Minnesota)

INDU Indiana Dunes National Lakeshore (Indiana)

ISRO Isle Royale National Park (Michigan)

NABBS North American Breeding Bird Survey

NABCI North American Bird Conservation Initiative

NPS National Park Service

SACN St. Croix National Scenic Riverway (Wisconsin/Minnesota)

SLBE Sleeping Bear Dunes National Lakeshore (Michigan)

VOYA Voyageurs National Park (Minnesota)

1

Introduction

The Great Lakes Inventory and Monitoring Network is composed of nine national park units in 

Michigan, Indiana, Wisconsin, and Minnesota (Figure 1). The parks span across two Bird 

Conservation Regions (Rich et al. 2004) and contain a wide variety of habitats including wetlands, 

prairie, savanna, lowland riparian forests, cedar swamps, and hardwood and conifer forests. The 

parks provide important breeding habitat for more than 100 species of landbirds, some of which are 

long-distance (Neotropical) migrants.

Figure 1. Locations of the nine national park units in the Great Lakes Inventory and Monitoring Network.

Six of the nine Great Lakes parks were monitoring songbirds prior to the creation of the Great Lakes 

Inventory and Monitoring (I&M) program in 2000 (Table 1). The longest-running monitoring 

program is at the St. Croix National Scenic Riverway (SACN), which began conducting surveys in 

1982 (Maercklein 1999). 
2

Table 1. Year of establishment and number of points for breeding bird surveys 

at Great Lakes Network parks.

Park Year Established No. of Points

Apostle Islands National Lakeshore 1990 106

Grand Portage National Monument 1999 38

Indiana Dunes National Lakeshore 1993 50

Isle Royale National Park 1994 130

Mississippi National River and Recreation Area 2009 ?

Pictured Rocks National Lakeshore 2011 50

St. Croix National Scenic Riverway 1982 50

Sleeping Bear Dunes National Lakeshore 2004 40

Voyageurs National Park 1995 80

Landbird monitoring in the parks has typically followed standardized methods for point count studies 

(e.g., Ralph et al. 1995, Howe et al. 1997, Matsuoka et al. 2014). Though implementation has varied 

depending on a park’s monitoring objectives, all parks share the objectives of monitoring species

trends and putting results into a regional context (Gostomski et al. 2010). Thus, count data that yield 

indices of relative abundance are sufficient to meet park goals. All parks followed similar guidelines

for data collection, including: (1) completing all surveys during the month of June, (2) conducting 

counts between approximately 1⁄2-hr before sunrise and 4 hrs after sunrise, (3) not conducting counts 

during poor weather conditions that reduce detectability of birds (i.e., rain, wind >8–12 mph, fog), 

and (4) ensuring observers had appropriate skills and hearing ability to perceive and identify bird 

vocalizations. See Lind et al. (2005) for additional details.

After the Great Lakes I&M Network (GLKN) was established in 2000, discussions were held to 

identify critical resources (“vital signs”) for long-term monitoring; monitoring bird communities 

ranked fourth in priority among 46 potential vital signs for the GLKN parks. Monitoring landbirds 

ranked highly, in part, because of the extensive datasets already available, the popularity of birds 

among park visitors, and the endangered, threatened, and special concern status of some species at 

state and/or federal levels (Route and Elias 2007, Gostomski et al. 2010).

A Network monitoring protocol and standard operating procedures were developed to standardize 

data collection across the nine parks (Gostomski et al. 2010). The primary goals of the protocol were 

to (1) develop and use a standardized sampling method that is flexible enough to fit the unique 

sampling challenges at each park but still yield data that are comparable across parks and can be 

integrated at regional and national levels, and (2) develop and integrate quality control measures such 
3

as training and certification for observers. Survey standards are based on techniques known to work 

well in forested habitats, yet across-park comparisons will be viewed cautiously given that each park 

initiated surveys independently, has unique and contrasting landscapes, and stratifies routes or data 

points in different ways.

Most parks had to make minor adjustments to their data collection methods to meet the standards set 

by the Network protocol. The most common adjustments were recording the minute-interval of each 

observation (Minute 0, Minute 1, Minute 2, up to Minute 9 for those doing 10-minute counts) so that 

data could be compared across parks regardless of count duration, and recording the distance to each 

bird in one of three distance-ring categories.

Specific questions we hope to address under this monitoring protocol include:

1. What are the long-term trends in population indices for priority landbird species or suites of 

birds?

2. What are the habitat associations of observed landbird species?

3. How do indices of population trends and habitat associations in the parks compare to those 

from other monitoring programs in the region?

This report provides analyses of long-term (≥5 yrs) monitoring data collected at seven of the nine 

GLKN parks. The number of years varies for each park, and two parks were not included because 

their monitoring programs were established recently and do not yet have sufficient data. We do not 

address all possible complications or biases associated with point count surveys (see Bibby et al. 

2010 and Nichols et al. 2009 for discussions), but we endeavored to make reliable determinations 

regarding the status and trends of bird populations in western Great Lakes parks.

5

Methods

All nine GLKN parks are collecting annual breeding bird point count data. Seven parks have >10 yrs 

of data, and five of those have >15 yrs of data (Appendix A). For adequate statistical sample sizes, 

Network parks included in this report are: Apostle Islands National Lakeshore (APIS) and St. Croix 

National Scenic Riverway (SACN) in Wisconsin; Grand Portage National Monument (GRPO) and 

Voyageurs National Park (VOYA) in Minnesota; Indiana Dunes National Lakeshore (INDU) in 

Indiana; and Isle Royale National Park (ISRO) and Sleeping Bear Dunes National Lakeshore (SLBE) 

in Michigan. Songbird monitoring is relatively new at Mississippi National River and Recreation 

Area (Minnesota) and Pictured Rocks National Lakeshore (Michigan), each with <5 yrs of data, so 

these parks were not included in analyses.

Spatial and Temporal Allocation of Samples

Survey points at APIS, GRPO, ISRO, and VOYA are located along trails and generally account for 

both representative habitats in and geographic distribution across the parks so as to achieve spatial 

balance (Stevens and Olsen 2004). At SACN, points are located along both the Namekagon and St. 

Croix rivers for the entire length of the park, and surveys are conducted from an anchored canoe. At 

SLBE, points were proportionally stratified by habitat type. Survey points at INDU are located along 

a single roadside transect in accordance with North American Breeding Bird Survey (NABBS)

methods (Sauer et al. 2014). Many point locations are permanently marked, as allowed for by 

individual park policies, but all are georeferenced, and observers use a GPS unit to ensure they are at 

the correct location prior to beginning a survey. Points are ≥250 m apart in forested areas and ≥500 m 

apart in grasslands to avoid double-counting of individual birds (Ralph et al. 1995, Matsuoka et al. 

2014). Points are sampled annually, except at SACN where surveys are done on alternating river 

sections each year (details below). The survey duration varies by park, with 3-, 5-, and 10-minute 

intervals all used.

Lind et al. (2005) carried out retrospective power analyses for six existing Network programs and 

found that all programs had sufficient power to detect a 5% change in abundance of common species 

over moderate time frames (10–15 years). For less abundant or rare species, sufficient statistical 

power to detect a trend will require more years of monitoring. Although Lind et al. (2005) did not 

evaluate the number of samples required for a specified level of power, they concluded that most 

parks had a sufficient number of survey stations.

Point Count Methods, Park Objectives, and Data Arrangement

The Network’s point count survey methods are described in detail in Knutson et al. (2010). In 

summary, we employ variable circular plot (VCP) counts that are conducted during the month of 

June after migrating birds have moved through the area and breeding species have begun establishing 

territories. Counts begin 30 minutes before sunrise and are finished no later than four hours after 

sunrise. Count duration varies by park, ranging from 3 to 10 minutes. Observations are recorded at 

one-minute intervals (noted as Minute 0, 1, 2, 3, ... up to Minute 9) to allow for comparisons 

between parks and to facilitate future analyses of detection probabilities (Etterson et al. 2009). For 

each observation, the data recorded are: the name of the bird using standardized four-letter codes
6

(Pyle and DeSante 2010), the time (minute-interval), the detection type (singing, calling, non-vocal 

sound [drumming grouse, tapping woodpeckers], observed, flyover), and the bird’s distance from the 

point center in one of three categories: 0–50 m, 51–100 m, and >100 m. Park-specific variations are 

detailed below and often include a transition from original methods to a sampling design that 

incorporates the Network standards.

All parks made changes to their data collection methods in 2010 to align with the Network protocol, 

so current methods may not be the same as what is described for each park below.

Apostle Islands National Lakeshore

Standardization of points using recognized protocols was accomplished in 1995 (Van Stappen and 

Dallman 1996). Ten survey routes were established, with points placed along hiking trails on Devils 

Island (DE), Oak Island (OA), Outer Island North-South Trail (OU), Sand Island (SA), Stockton 

Island–Presque Isle (STPI), and Stockton Island–Trout Point (STTP), and off-trail along the 

Mainland portion of the park (MD), on Long Island (LO), in the Outer Island Hemlock Stand 

(OUHS), and on Raspberry Island (RA) (Figure 2). Routes were almost completely surveyed 

between 1995 and 2009, except in 1998 due to weather and again in 2006 due to staffing issues 

(Table A1). Counts were 10 mins in length and all birds detected within a 100 m radius were 

recorded. Relatively comprehensive datasets from 1995 through 2009 were used for analyses (Table 

A1).

Figure 2. Locations of ten breeding bird survey routes at Apostle Islands National Lakeshore (Wisconsin), 

1995–2009.
7

Grand Portage National Monument

The GRPO survey has been completed annually since 1999, though not all points were completed in 

the first year. A single route along the historic canoe portage from Lake Superior to the Pigeon River

(Figure 3) covers 13.7 km (8.5 mi) and usually takes three days to complete. Unlimited distance

counts were conducted for 10 mins at each point. Analyses included 2000–2014 data, with all points 

completed in all years except one point missing in 2014.

Figure 3. Breeding bird survey points are distributed at ≥250 m intervals along the 13.7 km portage trail at 

Grand Portage National Monument (Minnesota).

Indiana Dunes National Lakeshore

Indiana Dunes conducted 3-min counts at 50 roadside points in accordance with NABBS standards 

(Sauer et al. 2014) (Figure 4). This is the only roadside survey among the GLKN parks. Counts 

documented all birds detected within a 0.40 km (0.25 mi) radius. 

Data discussed in this report were compiled from disparate sources. Annual species counts from 

1993–2005 were available from a summary document on the INDU website (www.nps.gov/indu). 

Data from 2004 and 2008–2013 were provided in spreadsheets with varying levels of detail. Only 

2004 included additional information on weather conditions. Only 35 of the 50 points were 
8

completed in 2008, and coverage for other years must be assumed due to a lack of detailed data. No 

data were reported for 2006 or 2007. 

Figure 4. Location of breeding bird survey points at Indiana Dunes National Lakeshore (Indiana). This is 

North American Breeding Bird Survey route 35901.

Isle Royale National Park

Egan and Gostomski (2013) provided details on route establishment and survey techniques at ISRO. 

The eight routes vary in length, with a total of 130 points across the park: Passage Island (PASS; 4

points), Three Mile-Lane Cove (TMLC; 16), Chippewa Harbor-Lake Richie (CHLR; 16), Mt. 

Ojibway Loop (MTOJ; 19), Lake Richie-Greenstone (LRGR; 20), Ishpeming Trail (ISTR; 18), 

Feldtmann Lake Trail (FELK; 16) and Windigo-Sugar Mountain (WIND; 21) (Figure 5). Counts 

were 5 mins in length, divided into one-minute intervals. Routes were standardized in 1996, so our 

analyses included data from that point forward. Weather conditions occasionally resulted in fewer 

than 130 points surveyed. All routes were surveyed annually since 1996, and all those data were 

included here. Even with only one year of new data since Egan and Gostomski’s (2013) analysis, the 

comprehensive goals of the Network project make inclusion of ISRO data important. 
9

Figure 5. Locations of eight breeding bird survey routes at Isle Royale National Park (Michigan).

Saint Croix National Scenic Riverway

Six river-based bird survey routes are surveyed at SACN (Figure 6): 

1. Upper Namekagon River (UNAM), from Namekagon Dam to Phipps Flowage;

2. Lower Namekagon River (LNAM), from County K Landing to Totogatic River;

3. Upper St. Croix River (USAC), from Gordon Dam to Riverside 

4. St. Croix River North (SACN), from Highway 77/48 to Highway 70;

5. Middle St. Croix River (MSAC), from Raspberry Landing to Nevers Dam; and

6. Lower St. Croix River (LOSA), from St. Croix Falls to Stillwater.
10

Figure 6. Six breeding bird survey river routes at St. Croix National Scenic Riverway 

(Wisconsin/Minnesota).

Routes with similar habitats and avian communities are SACN/MSAC/LOSA and UNAM/LNAM. 

The USAC route is unlike the other routes. Surveys along two of the routes (LOSA, LNAM) began 

in 1982 and 1983, respectively, but were not revisited until 1998. In order to more adequately cover 

park habitats and species not represented by the original routes, two additional routes were added in 

2000 (SACN, UNAM), another in 2003 (USAC), and one more in 2012 (MSAC). With a range from 

47 to 53 points along a given stretch, each route takes two mornings to complete. Unfortunately the 

“SACN” acronym is used both for the park and a route; except for this section of the report, SACN 

will always refer to the park.

Originally, 3-min, unlimited distance counts were conducted at each point by canoe or motorboat, 

with the boat allowed to drift in the current. Count duration increased to 5 mins in 2007. 

Standardization of the points and survey methods was accomplished using the Network protocol, and 

included anchoring the boat/canoe at fixed locations, using 6-minute counts, and placing each 

detection in one of three distance measurement categories (Gostomski et al. 2010).
11

A subset of surveyed routes and years was used to standardize data for regressions (Table A3). 

Removal of years or routes is not desirable because important data points are then missing from 

analyses. However, maintaining a relatively consistent set and number of annually surveyed points 

was important for analysis of equal survey effort across years. Only birds from 3-min counts were 

incorporated into trend analyses. Because of staggered annual route completion, trend analyses were 

divided into two strata: LOSA/LNAM and UNAM/SACN. In addition, regressions included both 

drifting (1998–2004) and anchored (2005–2014) point counts so that there were enough data points 

for adequate sample size. Data removed included those from 1982–1983 because the gap to 1998 was 

too long for useful speculation, and both 2000 and 2009 because each year was missing too many 

points. The USAC and MSAC routes were not included for two reasons: first, to extend data analyses 

as far back as possible using consistently surveyed routes, and second, with standardization of 

methods in 2008, these two routes can be included in future analyses that begin in that year and leave 

out prior data. This gives eight years of data for LOSA/LNAM and seven years of data for 

UNAM/SACN for current analyses (Table A3).

Sleeping Bear Dunes National Lakeshore

Sleeping Bear used 10-min surveys to sample 41 points along five routes within eight representative 

habitat types (Figure 7, Table A4). Points were distributed proportionately to the amount of habitat 

present in the park. Data were collected from 2004 to 2006 and 2009–2013. The latter time period 

included collection of additional data, including distance to birds, minute-by-minute categories of 

detection, and refined information on noise and weather (Gostomski et al. 2010). Otherwise survey 

methods for the two time periods were identical. The W-5 point (Peterson + Lasso) was removed 

from analysis because no surveys were completed there from 2004 to 2006.
12

Figure 7. Locations of 41 breeding bird survey points at Sleeping Bear Dunes National Lakeshore 

(Michigan).

Voyageurs National Park

Grim et al. (1995) provided a detailed survey protocol and rationale for point count surveys at 

VOYA. Each route consists of 10 points, with 80 points officially listed for landbird monitoring 

(Gostomski et al. 2010).

Consistent data collection began in 1997 (Table A5). Counts were conducted for 10 mins, and data 

were separated into 3-, 5-, and 10-minute intervals. Distances were recorded either inside or outside 

of a 100 m radius. Ten routes appear to have been surveyed since initiation of the VOYA bird 

protocol: Anderson Bay Loop Trail (ABLT), Ash River Trail (ARTR), Blind Ash Bay Trail (BABT), 

Black Bay Ski Trail (BBST), Cruiser Lake Trail (CLT), Dryweed Island (DWI), Echo Bay Trail 

(EBTR), Lost Bay Portage Trail (LBPT), Rainy Lake Visitor Center (RLVC), and Kabetogama Lake 

Trail (KATR) (Figure 8).
13

Figure 8. Locations of 80 breeding bird survey points (nine routes) at Voyageurs National Park 

(Minnesota).

Although ten routes have been surveyed since initiation of the survey in 1995, only eight routes have 

been regularly surveyed since 2004 (Table A5). Since 1997, four routes have been surveyed 

annually, with only one missing year (2011) for BABT. Implementation and consistency of 

surveying additional routes has been patchy. In order to take advantage of the most reliable and longterm data available, only the four most consistently surveyed routes were used in regression analyses: 

BABT, BBST, EBTR, and RLVC. Inclusion of additional routes would have led to 20%–40% of data 

missing from some years, and would probably require the removal of 2011 data entirely due to <50% 

coverage.

Analytical Methods

Trend analyses

For quality control, data were rearranged by year and species and scanned for errors. Problems were 

identified in all park datasets, and it was deemed prudent to remove all questionable records for

reliability of results. Data were removed prior to analyses due to: (1) unclear or contradictory entries; 

(2) records without a number of birds listed; and (3) years or routes with substantial data missing, 
14

which could alter trends. Following reformatting, data were imported to the statistical analysis 

program JMP®11. Trend analyses only included data from the most consistently surveyed routes in 

each park (see Appendix A).

The basic question posed was whether there were linear relationships for bird abundances over time. 

Annual counts for each species were log-transformed (log [x+1]) prior to normality and trend 

analyses (Nur et al. 1999, Southwood and Henderson 2000). The logarithmic transformation allows 

slope estimates from regressions to be interpreted as an instantaneous rate of change, or an average 

proportional change in the population over time. A Shapiro-Wilk goodness-of-fit was run for each 

species in all parks to test for normality of the data (see SAS 2013 for details). Analysis of Variance 

(ANOVA) and regression analyses were also calculated, with significance set at α = 0.05. The logtransformed annual count for each species served as the dependent variable, and time (year) was the 

independent variable. Outliers, which can distort a trend, were determined from distribution boxplots and removed from regressions for species that met the normality test.

Density and detectability

Trend analyses often use empirical abundance data to model population change over time, but this 

method can lead to unreliable and biased predictions (Norvell et al. 2003, Buckland et al. 2004). 

Detection of a bird is related to the spatial coverage of the sampling unit, the bird’s presence in the 

sampling unit, and the probability of detection, so that if availability of detection is not modelled a 

potentially poor result will be returned (Nichols et al. 2009). Detection varies by species, and for rare 

species with either cryptic behaviors or low abundances, detection may essentially be random 

(Buskirk and McDonald 1995). We used distance estimates to test differences between empirical 

regressions, as described above, and density-estimated regressions. Because time was not recorded 

uniformly in current datasets, we did not consider time-of-detection methods (Alldredge et al. 2007, 

Farnsworth et al. 2005).

The software package Distance 6.2 was used to estimate density and detectability of landbirds, along 

with guidelines from Thomas et al. (2010), Buckland et al. (2001, 2004) and Oedekoven et al. 

(2013). Assumptions of these analyses can be found in Buckland et al. (2001). Reformatted data were 

directly imported to the program without transformation. The non-random placement of survey 

routes in most parks (along trails or roads) may bias the ability to infer results to broader park 

landscapes. The influence of narrow roads and trails on the presence and relative abundance of birds 

should be limited, although edge species may be more common (Ralph et al. 1995). Data removed 

included flyover detections, unclear records, and individuals detected beyond 100 m. Estimating 

distances and detecting cryptic species and different individuals is difficult beyond 100 m in forested 

habitats (Bibby et al. 2000, Wolf et al. 1995), so although truncation reduces sample size it also 

improves estimates (Nichols et al. 2009). Records were binned in two categories of 0–50 m and 50–

100 m. Only species with at least 75 observations across all years (number of years varies per park) 

were included in order to meet sample size requirements (Buckland et al. 2001).

The detection function and density in Distance 6.2 were modelled globally and incorporated into 

separate post-stratified estimates by year and habitat (Buckland et al. 2004). Global density was 

estimated as the mean of replicated stratum estimates, weighted by the total effort in the stratum. 
15

Because data were binomial, only the half-normal key function model was available; goodness-of-fit 

tests were unavailable (Buckland et al. 2001). Three series expansions were used in the multiplecovariates distance sampling engine: cosine, simple polynomial, and hermite polynomial. The bestfitting model was inferred based on the lowest second-order Akaike’s Information Criterion (AICc) 

result, provided the precision was reasonable (i.e., standard error not largely exceeding the estimate 

value) (Saracco et al. 2014). The AICc has a small-sample bias correction, yet will work well with 

large samples (Buckland et al. 2001). Empirical variance estimates were used in the model definition 

because errors terminated bootstrap analyses. Five covariates (temperature, wind, background noise, 

cloud cover, and observer) were included in models to determine their effect on detectability and 

improve model outputs, with iterative inclusion of covariates based on AICc (Oedekoven et al. 

2013). Results with convergence failures were not considered. The density model results for each 

species were compared as a linear regression, when possible, to annual trends from the observational 

log(x+1) model.

Data available for analyses were different for each park. Density estimates for Grand Portage 

included 2004–2014 data, with 11 species having enough data to meet sample size requirements. For 

Voyageurs, nine species were analyzed from 2010–2013 data. No covariates were available for these 

two parks. At St. Croix, 25 species were available for analysis from 2009–2014 data. Covariates 

included temperature, sky conditions, wind, and background noise. Six species were analyzed from 

2009–2013 data at Sleeping Bear Dunes, using all covariates except temperature. Habitat 

associations were not available for any park except Sleeping Bear Dunes. Due to a lack of data, 

distance analyses were not possible for Apostle Islands, Indiana Dunes, or Isle Royale.

Guilds

Investigators have used the concept of guilds or functional groups to simplify analysis of complex 

ecological communities (Holmes et al. 1979, Short 1983, Verner 1984). Initial guild analyses, using 

foraging and nesting strata to determine how habitat change was reflected in avian communities, 

were criticized as too simplistic or unrealistic because of differential species responses to 

environmental perturbation (Szaro 1986, Hawkins and MacMahon 1989). A key argument had been 

that natural history observations were unreliable for some species and local models were needed. 

Guilds may not be useful at small spatial scales (DeGraff and Chadwick 1984), yet at regional scales 

natural history classifications for guilds are often empirically supported (Mac Nally et al. 2008, Hart 

et al. 2012). Hart et al. (2012) found that models using land cover correlations performed better, 

although natural-history-based preferences, as employed in the current analyses, were often 

satisfactory. Generally, basic avian ecology and expert opinion can lead to a strong predictive guild 

model that avoids both overfitting and false relationships (Hawkins and MacMahon 1989, Mac Nally 

et al. 2008).

Placement in guilds was based on categories defined by DeGraff et al. (1985), Peterjohn and Sauer 

(1993), and Ehrlich et al. (1988): 

 Migration (permanent resident, short-distance migrant, long-distance/Neotropical migrant);

 Habitat (grassland/open, wetland, successional/scrub, woodland, urban);

 Diet (frugivore, granivore, insectivore, omnivore); and 
16

 Forage substrate (air, bark, ground, shrub/low canopy, high canopy). 

Guild status for each species was confirmed or modified for the Great Lakes region using species 

profiles from the Birds of North America series (Cornell Lab of Ornithology 2015). Except for 

migration status, guilds were based on breeding season behaviors since these may dramatically 

change for some species due to food availability, changing competitive interactions, or different 

seasonal habitat occupancy (de Casenave et al. 2008). Four species were not included because of 

unique diet or feeding styles: Belted Kingfisher, Common Raven, Loggerhead Shrike, and Rubythroated Hummingbird. Many species fit multiple categories within a guild, such as feeding both on 

the ground and in the low canopy, and thus acted as cross-references.

Park landscapes are often highly protected, with mostly natural or historic fragmentation, so the 

urban guild––comprised of generalist species that can succeed in both human and natural 

landscapes––may only apply to Indiana Dunes. Future analyses that include data from Mississippi 

National River and Recreation Area may lend themselves to a larger discussion about the urban 

guild. 

Foraging technique was not included as a guild because definitions were difficult to determine 

clearly; for example, most passerines can be categorized as foragers or gleaners. DeGraff et al. 

(1985) defined a forager as a bird that consumes any food encountered on a substrate, while a gleaner 

chooses specific foods. Remsen and Robinson (1990) did not recognize a distinction in these 

behaviors. Since many insectivorous or granivorous birds are not known to choose particular 

categories of insects or seeds, a distinction in technique was not warranted. Diet and foraging 

substrate were more useful metrics that often reflected foraging techniques.

Guild trend calculations followed the same procedures as for individual species (log[x+1]), using the 

sum of guild individuals detected annually. Only species with at least five years of data were 

included, indicating a regular breeding species in each park. Our generalized model was intended to

assess whether ecologically similar species were responding to environmental conditions over time, 

or whether a more detailed model is required for GLKN guild analysis.
17

Results 

Trend Analyses

Comprehensive summaries and figures for all statistical analyses in JMP, including distributions, 

goodness-of-fit tests, and regressions for all species from all parks have been provided to GLKN and 

are available upon request. Most non-normal distributions were due to limited annual presence of a 

species or skewed data from occasionally abundant or irruptive species. Regression results were 

generally not reported for these species since trends are probably not meaningful (Smith et al. 1995). 

However, most common or regularly occurring species showed normal distribution and stable trends

when outliers were removed, although annual variability kept them from showing a significant trend. 

