Great Lakes

Inventory and Monitoring Network

National Park Service

U.S. Department of the Interior

A Decade of Science and Stewardship

2006-2016
Editor: Ted Gostomski (Network Science Writer/Biologist)

Layout and design: Laurence Wiland (Heart Graphics and Communications, Inc., Ashland, Wisconsin).

Contributors: 

Great Lakes Network Office: Rick Damstra (Aquatic Ecologist–Rivers), Ulf Gafvert (GIS Coordinator), Mark Hart (Data Manager), 

Rebecca Key (Data Management Specialist), Al Kirschbaum (Remote Sensing Specialist), Jessica Kirschbaum (Botanist), Mark 

Romanski (Aquatic Ecologist–Inland Lakes), Bill Route (Network Program Manager), Suzy Sanders (Forest Ecologist), and David 

VanderMeulen (Aquatic Ecologist).

Network Parks: Paul Brown (Chief of Resource Management, Isle Royale National Park); Cindy Heyd (Wildlife Biologist, Pictured 

Rocks National Lakeshore); Sue Jennings (Wildlife Program Manager, Sleeping Bear Dunes National Lakeshore); Byron Karns 

(Biologist, St. Croix National Scenic Riverway); Ryan Maki (Aquatic Ecologist, Voyageurs National Park); Trevor Russell (Water 

Program Director, Friends of the Mississippi River); Brandon Seitz (Biological Technician, Grand Portage National Monument); 

Kevin Skerl (Chief of Natural Resources, Sleeping Bear Dunes National Lakeshore); Wendy Smith (Education Specialist, 

Great Lakes Research and Education Center—Indiana Dunes National Lakeshore); Julie Van Stappen (Chief of Resource 

Management, Apostle Islands National Lakeshore); and Lark Weller (Water Quality Coordinator, Mississippi National River and 

Recreation Area).

Photography and graphics: All photos and graphics were created by NPS staff except

Pages 8–9: eaglets in nest (Jim Campbell-Spickler), climbers with landowner (Eli Nichols); pages 10–11: ovenbird (Dick Daniels, 

carolinabirds.org/Wikimedia Commons); pages 12–13: aerial photos (National Agriculture Imagery Program), prescribed 

fire (Grand Portage Band of Lake Superior Chippewa Trust Lands and Natural Resources Management Program); page 16: 

diatoms (St. Croix Watershed Research Station/Mark Edlund); page 18: aerial photo of river confluence (Metropolitan Council 

Environmental Services); pages 24–25: USGS scientist with lupine (University of Notre Dame), Karner blue butterfly–top view 

(A.E. Cole), Karner blue butterfly–side view (USFWS/Joel Trick); pages 28–29: family picnic (Wikimedia Commons/Carole 

Robertson), triclosan label (Jack Black’s Stunt Double/Flickr, CC BY-NC 4.0), child’s hand with berry (Wikimedia Commons/

Raphaël Quinet); pages 30–31: northern goshawk (Wikimedia Commons/Norbert Kenntner), aerial photo (National Agriculture 

Imagery Program, datagateway.nrcs.usda.gov); page 34: Higgins eye mussels (USFWS); pages 36–37: girl holding northern 

pike (Dave Larsen), fishing from a canoe (University of Wisconsin–La Crosse/Kris Rolfhus); page 38–39: cricket frog (Minnesota 

DNR, http://bit.ly/1jRxgHR), Ellie Hoopman at science fair and Sophie Howk in lab (Rick Erickson), dragonfly larvae and UW-L 

students dip-netting (University of Wisconsin–La Crosse/Roger Haro).

Special thanks to Lark Weller for her helpful advice on accomplishing a project like this; Julie Van Stappen, Kevin Skerl, and 

Bruce Leutscher—the ad hoc committee who helped to select the park stories that are told here; Myra Foster, Tammy Keniry, 

Jeff Selleck, Lucas Westcott, and Jessica Wildes for very helpful reviews of the first draft; Suzy Sanders for standardizing the 

format of all the graphs; Al Kirschbaum and Rebecca Key for creating the maps; and Steve Veit for help with photos at the 

very last minute.

Data Disclaimer: The National Park Service shall not be held liable for improper or incorrect use of the data described and/

or contained herein. These data and related graphics are not legal documents and are not intended to be used as such. The 

information contained in these data is dynamic and may change over time. The National Park Service gives no warranty, 

expressed or implied, as to the accuracy, reliability, or completeness of these data.

Please cite this report as: Gostomski, T. (editor). 2016. A decade of science and stewardship, 2006–2016. National Park Service, Great Lakes 

Inventory and Monitoring Network, Ashland, Wisconsin.
Table of Contents

A Great Lakes Network Timeline .................................................................................................................. 2

Celebrating 10 Years of Partnership in Natural Resource Monitoring............................................................ 4 

Network Map ............................................................................................................................................. 5 

Network Programs Climate and Weather

 Iconic Shifts .............................................................................................................. 6

 Contaminants

 Cool Little Birds Reveal a Human Story ...................................................................... 8

 Landbirds

 Keeping the Common Species Common .................................................................. 10

 Landscape Dynamics

 Changing From the Outside In .................................................................................. 12

 Vegetation

 Simplification Is Not Healthy For a Forest .................................................................. 14

 Water Quality—Inland Lakes

 History Emerges From the Deep ................................................................................ 16

 Water Quality—Large Rivers

 Going With the Flow ................................................................................................ 18

Park Programs Apostle Islands National Lakeshore

 Preserving Windows Into the Past ............................................................................. 20

 Grand Portage National Monument

 Regenerating a Cultural Landscape ........................................................................... 22

 Indiana Dunes National Lakeshore

 Saving a Spot of Blue ............................................................................................... 24

 Isle Royale National Park

 The Island as Refuge ................................................................................................. 26

 Mississippi National River and Recreation Area

 The Cleaner That Isn’t So Clean ................................................................................ 28

 Pictured Rocks National Lakeshore

 Beech Bark Disease Affects More Than Just Trees ...................................................... 30

 Sleeping Bear Dunes National Lakeshore

 Sharing the Beach With Piping Plovers ...................................................................... 32

 St. Croix National Scenic Riverway

 It Takes a Fish to Grow a Mussel ............................................................................... 34

 Voyageurs National Park

 Mercury Contamination: Improvements on the Horizon? .......................................... 36

Monitoring In Action ................................................................................................................................... 38

Literature Cited ............................................................................................................................................ 40
A Timeline of Great Lakes Network History

2

1910

1916

National Park Service created.

1929

George M. Wright conducts the first 

wildlife survey in the national parks.

1930

1931

Isle Royale National Park 

established.

1951

Grand Portage National Historic 

Site established. 

1958

Grand Portage NHS re-designated 

as a National Monument.

1950 1960 1970

1966

Pictured Rocks and Indiana Dunes 

National Lakeshores established.

1968

St. Croix National Scenic Riverway established.

1970

Sleeping Bear Dunes and Apostle Islands

National Lakeshores established. 
3

1980 1990 2000 2010

1975

Voyageurs National Park established.

1976

98% of Isle Royale designated 

as wilderness.

1988

Mississippi National River and Recreation 

Area established.

1999

Inventory and Monitoring Program 

created as part of the NPS’s 

Natural Resource Challenge.

2000

Great Lakes I&M Network established.

2004

Gaylord Nelson Wilderness established 

at Apostle Islands.

2006

Network’s Long-term Ecological Monitoring Plan

is approved. Annual field work begins. 

2009

Beaver Basin Wilderness designated 

at Pictured Rocks.

2014

Sleeping Bear Dunes Wilderness 

designated.

2016

Ten years of monitoring in the Great 

Lakes Network parks. 
4

Celebrating 10 Years of Partnership 

in Natural Resource Monitoring

Bill Route is the 

Great Lakes Network 

Program Manager, a 

position he has held 

since the Network’s 

creation in 2000.

UUnder the Organic Act that Pictured Rocks National Lakeshore, 

established the National Sleeping Bear Dunes National Lakeshore, 

and Indiana Dunes National Lakeshore are Park Service in 1916, all on one of the Great Lakes––the world’s 

national park managers are charged largest interconnected system of fresh water. 

with conserving park resources Grand Portage National Monument (also 

and providing for public use and on Lake Superior) and Voyageurs National 

Park help preserve significant portions enjoyment “in such a manner and of the waterways that were so important by such means as will leave them in the early fur trade, exploration, and 

unimpaired for future generations.” settlement of the upper Midwest. The St. 

Croix National Scenic Riverway was also 

But, park managers are faced with many an important historical waterway and was 

challenges, including invasive species, one of this nation’s first designated Wild 

environmental contamination, a changing and Scenic Rivers. The Mississippi National 

climate, and increased visitation. To meet River and Recreation Area is a NPS-led, 

these challenges, managers must rely on their multi-partner effort to protect green space 

own intimate knowledge of these places and along the nation’s largest working river. But 

they must engage the assistance of a variety these parks are about more than the water. 

of partners, cooperators, and researchers. Visitors come to these parks to fish, hike, 

Nine national parks in the upper Midwest boat, swim, canoe, and view wildlife, and 

are connected to one another through a the upper Midwest is fortunate to have these 

collegial partnership with a shared vision areas that set aside sand dunes and beaches, 

and need to monitor and assess the natural bogs and wetlands, northern temperate and 

resources they protect. Collectively, the nine southern boreal forests, and all the requisite 

parks are part of the Great Lakes Inventory fish, amphibians, birds, mammals, and other 

and Monitoring Network. Together, plants and animals. 

managers and scientists at the parks and at 

the Network conduct long-term monitoring To present a full accounting of the efforts 

of critical park resources––“vital signs”––to required to assess and manage natural 

assess the health of park ecosystems and resources in these parks would take many 

provide a scientific basis for management volumes. What we offer in the following 

actions. This report summarizes our first stories are examples that illustrate the 

decade of field work in collaboration with spectrum of issues park managers and 

the parks, and it is our way of acknowledging scientists are facing. Our stories reveal 

the National Park Service’s Centennial year. how bald eagles, freshwater mussels, and 

tiny diatoms can act as sentinels to help us 

Fresh water is critical for all life on Earth, monitor the health of lakes and rivers, while 

and it is a defining feature in these nine Karner blue butterflies, songbirds, and forest 

national parks. Apostle Islands National plant communities help us understand 

Lakeshore, Isle Royale National Park, 
5

National parks of the Great Lakes Inventory and Monitoring Network.

the direct effects of change on sensitive resources. In who work each day to find solutions that allow visitor 

addition, the weather, human population growth, and use while fulfilling the mandate of leaving the parks 

land use outside the parks are major drivers of change unimpaired for future generations. We focus on nine 

inside parks, and we must understand these forces to national parks in the upper Midwest, but these stories 

put change in perspective. These larger, regional issues have importance beyond their boundaries because 

are where Network scientists play their most important understanding what is happening to the natural world 

role––helping put individual park resource issues in within them sheds light on what is happening to nature 

a larger context. By contrast, park scientists are best that surrounds us every day. 

positioned to assess specific park resource issues such 

as locally threatened species. Together, Network and National parks are important places for people to 

park professionals work collaboratively to monitor and visit and experience the natural world. They are also 

manage natural resources in these protected areas. important for science, learning, and understanding. We 

hope these stories help you to understand some of the 

Through these stories, we hope to convey a sense of the challenges facing our parks and what we are doing to 

passion, dedication, and in some cases, urgency, that better understand and protect them. 

goes into assessing and managing natural resources in —Bill Route

our national parks. They are written by the professionals 
Network Program

Climate and Weather

Iconic Shifts

6

Above: A remote 

automated weather

station (RAWS) 

is installed in the 

Apostle Islands. 

Opposite page 

(bottom): Low 

lake levels create 

inconveniences and 

safety concerns for 

boats moored at 

park docks. 

Cooler by the lake! “Lake-effect 

snow.” We often hear how 

the Great Lakes influence 

local weather, but how climate might 

influence the Great Lakes region is an 

increasingly relevant question. 

The dictionary defines climate as “the average 

course or condition of the weather at a place, 

usually over a period of years.” Climate is 

what makes people think “warm and dry” 

when they think of the southwestern deserts 

or “hot and humid” for the Gulf Coast 

bayous. It is also what makes the Great Lakes 

region “northern temperate.” We have a 

moderate climate that is not excessive in 

one way or the other. Climate is what makes 

each part of the country distinct, and climate 

change is likely to cause a fundamental shift 

in the overall character of each region’s 

prevailing weather.

Climate change predictions for the Great 

Lakes region include higher average 

temperatures, more rainfall than snow during 

the winter, less rain in the summer, and 

more evaporation, creating drier and hotter 

summers (Saunders et al. 2011). 

In places like Isle Royale or the Apostle 

Islands, the current lake-influenced 

temperate climate makes it possible for 

arctic disjunct plants to survive. Separated 

from their typical home range in far 

northern Canada and Alaska by the glaciers 

thousands of years ago, these plants persist 

today because of the cold, wet climate 

maintained along the Lake Superior 

shoreline (see page 26). As we shift toward 

a generally warmer and drier climate, those 

Arctic disjunct plants could literally dry up 

and disappear. The predicted reduction in 

winter ice cover is expected to cause greater 

evaporation of water from the open lakes, 

increasing lake-effect snow in some parts of 

the region, but also lowering summer lake 

levels and leaving some docks and harbors 

difficult or impossible to reach. Lake 

Superior, Lake Michigan, and the large lakes 

at Voyageurs National Park will all bear 

witness to those changes.

For the river parks, the amount of 

precipitation that falls each year, both as 

snow and rain, determines if the Mississippi 

will overflow its banks in the spring (see 

page 18), or if the upper St. Croix and 

Namekagon rivers will have enough water to 

be passable by canoe during the busy visitor 

season. In both rivers and lakes, warmer 

temperatures combined with other factors 

have already created outbreaks of toxic 

algal blooms that make the water unsafe for 

people to swim in or drink (GLKN 2013, 

Edlund et al. 2014) and fatal to fish and 

the waterbirds such as loons that eat them 

(Lafrancois et al. 2011).

Across all of our parks, the shifting climate 

means that the plant communities and 

animals they support will also change 

(Saunders et al. 2011, NPCA 2009, Prasad et 

al. 2007) (see page 22). Some species such as 

balsam fir and paper birch are predicted to 
disappear from the 

southern portion of 

their range across the 

Lake States, leaving 

only those trees that 

thrive in warmer, 

drier conditions. 

Worse, though, 

are the predicted 

increases in incidents 

of exotic species 

invasions and disease 

and insect outbreaks, 

both of which will 

create inhospitable 

conditions for native 

plant communities 

(Saunders et al. 

2011, Fisichelli et 

al. 2014b). Loss of ice 

cover on Lake Superior 

has also decreased 

the chances of wolves 

naturally crossing over 

to Isle Royale (see page 26). 