Species showing significant change (P ≤0.05) are reported for each park in this section, as well as 

species showing trends worth consideration (P ≤0.10). Trends were compared to state-listed birds 

(Wisconsin Natural Heritage Program 2014, Minnesota Department of Natural Resources 2013, 

Michigan Natural Features Inventory 2013, Indiana Division of Fish and Wildlife 2014) and broader 

analyses from across the United States (NABCI 2014). Results for all species, with standard errors 

for significant trends, are in Appendix B.

Apostle Islands National Lakeshore

One-hundred-six focal landbird species were analyzed at APIS to assess average proportional change 

per year. Seven species increased significantly and four species declined significantly (Table 2). An 

additional four species had potentially important trends. No conclusions could be made for 55 

species, generally due to low abundance (Appendix Table B1).

Grand Portage National Monument

Eighty-six focal landbird species were analyzed from GRPO. Two species had significant increasing 

trends and seven species had significant declining trends (Table 3). Six additional species had 

potentially important trends. No conclusions could be made for 44 species, generally due to low 

abundance (Appendix Table B2).

Table 2. Regression trends (average proportional change per year) for species observed during 10-

minute point counts at Apostle Islands National Lakeshore, 1995–2009. Only species with strong or 

significant trends are shown. Species in bold indicate P ≤0.05. Data shown include r

2

, P, and total, 

mean, and log mean of individuals (with standard deviation) observed annually. Species listed as 

special concern (SC) in Wisconsin, and species common but in steep decline (SD) in the United States 

are noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

Log Mean 

Individuals 

(StDev)

Hermit Thrush + 0.04 0.42 0.0164 360 28 1.40 (0.25)

1.54 (0.25)

0.96 (0.19)

1.37 (0.16)

2.16 (0.08)

1.42 (0.12)

1.35 (0.12)

0.40 (0.29)

1.40 (0.20)

1.18 (0.14)

1.18 (0.16)

0.42 (0.32)

0.30 (0.29)

0.73 (0.24)

0.52 (0.41)

Blue Jay + 0.04 0.42 0.0167 509 39 1.54 (0.25)

Yellow-bellied Sapsucker* + 0.03 0.37 0.0348 152 12 0.96 (0.19)

Northern Parula + 0.02 0.43 0.0152 307 24 1.37 (0.16)

Ovenbird + 0.01 0.58 0.0026 1907 147 2.16 (0.08)

American Robin + 0.01 0.32 0.0432 338 26 1.42 (0.12)
18

Table 2 (continued). Regression trends (average proportional change per year) for species observed 

during 10-minute point counts at Apostle Islands National Lakeshore, 1995–2009. Only species with 

strong or significant trends are shown. Species in bold indicate P ≤0.05. Data shown include r2, P, and 

total, mean, and log mean of individuals (with standard deviation) observed annually. Species listed as 

special concern (SC) in Wisconsin, and species common but in steep decline (SD) in the United States 

are noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

Log Mean 

Individuals 

(StDev)

Chipping Sparrow + 0.01 0.31 0.0491 287 22 1.35 (0.12)

Savannah Sparrow + 0.03 0.29 0.06 27 2.1 0.40 (0.29)

American Crow + 0.02 0.23 0.10 344 26 1.40 (0.20)

Swainson’s Thrush* (SC) + 0.02 0.32 0.07 163 13 1.18 (0.14)

Chestnut-sided Warbler - 0.02 0.28 0.06 199 15 1.18 (0.16)

Tree Swallow - 0.04 0.32 0.0432 31 2.4 0.42 (0.32)

Common Grackle (SD) - 0.04 0.37 0.0261 19 1.5 0.30 (0.29)

Brown Creeper - 0.04 0.68 0.0005 67 5.2 0.73 (0.24)

Yellow-bellied Flycatcher (SC) - 0.07 0.64 0.0011 49 3.8 0.52 (0.41)

* Outliers were removed from trend analyses for these species.

Table 3. Regression trends (average proportional change per year) for species observed during 

10-minute point counts at Grand Portage National Monument, 2000–2014. Only species with 

strong or significant trends are shown. Species in bold indicate P ≤0.05. Data shown include r

2

,

P, and total, mean, and log mean of individuals (with standard deviation) observed annually. 

Species listed on the NABCI (2014) watch list (WL) in the United States are noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

Log Mean 

Individuals 

(StDev)

Yellow-rumped Warbler* + 0.03 0.28 0.0498 112 7.5 0.91 (0.22)

Nashville Warbler* + 0.01 0.38 0.0241 339 23 1.34 (0.12)

Alder Flycatcher + 0.01 0.21 0.08 108 7.2 0.90 (0.09)

Song Sparrow + 0.01 0.19 0.10 96 6.4 0.86 (0.08)

Veery - 0.01 0.20 0.09 352 23 1.38 (0.10)

Mourning Warbler - 0.02 0.20 0.09 237 16 1.19 (0.17)

Black-capped Chickadee - 0.03 0.20 0.10 149 9.9 0.95 (0.30)

Blackburnian Warbler - 0.03 0.25 0.06 221 15 1.14 (0.23)

Ovenbird - 0.01 0.31 0.0326 920 61 1.79 (0.08)

Hermit Thrush - 0.04 0.28 0.0406 65 4.3 0.58 (0.36)

Chestnut-sided Warbler - 0.04 0.45 0.0065 182 12 1.06 (0,25)

Pileated Woodpecker - 0.05 0.37 0.0170 97 6.5 0.70 (0.40)

Downy Woodpecker - 0.05 0.38 0.0143 60 4 0.54 (0.39)

Least Flycatcher - 0.05 0.44 0.0075 118 7.9 0.86 (0.31)

Evening Grosbeak1(WL) - 0.07 0.40 0.0115 59 3.9 0.34 (0.49)

1 EVGR does not fit normal distribution, but is included due to possible ecological importance of decline.

* Outliers were removed from trend analyses for these species.
19

Indiana Dunes National Lakeshore

Eighty-six landbird species were recorded at INDU. Six species had significantly increasing trends 

and three species had significantly declining trends (Table 4). Two additional species had potentially 

important declines. No conclusions could be made for 48 species, generally due to low abundance 

(Appendix Table B3).

Table 4. Regression trends (average proportional change per year) for species observed during 3-

minute roadside point counts at Indiana Dunes National Lakeshore, 1993–2013. Only species with 

strong or significant trends shown. Species in bold indicate P ≤0.05. Data shown include r

2

, P, and 

total, mean, and log mean of individuals (with standard deviation) observed annually. Species listed 

as endangered (EN) in Indiana and common but in steep decline (SD) in the United States are 

noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

Log Mean 

Individuals 

(StDev)

Red-bellied Woodpecker + 0.03 0.33 0.0101 108 5.7 0.73 (0.32)

Willow Flycatcher* + 0.02 0.36 0.0084 145 7.6 0.91 (0.21)

Marsh Wren (EN) + 0.02 0.23 0.0385 49 2.6 0.50 (0.24)

Warbling Vireo + 0.01 0.31 0.0137 65 3.4 0.62 (0.17)

Red-winged Blackbird + 0.01 0.21 0.0476 466 25 1.39 (0.13)

Chipping Sparrow* + 0.01 0.21 0.05 163 8.6 0.98 (0.13)

Ovenbird - 0.02 0.20 0.06 58 3.1 0.54 (0.26)

Chimney Swift* (SD) - 0.02 0.20 0.06 123 6.5 0.79 (0.29)

Veery - 0.02 0.33 0.0107 74 3.9 0.65 (0.20)

Blue Jay* - 0.02 0.52 0.0017 103 5.4 0.84 (0.13)

Cedar Waxwing - 0.04 0.39 0.0043 249 13 0.92 (0.40)

* Outliers were removed from trend analyses for these species.
20

Isle Royale National Park

Eighty-eight focal species were analyzed for ISRO. Seven species increased significantly and five 

species declined significantly (Table 5). Five additional species had potentially important trends. No 

conclusions can be made for 43 species, generally due to low abundance (Appendix Table B4).

Table 5. Regression trends (average proportional change per year) for species observed during 5-

minute point counts at Isle Royale National Park, 1996–2013. Only species with strong or 

significant trends shown. Species in bold indicate P ≤0.05. Data shown include r

2

, P, and total, 

mean, and log mean of individuals (with standard deviation) observed annually. Species listed as 

common but in steep decline (SD) or a watch list (WL) in the United States are noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

Log Mean 

Individuals 

(StDev)

Alder Flycatcher + 0.03 0.55 0.0004 421 23 1.34 (0.21)

Red-winged Blackbird + 0.03 0.25 0.0365 47 2.6 0.44 (0.33)

American Robin + 0.02 0.54 0.0005 830 46 1.65 (0.15)

Common Yellowthroat + 0.02 0.40 0.0046 110 6.1 0.82 (0.17)

Red-breasted Nuthatch1 + 0.02 0.38 0.0067 727 40 1.60 (0.13)

Swamp Sparrow* + 0.01 0.29 0.0303 172 9.6 1.05 (0.07)

Swainson’s Thrush + 0.01 0.24 0.0399 265 15 1.18 (0.13)

Golden-crowned Kinglet* + 0.02 0.22 0.06 339 19 1.29 (0.18)

Nashville Warbler* + 0.01 0.21 0.07 2409 134 2.13 (0.10)

Brown Creeper* - 0.01 0.19 0.09 365 20 1.35 (0.15)

Black-and-White Warbler* - 0.01 0.20 0.07 204 11 1.09 (0.12)

Downy Woodpecker - 0.02 0.17 0.09 183 10 0.98 (0.24)

American Crow - 0.02 0.40 0.0047 477 27 1.41 (0.16)

Common Raven - 0.03 0.61 0.0001 228 13 1.09 (0.21)

Chipping Sparrow - 0.04 0.58 0.0002 196 11 1.00 (0.28)

Cape May Warbler (SD)1

- 0.06 0.54 0.0005 45 2.5 0.26 (0.45)

Evening Grosbeak (WL)1

- 0.06 0.58 0.0003 35 1.9 0.26 (0.40)

1 Species do not fit normal distribution. RBNU included because of regularity of data and abundance across years; CMWA 

and EVGR included due to possible ecological importance of decline.

* Outliers were removed from trend analyses for these species.

St. Croix National Scenic Riverway

One-hundred focal landbird species were analyzed at SACN. Four species had significantly 

increasing trends and 22 species had significantly declining trends over the entire period of 1998–

2014 (Table 6). Generally the positive trends were not matched across both sets of years/routes, 

while for declining species the trend direction was typically the same. Four species showed

significant declines in both sets of years/routes: Black-capped Chickadee, Indigo Bunting, Mourning 

Warbler, and Black-and-white Warbler. No conclusions could be made for 25 species, generally due 

to low abundance (Table B5). When removing data from drifting surveys (pre-2005), the number of 

significant trends is reduced to four positive and six negative (Table 7).
21

Table 6. Regression trends (average proportional change per year) for species observed during 3-minute point counts at St. Croix National 

Scenic Riverway, 1998–2014. Arranged by strongest trend and P-value (bold indicates P ≤0.05). Data shown include r

2

, P, and total and mean

individuals observed annually. ▪ = Non-normal distribution. Species listed as special concern (SC) in Wisconsin are noted. Note: results must be 

viewed with caution; see discussion for details.

LOSA-LNAM routes UNAM-SACN routes

Increasing Trends, n = 4 Trend r

2

P

Total 

Individuals

Mean 

Individuals

Annually Trend r

2

P

Total 

Individuals

Mean 

Individuals

Annually

Tree Swallow - 0.01 0.12 0.40 455 57 + 0.03 0.60 0.0397 222 32

Yellow-throated Vireo - 0.00 0.00 0.93 118 15 + 0.03 0.56 0.0523 76 11

Warbling Vireo + 0.02 0.73 0.0072 211 26 - 0.05 0.49 0.08 18 2.6

Rose-breasted Grosbeak + 0.02 0.65 0.0162 220 28 - 0.02 0.31 0.19 197 28

Declining Trends, n = 22

Red-eyed Vireo - 0.02 0.72 0.0078 1063 133 - 0.02 0.46 0.09 967 138

American Crow - 0.02 0.73 0.0067 484 60.5 - 0.01 0.20 0.32 253 36

Downy Woodpecker - 0.03 0.50 0.0501 70 8.8 - 0.02 0.23 0.28 20 2.9

Belted Kingfisher - 0.03 0.60 0.0231 51 6.4 - 0.03 0.11 0.46 38 5.4

Least Flycatcher (SC) - 0.03 0.84 0.0013 150 19 - 0.01 0.07 0.58 90 13

Eastern Wood Pewee - 0.01 0.21 0.26 180 23 - 0.04 0.72 0.0163 127 18

Black-capped Chickadee - 0.03 0.88 0.0006 154 19 - 0.04 0.78 0.0079 92 13

Eastern Phoebe - 0.04 0.79 0.0032 141 18 - 0.03 0.38 0.14 39 5.6

Ovenbird - 0.01 0.07 0.52 249 31 - 0.04 0.98 <0.0001 377 54

Golden-winged Warbler (SC) + 0.01 0.08 0.50 40 5 - 0.05 0.58 0.0481 73 10

Chipping Sparrow - 0.05 0.57 0.0315 71 8.9 - 0.05 0.33 0.18 26 3.7

Cedar Waxwing - 0.05 0.67 0.0126 217 27 - 0.06 0.43 0.11 363 52

White-breasted Nuthatch - 0.05 0.92 0.0002 194 24 + 0.00 0.00 0.95 60 8.6

Winter Wren ▪ ▪ ▪ 4 0.5 - 0.06 0.59 0.0447 61 8.7

Northern Parula ▪ ▪ ▪ 2 0.25 - 0.06 0.68 0.0232 36 5.1

Indigo Bunting - 0.05 0.59 0.0259 52 6.5 - 0.06 0.77 0.0091 33 4.7

Nashville Warbler + 0.01 0.08 0.49 22 2.8 - 0.06 0.82 0.0051 99 14

Mourning Warbler - 0.03 0.55 0.0353 28 3.5 - 0.07 0.65 0.0279 39 5.6

Blue-gray Gnatcatcher - 0.07 0.68 0.0120 84 11 ▪ ▪ ▪ 12 1.7

Black-and-White Warbler - 0.03 0.64 0.0176 130 16 - 0.07 0.78 0.0087 115 16

Eastern Kingbird - 0.02 0.45 0.07 80 10 - 0.08 0.64 0.0313 43 6.1
22

Table 7. Regression trends (average proportional change per year) for species with 

significant increases or declines during 3-minute stationary point counts at St. Croix National 

Scenic Riverway, 2005–2014. Only species with significant trends are shown (P ≤0.05). Data 

shown include r

2

, P, and log mean of individuals (with standard deviation) observed annually. 

Watch list (WL) or state special concern species (SC) are noted.

Species Trend r

2

P

Log Mean 

Indivs. (StDev) Routes

Common Grackle (WL) + 0.13 0.86 0.0228 0.72 (0.45) UNAM-SACN

Yellow Warbler + 0.05 0.81 0.0388 1.59 (0.19) UNAM-SACN

Gray Catbird + 0.04 0.98 0.0012 1.31 (0.14) UNAM-SACN

Yellow-throated Vireo + 0.04 0.79 0.0452 1.08 (0.14) UNAM-SACN

White-breasted Nuthatch - 0.04 0.98 0.0116 1.14 (0.15) LOSA-LNAM

Ovenbird - 0.04 0.96 0.0033 1.62 (0.14) UNAM-SACN

Swamp Sparrow - 0.04 0.89 0.0159 1.17 (0.14) UNAM-SACN

Golden-winged Warbler (SC, WL) - 0.05 0.96 0.0215 0.82 (0.17) LOSA-LNAM

Black-capped Chickadee - 0.06 0.97 0.0024 1.07 (0.20) UNAM-SACN

Indigo Bunting - 0.08 0.85 0.0264 0.61 (0.29) UNAM-SACN

Sleeping Bear Dunes National Lakeshore

Ninety-one focal landbird species were analyzed for trends at SLBE. Five species had significantly 

increasing trends and no species showed significant declines (Table 8). Three other species may be 

showing important trends. No conclusions could be made for 30 species, generally due to low 

abundance (Table B6).

Table 8. Regression trends (average proportional change per year) for species observed during 

10-minute point counts at Sleeping Bear Dunes National Lakeshore, 2004–2006 and 2009–2013. 

Only species with strong or significant trends shown. Species in bold indicate P ≤0.05. Data 

shown include r

2

, P, and total, mean, and log mean of individuals (with standard deviation) 

observed annually. Species on a watch list (WL) or listed as common but in steep decline (SD) in 

the United States are noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

Log Mean 

Individuals 

(StDev)

Veery (SD) + 0.07 0.63 0.0185 19 2.38 0.45 (0.30)

Eastern Meadowlark (SD) + 0.05 0.75 0.0055 95 11.88 1.08 (0.18)

Wood Thrush* (WL) + 0.03 0.77 0.0099 65 8.13 0.93 (0.17)

American Robin* + 0.03 0.59 0.0450 297 37.13 1.51 (0.06)

Red-eyed Vireo + 0.02 0.52 0.0436 350 43.75 1.64 (0.08)

Field Sparrow + 0.05 0.44 0.07 26 3.25 0.57 (0.24)

Bobolink (WL) - 0.02 0.42 0.08 64 8 0.94 (0.12)

Gray Catbird - 0.03 0.44 0.07 40 5 0.76 (0.14)

* Outliers were removed from trend analyses for these species.

Voyageurs National Park

Of 78 landbird species from four routes at VOYA, nine showed significant changes. One species 

significantly increased and eight significantly declined (Table 9). Five additional species had 
23

potentially important trends. No conclusions could be made for 40 species, generally due to low 

abundance (Table B7).

Table 9. Regression trends (average proportional change per year) for species observed during 

10-minute point counts at Voyageurs National Park, 1997–2013. Only species with strong or 

significant trends shown. Species in bold indicate P ≤0.05. Data shown include r

2

, P, and total, 

mean, and log mean of individuals (with standard deviation) observed annually. Species on a 

watch list (WL) in the United States are noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

Log Mean 

Individuals 

(StDev)

Blue-headed Vireo + 0.02 0.25 0.0398 29 1.7 0.39 (0.20)

Yellow-rumped Warbler + 0.02 0.18 0.09 102 6 0.76 (0.28)

Canada Warbler 1 (WL) + 0.02 0.18 0.09 90 5.3 0.76 (0.18)

Black-and-White Warbler + 0.01 0.20 0.07 320 19 1.29 (0.07)

Red-breasted Nuthatch * + 0.01 0.19 0.09 242 14 1.19 (0.14)

Blackburnian Warbler - 0.01 0.22 0.06 352 21 1.32 (0.13)

Nashville Warbler - 0.01 0.25 0.0402 951 56 1.74 (0.13)

Ovenbird * - 0.01 0.55 0.0009 1424 84 1.94 (0.06)

American Crow * - 0.02 0.34 0.0173 488 29 1.45 (0.16)

Mourning Warbler * - 0.02 0.56 0.0008 249 15 1.20 (0.15)

Chestnut-sided Warbler * - 0.02 0.60 0.0004 342 20 1.32 (0.12)

Rose-breasted Grosbeak - 0.03 0.27 0.0320 63 3.7 0.56 (0.32)

Great Crested Flycatcher - 0.03 0.64 0.0001 93 5.5 0.78 (0.18)

Evening Grosbeak 1(WL) - 0.06 0.44 0.0036 45 2.6 0.26 (0.43)

1 CAWA does not fit normal distribution; included because of regularity of data and abundance across years. EVGR 

included due to possible ecological importance of decline.

* Outliers were removed from trend analyses for these species.

Density and Detectability

The density and logarithmic models returned very similar trends for most species in terms of 

direction and magnitude. A number of intuitive results gave confidence in distance analyses, such as 

quiet or thin-voiced species having a limited detection radius or loud species in open habitats having 

a high detection probability. When covariates were available, at least one covariate improved the 

model for all species. Sample sizes, based more on number of points surveyed annually than the 

number of years surveyed, were important in determining the number of species that could be 

analyzed and the strength of detectability estimates. Although three series expansions were used, 

there were no differences in AICc showing improvement on the half-normal model for most results. 

Figures in Appendix C show trend lines appearing similar, though the scale of the two y-axes, and 

therefore the slope, for models was different.

Observer data were not always available, and in many parks a single observer completes all points in 

a given year, making differences difficult to evaluate. Without exact distance measurements, 

observer differences could not be quantified, such as determining how observer experience or 

differences in hearing ability leads to a variable area effectively surveyed (Johnson 1995). A 
24

comparison of four parks (GRPO, SACN, SLBE, VOYA) revealed strong differences in the number 

of birds recorded for each of three distance categories (0–50 m, 50–100 m, and >100 m) (Figure 9). 

Grand Portage and St. Croix had nearly opposite proportional categorization, while Sleeping Bear 

Dunes and Voyageurs had similar results. 

Figure 9. Proportional and mean categorization of distances to birds recorded at Grand Portage (GRPO), 

Sleeping Bear Dunes (SLBE), Voyageurs (VOYA), and St. Croix Riverway (SACN). Mean distance 

categories: 0–50 m (1), 50–100 m (2), and >100 m (3).

Distance estimates had some important limitations (binomial data with only two distance categories, 

small sample sizes, and no covariates available for some parks) and bias (non-random route 

placement). When models returned highly variable results it was generally due to limited data from 

small sample sizes. Technically, inferences of density apply only to the survey routes, not to broader 

park landscapes.

Grand Portage National Monument

Detection radii were generally very high compared to other parks, and no species could be 

considered abundant (Table C1, Figure C1). Three species (Blackburnian Warbler, Canada Warbler, 

Ovenbird) had notably different p-values, but none of these had a significant trend (Table C2). Only 

White-throated Sparrow had an important difference between models, with the density model 

showing a significant decline and the logarithmic model showing a non-significant decline (at α = 
25

0.05). This decline was driven by two years of relatively high density in 2004 and 2005, after which 

the trend was flat. Covariates were not available for Grand Portage. Detection radii of 100 m, with a 

100% probability of detection, are not realistic and reflect a poor model fit for those species.

St. Croix National Scenic Riverway

All covariates were influential at St. Croix, with wind, background noise, and sky conditions each 

included in models for certain species (Table C3). Temperature improved detectability estimates for 

all species. Density trend analyses were not performed because temperature was not recorded in 

2010, so only five years of data were available, and because routes were completed in opposite years 

and could not be combined into a single trend. Detection radii were generally near 50 m, with a range 

of 34 m for American Redstart to 73 m for Ovenbird, and probabilities of detecting species were low, 

with a range of 12% and 53% for these species, respectively (Table C3).

Sleeping Bear Dunes National Lakeshore

The most comprehensive analyses were done for Sleeping Bear Dunes, with data stratified by year 

and habitat. Observer was the most influential covariate, and noise was the only other one that 

improved models (Table C4). Mean detection radii were all above 50 m (range = 55–75 m), and 

detection probabilities ranged from 31%–56%. Density per hectare varied widely across years, 

habitats, and species, with a spike in both density and individuals for three species in 2013. Increased 

detectability in 2013 may have been due to reduced noise and cloud cover, although wind speed 

averaged higher (Figure C2).

While four of the six species analyzed had no statistically different trend result, the p-values were 

often very different (Table C5). Trends for Red-eyed Vireo were similar, but the decline was 

significant using density estimates. The only instance in any park of a species exhibiting opposing 

trends occurred for the Red-winged Blackbird at SLBE. Observational results showed an increasing 

trend, while density results showed a decline (Figure C3); neither trend was significant. Habitat 

associations for each species generally followed expected patterns, with density models giving 

greater clarity to association differences (Figure C4).

Voyageurs National Park

Detection radii for Voyageurs were generally high, ranging from 46 m for Chipping Sparrow to 91 m

for both Ovenbird and Red-eyed Vireo (100 m radius for Veery should not be considered accurate), 

with detection probabilities matching the radii (Table C6). The two models returned very similar 

results for VOYA, with little divergence and no significant trends (Table C7, Figure C5).

Guilds

In most categories, little or no pattern was apparent from guild trends across all parks. The trends for 

each park were predominantly positive or negative, except for split patterns at Apostle Islands and 

Indiana Dunes. The wetland and bark foraging guilds both had generally positive trends, including

two significant trends each. The short-distance migrant guild was also largely positive across all 

parks. Five guilds were composed of mostly declining trends: successional/scrub habitat, frugivores, 

and foragers in aerial, lower canopy/shrub, and upper canopy strata. The frugivore guild in particular 

showed significant declines across the region. 
26

There was likely a strong correlation between dominant guilds, with the woodland-insectivoreNeotropical migrant guilds having many species in common. Separating guilds into subcategories, 

such as assessing woodland species by migration strategy, did not give useful results and are not 

reported. Results by table are divided into sub-regional strata within the Network: Wisconsin (Table 

10), upper Michigan and Minnesota (Table 11), and lower Michigan and Indiana (Table 12).

Table 10. Trends for combined species within guilds at Apostle Islands National Lakeshore (n = 68) 

and St. Croix National Scenic Riverway (n = 74), including number of species (n), proportion of 

species within the guild, p-value, and trend. Trends in bold indicate P ≤0.05.

Apostle Islands St. Croix*

Guild n % P Trend n % P Trend

Breeding Habitat

Grassland/Open 7 10 % 0.51 + 0.003 4 5 % 0.0084 - 0.012

Wetland 8 12 % 0.0439 - 0.016 6 8 % 0.68 + 0.002

Successional 16 24 % 0.12 - 0.007 23 31 % 0.0019 - 0.013

Urban 10 15 % 0.0023 + 0.015 18 24 % 0.0266 - 0.018

Woodland 53 78 % 0.08 + 0.003 55 74 % 0.0002 - 0.015

Diet

Frugivore 4 6 % 0.14 - 0.018 6 8 % 0.0253 - 0.014

Granivore 6 9 % 0.45 + 0.005 5 7 % 0.15 - 0.009

Omnivore 7 10 % 0.0003 + 0.026 13 18 % 0.06 - 0.010

Insectivore 59 87 % 0.52 + 0.001 59 80 % <0.0001 - 0.019

Forage Substrate

Air 12 18 % 0.0194 - 0.014 14 19 % 0.0013 - 0.039

Bark 10 15 % 0.048 + 0.008 11 15 % 0.0011 - 0.025

Ground 23 34 % <0.0001 + 0.010 29 39 % 0.0081 - 0.009

Shrub/low 

canopy

29 43 % 0.92 - 0.00 30 41 % 0.0018 - 0.011

Upper canopy 13 19 % 0.27 + 0.004 12 16 % 0.0035 - 0.015

Migration Strategy

Resident 15 22 % 0.0275 + 0.011 17 23 % 0.0019 - 0.018

Short-distance 20 29 % 0.23 + 0.003 20 27 % 0.15 - 0.004

Long-distance 33 49 % 0.33 + 0.002 38 51 % <0.0001 - 0.022

* See discussion section for cautions regarding SACN data.

Apostle Islands National Lakeshore

Mixed guild trends occurred at Apostle Islands (Table 10). Aerial wetland foragers, particularly the 

Tree Swallow, had a strong influence on the declining trends. Red-winged Blackbird, Common 

Grackle, and Yellow-bellied Flycatcher were also important driving forces. Generalists were on the 

rise, particularly those that do well in urban situations. Residents and bark foragers both increased, 

though these categories were probably correlated due to nuthatches and woodpeckers. Ovenbirds 

were very common and had a significant trend, which strongly influenced all guilds it was in.

Grand Portage National Monument

Although most trends were negative, only the frugivore guild had a significant decline (Table 11). 

Downy Woodpecker, with a 5% annual decline, was probably the driver in the frugivore category, 
27

with few observed annually in the past decade. The Downy Woodpecker frugivore designation would 

be limited to abundance of local fruits in the breeding season (Jackson and Oullet 2002), and is 

probably an imperfect classification. Declines of Veery, a common species in the park with a nonsignificant but low p-value, suggest frugivore declines could be a broader trend.

Indiana Dunes National Lakeshore

At Indiana Dunes, three guilds had significant negative trends and two had significant positive trends 

(Table 12). Wetland species increased overall, and the bark forager guild was driven by strong 

increases in the Red-bellied Woodpecker. Declines of frugivores were driven by Cedar Waxwing and 

Veery. Upper canopy foragers and resident species were generally declining, yet at least one species 

in each guild had a contradictory significant increasing trend. Blue Jay and Cedar Waxwing were 

important common influences across all three declining guilds.

Isle Royale National Park

Most trends were positive but not significant (Table 11). The wetland guild trend was significant, 

with three of the five species increasing (Alder Flycatcher, Red-winged Blackbird, Swamp Sparrow) 

and the other two with no distinct trend.

St. Croix National Scenic Riverway

Results from St. Croix showed unprecedented significant declines across many species and nearly all 

guilds (see Table 10). Only the wetland guild had a slight positive trend, although it was statistically 

irrelevant. However, these results are accompanied by a number of caveats––see Discussion for 

details.

Sleeping Bear Dunes National Lakeshore

Nearly all trends were positive yet none were significant (Table 12). Bark foragers and short-distance 

migrants had p-values suggesting ecologically important changes.

Voyageurs National Park

Seven guilds at Voyageurs had significant declining trends (Table 11). Two of these––

grassland/open and successional––can be explained by the strong declines of a small number of 

species (American Crow for grassland/open and Mourning and Chestnut-sided Warblers for 

successional). The general declines for woodland, omnivore, insectivore, ground forager, and 

shrub/low canopy forager suggest broad changes have been occurring in the past 15–20 years.
28

Table 11. Trends for combined species within guilds at Isle Royale National Park (n = 61), Voyageurs National Park (n = 54), 

and Grand Portage National Monument (n = 52), including number of species (n), proportion of species within the guild, pvalue and trend. Trends in bold indicate P ≤0.05.

Isle Royale Voyageurs Grand Portage

Guild n % P Trend n % P Trend n % P Trend

Breeding Habitat

Grassland/Open 3 5 % 0.11 - 0.010 4 7 % 0.0558 - 0.015 2 4 % 0.80 + 0.003

Wetland 5 8 % 0.041 + 0.014 4 7 % 0.91 + 0.002 5 10 % 0.20 + 0.008

Successional 11 18 % 0.39 + 0.003 12 22 % 0.0117 - 0.010 10 19 % 0.42 - 0.004

Urban 8 13 % 0.44 + 0.004 9 17 % 0.10 - 0.007 6 12 % 0.85 - 0.002

Woodland 53 87 % 0.48 + 0.001 48 89 % 0.0243 - 0.008 45 87 % 0.54 - 0.002

Diet

Frugivore 5 8 % 0.17 + 0.005 5 9 % 0.27 - 0.008 5 10 % 0.0118 - 0.018

Granivore 5 8 % 0.12 - 0.013 5 9 % 0.19 + 0.011 3 6 % 0.28 - 0.015

Omnivore 9 15 % 0.20 + 0.006 8 15 % 0.0028 - 0.015 8 15 % 0.83 - 0.002

Insectivore 50 82 % 0.55 + 0.001 44 81 % 0.0317 - 0.008 42 81 % 0.16 - 0.005

Forage Substrate

Air 9 15 % 0.46 + 0.003 8 15 % 0.62 - 0.004 7 13 % 0.95 -0.001

Bark 9 15 % 0.66 + 0.002 9 17 % 0.63 + 0.002 8 15 % 0.10 -0.012

Ground 22 36 % 0.68 + 0.001 22 41 % 0.0087 - 0.010 21 40 % 0.44 -0.003

Shrub/low 

canopy

30 49 % 0.38 + 0.002 26 48 % 0.0254 - 0.009 26 50 % 0.80 -0.001

Upper canopy 12 20 % 0.41 - 0.002 11 20 % 0.54 - 0.003 10 19 % 0.15 -0.007

Migration Strategy

Resident 17 28 % 0.09 + 0.007 15 28 % 0.46 - 0.003 15 29 % 0.49 - 0.007

Short-distance 14 23 % 0.20 + 0.005 18 33 % 0.48 - 0.003 15 29 % 0.21 + 0.007

Long-distance 30 49 % 0.92 + 0.000 23 43 % 0.94 - 0.000 22 42 % 0.15 - 0.005
29

Table 12. Trends for combined species within guilds at Sleeping Bear Dunes National 

Lakeshore (n = 66) and Indiana Dunes National Lakeshore (n = 62), including number of 

species (n), proportion of species within the guild, p-value and trend. Trends in bold indicate 

P ≤0.05.

Sleeping Bear Dunes Indiana Dunes

Guild n % P Trend n % P Trend

Breeding Habitat

Grassland/Open 11 17 % 0.19 + 0.010 6 10 % 0.57 + 0.002

Wetland 5 8 % 0.23 + 0.015 8 13 % 0.0008 + 0.014

Successional 21 32 % 0.22 + 0.010 21 34 % 0.10 - 0.004

Urban 16 24 % 0.15 + 0.014 19 31 % 0.29 - 0.003

Woodland 43 65 % 0.58 + 0.004 39 63 % 0.31 - 0.003

Diet

Frugivore 6 9 % 0.17 + 0.020 6 10 % 0.0339 - 0.010

Granivore 8 12 % 0.98 + 0.000 9 15 % 0.09 + 0.004

Omnivore 12 18 % 0.71 + 0.003 11 18 % 0.18 - 0.005

Insectivore 51 77 % 0.29 + 0.006 47 76 % 0.77 + 0.001

Forage Substrate

Air 11 17 % 0.37 + 0.020 14 23 % 0.14 - 0.008

Bark 9 14 % 0.07 + 0.035 5 8 % 0.0110 + 0.018

Ground 32 48 % 0.30 + 0.007 30 48 % 0.60 - 0.002

Shrub/low canopy 24 36 % 0.37 + 0.010 23 37 % 0.06 - 0.005

Upper canopy 9 14 % 0.14 + 0.022 10 16 % 0.0124 - 0.006

Migration Strategy

Resident 17 26 % 0.13 + 0.017 17 27 % 0.0412 - 0.007

Short-distance 21 32 % 0.09 + 0.017 18 29 % 0.08 + 0.005

Long-distance 28 42 % 0.79 - 0.002 28 45 % 0.76 + 0.001

31

Discussion

Each park in the Great Lakes Network contains unique ecological landscapes, which is reflected in 

the variability of avian communities and species’ trends within the region. Few species are shared 

across all parks, and there is general inconsistency in trend patterns (Appendix D). Populations in one 

park can be significantly increasing while showing declines elsewhere (e.g., Ovenbird, Nashville 

Warbler, and Chipping Sparrow). As a result, most species or guilds should be considered on a parkby-park basis, with comparisons made between parks having similar habitats (e.g., Voyageurs–Grand 

Portage–Isle Royale) or with broader studies such as the North American Breeding Bird Survey. 

Although most park landscapes are managed for high ecological integrity that contrast with 

surrounding human-modified settings, survey results often reflect general regional trends for some 

species.

The majority of trends, both in terms of direction and magnitude, were very similar when comparing 

log-transformed observational estimates and density estimates. Only a few species demonstrated 

contradictory results between the models or did not share statistical significance for a trend. This is 

encouraging because parks often have staffing constraints or limited technical expertise, so 

monitoring changes with observational results is supported as a reasonable way to estimate shortterm population fluctuations. Observational data collected prior to distance measurements may be 

accurate enough for cautious predictions regarding long-term trends, though it cannot be known if 

any particular trend is spurious (see Red-eyed Vireo at SLBE in the Park-specific Conclusions 

section below) or genuine (Thomas 1996). Overall, even though density modelling is more expensive 

and challenging (Diefenbach et al. 2007), field methods should continue to incorporate distances for 

a better approximation of long-term species trends.

Annual variation for a given species may be due to true population cycles, but detectability on the 

day of sampling also depends on both presence of a bird and the probability that it makes itself 

available for detection (Nichols et al. 2009). An important challenge in density analyses is the large 

sample size requirement. Yet for common species that show large fluctuations in annual survey

numbers, determining precise trends can be difficult. Another important factor is coverage, where 

surveys with many survey points are more likely to detect trends of uncommon species, even when 

employing shorter counts (Lynch 1995).

Observational Regression Trends

Species like the American Robin and Red-winged Blackbird have been increasing strongly in most 

parks in the region. This follows a continent-wide pattern for robins, but Red-winged Blackbirds 

have been declining in many regions and states in recent decades (Sauer et al. 2014). Other species 

increasing across Network parks include Northern Flicker, Alder Flycatcher, Red-breasted Nuthatch, 

Common Yellowthroat, and Yellow-rumped Warbler.

Few species had a general trend of significant declines, although American Crow and Chestnut-sided 

Warbler fit this pattern. Evening Grosbeak has sharply declining trends in northern parks, with a peak 

occurring in the late 1990s. Many surveys began during this peak, so the downward trend for this 

uncommon species is probably due to a high starting point coupled with low sample sizes. Evening 
32

Grosbeak trends are often associated with spruce budworm outbreaks, but this pattern may be a local 

phenomenon (Gillihan and Byers 2001). In addition, historic records (>100 years ago) of Evening 

Grosbeaks east of the Mississippi River were rare, so the western Great Lakes region may not offer 

high-quality year-round habitat. Because of these factors, the declines for this species probably do 

not reflect habitat conditions in the parks.

Many species that had both flat regression lines and a relatively high abundance can be interpreted as 

having a stable population within a park. Other species have such a high variability that a regression 

line does not fit the points well, as indicated in Appendix B by low r2 and high P. Species not fitting 

normal distribution are typically too scarce, due to natural rarity or cryptic habits, for adequate trend 

interpretation (Lynch 1995). Unless a park provides critical habitat for rare species, limited effort 

should be expended implementing management actions for them.

Density and Detectability

Detection probabilities generally showed that half or fewer of the birds present during point counts 

were detected. This is a common result in forest and riparian point counts and can strongly impact 

population estimates (e.g., Somershoe et al. 2006, Norvell et al. 2003). Detectability of 100% is 

never realistic, even in open habitats, since breeding songbirds are often vocally or visually 

unavailable (Diefenbach et al. 2007, Buckland et al. 2001). In addition, detection probabilities are 

likely to change with observer, weather, or habitat differences (Barker and Sauer 1995).

Detection radii by species often changed dramatically in different parks. American Redstarts had a 34 

m detection radius at SACN, 67 m at SLBE and 76 m at GRPO. Red-eyed Vireos had a 48 m radius 

at SACN, 75 m at SLBE and 91 m at VOYA. The reasons for the strong differences in number of 

birds detected in distance categories between GRPO and SACN could be related to (1) each park 

having common species with different detectability, (2) broad structural variation such as open 

forests versus shrubby riparian habitat, (3) attraction of insectivores to riparian areas with high food 

availability, (4) bird movements in response to observer presence, or (5) differential observer 

distance estimation, which cannot be tested with available data. Theoretically, the 50–100 m range 

should have greater numbers detected due to a four-fold increase in the area surveyed than the area in 

the inner ring, while beyond 100 m detectability should fall quickly for most species. As annual 

results are accrued in the future, distance analyses will become more widely available and robust for 

avian communities by using inclusive global estimates stratified by year or habitat. For across-park 

comparisons we limited analyses to the first 3-minutes of surveys, but parks with longer survey times 

could use Distance software to analyze additional species and improve their density estimates.

Covariate factors are usually not under an observer’s control, yet they commonly influence 

detectability (Conn et al. 2004). Differences in observer, temperature, wind, noise, and sky cover 

improved models for all species. In cases where a single observer collected all data from a park in a 

given year, there may be a false correlation influencing the covariates since annual abundances or 

weather variations are linked to that observer. The importance of the temperature covariate was likely 

due to patterns of increasing daytime temperature while species generally decrease singing as the 

morning progresses.
33

Habitat-based comparisons of observations and density estimates show that stratification of points 

based on park habitats can be a good indicator of, and management tool for, proportional use by and 

density of birds. While SLBE designed a survey based on habitat, no other parks have a similar 

strategy (although APIS has since implemented a form of this, with a focus on wetlands). Ideally, 

each point should be located within a single habitat, so that association to species is straightforward 

(Howe et al. 1995). 

As a comparative dataset, we began post hoc stratification of ISRO habitats to see if similar results 

were possible with a survey not originally designed to take habitat into account. We found that a 

majority of points broadly included two or more habitat types. Based on well-studied habitat 

associations for most species, this may be useful for managing or understanding local avian 

communities without having to redesign survey routes. Unfortunately, ISRO distance data did not 

allow for detectability to be estimated. For an example of how habitat data can enhance analyses, see 

the Sleeping Bear Dunes section below.

With heavily forested habitats across most GLKN parks, there is little latitude for improving on the 

current sampling protocol regarding distance data, such as increasing the number of distance bins or 

estimating exact distances to each bird. Although Norvell et al. (2003) implemented a highly 

controlled study with intensive training and professional ornithologists, they continued to find that 

observer bias influenced detectability. For survey observers to ensure high-quality results, accurate 

estimates for each distance category is crucial for minimizing error. Annual field practice should 

occur prior to counts, with range finders used during counts (Nichols et al. 2009).

Guilds

Contradictory problems arise with our current guild strata. A large majority of species are in both the 

woodland and insectivore guilds, tying together habitat and diet categories. Forage substrate and 

migration strategy guilds were more balanced. Some investigators caution against making too many 

small guilds (Verner 1984, Mac Nally et al. 2008), which is reasonable because one or two dominant 

species can drive the results. While large guilds increase sample sizes, they present problems for 

interpreting results in meaningful ways. Few guilds across parks had similar trends, supporting the 

idea that local results may not scale well to regional context (Hart et al. 2012). The only relatively 

clear commonalities were a decline in frugivores across many parks and increasing trends in wetland 

occupants and bark foragers. The decline of frugivores across Network parks prompts the question: 

Are berry-producing plants in decline generally? This supposition is strengthened by declines in 

omnivores with a large fruit component in their summer diet. 

In recent decades there has been concern regarding the decline of Neotropical migrant populations, 

yet GLKN data show no clear trends related to migration strategies. Results for each park should be 

used by managers who are familiar with vegetation and disturbance history within the parks to 

investigate possible relationships between avian communities and landscape changes. Because of the 

relatively unimpacted or rehabilitated aspect of NPS lands, bird responses to habitat change in the 

parks may not be the same as responses outside the parks where fragmentation or human impacts 

have a greater role.
34

Guilds are often used to predict avian responses to habitat change by using a qualitative biotic index 

model (Croonquist and Brooks 1991, O’Connell et al. 2000, Marshall et al. 2013) or multivariate 

models (Mac Nally et al. 2008, Korňan et al. 2013). In both cases, models are frequently designed for 

specific regional conditions because generalist species with adaptable behaviors can fit into different 

guilds. These techniques may be useful in creating Network-specific guilds and increasing the utility 

of guild-based analyses. However, the objectives for future guild analyses must first be defined since 

none of the individual parks have guild-oriented goals. 

Park-specific Conclusions

Apostle Islands National Lakeshore

The seven significantly increasing species at APIS have no continent-wide cause for concern, and the 

State of Wisconsin does not list them among their species of conservation concern (Rosenberg et al. 

2014, Wisconsin Natural Heritage Program 2014). Even so, the Common Grackle, which is declining 

at APIS, is one of the most common species that are exhibiting declining trends in North America. 

The Yellow-bellied Flycatcher is showing the strongest decline at APIS, which reflects statewide 

patterns. A few state-listed species of concern are increasing (Swainson’s Thrush, Cape May 

Warbler, Canada Warbler), which may be due to protected habitats in the park. Conversely, a few 

other species of concern (Least Flycatcher, Black-throated Blue Warbler, Veery) have shallow 

declining trends, which may indicate that even protected areas cannot sustain source populations for 

some species that are broadly in decline.

Two of the primary objectives of APIS bird surveys––monitoring long-term trends and having data 

available for comparison to other studies––have been successfully accomplished. The park recently 

reassessed its monitoring objectives based on interest in determining how climate change influences 

avian communities (Jukkala and Burkman, in press). Recent modifications to the survey will require 

keeping prior and future statistical analyses separate. Results reported here are probably safe to apply 

across park landscapes because survey routes provide broad coverage of park habitats. Based on 

detailed vegetation surveys in 2011, three of the primary habitats are late successional and the other 

two are developing toward mid-successional conditions (Sanders and Grochowski 2012), which may 

explain the positive trends in Ovenbird and resident bark foragers.

Grand Portage National Monument

Among the strong or significant trends at GRPO, only the Evening Grosbeak is of broader concern 

due to its inclusion on the NABCI watch list (NABCI 2014). However, three trends worth watching 

are those for the resident Downy, Hairy, and Pileated woodpeckers, all of which are in significant 

decline (Hairy Woodpecker data do not meet normality so the trend is not shown). Two other 

woodpeckers––the Northern Flicker and Yellow-bellied Sapsucker, both migratory––appear stable or 

slightly increasing. However, the number of birds reported as “unknown” on surveys increased 

strongly over the same time period. If data from other park surveys holds true for GRPO, many of

these unknowns are woodpeckers, which are notoriously difficult to identify based on drumming 

sounds alone. The Yellow-bellied Sapsucker has a distinctive drumming pattern, while Northern 

Flickers often give additional vocalizations that aid identifications, so declines in GRPO resident 

woodpeckers must be considered with caution. The narrow aspect of the park should allow general 
35

inference of data across the entire park, and there were no indications of large-scale habitat 

influences on guild trends.

Indiana Dunes National Lakeshore

INDU has an avian community that is distinct from other Network parks, and with approximately 20 

years of data, this is one of the longest running surveys in the Network. These data are fulfilling the 

park’s monitoring goals by adding important information to the NABBS and determining trends for 

common breeding species. However, without data on habitats, minute of detection, distance to birds, 

or weather conditions, only limited analyses are possible. Survey points located in specific habitats, 

as suggested by Lind et al. (2005), would be useful for monitoring species that may be absent from 

roadsides, but this should not be done at the expense of continuing data collection on the original 

route.

Comparing trends from INDU to region-wide data (2002–2012) (Sauer et al. 2014), some species 

show similar patterns between the local scale and regional scales while others are contradictory. Of 

the significantly increasing species, Red-bellied Woodpecker and Chipping Sparrow have been 

increasing across most regions and states in the southern Great Lakes area. Willow Flycatcher and 

Warbling Vireo show some increasing and some declining trends across the region, while Marsh 

Wren and Red-winged Blackbird are uniformly declining. Marsh Wren stands out as a bird that 

seems to be doing well at INDU but is in trouble across its range.

Of the three INDU species with significant declining trends (Blue Jay, Veery, and Cedar Waxwing),

the Blue Jay and Veery are similarly declining across most states and regions, although data for the 

Veery often have low confidence; the Cedar Waxwing is generally increasing across most states and 

regions. Declines of Cedar Waxwing and Blue Jay at INDU are interesting given the relative habitat 

flexibility of both species. Ovenbird and Chimney Swift are also showing declining trends at INDU, 

which may indicate problems in these populations. The Ovenbird is increasing in the northern parts 

of its western Great Lakes range, but is declining in the southern part of this range. However, the 

latter data have low confidence (Sauer et al. 2014). The Chimney Swift is uniformly declining across 

the western Great Lakes. Snags and small trees appear to be increasing at INDU (Sanders and 

Grochowski 2013), which may be important in the rise of Red-bellied Woodpeckers and the decline 

of upper canopy foragers.

Isle Royale National Park

Only the Swainson’s Thrush was new to the list of significantly increasing species since the previous 

analysis (Egan and Gostomski 2013). There were no new additions to the declining list. The trends 

for several common species changed to non-significant values with only one additional year of data, 

revealing that caution and broader perspective are required when interpreting results for some 

species. Most strong or significant trends are in agreement with regional patterns, although Redwinged Blackbird and Golden-crowned Kinglet are doing better than most other populations in the 

western Great Lakes. Common Raven continues to be atypical when compared to regional trends, 

with significant declines in ISRO habitats where it should prosper. In general, conclusions from the 

prior analysis remain unchanged. Although habitat is not considered, routes cover broad areas of the 
36

park and inference to broader populations is probably safe, if tentative. There were no indications of 

large-scale habitat influences to guild trends at ISRO.

St. Croix National Scenic Riverway

The large number of significantly declining trends at SACN stands apart from other western Great 

Lakes parks, states, and ecoregions. Indeed, to our knowledge there is no comparable North 

American dataset showing such pervasive significant declines in an avian community. This suggests 

either an important issue with the survey itself or that there has been a key change in riparian 

habitats. As a result, we will explore potential mechanisms in detail.

Forest changes are occurring within and near the riverway (Sanders and Grochowski 2014), but these 

changes do not show severe degradation or dramatic shifts in vegetation. Increased recruitment of 

black ash (Fraxinus nigra) in the park indicates that flooding has not been a major factor since 2007, 

but it is unlikely that limited flooding or high ash recruitment explains broad avian declines. An 

extreme wind event in 2011 had the effect of increasing snags, downed coarse woody material, tree 

density, and light reaching the forest floor (Sanders and Grochowski 2014). Under these conditions a 

sharp increase in early-successional bird species may be expected, but the opposite is revealed from 

surveys. If 2012–2014 data are excluded, nearly all trends remain in significant decline and appear to 

be influenced by particularly high values in the early years of the survey. 

Another potential habitat factor may be land-use changes along the river corridor or adjacent

landscapes. For instance, timber harvest has been an important disturbance factor (Kirschbaum and 

Gafvert 2013), yet the extent of harvest is probably limited in the vicinity of survey points. While the 

above landscape changes may have an interactive effect, it does not seem feasible that habitats are 

changing in the park in ways that can explain dramatic avian declines. Finally, with the same two 

experienced observers conducting the surveys since 1998, it is unlikely that observer differences are 

a problem. While the hearing of observers could be tested to ensure it is within acceptable ranges, the 

declines of highly detectable species and continued recording of high-pitched species suggests 

observer hearing loss is not a strong contributing factor.

The most likely explanation for the declines at SACN appears to be the change from floating counts 

to anchored counts in 2005. From 1998 to 2005, guilds showed comprehensive declines (eight guilds 

having significant declines and nine with non-significant declines), none of which had a significant 

relationship to river discharge rates (data not shown, all p-values ≥0.08). (Increased discharge rates

would affect what area was actually sampled while drifting.) In contrast, from 2006 to 2014 there 

were no significant guild trends in either direction (all p-values ≥0.22), which is similar to other park 

trends. This illustrates the importance of changing the study design to anchored surveys that 

standardized the sample units.

For individual species, data since 2005 probably reflect true trends in the park. Using this shorter 

time frame, the two declining species with broader concerns are Golden-winged Warbler, of special 

concern in Wisconsin and on the NABCI watch list (NABCI 2014), and Common Grackle, a 

common species showing general declines (Sauer et al. 2014). Pre-2005 data should not be used for 

future analyses, though they remain useful for birdwatching checklists indicating presence of species 
37

during breeding season. Density results for SACN use data collected since 2009 and are probably the 

most robust data for this park.

While the ideal for SACN was to survey the entire length of both rivers, the number of routes is 

probably maximized for realistic completion. Focus should remain on the six current routes, each of 

which have unique habitats present along them (Robin Maercklein, pers. comm.), with attempts to 

complete these routes completely and on schedule. The staggered biennial cycle of completing 

surveys introduces a few problems by lengthening the amount of time by which precise analyses can 

be made, requiring either separation of data (as in the current report) or use of more complex 

statistical techniques to combine data, and the influences of annual weather or population 

fluctuations may be more challenging to detect. However, it does allow more habitat types and a 

much larger number of points to be surveyed, and the strategy appears basically effective. Results 

apply to habitats adjacent to the rivers and probably not inland or upland locations.