Our climate monitoring efforts rely in part on weather 

stations maintained by other agencies, but we have 

worked to fill gaps in coverage. We have installed new 

Remote Automated Weather Stations (RAWS) that 

use solar panels and satellite transmission to provide 

hourly weather data from the most remote locations in 

the parks. For example, North Manitou Island (part of 

Sleeping Bear Dunes) is a popular destination that now 

has a RAWS providing valuable weather information for 

island visitors and boaters. The Network makes this near7

real-time weather data, along with other current and 

historic records from a variety of stations, available to 

park staff and the public online at (www.climateanalyzer.

org).

The warmer winters and extended periods of 

drought predicted in climate change models will have 

consequences for the natural treasures of our parks. Our 

monitoring efforts are intended to help park managers 

understand and prepare for those changes. 

—Mark Hart and Ted Gostomski

Average low winter temperatures (up to 2015) at the “four corners” of the Great Lakes Network––Indiana Dunes 

National Lakeshore in the southeast (starting in 1898), Mississippi National River and Recreation Area in the southwest 

(starting in 1873), Voyageurs National Park in the northwest (starting in 1898), and Pictured Rocks National Lakeshore 

in the northeast (starting in 1876). Mississippi River shows the sharpest rise, perhaps resulting from the growth of the 

city, while Voyageurs shows the least amount of change. Data compiled from the National Oceanic and Atmospheric 

Administration and made available at www.climateanalyzer.org.

 Noteworthy:

• Weather and climate are two of the main drivers of the Great Lakes system, 

both in the water and on land. 

The icons of some Great Lakes parks may be in jeopardy as our climate 

becomes warmer and drier. Plants and animals and how they interact will 

be affected. 

How park managers prepare for and respond to climate change will influence what the parks look like and how they biologically function in the 

coming decades.

• 

• 
Network Program

Contaminants

Cool Little Birds Reveal 

a Human Story

8

When it comes to chemicals, 

industry can provide 

useful products, but we 

must understand and weigh the 

consequences to the environment 

and human health. 

For example, the group of industrial 

chemicals known as polychlorinated 

biphenyls (PCBs) was banned in the U.S. 

in 1979 because they affected the health of 

humans and wildlife (USEPA 2016). A mere 

decade later tens of thousands of tons of 

polybrominated diphenyl ethers (PBDEs) 

were being dumped into the environment 

each year. These PBDEs were used as flame 

retardants on furniture and other fabrics, but 

were they safe? Maybe not; their chemical 

structure is so similar to the banned PCBs 

that they have many of the same effects 

on humans and wildlife (Zota et al. 2013). 

Laboratory studies in humans and other 

animals show that PBDEs can be transferred 

from mother to infant, interfere with immune 

and thyroid function, and alter human 

infant behavior (Talsness 2008). Similarly, 

perfluorinated compounds (PFCs) that 

make our clothing water- and stain-resistant 

are slowly breaking down, rubbing off, and 

adding to the mixture of chemicals in our 

lakes and rivers.

A National Symbol, A National Indicator

For more than 30 years, scientists have 

monitored bald eagles, collected and tested 

nonviable eggs, and collected blood and 

feathers from eagle nestlings to assess the 

levels and impacts of chemicals they ingest as 

predators atop the aquatic food web.

Nestling eagles are used, not only because 

they are easier to catch than adults, but 

because they have not yet been exposed to 

the variety of food sources that adults use 

throughout the year. An eaglet’s food comes 

from the area immediately surrounding the 

nest, so chemical levels in the eaglet’s blood 

are indicative of what is in the immediate 

environment. 

A great deal of this work has been done 

in national parks of the upper Midwest, 

including Voyageurs National Park (see 

page 36). Work done there has advanced 

our understanding of mercury in aquatic 

systems and alerted park managers to other 

chemicals of concern (Bowerman et al. 1995). 

From the 1980s through 2002, the Wisconsin 

Department of Natural Resources monitored 

eagles along the southern shore of Lake 

Superior, including the Apostle Islands. Our 

program built off their efforts by including 

eaglets from the St. Croix Riverway and the 

upper Mississippi River, and by testing for 

additional chemicals (Dykstra et al. 2010). 

All You Need is Blood...and Feathers

To monitor contaminants in eaglets, we 

collect a small amount of blood and a few 

breast feathers from 5- to 9-week-old birds. 

Above: A pair of 

eaglets watch as a 

climber approaches 

their nest. After a 

few minutes, the 

climber will enter the 

nest, gently place 

the eaglets in bags, 

then take them 

down to the ground 

for sample collection 

and measurements.

Opposite page 

(bottom): Climbers 

Jim CampbellSpickler (left) and 

Giacomo Renzulo 

(right) with a 

landowner and 

eaglets from the 

nest on his property.
Two groups of chemicals that eagles have helped us 

track are the PBDEs and PFCs. These chemicals end up 

in our municipal wastewater treatment plants through 

industrial and household waste streams, they do not 

break down in the environment, and they have been 

found in wildlife and humans around the world. High 

levels of PBDEs are found in house dust and laundry 

lint from normal wear and washing of clothes, carpets, 

and furniture that are coated with these chemicals.

We have found both PBDEs (Route et al. 2014a) and 

PFCs (Route et al. 2014b) at higher levels in eaglets 

that live near large population centers. In particular, 

eaglets that live near or downstream from municipal 

wastewater treatment plants, or near industrial 

waste release sites, have the highest levels. In fact, 

some eaglets along the Mississippi River are carrying 

the highest PFC levels ever reported for bald eagle 

nestlings. 

And Now For Some Good News

Numerous studies link high levels of these chemicals to 

potential human health risks (USEPA 2015). As a result, 

some countries (e.g., Canada, Europe) and states (e.g., 

California, Oregon) have banned or restricted their use. 

This led to the major chemical manufacturers reducing 

production and pledging to remove them from the 

market. In the case of PBDEs and PFCs, these positive 

steps have resulted in lower levels of these chemicals in 

bald eagle nestlings from parks of the upper Midwest.

—Bill Route

One of the primary PFCs we monitor is PFOS (perfluorooctane 

sulfonate), a fabric stain- and water-repellent. The amount of 

PFOS in eaglet blood is declining at most of our study sites. 

“ppb” = parts per billion. 

Distribution of PBDEs in bald eagle nestlings at Apostle Islands National 

Lakeshore (APIS), the Lake Superior South Shore (LSSS), upper and lower 

St. Croix National Scenic Riverway (U- and L-SACN), Mississippi National 

River and Recreation Area (MISS), and Pools 3 and 4 of the Mississippi 

River. (A) and (B) indicate municipal wastewater treatment plants. (C) 

indicates a municipal landfill. 

9

Noteworthy:

• Flame retardants and stain-resistant chemicals break 

down slowly and add to the mixture of chemicals in 

lakes and streams. 

• These chemicals are known to have dangerous effects 

on the health of both humans and wildlife and are 

found in the blood of bald eagle nestlings. 

• Bald eagle nestlings are showing us that levels of some 

of these chemicals have started to decline as major 

manufacturers reduce or cease production.
10

Network Program

Landbirds

Keeping the Common Species

Common

When talking about wildlife 

conservation, attention 

often narrows to focus 

only on the high priority, high visibility 

species listed under the Endangered 

Species Act. 

Of course, we must protect them, but we 

cannot forget the common species such as 

robins, woodpeckers, and chickadees. These 

are the ones visitors are most likely to see or 

hear in the national parks, so changes in these 

populations might be more readily noticed.

The Migratory Bird Treaty Act (MBTA) 

of 1918 charged federal land managers, 

including the National Park Service, with 

protecting the songbirds that use our parks 

either as rest stops during migration, for 

nesting during the breeding season, or as 

a year-round home. The MBTA ensures 

that we work to “keep the common species 

common.”

Trends—A Mixed Bag

Seven of the nine Network parks have 

conducted surveys for five or more years, 

giving us a sufficient amount of data for 

analysis. In those seven parks, among 21 

of the most common bird species, just five 

species show increasing population trends 

in all seven parks: the American robin, the 

red-bellied woodpecker, the red-breasted 

nuthatch, the red-winged blackbird, and 

the song sparrow. Others are increasing in 

one park but decreasing in another. Tree 

swallows, for example, are significantly 

increasing on the upper St. Croix Riverway, 

but are exhibiting a significant decline in the 

Apostle Islands. Meanwhile, four common 

species are showing significant trends in 

three or more of the parks: the ovenbird 

and chipping sparrow are increasing, while 

chestnut-sided warbler and American crow 

are decreasing.

Mixed results are expected across a large 

area. The trick is in finding patterns. One 

set of interesting patterns are those species 

whose trends in the parks are contrary to 

what is happening elsewhere in the state 

or region. For example, cedar waxwings 

at Indiana Dunes and American crows 

at Voyageurs are declining, but both are 

generally increasing elsewhere. Conversely, 

the meadowlark, veery, and wood thrush at 

Sleeping Bear Dunes are doing better in the 

parks than most other places in the Great 

Lakes region.

Conditions We Cannot Control

What does this mean for songbirds in the 

Great Lakes parks? If the future brings 

warmer temperatures and generally drier 

conditions, then northern species will have 

to move further north to find the appropriate 

habitats or temperatures. Matthews et al. 

(2004) predict ovenbirds will decrease 

substantially in abundance as climate changes 

force them to move further north. Nashville 

Above: Conducting 

point counts on the 

St. Croix Riverway 

(left). A male 

ovenbird (right).

Opposite page 

(bottom): A cedar 

waxwing with a 

wintergreen berry.
warblers are predicted to disappear from 

the eastern United States as summer 

temperatures become warmer and balsam 

fir––a primary component of its preferred 

nesting habitat––disappears (Matthews et 

al. 2004). Filling in behind these could be 

the blue-gray gnatcatchers and northern 

cardinals that are predicted to expand 

northward as winter temperatures become 

more moderate (Matthews et al. 2004).

Fluctuating weather patterns could also 

force birds to shift the timing of their 

northward migration to better match 

the arrival of spring and the emergence 

of insects. Because Nashville warblers rely on 

insects for their food year-round, they are more 

vulnerable to population declines if they are 

unable to adapt to climate change effects on the timing 

of insect emergence (Marra et al. 2014). 

What can the national parks do for birds when the 

changing conditions are beyond our control? What 

the national parks have always offered for the birds 

is a relatively safe place to nest and raise young. The 

majority of U.S. breeding habitat for at least 39 bird 

species is found in national parks (NABCI 2011). In th

Great Lakes region, that means forest habitats. Only 2

of forest bird species show high vulnerability to climate

change (NABCI 2010), but we cannot rest on that 

statistic. Recommended actions include maintaining 

natural processes in our parks such as fire to regenerat

trees (see page 14) and water flow to maintain riverside forests. We should also manage forests in a way 

that assists in the transition rather than trying to 

e 

% 

e 

block it. This means working to connect our parks 

with the surrounding landscapes in a way that provides 

forest corridors that plants and animals will need to 

successfully move north. 

A New Normal

Our next ten years (and more) are sure to bring some 

interesting observations. Perhaps there will be more 

questions than answers, but long-term monitoring 

is a finger on the pulse of the natural world. It 

provides information to help us in our conservation 

responsibilities and to adjust to a “new normal” for birds 

in our parks. Either way, we are working to keep the 

common species common and our parks wild.

—Ted Gostomski

Common ravens are declining on Isle Royale, yet outside the park they are thriving, 

with some of the strongest increases in Michigan and Minnesota (Sauer et al. 2014). 

What’s different for ravens on Isle Royale?

11

Noteworthy:

• Among 21 of the most common bird species, only five are 

increasing in all seven parks. 

There are no clear patterns in species trends across parks, but 

there are species trends in parks that run opposite of those in 

the larger state or region. 

Warmer, drier weather and the loss of habitat-specific 

requirements will cause shifts in what bird species future 

visitors will see and hear in the parks.

•

•
Network Program

Landscape Dynamics

12

Above: A former 

Bureau of Mines 

building complex 

along the Mississippi 

River (2008, left) is 

being restored to an 

oak savanna at the 

Coldwater Spring 

property (2013, 

right).

Opposite page 

(bottom): A 

prescribed fire at 

Grand Portage.

Changing From the Outside In

L

andscape dynamics describes 

the ever-changing nature of the 

land. Some of these changes are 

important and necessary to the health 

of forests, prairies, lakes, and rivers. 

Some disturbances—such as windstorms that 

blow down trees, or fires that kill non-native 

plants and open the resin-heavy cones of jack 

pines—are part of a natural cycle that creates 

a mosaic of habitats. Plants and animals can 

benefit from these disturbances. On the other 

hand, some human-caused changes have 

the opposite effect: the development of a 

subdivision or a parking lot eliminates natural 

habitats and puts obstacles in the migratory 

path of plant seeds and animals.

A Broader View

We monitor the land area inside the parks and 

large areas along their borders using satellite 

imagery and aerial photography, looking 

for changes affecting two acres or more. We 

have seen how natural events and human 

activities can change the landscape, and not 

surprisingly, changes inside the parks often 

differ from those outside their borders. This 

broad view also helps us to identify changes 

outside the parks that may influence the 

movement of plants and animals or affect 

other park resources. 

Changes Occurring Inside and Out

We typically find a healthy, natural 

disturbance regime inside the parks, with 

change usually caused by windstorms, insects 

and diseases, beaver activity, and fire. Some 

examples of natural disturbance regimes are 

seen at Voyageurs National Park where we 

have found disturbances due to fire, beaver, 

and blowdown in a short six-year period.

Insect activity at Apostle Islands (caused 

by an outbreak of the “saddled prominent” 

caterpillar) and Sleeping Bear Dunes (gypsy 

moths) resulted in large numbers of trees 

being defoliated. But defoliated trees do not 

die; the leaves return the next year.

The largest exception to the rule of natural 

disturbance in the parks is Pictured Rocks 

National Lakeshore. Logging is allowed 

within a portion of the park, so forest harvest 

is the main disturbance both inside and out. 

We also see a large amount of tree mortality 

due to beech bark disease spreading from 

east to west within the park. It is the second 

most common form of disturbance on both 
13

•

•

•

sides of the park boundary. 

As you might expect, human-related 

activities are the primary disturbance 

agents outside the parks. This is most 

notable on lands adjacent to northern 

parks such as Voyageurs, Apostle 

Islands, and Pictured Rocks, where 

logging is the dominant influence. 

Between 2006 and 2011, nearly 12,000 

acres were harvested in a contiguous 

block on the eastern edge of Pictured 

Rocks. Large-scale disturbances such 

as this create unique and sometimes 

beneficial habitats, but they also 

fragment the landscape and create 

the potential for invasive species to 

enter. In addition, some activities can 

affect water quality. Heavy logging doesn’t 

just remove trees; it also tramples and strips 

shrubs and low-growing plants from the soil, plants 

that normally slow the flow of water over the ground. 