Sleeping Bear Dunes National Lakeshore

Five species showed significant increasing trends in abundance at SLBE; no significant declining 

trends were identified. Comparisons with results both statewide (Michigan, Minnesota, and 

Wisconsin) and across bird conservation regions (Prairie Hardwood Transition and Boreal Hardwood 

Transition) over a comparable timespan (2001–2011) show American Robin and Red-eyed Vireo 

following increasing trends region-wide (Sauer et al. 2014). In contrast, Eastern Meadowlark, Veery,

and Wood Thrush are all broadly declining across the western Great Lakes. The discrepancies in 

trends may indicate positive responses to protected park habitats. Two species that should be watched 

in the future are Bobolink and Gray Catbird, both relatively common and showing strong, though 

non-significant, declines that may be important. There were no indications of large-scale habitat 

influences to guild trends at SLBE.

With points proportionally habitat-stratified, results can be applied across the park, though there may 

be an edge influence due to surveys along roadsides. Using Distance analyses for six species with 

adequate sample sizes, we can make the following observations on habitat associations and 

detectability estimates:

American Redstart–––Redstarts were detected in all habitats, but generally favored beechmaple forest, edges and shrubby habitat near water, which is typical (Sherry and Holmes 

1997). The detection radius neared the outer 100 m range ring in fields, yet was between 55

and 65 m in forested habitats. Overall, the probability of observing redstarts shows that only 

about 45% are detected, and the population is stable or slightly increasing.

American Robin––Robins were also detected in all habitats, though they distinctly favored 

beech-maple forest. Both radius and probability of detection were stable across years and 

habitats, at around 67 m and 45%, respectively. Annual trends between observational and 

density models were similar, with a stable or slightly increasing population.

Ovenbird––Due to low numbers, Ovenbirds were not modelled particularly well, yet 

observational and density comparisons both show a stable population. Compared to 
38

Ovenbirds in other parks, the radius and probability of detection were lower than expected 

from a bird with such a sharp, clear song. Beech-maple forest was strongly preferred and 

open habitats were avoided completely.

Red-eyed Vireo––Red-eyed Vireos were present in all habitats, but favored forests. Vireos 

occur in many forest types but are more common in the forest interior (Cimprich et al. 2000). 

Vireos at SLBE had a wide detection radius (75 m) and a 56% detection probability across 

habitats, which is a high detection value. Short-term trends (2009–2013) show a steep decline 

in both models, but only the density trend is significant. In contrast, the long-term trend 

(2004–2013) from the regression section shows vireos significantly increasing. This 

difference is explained in two ways. First, low numbers were observed in early years (2004–

2006) and high numbers in later years (2012–2013), which combine to show a significant 

increase (P = 0.04) of about 1.6% annually. Second, removal of vireos beyond 100 m for 

density estimates sharply reduced the number of detections from 51 to 29 in 2012 and 56 to 

31 in 2013, shifting the trend to a significant decline (P = 0.01) of about -1.4% annually. This 

suggests that results would have been misleading in the absence of sampling with distance 

bins. The decline in vireos is possibly part of long-term cyclical variation that should be 

followed in future surveys. There was no indication from NABBS results that Red-eyed 

Vireos were exhibiting steep declines in Michigan or regionally (Sauer et al. 2014).

Red-winged Blackbird––Red-winged Blackbirds favored field and wetland habitats, as 

expected (Yasukawa and Searcy 1995). Forest and dune habitats were avoided completely. 

Except for 2013, radius and probability of detection were very stable. Blackbirds had 

opposing trends between observational (positive) and density (negative) estimates––the only 

species in all parks to show this pattern. Although numbers observed in 2013 were not 

particularly low, density estimates suggested a sharp drop in the population. In the same time 

period there were declining trends for Red-winged Blackbirds in both the Boreal Hardwood 

Transition region and in Michigan (Sauer et al. 2014).

Song Sparrow––Song Sparrows were common in many SLBE habitats, particularly shrubby 

areas near water (Arcese et al. 2002). Observations were limited in forested settings. 

Detection radii and probability of observations were stable across years and habitats. Song 

Sparrow populations appeared to be stable or slightly increasing.

Voyageurs National Park

Blue-headed Vireo, a species typical of extensive mature forest with a complex understory (Morton 

and James 2014), was the only species showing a significant increasing trend. Generally, this species 

has become more abundant in recent decades, with significant population increases in Boreal 

Hardwood Transition (BHT) forest, and in Minnesota and Ontario (Sauer et al. 2014). 

Of the declining species, all but one exhibit similar trends in Minnesota, Ontario, and in the BHT 

forest. Due to the protected landscapes at VOYA, it is likely that the park offers good habitat for 

these species and declines reflect broader trends. American Crow, in contrast to park trends, has been 

increasing since 2002 in the BHT and in Minnesota and Ontario. Observed patterns of avian 
39

abundances from VOYA were similar to trends from ISRO, with high abundances in the mid-1990s 

(Egan and Gostomski 2013).

Declines within guilds at Voyageurs are suggestive of changing forest structure along survey routes. 

Yet it is difficult to assess what the changes may be since a general decline in woodland species 

implies gap creation, while the decline in open and successional species implies greater forest 

maturation. Recent landscape-level analyses show a small amount of landscape disturbance in the 

park (0.68%) from 2002–2007, and larger amounts in nearby areas of Minnesota (4.3%) and Ontario 

(7.1%) (Kirschbaum and Gafvert 2010). The largest disturbances in recent years, from natural fire 

and beaver dam blowout, occurred far from any survey routes.

Except for the four routes analyzed here, data collection has been inconsistent since 1997. This 

irregularity effectively halves the data available for some analyses. Our primary suggestion for 

VOYA is to consider the number of routes that can be effectively completed each year––it appears 

that six routes are more reasonable than eight. Routes follow short ski-trail loops because of a general 

lack of park trails, so results may not apply across park populations and may be strongly influenced 

by trail maintenance techniques.

43

Conclusions

Avian community trends show broad discrepancies across the region, which probably reflects the 

unique and variable landscapes occurring in each park. There was greater consistency within each 

park, particularly when considering species combined into guilds. Across GLKN parks, most species 

can be considered relatively stable or increasing, with only a few species exhibiting general declining 

trends: American Crow, Chestnut-sided Warbler, and Evening Grosbeak. Broadly increasing species 

include American Robin and Red-winged Blackbird, with a few more species sharing this pattern to a 

lesser degree. Species with strongly mixed trends––significantly increasing or declining, depending 

on the park––include Blue Jay, Hermit Thrush, Veery, Ovenbird, Nashville Warbler, and Chipping 

Sparrow. The majority of trend patterns in GLKN parks match findings from the continent-wide 

NABBS roadside surveys (Sauer et al. 2014).

Each park should consider how the trends determined here apply to local habitats and management 

goals. In particular, species that are state-listed or on the Partners in Flight Watch List have been 

determined to require management attention, either because they are already in jeopardy or have 

population traits suggesting that preemptive action could save considerable effort and expense by 

averting a significant decline (Rich et al. 2004). Conservation of healthy landscapes is already a 

priority in parks, but management decisions should consider influences to habitats used by species of 

concern. In this light, it is important to determine habitat use by species because it may help 

determine risk of local extirpations if climate change begins to strongly influence habitats.

Binomial distance estimates (using two range categories) for common species were a valuable 

improvement over observational results. Most species had no discernable difference in trend 

magnitude and direction between logarithmic and density models, although important differences 

were revealed for a small number of species. Therefore, observational index trends are valid 

surrogates for more refined analyses and can be used for annual reporting, while density trends 

should be used in synthesis reports (Conn et al. 2004). 

Migration, habitat, and diet guilds appear to be a useful complementary support tool for interpreting 

long-term avian trends in GLKN parks, though the guild model could be refined for better effect. 

Fruit-eating species, including omnivores that have a substantial fruit component of summer diet, 

appear to be declining in many parks. Other guilds with weaker but consistently declining trends 

include successional habitat occupants and birds foraging aerially and in the upper canopy. Wetland 

and bark-foraging species were generally increasing, as were, to a lesser degree, short-distance

migrants. Mechanisms for guild changes cannot be addressed with the bird survey data, but results 

should be considered for additional study or in conjunction with other surveys. Guilds should be 

compared to vegetation surveys as data become available for how park habitats are changing over 

time (Croonquist and Brooks 1991). Even preliminary data from vegetation plots were useful 

comparative tools to predict the reasons for changes in the avian community.

The priority list for GLKN includes 22 species requiring conservation attention (GLKN 2011). 

However, three of these species have not been recorded on any park survey (Henslow’s Sparrow, 

Kirtland’s Warbler, and Rusty Blackbird), and many other species on the list are found in such low 
44

abundances that trends cannot be reliably ascertained in all or most parks. There are exceptions, such 

as SLBE having adequate sample sizes for grassland species like Bobolink, Field Sparrow, and 

Grasshopper Sparrow. But only five priority species are reliably sampled across parks: Least 

Flycatcher, Veery, Black-and-white Warbler, Black-throated Blue Warbler, and Canada Warbler

(Appendix D). Therefore, to avoid the problem of managing for species that do not actually use 

parks, the list of priority species should be modified using criteria that includes not only Partners in 

Flight designations (including their list of common birds in steep decline), but also documented 

breeding presence in parks and abundance adequate enough to reliably track populations. Rare

species could be on a “watch list” or receive targeted surveys if deemed important to actively 

manage. The Network list may be more useful to parks if priority species were stratified or ranked 

based on conservation concern and ability for park habitats to sustain them. The list should highlight

species that can reliably indicate habitat change in parks and be reevaluated periodically for 

improvement and relevance (Beissinger et al. 2000). An important question for this list is whether 

parks are havens for a declining species or a marginal landscape unlikely to help avert a population 

crash.

Even though parks follow a common protocol (except INDU, which follows the NABBS protocol), 

variability based on detection probabilities, habitats, observers, and initial route establishment make 

direct park-to-park comparisons risky (Barker and Sauer 1995). Point counts can be used to good 

effect as an “early-warning system” to indicate when additional investigation is warranted or broad 

changes are occurring (Barker and Sauer 1995). Each park should consider these results using local 

expertise to determine if further study is needed. If rare species are of management concern they will 

require separate survey techniques or modifications to the current protocols (see Thompson 2004).

Prior to standardization, each park had its own approach for surveying birds. While techniques were 

generally similar, with compatible objectives, the lack of a cohesive protocol or strategy limited the 

ability for comparisons among these datasets. Current survey protocols are generally fulfilling 

monitoring goals defined by each park (Gostomski et al. 2010). Shared goals include assessment of

community diversity and long-term trends, which are best met in different ways. The first can be 

accomplished using unlimited distance counts to detect the most species possible, while the second is 

best served by including additional effort such as distance estimates for refined calculations. Our 

findings stand as a benchmark for avian studies in GLKN parks prior to the Network protocol. Future 

synthesis reports, ideally done every five years for effective reevaluation, should focus on surveys 

occurring since standardization, using this report for comparison.
45

Management Recommendations

Quality Control

The most important recommendation centers on consistency of data management. Data are often 

recorded and entered differently from park to park, and even from year to year. This complicates 

analyses by forcing assumptions or removing data entirely. A great deal of effort is wasted when 

quality control problems compromise the utility of data. The most common problems found during 

analyses for this report and some basic strategies to help overcome them are:

1. Common across all parks was the use of non-standard and/or inconsistent codes for site 

names and bird species, even within the same dataset. Creative yet unintelligible codes are 

sometimes generated, and these data are generally removed from analysis to avoid 

misinterpreting results. It is strongly advised that the most recent American Ornithologist’s 

Union (AOU) standards are followed, as outlined in the Network’s Standard Operating 

Procedure #5 (Knutson et al. 2010), and that spreadsheets and databases also include the 

common English name to avoid confusion among those who are entering data but may not be 

familiar with the codes.

2. Many park worksheets were missing basic data, including observer names, minute of 

detection, and transcription of the full species name, which can be double-checked against 

the code name. All data from field forms should be entered into worksheets and databases. 

All field sheets should be checked for accuracy on the same day as the survey.

3. Data entry is tedious and error-prone, particularly with the thousands of entries required for 

bird survey data. Data entry should be done slowly and methodically by personnel familiar 

with the survey and the datasheets. With two people, data entry can be split up, and doublechecking of the other person’s entries will help with quality control.

Reporting

Although all parks have objectives that include monitoring trends and comparing results to a broader 

geographic area, only ISRO has completed a peer-reviewed report to fulfill these goals. It is not clear 

how many parks produce internal reports about their annual surveys. The relatively recent formation 

of the GLKN office brings important resources for helping parks analyze and synthesize data, which 

is the goal of this report. It is advisable that all parks take advantage of this partnership by sharing 

data from annual surveys. Individual parks are likely to desire in-depth reports that address internal

management goals, while meta-analyses can be handled by the GLKN office.

Improved Analyses

Current protocols should be followed closely to allow comparison across parks. However, the 

following may be useful if Network or park managers desire refinements in techniques, depending on 

goals.

1. Distance data: Additional covariates could improve results and indicate factors influential 

to species density and detectability (e.g., vegetation cover, habitat characteristics, time of 
46

day, behaviors of species of interest). However, only data deemed important should be 

collected so primary goals are not compromised. Smaller distance bins could improve 

analyses, separating each current bin into two (i.e., 0–25 m, 25–50 m, 50–75 m, 75–100

m), but this should only be implemented if current precision estimates are deemed too 

low; otherwise this would have limited utility.

2. Habitat designation: Greater understanding of habitat use by the birds in each park would 

make management actions more effective. Even broad post hoc designations for each 

point could be useful (Buckland et al. 2001, Ralph et al. 1995). Occasional updating of 

habitat definitions may illuminate the response of avian communities to vegetation 

changes. Habitat designations are particularly important to implement in order to fulfill 

the stated goal of associating species with habitats.

3. Guilds utilized in the current analysis were basic and defined from studies of northern 

forests or general North American behaviors. Building a refined guild model for the 

western Great Lakes region may return more robust results. However, a north-south 

distinction exists within Network parks, particularly for migration strategies, so subregional guild analysis may be appropriate.

4. In the next meta-analysis of GLKN data, time-to-detection or removal models should be 

compared to distance models (e.g., Alldredge et al. 2007, Farnsworth et al. 2005).

Survey Effort

For some parks, incomplete sampling of survey routes on a regular basis suggests an overextension 

of resources, either in time or personnel. Gaps in data can be statistically problematic, so consistent 

and comprehensive sampling is advised. Some parks should either reconsider the number of routes 

or, if avian surveys are a high priority, ensure adequate resources are allocated. If all established

routes cannot be surveyed each year, managers should consider which routes are of primary 

importance based on habitats or representation of species of concern and make those a priority for 

annual sampling.
47

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55

Appendix A: Route Completion Details

Table A1. Breeding bird survey routes and number of annually completed survey points (106 total) at Apostle Islands 

National Lakeshore, 1995–2013. Bold numbers indicate data used in regression analyses. No data were collected in 

2006 or 2011–2013.

Year

Route* 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

DE 8 8 8 8 13 8 8 8 8 8 No 8 8 8 8

LO 12 12 12 12 12 12 12 12 12 12 12 data 12 12 12

OA 13 13 13 13 13 13 13 13 13 13 13 13 13

OU 15 15 15 15 15 15 15 15 15 15 15 15 15 15

OUHS 5 5 5 5 5 5 5 5 5 5 5 5 5 5

MD 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10

RA 9 9 9 9 9 9 9 9 9 9 9 8 9 8

SA 12 12 5 12 12 12 12 12 12 12 12 12 12 12

STPI 10 10 10 10 10 10 10 10 10 10 10 10 10 10

STTP 12 12 12 12 12 12 12 12 12 12 12 12 12 12

Total 106 106 99 76 106 106 106 106 106 106 106 106 105 106

* DE=Devils Island, LO=Long Island, OA=Oak Island, OU=Outer Island, OUHS=Outer Island Hemlock Stand, MD=Mainland Trail, RA=Raspberry 

Island, SA=Sand Island, STPI=Stockton Island, Presque Isle, STTP=Stockton Island, Trout Point Trail.
56

Table A2. Breeding bird survey routes and number of annually completed survey points (130 total) at Isle Royale National Park, 1994–2013. Bold 

numbers indicate data used in regression analyses.

Year

Route* 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

PASS 6 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4

TMLC 15 15 17 17 16 16 16 16 16 16 16 16 16 16 16 16 16 16 16 16

MTOJ 17 17 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19

CHLR 16 16 16 16 16 16 16 16 15 16 16 16 16 16 16 16 16 16

LRGR 9 20 16 20 20 19 20 20 20 20 20 20 20 20 20 20 20 20 20

ISTR 9 6 18 18 18 18 18 18 18 18 16 18 18 18 18 18 18 18 18 18

FELK 15 11 18 14 16 16 16 16 16 16 16 16 16 16 16 16 16 16 16 16

WIND 13 17 21 18 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21

Total 75 85 133 122 130 130 129 130 130 130 127 130 130 130 130 130 130 130 130 130

* PASS=Passage Island, TMLC=ThreeMile to Lane Cove Trail, MTOJ=Mt. Ojibway Loop, CHLR=Chippewa Harbor to Lake Richie, LRGR=Lake Richie to the Greenstone Ridge, 

ISTR=Ishpeming Trail, FELK=Feldtmann Lake, WIND=Windigo.
57

Table A3. Number of annual breeding bird survey points completed for routes at Saint Croix National Scenic Riverway, 1982–2013. Bold 

numbers indicate data used in regression analyses. Years with floating counts are distinguished from anchored counts. Length of count survey is 

also separated (** = 5-minute surveys were conducted in 2007).

Floating Counts Anchored Counts

3-minute surveys 6-minute surveys

Route* 1982 1983 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007** 2008 2009 2010 2011 2012 2013 2014

LOSA 50 53 52 52 53 45 53 52 53 53

LNAM 50 50 50 50 50 49 50 50 50

UNAM 50 50 50 49 50 50 4 50 50

SACN 19 50 50 50 34 50 49 50

USAC 46 41 40 47 47 47

MSAC 50 50

* LOSA =Lower St. Croix River, from St. Croix Falls to Stillwater; LNAM=Lower Namekagon River, from County K Landing to Totogatic River; UNAM=Upper Namekagon River, from 

Namekagon Dam to Phipps Flowage; SACN=St. Croix River North, from Highway 77/48 to Highway 70; USAC= Upper St. Croix River, from Gordon Dam to Riverside; MSAC=Middle 

St. Croix River, from Raspberry Landing to Nevers Dam.
58

Table A4. Breeding bird survey points, by habitat, at Sleeping Bear Dunes National Lakeshore, 

2004–2013. An “X” indicates points that were completed; dashes indicate points that were not 

completed.

Year

Location Name Point 2004 2005 2006 2009 2010 2011 2012 2013

Beech-Maple Forest

Shauger Hill BM-1 X X X X X X X X

Shauger Hill BM-2 X X X X X X X X

Burnham Road BM-3 X X X X X X X X

Burnham Road BM-4 X X X X X X X X

Treat Farm BM-5 X X X X X X X X

Treat Farm BM-6 X X X X X X X X

Scenic Drive #8 BM-7 X X X X X X X X

Coastal 

Oak-Pine Forest

Good Harbor CF1/7** X X X X X X X X

Good Harbor Bay CF-2 X X X X X X X X

Otter Creek CF-3 X X X X X X X X

Otter Creek CF-4 X X X X X X X X

Peterson Road CF-5 X X X X X X X X

Glen Haven CF-6 X X X X X X X X

Dunes

Dune Trail/Sleeping Bear Point* D-1 X X X X X X X X

Dune Trail/Sleeping Bear Point* D-2 X X X X X X X X

Cottonwood Trail D-3 X X X X X X X X

Cottonwood Trail D-4 X X X X X X X X

9/10 Overlook D-5 X X X X X X X X

Scenic Drive #5 D-6 X X X X X X X X

Fields

DH Day Field F-1 X X X X X X X X

Norconk/Stormer Road* F-2 X X X X X X X X

Aral Hills F-3 X X X -- X X X X

Kelderhouse Road F-4 X X X X X X X X

Air Station F-5 X X X X X X X X

Esch + M22 F-6 X X X X X X X X

Edge

9-10 Parking Lot/Scenic Drive* E-1 X X X X X X X X

School Lake E-2 X X X X X X X X

Glen Haven/Maritime Museum* E-3 X X X X X X X X

Mill Pond E-4 X X X X X X X X

Inland 

Lake

Tucker Lake IL-1 X X X X X X X X

Bass Lake/Benzie IL-2 X X X X X X X X

Narada Lake IL-3 X X X X X X X X

Shore/ 

Foredune

Glen Haven SF-1 X X X X X X X X

Otter Creek SF-2 X X X X X X X X

Peterson Road SF-3 X X X X -- X X X

Good Harbor SF-4 X X X X X X X X

Wetland

Mill Pond W-1 X X X X X X X X

Westman Road W-2 X X X X X X X X

Kelderhouse Road W-3 X X X X X X X X

Otter Creek W-4 -- X X X X X X X

Peterson + Lasso W-5 -- -- -- X X X X X

* = Site listed under two location names in the database but the point alpha-numeric is the same.

** = Good Harbor point CF-1 is sometimes listed as CF-7 in the park’s worksheet.
59

Table A5. Breeding bird survey routes and number of annually completed survey points at Voyageurs National Park, 1996–2013. Bold 

numbers indicate data used in regression analyses; other routes were considered too incomplete for valid regressions.

Year

Route* 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

BBST 10 10 10 10 10 10 10 10 10 9 10 10 10 9 10 10 10

EBTR 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10

RLVC 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10

BABT 10 9 10 10 10 10 10 10 10 10 10 10 10 10 10 10

DWI 10 10 10 10 10 10 10 10 10 10 10 10 7

LBPT 10 10 10 10 10 10 10 10 10 6 6

ABLT 10 10 10 10 9 10 1 10 8 10 10

KATR 10 10 10 10 10 10 10 10 10

CLT 7 10

ARTR 10 10

Total 7 40 59 60 60 70 60 80 70 80 68 80 61 80 69 38 73 66

* BBST=Black Bay Ski Trail, EBTR=Echo Bay Trail, RLVC=Rainy Lake Visitor Center, BABT=Blind Ash Bay Trail, DWI=Dryweed Island, LBPT=Lost Bay Portage Trail, 

ABLT=Anderson Bay Loop Trail, KATR=Kabetogama Lake Trail, CLT=Cruiser Lake Trail, ARTR=Ash River Ski Trail.

61

Appendix B: Regression Analysis Details

Table B1. Regression trends (average proportional change per year), r2, P and total and 

annual mean individuals observed during 10-minute point counts at Apostle Islands National 

Lakeshore, 1995–2009, arranged by trend and P-value. Species in bold indicate P≤0.05.

Species listed as special concern (SC) in Wisconsin and species on a watch list (WL) or 

common but in steep decline (SD) in the United States are noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

Hermit Thrush + 0.04 0.42 0.0164 360 28

Blue Jay + 0.04 0.42 0.0167 509 39

Yellow-bellied Sapsucker* + 0.03 0.37 0.0348 152 12

Northern Parula + 0.02 0.43 0.0152 307 24

Ovenbird + 0.01 0.58 0.0026 1907 147

American Robin + 0.01 0.32 0.0432 338 26

Chipping Sparrow + 0.01 0.31 0.0491 287 22

Savannah Sparrow + 0.03 0.29 0.06 27 2.1

American Crow + 0.02 0.23 0.10 344 26

Northern Flicker + 0.03 0.17 0.16 57 4.4

Swainson’s Thrush* (SC) + 0.02 0.32 0.07 163 13

Red-breasted Nuthatch + 0.02 0.17 0.16 223 17

Cape May Warbler (SC, SD) + 0.02 0.10 0.29 21 1.6

American Goldfinch + 0.02 0.08 0.36 48 3.7

Red-eyed Vireo1+ 0.01 0.20 0.13 1778 137

Yellow-rumped Warbler + 0.01 0.12 0.24 458 35

Eastern Wood Pewee + 0.01 0.11 0.27 102 7.8

Alder Flycatcher + 0.01 0.10 0.30 71 5.5

Canada Warbler* (SC, WL) + 0.01 0.09 0.33 85 6.5

Bay-breasted Warbler + 0.01 0.01 0.74 29 2.2

Common Yellowthroat* + 0.00 0.13 0.26 305 23

Black-throated Green Warbler* + 0.00 0.06 0.40 1296 100

White-throated Sparrow + 0.00 0.01 0.78 194 15

Black-capped Chickadee + 0.00 0.00 0.89 278 21

Swamp Sparrow + 0.00 0.00 0.90 26 2

Nashville Warbler + 0.00 0.00 0.95 851 65

Rose-breasted Grosbeak + 0.00 0.00 0.95 35 2.7

Downy Woodpecker + 0.00 0.00 0.96 23 1.8

Mourning Warbler* + 0.00 0.00 0.98 42 3.2

Black-and-White Warbler + 0.00 0.00 0.99 270 21

American Three-toed Woodpecker ▪ ▪ ▪ 1 0.08

Baltimore Oriole ▪ ▪ ▪ 3 0.23

Bank Swallow (SD) ▪ ▪ ▪ 2 0.15

Barn Swallow ▪ ▪ ▪ 21 1.6

Belted Kingfisher ▪ ▪ ▪ 18 1.4

Black-backed Woodpecker (SC) ▪ ▪ ▪ 2 0.15

Black-billed Cuckoo (SC, WL) ▪ ▪ ▪ 19 1.5

Blackpoll Warbler (SD) ▪ ▪ ▪ 2 0.15

Bobolink (SC, WL) ▪ ▪ ▪ 3 0.23

Brown-headed Cowbird ▪ ▪ ▪ 5 0.38

* Outliers were removed from trend anaylses for these species.