If they are removed, increased rates of runoff and 

higher amounts of sediment in that runoff can ruin fish 

spawning beds and smother developing fish eggs.

Finally, some disturbances cause permanent changes 

in the underlying habitat type. A forest harvest has a 

short-term effect because trees regrow and the land 

continues to function as a forest. But in urban areas, 

such as those around the Mississippi River, Indiana 

Dunes, and parts of the St. Croix River and Sleeping 

Bear Dunes, more permanent changes occur when 

forests are replaced by buildings and parking lots, 

leaving almost no habitat for native plants and animals.

Functioning in Isolation

The Great Lakes Network parks are part of a landscape 

that spans a wide range of cover types and land uses. The 

land around the more northern and rural parks is sparsely 

populated and densely forested. Forest harvest is the 

primary disturbance agent, fragmenting the landscape 

and affecting water quality and quantity. The parks in and 

near urban areas are true islands of natural habitat in a 

sea of human-dominated land use. Though the amount 

of disturbance around these parks is small, development 

continues to engulf what little natural area exists, further 

isolating the parks and limiting opportunities for animal 

migration and plant seed dispersal. 

—Ulf Gafvert and Al Kirschbaum

The proportion of land disturbed inside (top) and outside (bottom) of park boundaries, by 

disturbance agent. 

Noteworthy:

We monitor landscape changes as small as two acres in and 

around the parks using satellite imagery and aerial photography. 

Disturbances inside the parks are dominated by natural causes 

(windstorms, insects and diseases), while human activities, 

especially logging, are the primary disturbance agents outside 

the parks. 

Development is one of the few disturbances that causes 

permanent changes in the underlying habitat type.
Network Program

Vegetation

Simplification Is Not 

Healthy For a Forest

14

Altered Fire Regimes

Fire suppression is widespread throughout 

our national parks and is contributing to a 

process known as mesophication—a gradual 

change from a drier, open habitat to one with 

moderately moist soils and a more shadetolerant plant community. Without fire, 

fire-dependent tree species cannot release 

F

orests can change very slowly, 

gradually attaining a mature 

composition and structure, or 

they can change in an instant when 

fire, severe windstorms, or insect 

outbreaks sweep through. 

Our vegetation monitoring program tells us 

something about the threats and challenges 

parks face in meeting the NPS mandate 

to protect scenery and wildlife. The three 

biggest threats to park forests are altered 

fire cycles, heavy deer browse pressure, and 

invasive species. Collectively, these processes 

contribute to an overall simplification of 

forest composition and processes.

seeds and successfully regenerate, while fireintolerant species become common. With 

this change in species composition, there is 

a reduction in the amount of sunlight that 

reaches the forest floor. Red maple is one 

species that is becoming more widespread as 

a result of mesophication. Its leafy canopy 

promotes greater shading, which reduces 

evaporation and increases soil moisture, 

further reducing the likelihood of fire. All this 

leads to a set of conditions that ultimately 

changes the way a forest functions.

Deer Herbivory

High deer densities are prohibiting the 

regeneration of some canopy tree species, 

like white cedar and hemlock, and shrubs 

such as Canada yew (see page 20). Hardwood 

species such as beech, trembling aspen, 

and sugar maple may fill the gaps, but the 

simpler species assemblage that results 

can have significant impacts. Both cedar 

and hemlock provide extensive wildlife 

habitat by sheltering the understory from 

large snowfalls and providing animals with 

den and burrow sites. Deer are also overbrowsing the ground layer, reducing the 

number and diversity of herbaceous species 

including many wildflowers. These are being 

replaced by low diversity (i.e., simpler) stands 

of ferns, grasses, and sedges.

Above: The 

difference between 

a forest with a 

healthy ground layer 

(left) and one that 

has been browsed 

by deer (right).

Opposite page 

(bottom): The mark 

of deer browse on a 

bluebead lily leaf.
Invasive Species

Invasive species include non-native plants, as 

well as insects (e.g., emerald ash borer), fungi 

(e.g., Dutch elm disease), and earthworms. 

Once established, invasive species alter the 

forest community by limiting the amount 

of sunlight, water, and nutrients available to 

native species and can change the successional 

pathway. The biggest invasive species 

challenges for Network parks include the nonnative beech scale insect, a cause of beech bark 

disease, which has claimed most of the beech 

trees at Pictured Rocks (see page 30); nonnative 

earthworms that devour the leaf litter on the forest 

floor, denying plants the nutrients they need to thrive; 

and invasive plants such as the exotic honeysuckles 

that outcompete native shrubs such as the dogwoods, 

reducing forest richness and the amount of good quality 

food and habitat available to wildlife.

There Is Some Good News

All nine parks have large expanses of high-quality 

habitat. Many island parks are free from the threats 

facing mainland parks—deer populations are low or 

nonexistent (except for Sand and York Islands in the 

Apostles and North Manitou Island at Sleeping Bear 

Dunes) and invasive species are limited. As a result, 

the island forests more closely resemble the pre-EuroAmerican settlement period. A large number of tree 

species are regenerating, and the shrub and herb layers 

contain species not commonly found on the mainland, 

including a large number of orchids and Canada yew.

The abundant downed woody material and standing 

15

•

•

•

dead trees in the parks provide habitat for small 

mammals, serve as nursery beds for seed germination, 

and provide nutrients to the plant community. Standing 

dead trees, or snags, provide habitat for cavity-nesting 

birds, including woodpeckers, owls, nuthatches, and 

chickadees.

As climate change continues to affect the region, large 

blocks of native habitat in our northern parks, especially 

Isle Royale, will likely provide refuge for a number 

of boreal tree species, including paper birch, white 

spruce, and balsam fir. As the climate warms and the 

concentrations of these species move north, north-facing 

slopes and sheltered coves cooled by Lake Superior may 

provide niches where small populations can persist. 

Ensuring these pockets remain free of invasive species 

over the next 50–100 years will be a key management 

action.

—Suzanne Sanders and Jessica Kirschbaum

Red maple is most common among the smaller (younger) trees in upland 

mixed conifer-hardwood forests along the St. Croix Riverway. Though it is a 

native species, it can outcompete other trees and dominate an area.

Noteworthy:

Not enough fire, too many deer, and the introduction of invasive species are 

the most common threats to Great Lakes forests. 

Many forests are becoming overly simplified in both species composition 

and the processes that maintain quality habitat. 

All nine parks have large expanses of high quality habitat, some of which 

may play an important role as climate change continues to affect the region.
Network Program

Water Quality—Inland Lakes

History Emerges From the Deep

16

T

he undeveloped lakeshores 

that are found in the national 

parks may cause you to stop 

and wonder what the lake looked 

like before the upper Midwest was 

settled by Europeans.

Of course, the tools to measure things like 

water clarity, nutrients, and algae were 

not available back then, but we commonly 

measure these things today and use that 

information to describe lake water quality. 

Fortunately, we now also have an indirect but 

powerful tool to help us develop a reasonable 

idea of what a lake’s water quality conditions 

were like when European settlers arrived, and 

that tool is buried in the bottom of the lake.

The Small But Powerful Diatom

You are probably not thinking about algae 

when you try to imagine what a lake looked 

like in the past, but diatoms are a type of 

algae, or very small plants, that live in lakes 

and form the base of a lake’s food chain. 

What makes diatoms unique is that their cell 

walls are made of biologically produced glass, 

and when diatoms die, their cell walls are 

preserved in the lake bottom sediments.

Here’s where the history comes in. We 

collect long cores of sediment from the lake 

bottoms, assign dates to different layers 

(similar to how tree rings are counted and 

aged), then identify the kinds of diatoms that 

were present in the different time periods. 

Then, using what we know about the water 

quality conditions that certain diatoms prefer, 

we can use the identities of the diatoms in 

the sediment core to reconstruct past water 

quality conditions, including water nutrient 

levels (e.g., phosphorus) and acidity (pH).

These reconstructions are important because 

we actually measure those same conditions 

in park lakes today using special sensors 

and electronic equipment, and by analyzing 

water samples collected from the lakes. So we 

can compare our current data with what the 

diatoms tell us conditions were like hundreds 

of years ago, before lakes were protected 

through the creation of national parks.

Still the Same...Mostly

When we compare current water quality 

conditions with our “diatom-inferred” 

reconstructions of historic water quality 

Above (left to 

right): Short- and 

long-cores used to 

collect lake bottom 

sediments. Diatoms 

magnified 875–

1,250 times.
conditions, we can see periods where diatom 

communities were likely affected by events 

such as fires, logging, or agriculture. But we 

also see evidence that water quality in most 

lakes has not been significantly altered in the 

last 100 to 200 years (Edlund et al. 2011). 

Of course, there is one small but important 

wrinkle in this story: many of the inland 

lakes where we monitor water quality have 

experienced notable changes in their diatom 

communities in the last 10 to 20 years 

(Edlund et al. 2011). This might be some sort 

of climate change signal that has the potential 

to alter our lakes in ways that we are just 

beginning to explore. 

—David VanderMeulen 

and Mark Romanski

17

•

•

•

A comparison of total phosphorous levels in three lakes at Voyageurs National 

Park. Measurements for the years 1780–2000 (red lines) are inferred from 

the diatom record in lake bottom sediments. Their proximity to levels actually 

measured by Network staff between 2006 and 2012 (black square and vertical 

bars) indicates that water quality in these lakes has not changed much in the last 

200 years. 

Summer temperatures in the shallow waters of Lake Richie on 

Isle Royale have increased by nearly 2o Celsius since 1960. Similar 

increases have been seen in three other lakes on the island and at 

four lakes in Voyageurs National Park. Such changes could affect 

diatom communities in these lakes, which is something we will watch 

for in future years.

 Noteworthy:

The glass-like cell walls of diatoms are preserved in lake bottom 

sediments after the algae dies. Different species require different 

conditions to survive. 

By dating the layers of lake bottom sediments, then identifying the 

diatoms in each layer, we can reconstruct historic water quality 

conditions. 

Comparisons with current data show that water quality in most 

lakes has not been significantly altered in the last 100 to 200 years.
Network Program

Water Quality—Large Rivers

Going With the Flow

18

Understanding how rivers 

were abused in the past 

is key to appreciating just 

how much their water quality has 

improved since the middle of the 

20th century. 

Early problems were caused by logging and 

the increase of sediment that washed into 

the rivers as a result. The construction of 

dams and wingdams to facilitate logging and, 

later, locks and dams to aid in navigation 

altered the river flow, which also degraded 

conditions for aquatic life. Urbanization 

and increased wastewater, and a dramatic 

increase in the use of fertilizer on agricultural 

lands since the 1950s resulted in high nutrient 

levels (primarily phosphorous). Combined 

with increased sediment runoff, the water 

became a toxic brew, especially in the 

Mississippi River. 

Along with the passage of key legislation such 

as the Clean Water Act of 1972, changes in 

land use practices and the technology used 

in wastewater treatment plants are helping to 

improve water quality, sustain the rivers, and 

in some cases bring life back to them.

Our water quality monitoring efforts on 

the Namekagon/St. Croix Rivers and on 

the Mississippi River allow us to track both 

current conditions and long-term changes. 

In addition, the U.S. Geological Survey, 

U.S. Army Corps of Engineers, Minnesota 

and Wisconsin Departments of Natural 

Resources, Minnesota Pollution Control 

Agency, and Metropolitan Council of 

Environment Services all conduct long-term 

water quality monitoring at one or both river 

parks.

Our monitoring was designed to complement 

and add to existing efforts, but after 

comparing several years of data we collected 

with that collected by others, we found that 

our efforts on the Mississippi River were not 

contributing in any substantial way to a better 

understanding of water quality conditions. 

So we suspended our field work on the 

Mississippi River in 2013 and shifted our 

focus to tracking and periodically analyzing 

the data collected by the other agencies. 

On the St. Croix we now primarily monitor 

water quality at previously underrepresented 

areas in the upper Riverway, including areas 

that the U.S. Environmental Protection 

Agency considers to be “the best of what is 

Above: Differences 

in land use along 

the rivers become 

evident where 

the blue St. Croix 

meets the muddy 

Mississippi (left). 

A depth gauge 

on a bridge piling 

provides an indicator 

of river flow (right).

Opposite page: 

Spring flood on 

the Apple River, a 

tributary of the St. 

Croix
19

•

•

. 

•

left” for navigable rivers (USEPA 2008). 

The constantly changing nature of rivers make trends 

difficult to verify, but annual monitoring helps us 

to understand what is happening in a given year. 

Sometimes that is enough, because, as Leonardo Da 

Vinci said, “In rivers, the water that you touch is the last 

of what has passed and the first of that which comes.”

—David VanderMeulen and Rick Damstra

Select high and low flow events on the Mississippi River over the last 80 years, as measured by a gauge in St. 

Paul, Minnesota. We monitor river flow through the use of stream gauges operated by the U.S. Geological 

Survey and the U.S. Army Corps of Engineers. 

Long-term average 

flow = 15,000 cfs

Noteworthy:

Legislation, changes in land use practices, and advances in 

wastewater treatment technology are helping to improve 

water quality in the St. Croix and Mississippi Rivers. 

Many state and federal agencies and municipal organizations 

monitor water quality on the St. Croix and Mississippi Rivers

Our monitoring is focused on underrepresented areas of 

the St. Croix River, including “the best of what is left” for 

navigable rivers in the U.S.
Park Program

Apostle Islands National Lakeshore (Wisconsin)

Preserving Windows Into the Past

20

You walk into the forest and 

are greeted by a sea of green. 

There are places where the 

shrubs grow so close together and the 

tangle of branches is so dense and 

tall that you swim, rather than walk, 

to make progress; at times your feet 

don’t even touch the ground. 

The shrub is Canada yew, and the place is York 

Island. This experience is a very rare one today, 

but Canada yew used to be very abundant in 

coastal areas and islands throughout the Great 

Lakes and the northeastern portion of the 

United States.

“Deer Candy”

Canada yew is known as “deer candy” because 

deer so strongly prefer it over anything else. 

Consequently, Canada yew has declined in 

abundance in recent years, primarily due 

to over browsing by white-tailed deer. In 

the Apostles, large increases in the deer 

population during the 1950s and 1960s, 

combined with logging and fire, greatly 

reduced yew’s abundance on many of the 

islands. Yet, some islands provided refuge to 

the plant, and on those islands, Canada yew 

continued to blanket the ground. This was 

the case for Sand and York Islands until the 

early 2000s.

Deer became established on Sand and 

York Islands in the early 2000s and rapidly 

multiplied. In less than 10 years, the 

population on Sand Island grew from near 

zero to more the 50 deer/mi2

, and browse and 

pellet survey results revealed that deer were 

having a severe impact on Canada yew (Smith 

2007). The situation was even more apparent 

on York Island, where the biomass of Canada 

yew dramatically declined in just a few years 

(Allison 2006).