1 AMRE and REVI do not fit normal distribution; included because of regularity of data and abundance across years.
62

Table B1 (continued). Regression trends (average proportional change per year), r2, P and 

total and annual mean individuals observed during 10-minute point counts at Apostle Islands 

National Lakeshore, 1995–2009, arranged by trend and P-value. Species in bold indicate 

P≤0.05. Species listed as special concern (SC) in Wisconsin and species on a watch list 

(WL) or common but in steep decline (SD) in the United States are noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

Brown Thrasher (SC) ▪ ▪ ▪ 2 0.15

Chimney Swift (SD) ▪ ▪ ▪ 110 8.5

Clay-colored Sparrow ▪ ▪ ▪ 10 0.77

Cliff Swallow ▪ ▪ ▪ 1 0.08

Connecticut Warbler (SC, WL) ▪ ▪ ▪ 14 1.1

Dark-eyed Junco ▪ ▪ ▪ 6 0.46

Eastern Bluebird ▪ ▪ ▪ 4 0.31

European Starling ▪ ▪ ▪ 2 0.15

Evening Grosbeak (SC, WL) ▪ ▪ ▪ 13 1

Field Sparrow (SC) ▪ ▪ ▪ 1 0.08

Golden-crowned Kinglet ▪ ▪ ▪ 44 3.4

Grasshopper Sparrow (SC, SD) ▪ ▪ ▪ 1 0.08

Gray-cheeked Thrush ▪ ▪ ▪ 1 0.08

Gray Catbird ▪ ▪ ▪ 4 0.31

Great Crested Flycatcher ▪ ▪ ▪ 20 1.5

House Wren ▪ ▪ ▪ 1 0.08

Indigo Bunting ▪ ▪ ▪ 2 0.15

Killdeer ▪ ▪ ▪ 20 1.5

Lincoln’s Sparrow ▪ ▪ ▪ 8 0.62

Marsh Wren ▪ ▪ ▪ 6 0.46

Mourning Dove ▪ ▪ ▪ 1 0.08

Northern Cardinal ▪ ▪ ▪ 1 0.08

Northern Waterthrush ▪ ▪ ▪ 4 0.31

Olive-sided Flycatcher (SC, WL) ▪ ▪ ▪ 9 0.69

Palm Warbler ▪ ▪ ▪ 13 1

Purple Finch ▪ ▪ ▪ 4 0.31

Pileated Woodpecker ▪ ▪ ▪ 57 4.4

Pine Siskin (SD) ▪ ▪ ▪ 13 1

Pine Warbler ▪ ▪ ▪ 35 2.7

Philadelphia Vireo (SC) ▪ ▪ ▪ 27 2.1

Red Crossbill (SC) ▪ ▪ ▪ 5 0.38

Ruby-crowned Kinglet (SC) ▪ ▪ ▪ 8 0.62

Ruby-throated Hummingbird ▪ ▪ ▪ 11 0.85

Ruffed Grouse ▪ ▪ ▪ 3 0.23

Scarlet Tanager ▪ ▪ ▪ 16 1.2

Sedge Wren ▪ ▪ ▪ 4 0.31

Tennessee Warbler ▪ ▪ ▪ 12 0.92

Vesper Sparrow (SC) ▪ ▪ ▪ 1 0.08

White-breasted Nuthatch ▪ ▪ ▪ 19 1.5

Western Meadowlark (SC) ▪ ▪ ▪ 1 0.08

* Outliers were removed from trend anaylses for these species.

1 AMRE and REVI do not fit normal distribution; included because of regularity of data and abundance across years.
63

Table B1 (continued). Regression trends (average proportional change per year), r2, P and 

total and annual mean individuals observed during 10-minute point counts at Apostle Islands 

National Lakeshore, 1995–2009, arranged by trend and P-value. Species in bold indicate 

P≤0.05. Species listed as special concern (SC) in Wisconsin and species on a watch list 

(WL) or common but in steep decline (SD) in the United States are noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

White-winged Crossbill (SC) ▪ ▪ ▪ 9 0.69

Willow Flycatcher (SC) ▪ ▪ ▪ 6 0.46

Wilson’s Warbler (SC, SD) ▪ ▪ ▪ 11 0.85

Wood Thrush (SC, WL) ▪ ▪ ▪ 3 0.23

Yellow-throated Vireo ▪ ▪ ▪ 2 0.15

Common Raven - 0.00 0.00 0.91 43 3.3

Eastern Phoebe - 0.00 0.00 0.89 23 1.8

Magnolia Warbler - 0.00 0.01 0.76 205 16

Least Flycatcher* (SC) - 0.01 0.04 0.52 118 9.1

Blackburnian Warbler* - 0.01 0.05 0.49 180 14

Black-throated Blue Warbler (SC) - 0.01 0.04 0.49 125 9.6

Eastern Kingbird - 0.01 0.05 0.47 29 2.2

Veery (SC) - 0.01 0.08 0.36 269 21

Song Sparrow - 0.01 0.19 0.14 426 33

American Redstart1- 0.01 0.20 0.13 847 65

Blue-headed Vireo - 0.02 0.09 0.32 50 3.8

Winter Wren - 0.02 0.16 0.17 285 22

Red-winged Blackbird - 0.02 0.19 0.14 247 19

Chestnut-sided Warbler - 0.02 0.28 0.06 199 15

Cedar Waxwing - 0.03 0.08 0.36 163 13

Yellow Warbler - 0.03 0.15 0.19 54 4.2

Hairy Woodpecker - 0.03 0.17 0.17 45 3.5

Tree Swallow - 0.04 0.32 0.0432 31 2.4

Common Grackle (SD) - 0.04 0.37 0.0261 19 1.5

Brown Creeper - 0.04 0.68 0.0005 67 5.2

Yellow-bellied Flycatcher (SC) - 0.07 0.64 0.0011 49 3.8

* Outliers were removed from trend anaylses for these species.

1 AMRE and REVI do not fit normal distribution; included because of regularity of data and abundance across years.
64

Table B2. Regression trends (average proportional change per year), r2, P and total 

and mean individuals observed during 10-minute point counts at Grand Portage 

National Monument, 1999–2014, arranged by trend and P-value. Species in bold

indicate P≤0.05. Species listed as special concern (SC) in Minnesota, species common 

but in steep decline (SD), or on the NABCI (2014) watch list (WL) in the United States 

are noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

Yellow-rumped Warbler* + 0.03 0.28 0.0498 112 7.5

Nashville Warbler* + 0.01 0.38 0.0241 339 23

Northern Flicker* + 0.03 0.19 0.12 101 6.7

Alder Flycatcher + 0.01 0.21 0.08 108 7.2

Song Sparrow + 0.01 0.19 0.10 96 6.4

Magnolia Warbler + 0.01 0.11 0.24 383 26

American Robin + 0.01 0.10 0.26 324 22

Winter Wren + 0.01 0.09 0.29 268 18

Purple Finch + 0.01 0.05 0.40 32 2.1

American Redstart* + 0.01 0.06 0.41 353 24

Yellow-bellied Sapsucker + 0.01 0.04 0.47 344 23

Brown Creeper* + 0.01 0.05 0.47 85 5.7

Blue Jay + 0.01 0.01 0.69 177 12

Common Yellowthroat* + 0.00 0.03 0.57 60 4

Canada Warbler (WL) + 0.00 0.01 0.67 167 11

White-throated Sparrow + 0.00 0.01 0.68 732 49

Swainson’s Thrush + 0.00 0.01 0.70 268 18

Swamp Sparrow1+ 0.00 0.01 0.76 46 3.1

American Goldfinch + 0.00 0.00 0.81 21 1.4

American Crow + 0.00 0.00 0.85 170 11

Black-and-White Warbler* + 0.00 0.00 0.90 124 8.3

American Bittern ▪ ▪ ▪ 5 0.33

Bay-breasted Warbler ▪ ▪ ▪ 2 0.13

Belted Kingfisher ▪ ▪ ▪ 3 0.2

Black-billed Cuckoo (WL) ▪ ▪ ▪ 7 0.47

Black-throated Blue Warbler ▪ ▪ ▪ 13 0.87

Blue-headed Vireo ▪ ▪ ▪ 31 2.1

Brown-headed Cowbird ▪ ▪ ▪ 2 0.13

Cerulean Warbler (SC, WL) ▪ ▪ ▪ 3 0.2

Chimney Swift (SD) ▪ ▪ ▪ 4 0.27

Common Grackle (SD) ▪ ▪ ▪ 9 0.6

Dark-eyed Junco ▪ ▪ ▪ 1 0.07

Eastern Kingbird ▪ ▪ ▪ 1 0.07

Eastern Phoebe ▪ ▪ ▪ 11 0.73

Gray Catbird ▪ ▪ ▪ 3 0.2

Gray Jay ▪ ▪ ▪ 14 0.93

Great Crested Flycatcher ▪ ▪ ▪ 10 0.67

Hairy Woodpecker ▪ ▪ ▪ 38 2.5

House Wren ▪ ▪ ▪ 2 0.13

Indigo Bunting ▪ ▪ ▪ 3 0.2

1 SWSP did not fit normal distribution; included because of regularity of data and abundance across years. 

EVGR included due to likely ecological importance of decline.

* Outliers were removed from trend analyses for these species.
65

Table B2 (continued). Regression trends (average proportional change per year), r2, 

P and total and mean individuals observed during 10-minute point counts at Grand 

Portage National Monument, 1999–2014, arranged by trend and P-value. Species in 

bold indicate P≤0.05. Species listed as special concern (SC) in Minnesota, species 

common but in steep decline (SD), or on the NABCI (2014) watch list (WL) in the 

United States are noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

Lincoln’s Sparrow ▪ ▪ ▪ 2 0.13

Mourning Dove ▪ ▪ ▪ 1 0.07

Northern Cardinal ▪ ▪ ▪ 2 0.13

Northern Waterthrush ▪ ▪ ▪ 21 1.4

Orange-crowned Warbler ▪ ▪ ▪ 1 0.07

Olive-sided Flycatcher (WL) ▪ ▪ ▪ 2 0.13

Pine Siskin (SD) ▪ ▪ ▪ 3 0.2

Pine Warbler ▪ ▪ ▪ 1 0.07

Philadelphia Vireo ▪ ▪ ▪ 6 0.4

Red-winged Blackbird ▪ ▪ ▪ 4 0.27

Ruby-crowned Kinglet ▪ ▪ ▪ 11 0.73

Ruby-throated Hummingbird ▪ ▪ ▪ 33 2.2

Ruffed Grouse ▪ ▪ ▪ 95 6.3

Scarlet Tanager ▪ ▪ ▪ 7 0.47

Sedge Wren ▪ ▪ ▪ 12 0.8

Tennessee Warbler ▪ ▪ ▪ 2 0.13

Tree Swallow ▪ ▪ ▪ 10 0.67

Warbling Vireo ▪ ▪ ▪ 1 0.07

White-breasted Nuthatch ▪ ▪ ▪ 8 0.53

White-winged Crossbill ▪ ▪ ▪ 1 0.07

Wilson’s Snipe ▪ ▪ ▪ 7 0.47

Wilson’s Warbler (SD) ▪ ▪ ▪ 4 0.27

Wood Thrush ▪ ▪ ▪ 1 0.07

Yellow-bellied Flycatcher ▪ ▪ ▪ 44 2.9

Yellow Warbler ▪ ▪ ▪ 2 0.13

Cedar Waxwing - 0.00 0.00 0.96 86 5.7

Golden-crowned Kinglet - 0.00 0.00 0.90 86 5.7

Red-breasted Nuthatch - 0.00 0.00 0.88 252 17

Red-eyed Vireo - 0.00 0.01 0.74 681 45

Black-throated Green Warbler* - 0.00 0.02 0.58 516 34

Eastern Wood Pewee - 0.01 0.03 0.57 23 1.5

Rose-breasted Grosbeak - 0.01 0.05 0.42 97 6.5

Northern Parula - 0.01 0.07 0.34 338 23

Veery - 0.01 0.20 0.09 352 23

Common Raven - 0.02 0.04 0.47 88 5.9

Chipping Sparrow - 0.02 0.07 0.33 81 5.4

Mourning Warbler - 0.02 0.20 0.09 237 16

Black-capped Chickadee - 0.03 0.20 0.10 149 9.9

Blackburnian Warbler - 0.03 0.25 0.06 221 15

Ovenbird - 0.01 0.31 0.0326 920 61

1 SWSP did not fit normal distribution; included because of regularity of data and abundance across years. 

EVGR included due to likely ecological importance of decline.

* Outliers were removed from trend analyses for these species.
66

Table B2 (continued). Regression trends (average proportional change per year), r2, 

P and total and mean individuals observed during 10-minute point counts at Grand 

Portage National Monument, 1999–2014, arranged by trend and P-value. Species in 

bold indicate P≤0.05. Species listed as special concern (SC) in Minnesota, species 

common but in steep decline (SD), or on the NABCI (2014) watch list (WL) in the 

United States are noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

Hermit Thrush - 0.04 0.28 0.0406 65 4.3

Chestnut-sided Warbler - 0.04 0.45 0.0065 182 12

Pileated Woodpecker - 0.05 0.37 0.0170 97 6.5

Downy Woodpecker - 0.05 0.38 0.0143 60 4

Least Flycatcher - 0.05 0.44 0.0075 118 7.9

Evening Grosbeak1(WL) - 0.07 0.40 0.0115 59 3.9

1 SWSP did not fit normal distribution; included because of regularity of data and abundance across years. 

EVGR included due to likely ecological importance of decline.

* Outliers were removed from trend analyses for these species.
67

Table B3. Regression trends (average proportional change per year), r2, P and total and 

mean individuals observed during 3-minute roadside point counts at Indiana Dunes 

National Lakeshore, 1993–2013, arranged by trend and P-value. Species in bold indicate 

P≤0.05. Species listed as endangered (EN) or special concern (SC) in Indiana are noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

Red-bellied Woodpecker + 0.03 0.33 0.0101 108 5.7

Willow Flycatcher* + 0.02 0.36 0.0084 145 7.6

Marsh Wren (EN) + 0.02 0.23 0.0385 49 2.6

Warbling Vireo + 0.01 0.31 0.0137 65 3.4

Red-winged Blackbird + 0.01 0.21 0.0476 466 25

Chipping Sparrow* + 0.01 0.21 0.05 163 8.6

Common Grackle + 0.01 0.11 0.17 95 5

Barn Swallow + 0.01 0.09 0.22 134 7.1

Eastern Wood Pewee* + 0.01 0.09 0.23 179 9.4

Mourning Dove* + 0.01 0.06 0.33 87 4.6

Great Crested Flycatcher + 0.01 0.06 0.33 141 7.4

American Goldfinch* + 0.01 0.04 0.46 278 15

Yellow Warbler* + 0.00 0.07 0.29 462 24

Blue-gray Gnatcatcher* + 0.00 0.02 0.56 118 6.2

House Wren + 0.00 0.02 0.57 291 15

Common Yellowthroat + 0.00 0.01 0.64 374 20

Gray Catbird + 0.00 0.01 0.70 359 19

Downy Woodpecker + 0.00 0.00 0.89 60 3.2

Acadian Flycatcher ▪ ▪ ▪ 47 2.5

Alder Flycatcher ▪ ▪ ▪ 18 0.95

Baltimore Oriole ▪ ▪ ▪ 19 1

Bank Swallow ▪ ▪ ▪ 10 0.53

Belted Kingfisher ▪ ▪ ▪ 4 0.21

Black-billed Cuckoo ▪ ▪ ▪ 1 0.05

Black-throated Green Warbler ▪ ▪ ▪ 4 0.21

Blue-winged Warbler ▪ ▪ ▪ 9 0.47

Bobolink ▪ ▪ ▪ 1 0.05

Brown Thrasher ▪ ▪ ▪ 13 0.68

Canada Warbler ▪ ▪ ▪ 1 0.05

Carolina Wren ▪ ▪ ▪ 2 0.11

Cerulean Warbler (EN) ▪ ▪ ▪ 19 1

Chestnut-sided Warbler ▪ ▪ ▪ 22 1.15

Dickcissel ▪ ▪ ▪ 2 0.11

Eastern Bluebird ▪ ▪ ▪ 17 0.89

Eastern Kingbird ▪ ▪ ▪ 16 0.84

Eastern Meadowlark ▪ ▪ ▪ 3 0.16

Eastern Phoebe ▪ ▪ ▪ 26 1.4

Field Sparrow ▪ ▪ ▪ 71 3.7

Golden-winged Warbler (EN) ▪ ▪ ▪ 1 0.05

Hairy Woodpecker ▪ ▪ ▪ 4 0.21

Hooded Warbler (SC) ▪ ▪ ▪ 24 1.3

House Finch ▪ ▪ ▪ 28 1.5

Killdeer ▪ ▪ ▪ 11 0.58

* Outliers were removed from trend analyses for these species.
68

Table B3 (continued). Regression trends (average proportional change per year), r2, P 

and total and mean individuals observed during 3-minute roadside point counts at Indiana 

Dunes National Lakeshore, 1993–2013, arranged by trend and P-value. Species in bold

indicate P≤0.05. Species listed as endangered (EN) or special concern (SC) in Indiana are 

noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

Least Flycatcher ▪ ▪ ▪ 6 0.32

Louisiana Waterthrush ▪ ▪ ▪ 9 0.47

Mourning Warbler ▪ ▪ ▪ 1 0.05

Northern Flicker ▪ ▪ ▪ 11 0.58

Northern Parula ▪ ▪ ▪ 1 0.05

Northern Rough-winged Swallow ▪ ▪ ▪ 3 0.16

Pileated Woodpecker ▪ ▪ ▪ 8 0.42

Prairie Warbler ▪ ▪ ▪ 13 0.68

Purple Martin ▪ ▪ ▪ 5 0.26

Red-headed Woodpecker ▪ ▪ ▪ 4 0.21

Rock Pigeon ▪ ▪ ▪ 13 0.68

Rose-breasted Grosbeak ▪ ▪ ▪ 21 1.1

Ruby-throated Hummingbird ▪ ▪ ▪ 14 0.74

Scarlet Tanager ▪ ▪ ▪ 32 1.7

Sedge Wren (EN) ▪ ▪ ▪ 4 0.21

Summer Tanager ▪ ▪ ▪ 1 0.05

Swainson’s Thrush ▪ ▪ ▪ 1 0.05

Tree Swallow ▪ ▪ ▪ 80 4.2

White-breasted Nuthatch ▪ ▪ ▪ 45 2.4

White-eyed Vireo ▪ ▪ ▪ 13 0.68

Yellow-billed Cuckoo ▪ ▪ ▪ 1 0.05

Yellow-breasted Chat ▪ ▪ ▪ 3 0.16

Yellow-throated Vireo ▪ ▪ ▪ 65 3.4

American Redstart - 0.00 0.00 0.98 229 12

Red-eyed Vireo* - 0.00 0.00 0.96 315 17

Wood Thrush* - 0.00 0.00 0.86 98 5.2

House Sparrow - 0.00 0.00 0.80 110 5.8

Swamp Sparrow* - 0.00 0.01 0.74 89 4.7

Indigo Bunting - 0.00 0.02 0.59 215 11

American Robin - 0.00 0.03 0.51 475 25

Eastern Towhee - 0.00 0.03 0.48 182 9.6

Brown-headed Cowbird - 0.00 0.03 0.47 301 15.8

Black-capped Chickadee* - 0.00 0.06 0.33 101 5.3

Northern Cardinal - 0.00 0.06 0.30 502 26

American Crow* - 0.01 0.07 0.31 358 19

Tufted Titmouse - 0.01 0.06 0.30 183 9.6

Song Sparrow* - 0.01 0.10 0.21 259 14

European Starling - 0.02 0.09 0.21 89 4.7

Ovenbird - 0.02 0.20 0.06 58 3.1

Chimney Swift* - 0.02 0.20 0.06 123 6.5

Veery - 0.02 0.33 0.0107 74 3.9

Blue Jay* - 0.02 0.52 0.0017 103 5.4

Cedar Waxwing - 0.04 0.39 0.0043 249 13

* Outliers were removed from trend analyses for these species.
69

Table B4. Regression trends (average proportional change per year), r2, P and total and 

mean individuals observed during 5-minute point counts at Isle Royale National Park, 

1996–2013, arranged by trend and P-value. Species in bold indicate P≤0.05. Species 

listed as special concern (SC) in Michigan and species common but in steep decline (SD) 

in the United States are noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

Alder Flycatcher + 0.03 0.55 0.0004 421 23

Red-winged Blackbird + 0.03 0.25 0.0365 47 2.6

American Robin + 0.02 0.54 0.0005 830 46

Common Yellowthroat + 0.02 0.40 0.0046 110 6.1

Red-breasted Nuthatch1

+ 0.02 0.38 0.0067 727 40

Swamp Sparrow* + 0.01 0.29 0.0303 172 9.6

Swainson’s Thrush + 0.01 0.24 0.0399 265 15

Golden-crowned Kinglet* + 0.02 0.22 0.06 339 19

Northern Parula + 0.02 0.13 0.14 39 2.2

Nashville Warbler* + 0.01 0.21 0.07 2409 134

Blue Jay* + 0.01 0.15 0.12 735 41

Song Sparrow + 0.01 0.14 0.12 200 11

Hermit Thrush*

1

+ 0.01 0.13 0.14 1166 65

Northern Waterthrush* + 0.01 0.13 0.15 66 3.7

Northern Flicker* + 0.01 0.12 0.16 188 10

Hairy Woodpecker + 0.01 0.10 0.21 196 11

Black-throated Green Warbler* + 0.01 0.09 0.21 1245 69

Winter Wren + 0.01 0.09 0.22 2094 116

Yellow-bellied Flycatcher + 0.01 0.05 0.35 265 15

Mourning Warbler + 0.01 0.05 0.37 344 19

Wilson’s Snipe* + 0.01 0.04 0.43 200 11

Pileated Woodpecker* + 0.01 0.05 0.44 195 11

White-throated Sparrow* + 0.00 0.13 0.20 2599 144

Yellow-rumped Warbler + 0.00 0.04 0.42 502 28

Magnolia Warbler + 0.00 0.03 0.46 986 55

Black-capped Chickadee + 0.00 0.01 0.67 633 35

Veery + 0.00 0.00 0.84 188 10

American Bittern (SC) ▪ ▪ ▪ 25 1.4

American Goldfinch ▪ ▪ ▪ 35 1.9

Barn Swallow ▪ ▪ ▪ 1 0.06

Bay-breasted Warbler ▪ ▪ ▪ 6 0.33

Belted Kingfisher ▪ ▪ ▪ 15 0.83

Black-backed Woodpecker (SC) ▪ ▪ ▪ 1 0.06

Black-billed Cuckoo ▪ ▪ ▪ 15 0.83

Black-headed Grosbeak ▪ ▪ ▪ 1 0.06

Blue-headed Vireo ▪ ▪ ▪ 29 1.6

Brown Thrasher ▪ ▪ ▪ 1 0.06

Chimney Swift (SD) ▪ ▪ ▪ 24 1.3

Dark-eyed Junco ▪ ▪ ▪ 4 0.22

Eastern Bluebird ▪ ▪ ▪ 1 0.06

1 Species do not fit normal distribution; HETH and RBNU included because of regularity of data and abundance 

across years; CMWA and EVGR included due to possible ecological importance of decline.

* Outliers were removed from trend analyses.
70

Table B4 (continued). Regression trends (average proportional change per year), r2, P 

and total and mean individuals observed during 5-minute point counts at Isle Royale 

National Park, 1996–2013, arranged by trend and P-value. Species in bold indicate 

P≤0.05. Species listed as special concern (SC) in Michigan and species common but in 

steep decline (SD) in the United States are noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

Eastern Kingbird ▪ ▪ ▪ 2 0.11

Eastern Phoebe ▪ ▪ ▪ 1 0.06

Eastern Wood Pewee ▪ ▪ ▪ 12 0.67

Gray Catbird ▪ ▪ ▪ 2 0.11

Gray Jay ▪ ▪ ▪ 70 3.9

Great Crested Flycatcher ▪ ▪ ▪ 6 0.33

Indigo Bunting ▪ ▪ ▪ 28 1.6

Marsh Wren (SC) ▪ ▪ ▪ 1 0.06

Mourning Dove ▪ ▪ ▪ 1 0.06

Northern Cardinal ▪ ▪ ▪ 2 0.11

Olive-sided Flycatcher ▪ ▪ ▪ 17 0.94

Orange-crowned Warbler ▪ ▪ ▪ 1 0.06

Palm Warbler ▪ ▪ ▪ 3 0.17

Philadelphia Vireo ▪ ▪ ▪ 2 0.11

Pine Siskin (SD) ▪ ▪ ▪ 68 3.8

Pine Warbler ▪ ▪ ▪ 5 0.28

Purple Finch ▪ ▪ ▪ 21 1.2

Red Crossbill ▪ ▪ ▪ 53 2.9

Rose-breasted Grosbeak ▪ ▪ ▪ 27 1.5

Ruby-crowned Kinglet ▪ ▪ ▪ 35 1.9

Scarlet Tanager ▪ ▪ ▪ 25 1.4

Sedge Wren ▪ ▪ ▪ 3 0.17

Tennessee Warbler ▪ ▪ ▪ 14 0.78

White-breasted Nuthatch ▪ ▪ ▪ 21 1.2

White-winged Crossbill ▪ ▪ ▪ 70 3.9

Wood Thrush ▪ ▪ ▪ 1 0.06

Yellow-bellied Sapsucker ▪ ▪ ▪ 70 3.9

Yellow-billed Cuckoo (SD) ▪ ▪ ▪ 1 0.06

Yellow-breasted Chat ▪ ▪ ▪ 1 0.06

Yellow Warbler ▪ ▪ ▪ 3 0.17

Common Grackle (SD)* - 0.00 0.00 0.98 102 5.7

Blackburnian Warbler - 0.00 0.00 0.97 175 9.7

Cedar Waxwing* - 0.00 0.00 0.97 395 22

Black-throated Blue Warbler - 0.00 0.00 0.88 147 8.2

Ovenbird - 0.00 0.00 0.81 2472 137

Canada Warbler* - 0.00 0.02 0.63 78 4.3

Red-eyed Vireo* - 0.00 0.03 0.62 1620 90

Least Flycatcher - 0.01 0.04 0.45 64 3.6

Chestnut-sided Warbler - 0.01 0.12 0.15 861 48

American Redstart - 0.01 0.15 0.11 491 27

1 Species do not fit normal distribution; HETH and RBNU included because of regularity of data and abundance 

across years; CMWA and EVGR included due to possible ecological importance of decline.

* Outliers were removed from trend analyses.
71

Table B4 (continued). Regression trends (average proportional change per year), r2, P 

and total and mean individuals observed during 5-minute point counts at Isle Royale 

National Park, 1996–2013, arranged by trend and P-value. Species in bold indicate 

P≤0.05. Species listed as special concern (SC) in Michigan and species common but in 

steep decline (SD) in the United States are noted.

Species Trend r

2

P

Total

Individuals

Mean 

Individuals 

Annually

Brown Creeper* - 0.01 0.19 0.09 365 20

Black-and-White Warbler* - 0.01 0.20 0.07 204 11

Downy Woodpecker - 0.02 0.17 0.09 183 10

American Crow - 0.02 0.40 0.0047 477 27

Common Raven - 0.03 0.61 0.0001 228 13

Chipping Sparrow - 0.04 0.58 0.0002 196 11

Cape May Warbler (SD) 1

- 0.06 0.54 0.0005 45 2.5

Evening Grosbeak 1

- 0.06 0.58 0.0003 35 1.9

1 Species do not fit normal distribution; HETH and RBNU included because of regularity of data and abundance 

across years; CMWA and EVGR included due to possible ecological importance of decline.

* Outliers were removed from trend analyses.
72

Table B5. Regression trends (average proportional change per year) for species showing no significant change, including r2, P and total and 

mean individuals observed annually during 3-minute point counts at Saint Croix National Scenic Riverway, 1998–2014, arranged alphabetically 

by trend and P-value. Non-normal distribution indicated by “▪” symbol; species not occurring indicated by “n/a”. Species listed as threatened 

(THR) or special concern (SC) in Wisconsin and species that are on a watch list (WL) or common but in steep decline (SD) in the United States 

are noted. See discussion section for cautions regarding SACN data.

LOSA-LNAM routes UNAM-SACN routes

Increasing Trends, n = 10 Trend r

2

P

Total 

Individuals

Mean 

Individuals Trend r

2

P

Total 

Individuals

Mean 

Individuals

American Robin + 0.00 0.02 0.76 349 44 ▪ ▪ ▪ 240 35

Common Grackle (SD) + 0.03 0.36 0.12 101 13 + 0.03 0.10 0.50 54 7.7

Eastern Towhee + 0.00 0.00 0.89 14 1.8 ▪ ▪ ▪ 4 0.57

Gray Catbird + 0.00 0.00 0.96 206 26 + 0.01 0.13 0.42 149 21

Northern Waterthrush ▪ ▪ ▪ 3 0.38 + 0.02 0.06 0.61 21 3

Red-winged Blackbird + 0.01 0.14 0.36 238 30 + 0.01 0.12 0.45 314 45

Rock Pigeon + 0.03 0.23 0.23 17 2.1 ▪ ▪ ▪ 3 0.43

Ruby-throated Hummingbird ▪ ▪ ▪ 8 1 + 0.01 0.04 0.66 10 1.4

Wood Thrush (SC, WL) + 0.01 0.20 0.26 21 2.6 + 0.01 0.17 0.36 83 12

Yellow Warbler + 0.02 0.34 0.13 236 30 + 0.02 0.32 0.19 272 39

Mixed or No Trends, n = 38

Acadian Flycatcher (THR) ▪ ▪ ▪ 1 0.13 ▪ ▪ ▪ 1 0.14

Alder Flycatcher + 0.01 0.03 0.70 33 4.1 - 0.01 0.21 0.30 83 12

Black-billed Cuckoo (SC, WL) + 0.00 0.02 0.76 12 1.5 ▪ ▪ ▪ 5 0.71

Blackpoll Warbler (SD) ▪ ▪ ▪ 2 0.25 ▪ ▪ ▪ 2 0.29

Blue-winged Warbler (SC) ▪ ▪ ▪ 1 0.13 ▪ ▪ ▪ 10 1.4

Brown Creeper ▪ ▪ ▪ 1 0.13 ▪ ▪ ▪ 3 0.43

Brown-headed Cowbird - 0.02 0.44 0.07 255 32 + 0.00 0.01 0.87 71 10

Canada Warbler (SC, WL) + 0.03 0.38 0.10 47 5.9 - 0.01 0.33 0.23 73 10

Cape May Warbler (SC, SD) n/a n/a n/a n/a n/a ▪ ▪ ▪ 3 0.43

Cerulean Warbler (THR, WL) ▪ ▪ ▪ 4 0.5 ▪ ▪ ▪ 1 0.14

Chestnut-sided Warbler + 0.01 0.06 0.55 191 24 - 0.01 0.43 0.15 380 54

Clay-colored Sparrow ▪ ▪ ▪ 2 0.25 ▪ ▪ ▪ 1 0.14

Connecticut Warbler (SC) ▪ ▪ ▪ 1 0.13 n/a n/a n/a n/a n/a

Eastern Bluebird ▪ ▪ ▪ 7 0.88 ▪ ▪ ▪ 2 0.29

Evening Grosbeak (SC, WL) ▪ ▪ ▪ 1 0.13 ▪ ▪ ▪ 5 0.71

Field Sparrow (SC, SD) ▪ ▪ ▪ 3 0.38 n/a n/a n/a n/a n/a

Great Crested Flycatcher + 0.00 0.11 0.47 294 37 - 0.03 0.26 0.24 125 18

Hairy Woodpecker + 0.00 0.14 0.41 118 15 - 0.00 0.00 0.88 65 9.3
73

Table B5 (continued). Regression trends (average proportional change per year) for species showing no significant change, including r2, P 

and total and mean individuals observed annually during 3-minute point counts at Saint Croix National Scenic Riverway, 1998–2014, arranged

alphabetically by trend and P-value. Non-normal distribution indicated by “▪” symbol; species not occurring indicated by “n/a”. Species listed as 

threatened (THR) or special concern (SC) in Wisconsin and species that are on a watch list (WL) or common but in steep decline (SD) in the 

United States are noted. See discussion section for cautions regarding SACN data.

LOSA-LNAM routes UNAM-SACN routes

Mixed or No Trends, n = 38 Trend r

2

P

Total 

Individuals

Mean 

Individuals Trend r

2

P

Total 

Individuals

Mean

Individuals

Hermit Thrush ▪ ▪ ▪ 7 0.88 ▪ ▪ ▪ 9 1.3

House Finch ▪ ▪ ▪ 2 0.25 n/a n/a n/a n/a n/a

House Sparrow ▪ ▪ ▪ 1 0.13 n/a n/a n/a n/a n/a

Killdeer ▪ ▪ ▪ 2 0.25 ▪ ▪ ▪ 1 0.14

Magnolia Warbler n/a n/a n/a n/a n/a ▪ ▪ ▪ 2 0.29

Marsh Wren ▪ ▪ ▪ 7 0.88 n/a n/a n/a n/a n/a

Mourning Dove - 0.02 0.31 0.15 99 12 + 0.02 0.40 0.13 59 8.4

Purple Finch n/a n/a n/a n/a n/a ▪ ▪ ▪ 5 0.71

Purple Martin (SC) n/a n/a n/a n/a n/a ▪ ▪ ▪ 1 0.14

Red-bellied Woodpecker - 0.00 0.01 0.85 138 17 + 0.01 0.21 0.30 44 6.3

Red-breasted Nuthatch - 0.01 0.07 0.53 24 3 + 0.00 0.02 0.79 72 10

Ruffed Grouse ▪ ▪ ▪ 3 0.38 ▪ ▪ ▪ 3 0.43

Song Sparrow - 0.01 0.43 0.08 1174 147 + 0.00 0.00 0.89 809 116

Swainson’s Thrush (SC) ▪ ▪ ▪ 1 0.13 n/a n/a n/a n/a n/a

Veery (SC) - 0.01 0.36 0.12 413 52 + 0.02 0.55 0.06 359 51

Willow Flycatcher ▪ ▪ ▪ 1 0.13 n/a n/a n/a n/a n/a

Wilson’s Snipe n/a n/a n/a n/a n/a ▪ ▪ ▪ 1 0.14

Yellow-bellied Sapsucker - 0.02 0.11 0.41 44 5.5 + 0.00 0.01 0.80 37 5.3

Yellow-headed Blackbird (SC) ▪ ▪ ▪ 5 0.63 n/a n/a n/a n/a n/a

Yellow-rumped Warbler ▪ ▪ ▪ 4 0.5 ▪ ▪ ▪ 13 1.9

Negative Trends, n = 27

American Goldfinch - 0.00 0.03 0.70 246 30 ▪ ▪ ▪ 76 11

American Redstart - 0.02 0.31 0.15 208 26 - 0.01 0.05 0.62 229 33

Baltimore Oriole - 0.01 0.06 0.57 400 50 - 0.00 0.01 0.87 100 14

Bank Swallow (SD) - 0.06 0.30 0.16 1168 146 n/a n/a n/a n/a n/a

Barn Swallow - 0.04 0.46 0.07 22 2.8 ▪ ▪ ▪ 2 0.29

Blackburnian Warbler ▪ ▪ ▪ 3 0.38 - 0.06 0.37 0.14 28 4
74

Table B5 (continued). Regression trends (average proportional change per year) for species showing no significant change, including r2, P 

and total and mean individuals observed annually during 3-minute point counts at Saint Croix National Scenic Riverway, 1998–2014, arranged

alphabetically by trend and P-value. Non-normal distribution indicated by “▪” symbol; species not occurring indicated by “n/a”. Species listed as 

threatened (THR) or special concern (SC) in Wisconsin and species that are on a watch list (WL) or common but in steep decline (SD) in the 

United States are noted. See discussion section for cautions regarding SACN data.

LOSA-LNAM routes UNAM-SACN routes

Negative Trends, n = 27 Trend r

2

P

Total 

Individuals

Mean 

Individuals Trend r

2

P

Total 

Individuals

Mean 

Individuals

Black-throated Green Warbler n/a n/a n/a n/a n/a - 0.03 0.20 0.31 7 1

Blue-headed Vireo ▪ ▪ ▪ 4 0.5 - 0.02 0.28 0.22 16 2.3

Blue Jay - 0.00 0.07 0.53 250 31 - 0.01 0.09 0.52 237 34

Brown Thrasher (SC) - 0.02 0.17 0.31 10 1.3 ▪ ▪ ▪ 12 1.7

Chimney Swift (SD) - 0.03 0.22 0.25 20 2.5 n/a n/a n/a n/a n/a

Cliff Swallow - 0.02 0.02 0.72 476 60 ▪ ▪ ▪ 2 0.29

Common Raven - 0.00 0.00 0.92 24 3 - 0.01 0.05 0.62 18 2.6

Common Yellowthroat - 0.02 0.43 0.08 557 70 - 0.02 0.24 0.27 564 81

European Starling - 0.02 0.09 0.48 26 3.3 ▪ ▪ ▪ 3 0.43

House Wren - 0.03 0.39 0.10 95 12 ▪ ▪ ▪ 4 0.57

Louisiana Waterthrush (SC) - 0.02 0.07 0.54 25 3.1 ▪ ▪ ▪ 10 1.4

Northern Cardinal - 0.01 0.15 0.35 92 12 ▪ ▪ ▪ 3 0.43

Northern Flicker - 0.00 0.03 0.68 88 11 - 0.02 0.11 0.48 80 11

Northern Rough-winged Swallow - 0.03 0.42 0.08 271 34 - 0.05 0.41 0.12 17 2.4

Pileated Woodpecker - 0.01 0.11 0.41 54 6.8 - 0.02 0.26 0.25 34 4.9

Pine Warbler - 0.01 0.09 0.48 75 9.4 - 0.01 0.22 0.35 59 8.4

Prothonotary Warbler (SC, WL) - 0.01 0.05 0.59 216 27 n/a n/a n/a n/a n/a

Scarlet Tanager - 0.03 0.38 0.11 131 16 - 0.02 0.44 0.11 47 6.7

Swamp Sparrow - 0.01 0.21 0.25 44 5.5 - 0.01 0.15 0.40 96 14

White-throated Sparrow ▪ ▪ ▪ 1 0.13 - 0.00 0.22 0.29 151 22

Yellow-billed Cuckoo (SC, SD) ▪ ▪ ▪ 28 3.5 - 0.05 0.26 0.25 27 3.9
75

Table B6. Regression trends (average proportional change per year), r2, P and total and 

mean individuals observed during 10-minute point counts at Sleeping Bear Dunes National 

Lakeshore, 2004–2006 and 2009–2013, arranged by trend and P-value. Species in bold

indicate P≤0.05. Species listed as special concern (SC) in Michigan, species common but in 

steep decline (SD), or on the NABCI (2014) watch list (WL) in the United States are noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

Veery (SD) + 0.07 0.63 0.0185 19 2.38

Eastern Meadowlark (SD) + 0.05 0.75 0.0055 95 11.88

Wood Thrush* (WL) + 0.03 0.77 0.0099 65 8.13

American Robin* + 0.03 0.59 0.0450 297 37.13

Red-eyed Vireo + 0.02 0.52 0.0436 350 43.75

Field Sparrow + 0.05 0.44 0.07 26 3.25

Hairy Woodpecker + 0.05 0.37 0.11 16 2

Eastern Bluebird + 0.04 0.37 0.11 49 6.13

Eastern Towhee + 0.04 0.31 0.15 24 3

Cedar Waxwing + 0.04 0.20 0.26 105 13.13

Black-capped Chickadee + 0.03 0.36 0.12 72 9

Red-bellied Woodpecker + 0.03 0.30 0.16 14 1.75

Pine Warbler + 0.03 0.21 0.25 54 6.75

Yellow-rumped Warbler + 0.03 0.10 0.44 28 3.5

Bank Swallow + 0.03 0.04 0.62 48 6

American Redstart* + 0.02 0.42 0.11 132 16.5

Red-winged Blackbird + 0.02 0.29 0.17 300 37.5

Common Yellowthroat + 0.02 0.23 0.23 98 12.25

Eastern Wood Pewee + 0.02 0.19 0.28 97 12.13

Rose-breasted Grosbeak + 0.02 0.16 0.32 104 13

Yellow Warbler + 0.02 0.16 0.33 54 6.75

Pileated Woodpecker + 0.02 0.12 0.40 15 1.88

Northern Flicker + 0.02 0.11 0.43 59 7.38

Song Sparrow + 0.01 0.16 0.33 168 21

Least Flycatcher + 0.01 0.06 0.56 51 6.38

Chipping Sparrow* + 0.01 0.05 0.62 103 12.88

White-throated Sparrow + 0.01 0.04 0.64 15 1.88

Hermit Thrush + 0.01 0.03 0.69 36 4.5

Great Crested Flycatcher + 0.01 0.02 0.74 57 7.13

Yellow-throated Vireo + 0.01 0.02 0.75 17 2.13

Indigo Bunting + 0.00 0.02 0.77 71 8.88

Grasshopper Sparrow* (SC) + 0.00 0.01 0.82 14 1.75

Ovenbird* + 0.00 0.01 0.84 187 23.38

Vesper Sparrow + 0.00 0.00 0.88 68 8.5

Red-breasted Nuthatch + 0.00 0.00 0.92 18 2.25

Blue Jay + 0.00 0.00 0.94 133 16.6

Black-and-White Warbler ▪ ▪ ▪ 7 0.88

Blue-headed Vireo ▪ ▪ ▪ 4 0.5

Brown-headed Cowbird ▪ ▪ ▪ 10 1.25

Brown Creeper ▪ ▪ ▪ 6 0.75

* Outliers were removed from trend analyses for these species.
76

Table B6 (continued). Regression trends (average proportional change per year), r2, P and 

total and mean individuals observed during 10-minute point counts at Sleeping Bear Dunes 

National Lakeshore, 2004–2006 and 2009–2013, arranged by trend and P-value. Species 

in bold indicate P≤0.05. Species listed as special concern (SC) in Michigan, species 

common but in steep decline (SD), or on the NABCI (2014) watch list (WL) in the United 

States are noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

Canada Warbler (WL) ▪ ▪ ▪ 1 1.13

Chestnut-sided Warbler ▪ ▪ ▪ 8 1

Chimney Swift (SD) ▪ ▪ ▪ 6 0.75

Clay-colored Sparrow ▪ ▪ ▪ 1 0.13

Dickcissel (SC) ▪ ▪ ▪ 6 0.75

Downy Woodpecker ▪ ▪ ▪ 11 1.38

House Finch ▪ ▪ ▪ 6 0.75

Magnolia Warbler ▪ ▪ ▪ 2 0.25

Mourning Warbler ▪ ▪ ▪ 1 0.13

Nashville Warbler ▪ ▪ ▪ 17 2.13

Northern Mockingbird ▪ ▪ ▪ 1 0.13

Northern Parula ▪ ▪ ▪ 1 0.13

Northern Waterthrush ▪ ▪ ▪ 4 0.5

Olive-sided Flycatcher (WL) ▪ ▪ ▪ 1 0.13

Prairie Warbler (WL) ▪ ▪ ▪ 10 1.25

Purple Finch ▪ ▪ ▪ 1 0.13

Red-headed Woodpecker (WL) ▪ ▪ ▪ 1 0.13

Ruby-throated Hummingbird ▪ ▪ ▪ 9 1.13

Savannah Sparrow ▪ ▪ ▪ 2 0.25

Sedge Wren ▪ ▪ ▪ 5 0.63

Swainson’s Thrush ▪ ▪ ▪ 1 0.13

Tufted Titmouse ▪ ▪ ▪ 5 0.63

White-breasted Nuthatch ▪ ▪ ▪ 15 1.88

Winter Wren ▪ ▪ ▪ 9 1.13

Yellow-bellied Sapsucker ▪ ▪ ▪ 7 0.88

Yellow-billed Cuckoo (SD) ▪ ▪ ▪ 18 2.25

Warbling Vireo - 0.00 0.00 0.99 30 3.75

Brown Thrasher - 0.00 0.00 0.98 29 3.63

Mourning Dove - 0.00 0.00 0.93 177 22.13

Common Grackle* (SD) - 0.00 0.01 0.83 87 10.88

European Starling - 0.01 0.01 0.87 68 8.5

Black-throated Green Warbler - 0.01 0.01 0.79 35 4.38

Swamp Sparrow - 0.01 0.02 0.77 35 4.38

Common Raven - 0.01 0.02 0.77 45 5.63

Tree Swallow - 0.01 0.02 0.76 113 14.13

Baltimore Oriole - 0.01 0.03 0.67 80 10

Eastern Kingbird* - 0.01 0.04 0.66 76 9.5

Scarlet Tanager - 0.01 0.04 0.62 90 11.25

Alder Flycatcher* - 0.01 0.08 0.60 14 1.75

American Crow - 0.01 0.20 0.27 204 25.5

* Outliers were removed from trend analyses for these species.
77

Table B6 (continued). Regression trends (average proportional change per year), r2, P and 

total and mean individuals observed during 10-minute point counts at Sleeping Bear Dunes 

National Lakeshore, 2004–2006 and 2009–2013, arranged by trend and P-value. Species 

in bold indicate P≤0.05. Species listed as special concern (SC) in Michigan, species 

common but in steep decline (SD), or on the NABCI (2014) watch list (WL) in the United 

States are noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

Eastern Phoebe - 0.02 0.05 0.59 17 2.13

Barn Swallow - 0.02 0.06 0.56 19 2.38

Upland Sandpiper - 0.02 0.07 0.52 21 2.63

American Goldfinch - 0.02 0.17 0.32 108 13.5

Northern Cardinal - 0.02 0.17 0.32 17 2.13

Bobolink (WL) - 0.02 0.42 0.08 64 8

Gray Catbird - 0.03 0.44 0.07 40 5

House Wren - 0.03 0.12 0.40 23 2.88

Belted Kingfisher - 0.04 0.27 0.19 14 1.75

Black-throated Blue Warbler - 0.05 0.35 0.12 11 1.38

Black-billed Cuckoo (WL) - 0.08 0.33 0.14 31 3.88

* Outliers were removed from trend analyses for these species.
78

Table B7. Regression trends (average proportional change per year), r2, P and total and 

mean individuals observed during 10-minute point counts at Voyageurs National Park, 

1997–2013, arranged by trend and P-value. Species in bold indicate P≤0.05. Species 

listed as common but in steep decline (SD), or on the NABCI (2014) watch list (WL) in the 

United States are noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

Blue-headed Vireo + 0.02 0.25 0.0398 29 1.7

Common Grackle (SD) + 0.03 0.09 0.23 73 4.3

Yellow-rumped Warbler + 0.02 0.18 0.09 102 6

Canada Warbler 1(WL) + 0.02 0.18 0.09 90 5.3

Black-and-White Warbler + 0.01 0.20 0.07 320 19

Red-breasted Nuthatch* + 0.01 0.19 0.09 242 14

Common Raven + 0.01 0.04 0.42 95 5.6

Hermit Thrush + 0.01 0.04 0.44 253 15

Winter Wren + 0.01 0.03 0.54 208 12

Black-throated Green Warbler* + 0.00 0.03 0.56 193 11

Least Flycatcher + 0.00 0.01 0.68 266 16

Common Yellowthroat + 0.00 0.01 0.73 106 6.2

Northern Flicker* + 0.00 0.00 0.87 117 6.9

Alder Flycatcher ▪ ▪ ▪ 3 0.18

American Bittern ▪ ▪ ▪ 23 1.4

American Goldfinch ▪ ▪ ▪ 28 1.6

American Redstart ▪ ▪ ▪ 63 3.7

Baltimore Oriole ▪ ▪ ▪ 4 0.24

Bay-breasted Warbler ▪ ▪ ▪ 1 0.06

Belted Kingfisher ▪ ▪ ▪ 1 0.06

Black-throated Blue Warbler ▪ ▪ ▪ 1 0.06

Blue-winged Warbler ▪ ▪ ▪ 7 0.41

Brown-headed Cowbird ▪ ▪ ▪ 12 0.71

Cape May Warbler (SD) ▪ ▪ ▪ 7 0.41

Cedar Waxwing ▪ ▪ ▪ 125 7.4

Downy Woodpecker ▪ ▪ ▪ 19 1.1

Eastern Kingbird ▪ ▪ ▪ 7 0.41

Eastern Phoebe ▪ ▪ ▪ 8 0.47

European Starling ▪ ▪ ▪ 1 0.06

Golden-crowned Kinglet ▪ ▪ ▪ 13 0.76

Gray Jay ▪ ▪ ▪ 21 1.2

Indigo Bunting ▪ ▪ ▪ 3 0.18

Northern Waterthrush ▪ ▪ ▪ 7 0.41

Olive-sided Flycatcher (WL) ▪ ▪ ▪ 1 0.06

Palm Warbler ▪ ▪ ▪ 1 0.06

Philadelphia Vireo ▪ ▪ ▪ 1 0.06

Pileated Woodpecker ▪ ▪ ▪ 58 3.4

Pine Siskin (SD) ▪ ▪ ▪ 1 0.06

Pine Warbler ▪ ▪ ▪ 35 2.1

Purple Finch ▪ ▪ ▪ 30 1.8

Red-headed Woodpecker (WL) ▪ ▪ ▪ 2 0.12

1 BCCH and CAWA do not fit normal distribution; included because of regularity of data and abundance across 

years. EVGR included due to likely ecological importance of decline.

* Outliers were removed from trend analyses for these species.
79

Table B7 (continued). Regression trends (average proportional change per year), r2, P 

and total and mean individuals observed during 10-minute point counts at Voyageurs 

National Park, 1997–2013, arranged by trend and P-value. Species in bold indicate 

P≤0.05. Species listed as common but in steep decline (SD), or on the NABCI (2014)

watch list (WL) in the United States are noted.