The Appropriate Management Tool

In 2004 we began taking actions to reduce the 

deer population and save this rare plant and 

its associated forest community. We started 

by encouraging hunters to participate in an 

October muzzleloader hunting season on 

Sand and York Islands. At the same time, we 

requested the help of our tribal and state 

partners in developing a harvestable species 

plan (NPS 2007; updated in 2014), which 

established two deer management zones 

in the park. Zone 1 includes 11 islands that 

historically had few to no deer and has the 

management goal of keeping deer numbers 

Above: There is a 

stark difference 

between healthy 

yew and yew that 

has been browsed 

by deer. 

Opposite page 

(bottom): Deer 

are able to swim 

to the islands that 

are closest to the 

mainland and 

from one island to 

another.
as low as possible. The remaining nine islands are within 

Zone 2. These islands have a history of deer presence 

and a management goal of keeping deer populations at or 

below estimated historic levels (<10 deer/mi2

). The park 

worked closely with the Wisconsin DNR on changes to 

State regulations needed to implement the plan. 

Unfortunately, hunting alone was not enough. Deer 

numbers continued to increase. Even the addition of 

Park and volunteers cullers was not enough to stop a 

burgeoning deer population. Thanks to Great Lakes 

Restoration Initiative funding, the park was able to 

enter into an agreement with the U.S. Department of 

Agriculture’s Wildlife Services that brought deer culling 

specialists to the islands from 2009 to 2012, resulting in 

a dramatic decline in deer numbers. (All venison 

acquired through these culling operations was donated 

to the local tribal food shelf.) 

A Slow Return

Annual browse and pellet surveys, along with remote 

cameras, allow us to monitor the deer population and 

determine if we are reaching our management goal. 

There are hopeful signs. The number of deer pellet 

groups/acre on Sand Island decreased from a high of 

240 in 2008 to 1 in 2014, and Canada yew is slowly 

showing signs of recovery (Sizer and Johnson 2014).

The story of deer impacts on rare and sensitive plants is 

a common one. Managing the issue means balancing a 

vibrant and diverse plant community with a highly visible 

and beloved animal. Many parks share similar concerns, 

and we are all striving to achieve that balance.

—Julie Van Stappen

21

•

•

•

Special deer management zones were created in the Apostle Islands as part 

of the park’s Harvestable Species Plan. The Mainland Unit and Long Island 

were not included in the park plan.

Average percentage of Canada yew browsed by deer in monitoring plots 

on Sand and York Islands, 2006–2014. Intensive deer culling on the two 

islands began in 2009.

Noteworthy:

Canada yew was once so abundant on York Island that it was one 

of the most difficult islands on which to hike. 

Canada yew has been nearly eliminated from the forest on Sand 

and York Islands due to deer browsing. 

Strategies to manage deer on the islands have successfully 

reduced the herd so that yew is now showing signs of recovery.
Park Program

Grand Portage National Monument (Minnesota)

Regenerating a Cultural Landscape

22

T he southern boreal forest 

plant community has always 

been an important part of the 

heritage and culture of the Grand 

Portage Ojibwe as well as a critical 

component of the natural scene 

along Lake Superior’s north shore. 

Because of our focus on the Ojibwe people as 

well as the fur trade, their cultural perspective 

is the starting point for forest management at 

Grand Portage National Monument.

There Goes the Neighborhood

Climate change models predict that boreal 

forest tree species may disappear from the 

Great Lakes as the region becomes warmer 

and drier (Fisichelli et al. 2014a). White pine, 

black spruce, and tamarack—species native 

to the boreal forest and part of Grand Portage 

Ojibwe culture for the last 300–400 years—

may vanish and be replaced by species such 

as black and white oak and black cherry. To 

lose white pine would be similar to waking 

up one day to find your entire neighborhood 

re-built around you; nothing is familiar and 

all the signs of “home” are gone.

Forest managers have several options for 

responding to these predicted changes. One 

is to embrace the potential new species as 

a novel environment and manage the “new 

forest” for maximum biodiversity regardless 

of impacts to cultural practices. A second 

option is to manage the forest as a historical 

garden in which we weed out the “exotic” 

migrants and deny the shift in forest habitat. 

A third option is to invest in an aggressive 

program to propagate, restore, and regenerate 

those native species that are predicted to 

persist in greater numbers than they do now, 

species such as black ash, balsam poplar, 

sugar maple, tamarack, red and white pine, 

and bigtooth aspen (Fisichelli 2014b). 

Nurturing this suite of species will create 

forests that are more resilient to climateinduced changes and maintain a reasonable 

amount of cultural integrity.

White pine has endured a number of 

challenges since Euro-American settlement: 

early 20th century logging, the white pine 

weevil, fire suppression, and the introduction 

of white pine blister rust. All of these 

combined to drastically reduce white pine 

abundance and genetic diversity in the Great 

Lakes region (White and Host 2003, Host 

2011). White pine occupies a forest niche 

that could otherwise be filled by red maple, 

a native species that is considered to be the 

most aggressive climate change–induced 

invader of northern forests (Drake et al. 

2011) (see page 14). 

Selecting For Resilience

Cliff and Isabel Ahlgren—two champions 

of the white pine—sought to restore the 

tree to its former grandeur. To do this, they 

selectively bred white pines on the shores of 

Basswood Lake in northern Minnesota 

Above: White pine is 

a dominant tree on 

Lake Superior’s north 

shore landscape, 

making it an integral 

part of what the 

Ojibwe call “home.” 
23

•

•

•

When seeds fall from the cones of a white pine (called seed rain), they can travel 200 feet within a stand of trees and more than 700 feet in the open. But 

gaps between stands of white pine are also vulnerable to invasion by non-native or invasive species. By planting disease-resistant white pines in the gaps 

beyond the 700-foot seed rain buffers of adjacent white pine stands, pine forests have a chance to remain dominant and healthy.

White pine seeds travel 200 700 feet Plant disease-resistant white pine feet within a stand and more Vulnerable to 700 feet seedlings in the seed rain gaps to prevent than 700 feet in the open. invasive species non-native species from taking root

to unravel the secrets of blister rust tolerance (Isabel 

Ahlgren, personal communication, 2011). After decades 

of work, they identified a wide diversity of traits that 

allowed white pine to tolerate blister rust in different 

ways. To combine these different traits, the Ahlgrens 

gathered seed from tens of thousands of the most 

promising trees in northeastern Minnesota and parts 

of northern Wisconsin, and planted them in U.S. Forest 

Service nurseries in Michigan and Minnesota. The 

progeny from these nurseries were then planted in 

some of the worst blister rust areas on the Minnesota 

north shore of Lake Superior. To make it even more 

challenging, every possible alternate host plant for 

white pine blister rust was planted between the rows of 

pines. Of course, many pines succumbed to blister rust, 

but several thousand trees survived unharmed. These 

remaining trees cross-pollinated each other and created 

the seed we are using for our restoration project.

Before we planted trees, we used the recently completed 

forest vegetation inventory (Hop et al. 2010), soils 

inventory (Gafvert 2009), and forest vegetation 

monitoring report (Sanders 2008) to identify suitable 

stands for white pine restoration as well as stands already 

containing white pine that needed some “regenerative 

assistance.” Next, we mapped a “seed rain” buffer 

zone around each existing pine or groups of pines, 

representing the area where seed normally falls from 

a reproducing tree. Using this map, we planted 700 

seedlings in the spaces between seed rain buffers. 

Additionally, in the pine stands that were already 

established, we removed vegetation from around the 

young pines so they had every advantage in reaching the 

canopy.