Species Trend r

2

P

Total 

Individuals

Mean 

Individuals 

Annually

Red Crossbill ▪ ▪ ▪ 21 1.2

Ruby-crowned Kinglet ▪ ▪ ▪ 23 1.4

Ruby-throated Hummingbird ▪ ▪ ▪ 22 1.3

Ruffed Grouse ▪ ▪ ▪ 35 2.1

Scarlet Tanager ▪ ▪ ▪ 32 1.9

Swainson’s Thrush ▪ ▪ ▪ 12 0.71

Tennessee Warbler ▪ ▪ ▪ 10 0.59

Tree Swallow ▪ ▪ ▪ 19 1.1

White-breasted Nuthatch ▪ ▪ ▪ 8 0.47

Wilson’s Snipe ▪ ▪ ▪ 1 0.06

Yellow-bellied Flycatcher ▪ ▪ ▪ 4 0.24

Yellow Warbler ▪ ▪ ▪ 3 0.18

Brown Creeper - 0.00 0.00 0.97 87 5.1

Eastern Wood Pewee - 0.00 0.00 0.93 100 5.9

Swamp Sparrow - 0.00 0.00 0.85 53 3.1

Hairy Woodpecker - 0.00 0.00 0.81 32 1.9

Blue Jay - 0.00 0.01 0.78 281 17

American Robin - 0.00 0.01 0.77 233 14

Magnolia Warbler* - 0.00 0.01 0.75 245 14

Chipping Sparrow* - 0.00 0.02 0.65 272 16

Black-capped Chickadee 1- 0.00 0.02 0.60 189 11

Red-eyed Vireo* - 0.00 0.06 0.37 1381 81

Northern Parula* - 0.00 0.14 0.17 226 13

Song Sparrow - 0.01 0.01 0.69 39 2.3

Yellow-bellied Sapsucker - 0.01 0.05 0.41 251 15

White-throated Sparrow - 0.01 0.14 0.15 1174 69

Veery* - 0.01 0.14 0.15 341 20

Blackburnian Warbler - 0.01 0.22 0.06 352 21

Red-winged Blackbird* - 0.02 0.08 0.28 135 7.9

Nashville Warbler - 0.01 0.25 0.0402 951 56

Ovenbird* - 0.01 0.55 0.0009 1424 84

American Crow* - 0.02 0.34 0.0173 488 29

Mourning Warbler* - 0.02 0.56 0.0008 249 15

Chestnut-sided Warbler* - 0.02 0.60 0.0004 342 20

Rose-breasted Grosbeak - 0.03 0.27 0.0320 63 3.7

Great Crested Flycatcher - 0.03 0.64 0.0001 93 5.5

Evening Grosbeak 1(WL) - 0.06 0.44 0.0036 45 2.6

1 BCCH and CAWA do not fit normal distribution; included because of regularity of data and abundance across 

years. EVGR included due to likely ecological importance of decline.

* Outliers were removed from trend analyses for these species.

81

Appendix C: Distance Analysis Details

Terms defined from Buckland et al. (2001) include density of animals in the area (D), encounter rate 

for observed objects per transect effort (n/K), effective detection radius (EDR), and the probability 

that an object is observed in the area (p). Area equals one hectare; EDR is the radius around a point 

where as many objects beyond the radius are detected as those remaining undetected within the 

radius; AICc is the lowest Akaike’s Information Criterion result based on iterative covariate 

inclusion and realistic standard error.

Table C1. Results from distance-detectability models of point count surveys at Grand Portage 

National Monument, including estimates of density per hectare (D) with standard error (SE), 

encounter rate (n/K, or observations per unit of effort), global detection radius (EDR) in meters, 

global probability of observing a bird (p) per hectare, and individuals observed. All models were 

Half-normal.

American Redstart Blackburnian Warbler

Year D (SE) n/K Observed Year D (SE) n/K Observed

2004 0.030 (0.009) 0.055 23 2004 0.021 (0.008) 0.026 11

2005 0.014 (0.005) 0.026 11 2005 0.006 (0.003) 0.007 3

2006 0.026 (0.009) 0.048 20 2006 0.025 (0.008) 0.031 13

2007 0.038 (0.010) 0.069 29 2007 0.044 (0.012) 0.055 23

2008 0.045 (0.012) 0.081 34 2008 0.017 (0.007) 0.022 9

2009 0.034 (0.009) 0.062 26 2009 0.015 (0.006) 0.019 8

2010 0.017 (0.006) 0.031 13 2010 0.010 (0.005) 0.012 5

2011 0.020 (0.006) 0.036 15 2011 0.019 (0.007) 0.024 10

2012 0.025 (0.008) 0.045 19 2012 0.011 (0.005) 0.014 6

2013 0.014 (0.005) 0.026 11 2013 0.015 (0.006) 0.019 8

2014 0.029 (0.010) 0.053 22 2014 0.019 (0.007) 0.024 10

Global 0.027 223 Global 0.018 106

(AICc: 296.43, EDR: 76.1, p: 0.580) (AICc: 148.83, EDR: 63.0, p: 0.397)

Black-throated Green Warbler Canada Warbler

Year D (SE) n/K Observed Year D (SE) n/K Observed

2004 0.008 (0.003) 0.026 11 2004 0.004 (0.002) 0.010 4

2005 0.011 (0.004) 0.036 15 2005 0.007 (0.003) 0.017 7

2006 0.008 (0.003) 0.026 11 2006 0.008 (0.003) 0.019 8

2007 0.010 (0.003) 0.031 13 2007 0.011 (0.004) 0.026 11

2008 0.012 (0.004) 0.038 16 2008 0.010 (0.004) 0.024 10

2009 0.008 (0.003) 0.026 11 2009 0.005 (0.002) 0.012 5

2010 0.009 (0.004) 0.029 12 2010 0.003 (0.002) 0.007 3

2011 0.004 (0.002) 0.012 5 2011 0.002 (0.002) 0.005 2

2012 0.006 (0.003) 0.019 8 2012 0.008 (0.004) 0.019 8

2013 0.005 (0.003) 0.017 7 2013 0.008 (0.003) 0.019 8

2014 0.009 (0.004) 0.029 12 2014 0.014 (0.006) 0.036 15

Global 0.008 121 Global 0.007 81

(AICc: 122.19, EDR: 100, p: 1.0) (AICc: 100.50, EDR: 89.2, p: 0.80)
82

Table C1 (continued). Results from distance-detectability models of point count surveys at 

Grand Portage National Monument, including estimates of density per hectare (D) with standard 

error (SE), encounter rate (n/K, or observations per unit of effort), global detection radius (EDR) 

in meters, global probability of observing a bird (p) per hectare, and individuals observed. All 

models were Half-normal.

Magnolia Warbler Nashville Warbler

Year D (SE) n/K Observed Year D (SE) n/K Observed

2004 0.008 (0.003) 0.026 11 2004 0.006 (0.002) 0.019 8

2005 0.010 (0.004) 0.031 13 2005 0.004 (0.002) 0.012 5

2006 0.007 (0.003) 0.022 9 2006 0.009 (0.003) 0.029 12

2007 0.016 (0.005) 0.050 21 2007 0.011 (0.004) 0.033 14

2008 0.016 (0.005) 0.050 21 2008 0.018 (0.005) 0.055 23

2009 0.014 (0.005) 0.045 19 2009 0.021 (0.006) 0.067 28

2010 0.014 (0.005) 0.045 19 2010 0.010 (0.004) 0.031 13

2011 0.007 (0.003) 0.022 9 2011 0.005 (0.002) 0.014 6

2012 0.010 (0.003) 0.031 13 2012 0.009 (0.003) 0.029 12

2013 0.011 (0.004) 0.033 14 2013 0.007 (0.003) 0.022 9

2014 0.016 (0.005) 0.050 21 2014 0.017 (0.005) 0.053 22

Global 0.012 170 Global 0.011 152

(AICc: 189.92, EDR: 100, p: 1.0) (AICc: 170.78, EDR: 100, p: 1.0)

Northern Parula Ovenbird

Year D (SE) n/K Observed Year D (SE) n/K Observed

2004 0.009 (0.003) 0.029 12 2004 0.030 (0.008) 0.096 40

2005 0.005 (0.002) 0.017 7 2005 0.021 (0.006) 0.065 27

2006 0.002 (0.001) 0.007 3 2006 0.003 (0.002) 0.010 4

2007 0.012 (0.004) 0.038 16 2007 0.008 (0.003) 0.024 10

2008 0.010 (0.003) 0.031 13 2008 0.011 (0.004) 0.036 15

2009 0.008 (0.003) 0.024 10 2009 0.012 (0.004) 0.038 16

2010 0.006 (0.002) 0.019 8 2010 0.007 (0.003) 0.022 9

2011 0.009 (0.003) 0.029 12 2011 0.003 (0.002) 0.010 4

2012 0.010 (0.004) 0.031 13 2012 0.008 (0.003) 0.026 11

2013 0.008 (0.003) 0.026 11 2013 0.009 (0.003) 0.029 12

2014 0.014 (0.005) 0.043 18 2014 0.018 (0.005) 0.057 24

Global 0.009 123 Global 0.012 172

(AICc: 136.52, EDR: 100, p: 1.0) (AICc: 182.28, EDR: 100, p: 1.0)

Red-eyed Vireo White-throated Sparrow

Year D (SE) n/K Observed Year D (SE) n/K Observed

2004 0.020 (0.006) 0.062 26 2004 0.033 (0.010) 0.053 22

2005 0.013 (0.005) 0.041 17 2005 0.033 (0.012) 0.053 22

2006 0.003 (0.002) 0.010 4 2006 0.009 (0.004) 0.014 6

2007 0.018 (0.006) 0.057 24 2007 0.018 (0.007) 0.029 12

2008 0.018 (0.005) 0.055 23 2008 0.006 (0.003) 0.010 4

2009 0.014 (0.005) 0.043 18 2009 0.012 (0.005) 0.019 8

2010 0.006 (0.002) 0.019 8 2010 0.013 (0.005) 0.022 9

2011 0.005 (0.003) 0.017 7 2011 0.007 (0.004) 0.012 5

2012 0.008 (0.003) 0.026 11 2012 0.016 (0.006) 0.026 11

2013 0.005 (0.002) 0.014 6 2013 0.010 (0.005) 0.017 7

2014 0.011 (0.004) 0.036 15 2014 0.010 (0.005) 0.017 7

Global 0.011 159 Global 0.015 113

(AICc: 161.62, EDR: 100, p: 1.0) (AICc: 154.76, EDR: 71.4, p: 0.510)
83

Table C1 (continued). Results from distance-detectability models of point count surveys at 

Grand Portage National Monument, including estimates of density per hectare (D) with standard 

error (SE), encounter rate (n/K, or observations per unit of effort), global detection radius (EDR) 

in meters, global probability of observing a bird (p) per hectare, and individuals observed. All 

models were Half-normal.

Yellow-bellied Sapsucker

Year D (SE) n/K Observed

2004 0.010 (0.005) 0.017 7

2005 0.017 (0.007) 0.029 12

2006 0.007 (0.003) 0.012 5

2007 0.011 (0.005) 0.019 8

2008 0.006 (0.003) 0.010 4

2009 0.018 (0.007) 0.031 13

2010 0.018 (0.006) 0.031 13

2011 0.007 (0.004) 0.012 5

2012 0.007 (0.004) 0.012 5

2013 0.013 (0.005) 0.022 9

2014 0.011 (0.005) 0.019 8

Global 0.012 89

(AICc: 121.34, EDR: 73.2, p: 0.536)

Table C2. Trend comparisons for n(log+1) indices and 

density estimates for common species at Grand Portage 

National Monument, from annual surveys in 2004–2014. Bold

= significant trend.

Species by model P r2

American Redstart n(log+1) 0.535 0.044

Density 0.521 0.047

Blackburnian Warbler n(log+1) 0.799 0.008

Density 0.518 0.048

Black-throated Green Warbler n(log+1) 0.110 0.258

Density 0.123 0.244

Canada Warbler n(log+1) 0.657 0.023

Density 0.473 0.059

Magnolia Warbler n(log+1) 0.447 0.066

Density 0.412 0.076

Nashville Warbler n(log+1) 0.407 0.078

Density 0.456 0.063

Northern Parula n(log+1) 0.170 0.198

Density 0.148 0.217

Ovenbird n(log+1) 0.502 0.052

Density 0.230 0.155

Red-eyed Vireo n(log+1) 0.263 0.136

Density 0.116 0.251

White-throated Sparrow n(log+1) 0.093 0.281

Density 0.0346 0.407

Yellow-bellied Sapsucker n(log+1) 0.954 0.000

Density 0.893 0.002
84

Figure C1. Trend comparisons for n(log+1) indices (long dash) and density estimates (short dash) for 

common species at Grand Portage National Monument during annual surveys, 2004–2014. Density 

estimates include standard error bars. Note changing scales on y-axes.
85

Figure C1 (continued). Trend comparisons for n(log+1) indices (long dash) and density estimates (short 

dash) for common species at Grand Portage National Monument during annual surveys, 2004–2014. 

Density estimates include standard error bars. Note changing scales on y-axes. 
86

Table C3. Results from distance-detectability models of point count surveys at Saint Croix 

National Scenic Riverway, including estimates of density per hectare (D) with standard error 

(SE), encounter rate (n/K, or observations per unit of effort), global detection radius (EDR) in 

meters, global probability of observing a bird (p) per hectare, and individuals observed. All 

models were Half-normal.

American Goldfinch American Redstart

Year D (SE) n/K Observed Year D (SE) n/K Observed

2009 0.112 (0.031) 0.047 38 2009 0.147 (0.033) 0.055 44

2011 0.102 (0.024) 0.068 55 2011 0.164 (0.034) 0.064 52

2012 0.027 (0.011) 0.016 13 2012 **0.269 (0.528) 0.076 61

2013 0.055 (0.023) 0.026 21 2013 **0.105 (0.216) 0.050 40

2014 0.014 (0.009) 0.006 5 2014 0.227 (0.042) 0.086 69

Global 0.052 132 Global 0.152 266

(Covariates: Temperature, Wind; AICc: 148.22, 

EDR: 40.9, p: 0.167)

(Covariates: Temperature, Sky; AICc: 213.19, EDR: 

33.9, p: 0.115)

American Robin Baltimore Oriole

Year D (SE) n/K Observed Year D (SE) n/K Observed

2009 0.081 (0.016) 0.083 67 2009 0.077 (0.017) 0.057 46

2011 0.109 (0.020) 0.104 84 2011 0.105 (0.019) 0.078 63

2012 0.083 (0.016) 0.081 65 2012 0.061 (0.014) 0.047 38

2013 0.072 (0.014) 0.069 56 2013 0.063 (0.014) 0.048 39

2014 0.039 (0.010) 0.038 31 2014 0.029 (0.009) 0.021 17

Global 0.064 303 Global 0.056 203

(Covariate: Temperature; AICc: 416.41, EDR: 55.8, 

p: 0.311)

(Covariate: Temperature; AICc: 265.88, EDR: 49.0, 

p: 0.240)

Black-and-White Warbler Black-capped Chickadee

Year D (SE) n/K Observed Year D (SE) n/K Observed

2009 0.042 (0.015) 0.017 14 2009 0.018 (0.010) 0.010 8

2011 0.111 (0.026) 0.048 39 2011 0.058 (0.020) 0.026 21

2012 0.030 (0.013) 0.012 10 2012 0.063 (0.022) 0.025 20

2013 0.038 (0.015) 0.016 13 2013 0.041 (0.014) 0.022 18

2014 0.018 (0.010) 0.074 6 2014 0.030 (0.018) 0.010 8

Global 0.040 82 Global 0.035 75

(Covariate: Temperature; AICc: 75.64, EDR: 36.8, p: 

0.135)

(Covariates: Temperature, Noise; AICc: 78.15, EDR: 

37.5, p: 0.141)

Brown-headed Cowbird Blue Jay

Year D (SE) n/K Observed Year D (SE) n/K Observed

2009 0.090 (0.024) 0.059 48 2009 **0.031 (0.121) 0.032 26

2011 0.102 (0.079) 0.050 40 2011 0.055 (0.010) 0.084 68

2012 **0.077 (0.168) 0.025 20 2012 **0.029 (0.132) 0.024 19

2013 0.027 (0.011) 0.022 18 2013 **0.022 (0.106) 0.026 21

2014 0.015 (0.008) 0.010 8 2014 0.019 (0.005) 0.035 28

Global 0.052 134 Global 0.026 162

(Covariates: Temperature, Sky, Wind; AICc: 168.09, 

EDR: 41.3, p: 0.170)

(Covariates: Temperature, Sky; AICc: 223.12, EDR: 

64.2, p: 0.412)

*2010 missing since temperature was not recorded

** SE > density
87

Table C3 (continued). Results from distance-detectability models of point count surveys at Saint 

Croix National Scenic Riverway, including estimates of density per hectare (D) with standard 

error (SE), encounter rate (n/K, or observations per unit of effort), global detection radius (EDR) 

in meters, global probability of observing a bird (p) per hectare, and individuals observed. All 

models were Half-normal.

Common Yellowthroat Chestnut-sided Warbler

Year D (SE) n/K Observed Year D (SE) n/K Observed

2009 0.188 (0.064) 0.145 117 2009 0.069 (0.018) 0.045 36

2011 0.253 (0.062) 0.187 151 2011 0.129 (0.026) 0.078 63

2012 0.185 (0.027) 0.147 119 2012 0.128 (0.027) 0.079 64

2013 0.130 (0.021) 0.103 83 2013 0.068 (0.017) 0.042 34

2014 0.113 (0.019) 0.089 72 2014 0.104 (0.022) 0.063 51

Global 0.145 542 Global 0.083 248

(Covariates: Temperature, Noise; AICc: 710.90, 

EDR: 49.6, p: 0.246)

(Covariate: Temperature; AICc: 296.89, EDR: 44.3, 

p: 0.196)

Great Crested Flycatcher Gray Catbird

Year D (SE) n/K Observed Year D (SE) n/K Observed

2009 0.037 (0.009) 0.048 39 2009 0.120 (0.029) 0.051 41

2011 0.065 (0.012) 0.073 59 2011 0.137 (0.030) 0.068 55

2012 0.026 (0.007) 0.030 24 2012 0.080 (0.021) 0.042 34

2013 0.027 (0.008) 0.036 29 2013 0.112 (0.022) 0.078 63

2014 0.024 (0.006) 0.035 28 2014 0.126 (0.027) 0.064 52

Global 0.030 179 Global 0.096 245

(Covariates: Temperature, Noise; AICc: 246.99, 

EDR: 62.8, p: 0.395)

(Covariates: Temperature, Sky; AICc: 273.48, EDR: 

41.0, p: 0.168)

Hairy Woodpecker Least Flycatcher

Year D (SE) n/K Observed Year D (SE) n/K Observed

2009 **0.042 (0.352) 0.026 21 2009 0.033 (0.011) 0.022 18

2011 0.061 (0.015) 0.042 34 2011 0.043 (0.014) 0.029 23

2012 0.028 (0.012) 0.016 13 2012 0.041 (0.013) 0.029 23

2013 0.042 (0.012) 0.031 25 2013 0.030 (0.010) 0.020 16

2014 0.038 (0.014) 0.024 19 2014 0.031 (0.011) 0.021 17

Global 0.0353 112 Global 0.030 97

(Covariates: Temperature, Noise; AICc: 143.94, 

EDR: 45.7, p: 0.209)

(Covariate: Temperature; AICc: 123.81, EDR: 46.3, 

p: 0.214)

Ovenbird Rose-breasted Grosbeak

Year D (SE) n/K Observed Year D (SE) n/K Observed

2009 0.016 (0.005) 0.027 22 2009 0.043 (0.011) 0.037 30

2011 0.043 (0.008) 0.072 58 2011 0.091 (0.017) 0.078 63

2012 0.033 (0.007) 0.056 45 2012 0.058 (0.014) 0.047 38

2013 0.025 (0.006) 0.042 34 2013 0.061 (0.014) 0.050 40

2014 0.034 (0.007) 0.057 46 2014 0.032 (0.009) 0.027 22

Global 0.025 205 Global 0.047 193

(Covariate: Temperature; AICc: 279.13, EDR: 73.1, 

p: 0.534)

(Covariate: Temperature; AICc: 260.40, EDR: 51.7, 

p: 0.267)

** SE > density
88

Table C3 (continued). Results from distance-detectability models of point count surveys at Saint 

Croix National Scenic Riverway, including estimates of density per hectare (D) with standard 

error (SE), encounter rate (n/K, or observations per unit of effort), global detection radius (EDR) 

in meters, global probability of observing a bird (p) per hectare, and individuals observed. All 

models were Half-normal.

Red-eyed Vireo Red-winged Blackbird

Year D (SE) n/K Observed Year D (SE) n/K Observed

2009 0.256 (0.039) 0.181 146 2009 0.095 (0.028) 0.087 70

2011 0.424 (0.051) 0.274 221 2011 0.062 (0.016) 0.069 56

2012 0.264 (0.093) 0.176 142 2012 0.027 (0.008) 0.031 25

2013 0.232 (0.030) 0.195 157 2013 0.038 (0.011) 0.036 29

2014 0.284 (0.033) 0.233 188 2014 0.050 (0.013) 0.045 36

Global 0.243 854 Global 0.045 216

(Covariates: Temperature, Sky, Wind; AICc: 1097.4, 

EDR: 48.0, p: 0.231)

(Covariates: Temperature, Wind; AICc: 300.84, 

EDR: 56.1, p: 0.314)

Song Sparrow Tree Swallow

Year D (SE) n/K Observed Year D (SE) n/K Observed

2009 0.373 (0.047) 0.249 201 2009 0.149 (0.033) 0.098 79

2011 0.466 (0.051) 0.304 245 2011 0.169 (0.037) 0.100 81

2012 0.378 (0.043) 0.253 204 2012 0.020 (0.012) 0.010 8

2013 0.302 (0.037) 0.198 160 2013 0.013 (0.008) 0.009 7

2014 0.323 (0.040) 0.218 176 2014 0.016 (0.011) 0.020 16

Global 0.307 986 Global 0.061 191

(Covariate: Temperature; AICc: 1211.5, EDR: 45.9, 

p: 0.211)

(Covariates: Temperature, Wind, Noise; AICc: 

237.54, EDR: 45.3, p: 0.205)

Veery Warbling Vireo

Year D (SE) n/K Observed Year D (SE) n/K Observed

2009 0.070 (0.017) 0.055 44 2009 0.037 (0.011) 0.031 25

2011 0.153 (0.026) 0.124 100 2011 0.054 (0.013) 0.043 35

2012 0.124 (0.021) 0.100 80 2012 0.000 (0.000) 0.000 0

2013 0.126 (0.022) 0.100 81 2013 0.055 (0.014) 0.045 36

2014 0.119 (0.020) 0.095 77 2014 0.005 (0.003) 0.004 3

Global 0.099 382 Global 0.030 99

(Covariate: Temperature; AICc: 506.66, EDR: 50.4, 

p: 0.254)

(Covariate: Temperature; AICc: 134.90, EDR: 50.8, 

p: 0.258)

White-breasted Nuthatch Yellow Warbler

Year D (SE) n/K Observed Year D (SE) n/K Observed

2009 0.057 (0.018) 0.031 25 2009 0.068 (0.016) 0.046 37

2011 0.063 (0.018) 0.035 28 2011 0.141 (0.025) 0.100 81

2012 0.064 (0.017) 0.037 30 2012 0.139 (0.028) 0.093 75

2013 0.027 (0.011) 0.015 12 2013 0.092 (0.019) 0.063 51

2014 0.029 (0.011) 0.016 13 2014 0.149 (0.026) 0.102 82

Global 0.040 108 Global 0.098 326

(Covariate: Temperature; AICc: 124.22, EDR: 42.2, 

p: 0.178)

(Covariate: Temperature; AICc: 409.77, EDR: 46.7, 

p: 0.218)
89

Table C3 (continued). Results from distance-detectability models of point count surveys at Saint 

Croix National Scenic Riverway, including estimates of density per hectare (D) with standard 

error (SE), encounter rate (n/K, or observations per unit of effort), global detection radius (EDR) 

in meters, global probability of observing a bird (p) per hectare, and individuals observed. All 

models were Half-normal.

Yellow-throated Vireo 

Year D (SE) n/K Observed

2009 0.028 (0.008) 0.029 23

2011 0.033 (0.009) 0.030 24

2012 0.045 (0.010) 0.045 36

2013 0.018 (0.006) 0.017 14

2014 0.030 (0.008) 0.031 25

Global 0.026 122

(Covariate: Temperature; AICc: 170.77, EDR: 55.9, 

p: 0.313)
90

Table C4. Results from distance-detectability models of point count surveys at Sleeping Bear 

Dunes National Lakeshore, including estimates of density per hectare (D) with standard error 

(SE), encounter rate (n/K, or observations per unit of effort), estimated detection radius (EDR) in 

meters, probability of observing a bird (p) per hectare, and individuals observed. All models 

were Half-normal/cosine.

Species by year and habitat D (SE) n/K EDR (m) p Observed

American Redstart

2009 0.062 (0.025) 0.059 55.0 0.30 12

2010 0.062 (0.024) 0.059 55.0 0.30 12

2011 0.051 (0.021) 0.049 55.0 0.30 10

2012 0.077 (0.028) 0.073 55.0 0.30 15

2013 0.069 (0.018) 0.210 98.5 0.97 43

Beech-maple forest 0.095 (0.033) 0.127 65.3 0.43 26

Coastal oak-pine forest 0.010 (0.010) 0.010 55.0 0.30 2

Dune 0.010 (0.008) 0.020 79.0 0.62 4

Edge 0.078 (0.028) 0.098 63.1 0.40 20

Field 0.005 (0.004) 0.015 98.5 0.97 3

Inland lake 0.040 (0.020) 0.059 67.9 0.46 12

Shore-foredune 0.013 (0.010) 0.020 67.9 0.46 4

Wetland 0.069 (0.027) 0.102 68.7 0.47 21

Global (annual mean) 0.064 66.7 0.45 92

(Covariate: observer; AICc: 119.96)

American Robin

2009 0.077 (0.023) 0.102 64.9 0.42 21

2010 0.092 (0.024) 0.122 64.9 0.42 25

2011 0.107 (0.031) 0.141 64.9 0.42 29

2012 0.074 (0.023) 0.098 64.9 0.42 20

2013 0.124 (0.040) 0.215 74.1 0.55 44

Beech-maple forest 0.154 (0.043) 0.220 67.4 0.45 45

Coastal oak-pine forest 0.060 (0.020) 0.088 68.5 0.47 18

Dune 0.022 (0.013) 0.029 64.9 0.42 6

Edge 0.060 (0.021) 0.083 66.3 0.44 17

Field 0.036 (0.017) 0.049 65.6 0.43 10

Inland lake 0.055 (0.025) 0.083 69.3 0.48 17

Shore-foredune *0.004 (0.005) 0.005 64.9 0.42 1

Wetland 0.084 (0.029) 0.122 67.8 0.46 25

Global (annual mean) 0.095 67.4 0.45 139

(Covariate: observer; AICc: 193.99)

* density < SE
91

Table C4 (continued). Results from distance-detectability models of point count surveys at 

Sleeping Bear Dunes National Lakeshore, including estimates of density per hectare (D) with 

standard error (SE), encounter rate (n/K, or observations per unit of effort), estimated detection 

radius (EDR) in meters, probability of observing a bird (p) per hectare, and individuals observed. 

All models were Half-normal/cosine.

Species by year and habitat D (SE) n/K EDR (m) p Observed

Ovenbird**

2009 0.041 (0.015) 0.063 70.0 0.49 14

2010 0.054 (0.017) 0.083 70.0 0.49 18

2011 0.054 (0.019) 0.083 70.0 0.49 10

2012 0.025 (0.012) 0.039 70.0 0.49 8

2013 0.073 (0.026) 0.093 63.8 0.41 25

Beech-maple forest -- -- -- -- 45

Coastal oak-pine forest -- -- -- -- 15

Dune -- -- -- -- 0

Edge -- -- -- -- 5

Field -- -- -- -- 0

Inland lake -- -- -- -- 0

Shore-foredune -- -- -- -- 0

Wetland -- -- -- -- 10

Global (annual mean) 0.049 68.2 0.47 75

(Covariate: observer; AICc: 105.24)

**No habitat model was adequate for Ovenbird.

Red-eyed Vireo

2009 0.125 (0.034) 0.224 75.5 0.57 46

2010 0.124 (0.030) 0.200 71.6 0.51 41

2011 0.102 (0.026) 0.156 70.0 0.49 32

2012 0.080 (0.023) 0.141 75.2 0.57 29

2013 0.079 (0.022) 0.180 85.3 0.73 37

Beech-maple forest 0.156 (0.032) 0.288 76.7 0.59 59

Coastal oak-pine forest 0.127 (0.034) 0.180 67.2 0.45 37

Dune 0.036 (0.020) 0.078 83.0 0.69 16

Edge 0.043 (0.017) 0.083 78.2 0.61 17

Field 0.036 (0.014) 0.063 75.3 0.57 13

Inland lake 0.039 (0.015) 0.078 80.1 0.64 16

Shore-foredune 0.015 (0.010) 0.024 72.2 0.52 5

Wetland 0.058 (0.018) 0.107 76.7 0.59 22

Global (annual mean) 0.102 75.1 0.56 185

(Covariate: noise; AICc: 239.51)
92

Table C4 (continued). Results from distance-detectability models of point count surveys at 

Sleeping Bear Dunes National Lakeshore, including estimates of density per hectare (D) with 

standard error (SE), encounter rate (n/K, or observations per unit of effort), estimated detection 

radius (EDR) in meters, probability of observing a bird (p) per hectare, and individuals observed. 

All models were Half-normal/cosine.

Species by year and habitat D (SE) n/K EDR (m) p Observed

Red-winged Blackbird

2009 0.106 (0.048) 0.088 51.3 0.26 18

2010 0.141 (0.056) 0.117 51.3 0.26 24

2011 0.147 (0.054) 0.122 51.3 0.26 25

2012 0.177 (0.067) 0.146 51.3 0.26 30

2013 0.034 (0.015) 0.107 99.9 1.00 22

Beech-maple forest -- -- -- -- 0

Coastal oak-pine forest -- -- -- -- 0

Dune -- -- -- -- 0

Edge 0.018 (0.016) 0.015 51.3 0.26 3

Field 0.226 (0.068) 0.205 53.7 0.29 42

Inland lake 0.096 (0.044) 0.112 60.8 0.37 23

Shore-foredune -- -- -- -- 0

Wetland 0.266 (0.074) 0.249 54.6 0.30 51

Global (annual mean) 0.121 55.2 0.31 119

(Covariate: observer; AICc: 156.68)

Song Sparrow

2009 0.041 (0.015) 0.063 70.0 0.49 13

2010 0.054 (0.017) 0.083 70.0 0.49 17

2011 0.054 (0.019) 0.083 70.0 0.49 17

2012 0.025 (0.012) 0.039 70.0 0.49 8

2013 0.073 (0.026) 0.093 63.8 0.41 19

Beech-maple forest -- -- -- -- 0

Coastal oak-pine forest 0.007 (0.006) 0.010 66.7 0.44 2

Dune 0.043 (0.016) 0.063 68.9 0.47 13

Edge 0.043 (0.016) 0.063 68.4 0.47 13

Field 0.034 (0.015) 0.049 67.9 0.46 10

Inland lake 0.019 (0.011) 0.029 70.0 0.49 6

Shore-foredune 0.054 (0.021) 0.078 67.9 0.46 16

Wetland 0.048 (0.019) 0.068 67.6 0.46 14

Global (annual mean) 0.049 68.2 0.47 74

(Covariate: observer; AICc: 105.24)
93

Table C5. Trend comparisons for n(log+1) indices and density 

estimates for common species at Sleeping Bear Dunes 

National Lakeshore during annual surveys, 2009–2013. 

Significant trend in bold. Note: there were no distribution 

outliers in these data.

Species by model P r2

American Redstart n(log+1) 0.143 0.564

Density 0.417 0.227

American Robin n(log+1) 0.256 0.395

Density 0.313 0.328

Ovenbird n(log+1) 0.833 0.017

Density 0.610 0.097

Red-eyed Vireo n(log+1) 0.218 0.446

Density *0.011 0.913

Red-winged Blackbird* n(log+1) 0.360 0.279

Density 0.610 0.100

Song Sparrow n(log+1) 0.987 0.000

Density 0.610 0.100

*Opposing trend directions, see Figure C3.
94

Figure C2. Annual variation in wind, noise and sky cover/clouds, reported as annual means of ordinal 

ranking, on bird surveys at Sleeping Bear Dunes National Lakeshore. Higher numbers indicate louder or 

cloudier conditions.
95

Figure C3. Observations and estimated density per hectare, by year, of common species at Sleeping 

Bear Dunes National Lakeshore. Density estimates includes standard error bars.Trends are included for 

observations (long dash) and densities (short dash). Note scale changes on y-axes.
96

Figure C4. Observations and estimated density per hectare of common species, by habitat, of common 

species at Sleeping Bear Dunes National Lakeshore. Density estimates include standard error bars. 

Trends are included for observations (long dash) and densities (short dash). Note scale changes on yaxes. Habitats include beech-maple forest (BMF), coastal oak-pine forest (COP), dunes (D), edge (E), 

fields (F), inland lake (IL), shore and foredune (SF), and wetland (W). No density model was adequate for 

Ovenbird.
97

Table C6. Distance-detectability model results from point count surveys at Voyageurs National 

Park, including estimates of density per hectare (D) with standard error (SE), encounter rate (n/K, 

or observations per unit of effort), global detection radius (EDR) in meters, global probability of 

observing a bird (p) per hectare, and individuals observed. All models were Half-normal.

Black-and-White Warbler Blackburnian Warbler 

Year D (SE) n/K Observed Year D (SE) n/K Observed

2010 0.139 (0.032) 0.113 28 2010 0.168 (0.037) 0.117 29

2011 0.109 (0.029) 0.089 22 2011 0.098 (0.027) 0.069 17

2012 0.149 (0.035) 0.121 30 2012 0.185 (0.039) 0.130 32

2013 0.104 (0.030) 0.085 21 2013 0.197 (0.047) 0.138 34

Global 0.125 101 Global 0.162 112

(AICc: 135.80, EDR: 51.0, p: 0.260) (AICc: 142.70, EDR: 47.2, p: 0.223)

Chipping Sparrow Nashville Warbler 

Year D (SE) n/K Observed Year D (SE) n/K Observed

2010 0.191 (0.045) 0.126 31 2010 0.182 (0.031) 0.401 99

2011 0.111 (0.031) 0.073 18 2011 0.072 (0.016) 0.158 39

2012 0.216 (0.050) 0.142 35 2012 0.194 (0.033) 0.425 105

2013 0.080 (0.031) 0.053 13 2013 0.101 (0.021) 0.223 55

Global 0.150 97 Global 0.137 298

(AICc: 120.38, EDR: 45.7, p: 0.209) (AICc: 378.06, EDR: 83.6, p: 0.699)

Ovenbird Red-breasted Nuthatch

Year D (SE) n/K Observed Year D (SE) n/K Observed

2010 0.079 (0.016) 0.206 51 2010 0.099 (0.025) 0.113 28

2011 0.056 (0.015) 0.146 36 2011 0.043 (0.014) 0.049 12

2012 0.104 (0.022) 0.271 67 2012 0.131 (0.030) 0.150 37

2013 0.112 (0.023) 0.292 72 2013 0.068 (0.020) 0.077 19

Global 0.088 226 Global 0.085 96

(AICc: 273.22, EDR: 91.0, p: 0.828) (AICc: 135.09, EDR: 60.2, p: 0.363)

Red-eyed Vireo Veery

Year D (SE) n/K Observed Year D (SE) n/K Observed

2010 0.135 (0.025) 0.352 87 2010 0.035 (0.012) 0.109 27

2011 0.075 (0.017) 0.194 48 2011 0.021 (0.008) 0.065 16

2012 0.151 (0.027) 0.393 97 2012 0.028 (0.010) 0.089 22

2013 0.083 (0.017) 0.215 53 2013 0.018 (0.008) 0.057 14

Global 0.111 285 Global 0.025 79

(AICc: 344.07, EDR: 91.0, p: 0.828) (AICc: 87.06, EDR: 100, p: 1.0)

White-throated Sparrow

Year D (SE) n/K Observed

2010 0.122 (0.025) 0.259 64

2011 0.090 (0.020) 0.190 47

2012 0.150 (0.029) 0.320 79

2013 0.112 (0.024) 0.239 59

Global 0.119 249

(AICc: 319.00, EDR: 82.3, p: 0.677)
98

Table C7. Trend comparisons for n(log+1) indices and 

density estimates for common species at Voyageurs National 

Park during annual surveys, 2010–2013.

Species by model p r2

Black-and-White Warbler n(log+1) 0.595 0.164

Density 0.621 0.144

Blackburnian Warbler n(log+1) 0.546 0.206

Density 0.493 0.257

Chipping Sparrow n(log+1) 0.464 0.287

Density 0.543 0.209

Nashville Warbler n(log+1) 0.790 0.044

Density 0.740 0.068

Ovenbird n(log+1) 0.319 0.464

Density 0.253 0.558

Red-breasted Nuthatch n(log+1) 0.988 0.000

Density 0.983 0.000

Red-eyed Vireo n(log+1) 0.712 0.083

Density 0.726 0.075

Veery n(log+1) 0.286 0.510

Density 0.252 0.560

White-throated Sparrow n(log+1) 0.835 0.027

Density 0.684 0.010
99

Figure C5. Trend comparisons for n(log+1) indices and density estimates for common species at 

Voyageurs National Park during annual surveys, 2010–2013. Density estimates includes standard error 

bars. Trends are included for observations (long dash) and densities (short dash). Note changing scales 

on y-axes.
100

Figure C5 (continued). Trend comparisons for n(log+1) indices and density estimates for common 

species at Voyageurs National Park during annual surveys, 2010–2013. Density estimates include 

standard error bars. Trends are included for observations (long dash) and densities (short dash). Note 

changing scales on y-axes.
101

Appendix D: Taxonomic Species List

Table D. Taxonomic list and trend summary of landbirds reported during point count surveys in six Great 

Lakes Network parks (does not include SACN; see text for those data). A “▪” indicates low abundance, 

blank cells indicate species not recorded, and boxes indicate priority species for GLKN.

Park

Species VOYA GRPO ISRO APIS SLBE INDU

Ruffed Grouse (Bonasa umbellus) ▪ ▪ ▪

American Bittern (Botaurus lentiginosus) ▪ ▪ ▪

Killdeer (Charadrius vociferus) ▪ ▪

Wilson's Snipe (Gallinago delicata) ▪ ▪ + 0.01

Rock Pigeon (Columba livia) ▪

Mourning Dove (Zenaida macroura) ▪ ▪ ▪ - 0.00 + 0.01

Yellow-billed Cuckoo (Coccyzus americanus) ▪ ▪ ▪

Black-billed Cuckoo (Coccyzus erythropthalmus) ▪ ▪ ▪ - 0.08 ▪

Common Nighthawk (Chordeiles minor)

Chimney Swift (Chaetura pelagica) ▪ ▪ ▪ ▪ - 0.02

Ruby-throated Hummingbird (Archilochus colubris) ▪ ▪ ▪ ▪ ▪

Belted Kingfisher (Megaceryle alcyon) ▪ ▪ ▪ ▪ - 0.04 ▪

Red-headed Woodpecker (Melanerpes erythrocephalus) ▪ ▪ ▪

Red-bellied Woodpecker (Melanerpes carolinus) + 0.03 + 0.03

Yellow-bellied Sapsucker (Sphyrapicus varius) - 0.01 + 0.01 ▪ + 0.03 ▪

Downy Woodpecker (Picoides pubescens) ▪ - 0.05 - 0.02 + 0.00 ▪ + 0.00

Hairy Woodpecker (Picoides villosus) - 0.00 ▪ + 0.01 - 0.03 + 0.05 ▪

American Three-toed Woodpecker (Picoides dorsalis) ▪

Black-backed Woodpecker (Picoides arcticus) ▪ ▪

Northern Flicker (Colaptes auratus) + 0.00 + 0.03 + 0.01 + 0.03 + 0.02 ▪

Pileated Woodpecker (Dryocopus pileatus) ▪ - 0.05 + 0.01 ▪ + 0.02 ▪

Olive-sided Flycatcher (Contopus cooperi) ▪ ▪ ▪ ▪ ▪

Eastern Wood-Pewee (Contopus virens) - 0.00 - 0.01 ▪ + 0.01 + 0.02 + 0.01

Yellow-bellied Flycatcher (Empidonax flaviventris) ▪ ▪ + 0.01 - 0.07

Acadian Flycatcher (Empidonax virescens) ▪

Willow Flycatcher (Empidonax traillii) ▪ + 0.02

Alder Flycatcher (Empidonax alnorum) ▪ + 0.01 + 0.03 + 0.01 - 0.01 ▪

Least Flycatcher (Empidonax minimus) + 0.00 - 0.05 - 0.01 - 0.01 + 0.01 ▪

Eastern Phoebe (Sayornis phoebe) ▪ ▪ ▪ - 0.00 - 0.02 ▪

Great Crested Flycatcher (Myiarchus crinitus) - 0.03 ▪ ▪ ▪ + 0.01 + 0.01

Eastern Kingbird (Tyrannus tyrannus) ▪ ▪ ▪ - 0.01 - 0.01 ▪

White-eyed Vireo (Vireo griseus) ▪

Blue-headed Vireo (Vireo solitarius) + 0.02 ▪ ▪ - 0.02 ▪

Yellow-throated Vireo (Vireo flavifrons) ▪ + 0.01 ▪

Warbling Vireo (Vireo gilvus) ▪ - 0.00 + 0.01
102

Table D (continued). Taxonomic list and trend summary of landbirds reported during point count surveys 

in six Great Lakes Network parks (does not include SACN; see text for those data). A “▪” indicates low 

abundance, blank cells indicate species not recorded, and boxes indicate priority species for GLKN.

Park

Species VOYA GRPO ISRO APIS SLBE INDU

Philadelphia Vireo (Vireo philadelphicus) ▪ ▪ ▪ ▪

Red-eyed Vireo (Vireo olivaceus) - 0.00 - 0.00 - 0.00 + 0.01 + 0.02 - 0.00

Blue Jay (Cyanocitta cristata) - 0.00 + 0.01 + 0.01 + 0.04 + 0.00 - 0.02

Gray Jay (Perisoreus canadensis) ▪ ▪ ▪

Common Raven (Corvus corax) + 0.01 - 0.02 - 0.03 - 0.00 - 0.01

American Crow (Corvus brachyrhynchos) - 0.02 + 0.00 - 0.02 + 0.02 - 0.01 - 0.01

Purple Martin (Progne subis) ▪

Tree Swallow (Tachycineta bicolor) ▪ ▪ - 0.04 - 0.01 ▪

Bank Swallow (Riparia riparia) ▪ + 0.03 ▪

Northern Rough-winged Swallow (Stelgidopteryx serripennis) ▪

Cliff Swallow (Petrochelidon pyrrhonota) ▪

Barn Swallow (Hirundo rustica) ▪ ▪ - 0.02 + 0.01

Black-capped Chickadee (Poecile atricapillus) - 0.00 - 0.03 + 0.00 + 0.00 + 0.03 - 0.00

Tufted Titmouse (Baeolophus bicolor) ▪ - 0.01

Red-breasted Nuthatch (Sitta canadensis) + 0.01 - 0.00 + 0.02 + 0.02 + 0.00

White-breasted Nuthatch (Sitta carolinensis) ▪ ▪ ▪ ▪ ▪ ▪

Brown Creeper (Certhia americana) - 0.00 + 0.01 - 0.01 - 0.04 ▪

Carolina Wren (Thryothorus ludovicianus) ▪

House Wren (Troglodytes aedon) ▪ ▪ - 0.03 + 0.00

Winter Wren (Troglodytes hiemalis) + 0.01 + 0.01 + 0.01 - 0.02 ▪

Sedge Wren (Cistothorus platensis) ▪ ▪ ▪ ▪ ▪

Marsh Wren (Cistothorus palustris) ▪ ▪ + 0.02

Blue-gray Gnatcatcher (Polioptila caerulea) + 0.00

Golden-crowned Kinglet (Regulus satrapa) ▪ - 0.00 + 0.02 ▪

Ruby-crowned Kinglet (Regulus calendula) ▪ ▪ ▪ ▪

Eastern Bluebird (Sialia sialis) ▪ ▪ + 0.04 ▪

Wood Thrush (Hylocichla mustelina) ▪ ▪ ▪ + 0.03 - 0.00

Veery (Catharus fuscescens) - 0.01 - 0.01 + 0.00 - 0.01 + 0.07 - 0.02

Hermit Thrush (Catharus guttatus) + 0.01 - 0.04 + 0.01 + 0.04 + 0.01

Gray-cheeked Thrush (Catharus minimus) ▪

Swainson’s Thrush (Catharus ustulatus) ▪ + 0.00 + 0.01 + 0.02 ▪ ▪

American Robin (Turdus migratorius) - 0.00 + 0.01 + 0.02 + 0.01 + 0.03 - 0.00

Northern Mockingbird (Mimus polyglottos) ▪

Gray Catbird (Dumetella carolinensis) ▪ ▪ ▪ - 0.03 + 0.00

Brown Thrasher (Toxostoma rufum) ▪ ▪ - 0.00 ▪

European Starling (Sturnus vulgaris) ▪ ▪ - 0.01 - 0.02

Cedar Waxwing (Bombycilla cedrorum) ▪ - 0.00 - 0.00 - 0.03 + 0.04 - 0.04
103

Table D (continued). Taxonomic list and trend summary of landbirds reported during point count surveys 

in six Great Lakes Network parks (does not include SACN; see text for those data). A “▪” indicates low 

abundance, blank cells indicate species not recorded, and boxes indicate priority species for GLKN.

Park

Species VOYA GRPO ISRO APIS SLBE INDU

Ovenbird (Seiurus aurocapilla) - 0.01 - 0.01 - 0.00 + 0.01 + 0.00 - 0.02

Louisiana Waterthrush (Parkesia motacilla) ▪

Northern Waterthrush (Parkesia noveboracensis) ▪ ▪ + 0.01 ▪ ▪

Black-and-White Warbler (Mniotilta varia) + 0.01 + 0.00 - 0.01 + 0.00 ▪

Golden-winged Warbler (Vermivora chrysoptera) ▪

Blue-winged Warbler (Vermivora cyanoptera) ▪ ▪

Orange-crowned Warbler (Oreothlypis celata) ▪ ▪

Tennessee Warbler (Oreothlypis peregrina) ▪ ▪ ▪ ▪

Nashville Warbler (Oreothlypis ruficapilla) - 0.01 + 0.01 + 0.01 + 0.00 ▪

Connecticut Warbler (Oporornis agilis) ▪

Mourning Warbler (Geothlypis philadelphia) - 0.02 - 0.02 + 0.01 + 0.00 ▪ ▪

Common Yellowthroat (Geothlypis trichas) + 0.00 + 0.00 + 0.02 + 0.00 + 0.02 + 0.00

Hooded Warbler (Setophaga citrina) ▪

American Redstart (Setophaga ruticilla) ▪ + 0.01 - 0.01 - 0.01 + 0.02 - 0.00

Cape May Warbler (Setophaga tigrina) ▪ - 0.06 + 0.02

Cerulean Warbler (Setophaga cerulea) ▪ ▪

Northern Parula (Setophaga americana) - 0.00 - 0.01 + 0.02 + 0.02 ▪ ▪

Magnolia Warbler (Setophaga magnolia) - 0.00 + 0.01 + 0.00 - 0.00 ▪

Blackburnian Warbler (Setophaga fusca) - 0.01 - 0.03 - 0.00 - 0.01

Yellow Warbler (Setophaga petechia) ▪ ▪ ▪ - 0.03 + 0.02 + 0.00

Chestnut-sided Warbler (Setophaga pensylvanica) - 0.02 - 0.04 - 0.01 - 0.02 ▪ ▪

Black-throated Blue Warbler (Setophaga caerulescens) ▪ ▪ - 0.00 - 0.01 - 0.05

Blackpoll Warbler (Setophaga striata) ▪

Bay-breasted Warbler (Setophaga castanea) ▪ ▪ ▪ + 0.01

Pine Warbler (Setophaga pinus) ▪ ▪ ▪ ▪ + 0.03

Prairie Warbler (Setophaga discolor) ▪ ▪

Palm Warbler (Setophaga palmarum) ▪ ▪ ▪

Yellow-rumped Warbler (Setophaga coronata) + 0.02 + 0.03 + 0.00 + 0.01 + 0.03

Black-throated Green Warbler (Setophaga virens) + 0.00 - 0.00 + 0.01 + 0.00 - 0.01 ▪

Wilson's Warbler (Cardellina pusilla) ▪ ▪

Canada Warbler (Cardellina canadensis) + 0.02 + 0.00 - 0.00 + 0.01 ▪ ▪

Yellow-breasted Chat (Icteria virens) ▪ ▪

Eastern Towhee (Pipilo erythrophthalmus) + 0.04 - 0.00

Field Sparrow (Spizella pusilla) ▪ + 0.05 ▪

Clay-colored Sparrow (Spizella pallida) ▪ ▪

Chipping Sparrow (Spizella passerina) - 0.00 - 0.02 - 0.04 + 0.01 + 0.01 + 0.01
104

Table D (continued). Taxonomic list and trend summary of landbirds reported during point count surveys 

in six Great Lakes Network parks (does not include SACN; see text for those data). A “▪” indicates low 

abundance, blank cells indicate species not recorded, and boxes indicate priority species for GLKN.

Park

Species VOYA GRPO ISRO APIS SLBE INDU

Savannah Sparrow (Passerculus sandwichensis) + 0.03 ▪

Vesper Sparrow (Pooecetes gramineus) ▪ + 0.00

Grasshopper Sparrow (Ammodramus savannarum) ▪ + 0.00

Song Sparrow (Melospiza melodia) - 0.01 + 0.01 + 0.01 - 0.01 + 0.01 - 0.01

Lincoln's Sparrow (Melospiza lincolnii) ▪ ▪

Swamp Sparrow (Melospiza georgiana) - 0.00 + 0.00 + 0.01 + 0.00 - 0.01 - 0.00

Dark-eyed Junco (Junco hyemalis) ▪ ▪ ▪

White-throated Sparrow (Zonotrichia albicollis) - 0.01 + 0.00 + 0.00 + 0.00 + 0.01

Summer Tanager (Piranga rubra) ▪

Scarlet Tanager (Piranga olivacea) ▪ ▪ ▪ ▪ - 0.01 ▪

Northern Cardinal (Paroaria capitata) ▪ ▪ ▪ - 0.02 - 0.00

Black-headed Grosbeak (Pheucticus melanocephalus) ▪

Rose-breasted Grosbeak (Pheucticus ludovicianus) - 0.03 - 0.01 ▪ + 0.00 + 0.02 ▪

Dickcissel (Spiza americana) ▪ ▪

Indigo Bunting (Passerina cyanea) ▪ ▪ ▪ ▪ + 0.00 - 0.00

Common Grackle (Quiscalus quiscula) + 0.03 ▪ - 0.00 - 0.04 - 0.00 + 0.01

Red-winged Blackbird (Agelaius phoeniceus) - 0.02 ▪ + 0.03 - 0.02 + 0.02 + 0.01

Yellow-headed Blackbird (Xanthocephalus xanthocephalus)

Brown-headed Cowbird (Molothrus ater) ▪ ▪ ▪ ▪ - 0.00

Bobolink (Dolichonyx oryzivorus) ▪ - 0.02 ▪

Western Meadowlark (Sturnella neglecta) ▪

Eastern Meadowlark (Sturnella magna) + 0.05 ▪

Baltimore Oriole (Icterus galbula) ▪ ▪ - 0.01 ▪

Evening Grosbeak (Coccothraustes vespertinus) - 0.06 - 0.07 - 0.06 ▪

Purple Finch (Haemorhous purpureus) ▪ + 0.01 ▪ ▪ ▪

House Finch (Haemorhous mexicanus) ▪ ▪

Red Crossbill (Loxia curvirostra) ▪ ▪ ▪

White-winged Crossbill (Loxia leucoptera) ▪ ▪ ▪

Pine Siskin (Spinus pinus) ▪ ▪ ▪ ▪

American Goldfinch (Spinus tristis) ▪ + 0.00 ▪ + 0.02 - 0.02 + 0.01

House Sparrow (Passer domesticus) - 0.00
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