Tamarack Is Next

Our next step is to invest in tamarack restoration, but 

only three tamarack trees remain at Grand Portage, so we 

have far fewer options for restoration. Still, with a lot of 

hard work and a little luck, niches abandoned by climateinduced tree migrations will have a good chance of being 

filled by ecologically and culturally important white pine 

and tamarack.

—Brandon Seitz

 Noteworthy:

Climate change modeling predicts that some boreal forest tree species will 

disappear from the northern United States as warmer and drier conditions 

become the norm. 

Many boreal tree species hold a special place in the culture and history of 

the Ojibwe people. Losing the trees also means losing a piece of that culture 

and history. 

Park staff are working to regenerate and restore some boreal tree species 

including white pine and tamarack.
Park Program

Indiana Dunes National Lakeshore (Indiana)

Saving a Spot of Blue

24

I

n late spring and early to midsummer, wildlife biologists at 

Indiana Dunes National Lakeshore

are frequently found walking 

transects and counting Karner blue 

butterflies. 

The Karner blue is a small butterfly 

whose range formerly extended across 12 

states—from Minnesota to Maine—and the 

province of Ontario, Canada. Today it can 

only be found in seven states—Minnesota, 

Wisconsin, Michigan, Ohio, New York, 

New Hampshire, and Indiana (U.S. Fish 

and Wildlife Service 2003). The Karner 

blue is native to Indiana Dunes National 

Lakeshore, where it favors black oak savanna 

and the wild lupine that is found there. 

Wild lupine is the sole host plant for Karner 

blues during their larval (caterpillar) stage. 

Restoration of the oak savanna and carefully 

managed prescribed burns help ensure that 

populations of wild lupine remain plentiful.

A Slight Change of Plan

The Karner blue butterfly was listed 

as federally endangered in 1992, so we 

enlisted a butterfly expert to help design a 

monitoring protocol and train park staff in its 

implementation. Intensive monitoring began 

in 1994 and has continued over the last 21 

years.

In the early 2000s, when population 

monitoring data began to show an alarming 

downward trend, we worked with multiple 

partners to develop and carry out a five-year 

propagation program that began in 2006. 

As a result of that program, 885 pupae were 

successfully reared. However, despite both 

habitat management and propagation efforts, 

the butterfly population continued to decline. 

Why?

To find out, we provided funding to the 

U.S. Geological Survey and the University 

of Notre Dame to investigate the impacts 

of climate change on the Karner blue. They 

raised eggs into multiple generations of 

butterflies in the laboratory and found that 

Karner blues produced additional broods 

in warmer temperatures. Unfortunately, 

each successive brood yielded lighter-weight 

butterflies, and lighter-weight females laid 

fewer eggs. Additional broods also develop 

later in the season, increasing the risk that 

wild lupine will die back before the butterflies 

have fully developed. 

But in 2012, it wasn’t late broods that 

were lost. Instead, hot weather came 

early to northwestern Indiana, with 

March temperatures reaching 86 degrees 

Fahrenheit—something that would normally 

not happen until April or May. Karner blue 

eggs hatched much earlier than normal, 

before many of their wild lupine host plants 

had emerged. With little to no food, we 

believe the majority of the Karner blue larva 

died.

Above: Checking 

lupine for Karner 

blue eggs or 

caterpillars (left). An 

adult Karner blue 

butterfly (right).

Opposite page: 

Karner blue 

caterpillars were 

raised in individual 

plastic containers 

with fresh lupine 

leaves for food. 

Team members 

checked them 

every day, cleaning 

the containers 

and providing 

fresh leaves until 

the caterpillars 

transitioned to the 

chrysalis (pupal) 

stage.
Augmenting the Population

Monitoring data paint a grim picture of the 

Karner blue butterfly population at Indiana 

Dunes––only two butterflies were observed in 

2014. The population here may be extirpated, 

or at the very least is extremely low. But we 

have not given up hope. Eggs from the Karner 

blues reared in the laboratory experiment 

are still alive. With the help of partners like 

the Peggy Notebaert Nature Museum (the 

educational arm of the Chicago Academy 

of Sciences), a small number of Karner 

blue butterflies from other locations will be 

brought in to augment the Indiana Dunes gene 

pool. Perhaps this population can be saved. 

In the meantime, erratic shifts in weather 

like those in 2012 are predicted to become 

more frequent as our climate continues 

to change at an unprecedented rate. It is 

a new game, and resource managers must 

consider new strategies to protect our park 

resources. 

—Wendy Smith

25

•

•

•

Numbers of Karner blue butterflies observed during surveys on six routes at 

Indiana Dunes. Surveys are conducted twice a year because Karner blues produce 

two broods of young each year. 

 Noteworthy:

Indiana Dunes National Lakeshore has been managing for and 

monitoring the endangered Karner blue butterfly since 1992. 

Despite propagation and habitat management efforts, the 

Karner blue population at Indiana Dunes continues to decline. 

Climate shifts threaten the success of efforts to save this 

endangered species.
Park Program

Isle Royale National Park (Michigan)

The Island as Refuge

26

Many people, when they 

hear the word “island,” 

immediately envision a 

tropical landscape with palm trees 

and white sand beaches. 

Indeed, many islands fit this stereotype, but 

islands in the boreal forest are quite different 

from this mental image. On Isle Royale, for 

example, the islands were created by ancient 

lava flows and are covered in shallow soils 

and dense forests. But, like islands found 

the world over, Isle Royale is a dynamic 

ecosystem, influenced by the size of the 

island and its distance from the mainland. It 

is this isolation that can significantly hinder 

some plant and animal populations from 

thriving—such as the inbreeding currently 

afflicting Isle Royale wolves (Räikkönen et 

al. 2009)—while others find a refuge from 

potential stressors. Those that thrive may 

even, over time, become genetically distinct 

from mainland populations of the same 

species (Howell 1936).

At Isle Royale National Park we see many 

examples of flora and fauna that have taken 

refuge here. Numerous plant species in 

the park are disjuncts, cut off from their 

arctic and western origins. The island is also 

home to the federally threatened northern 

long-eared bat, and more than one-third of 

Michigan’s breeding common loons and twothirds of the state’s moose. 

Arctic and Western Plants

The island’s rocky shores and the cold waters 

of Lake Superior that surround it provide 

perfect ecological niches for nearly two 

dozen plant species that are western disjuncts 

or have arctic-alpine affinities (Slavick and 

Janke 1987). Disjunct species are those 

with unusually wide gaps in their overall 

geographic distribution. Most of the disjunct 

plants on Isle Royale found refuge here as the 

ice sheets receded from the Laurentian Great 

Lakes almost 10,000 years ago, so the next 

closest place to find them is in the Black Hills 

of South Dakota and further west to the coast 

of the U.S. and Canada.

Wildlife, From Small to Tall

Disjunct species on the island are not limited 

to the plants. A recent bee survey found 

over 30 species of native bees on the island 

(Rodman et al. 2015), many of which exhibit 

this disjunct distribution; two are being 

evaluated as potentially new, previously 

unknown species.

The federally threatened northern long-eared 

bat is one of the six species of bats known to 

spend summers on Isle Royale. Bats are fully 

protected within the park boundaries, and 

the island provides ample high-quality habitat 

and abundant food. What we do not have is 

good winter habitat, so the bats migrate off 

the island to find hibernation sites for the 

winter. As a result, even though Isle Royale 

can serve as a summer refuge, it cannot 

protect this species from its greatest threat: 

white-nose syndrome, a fungal infection 

Above: Common 

loons (left) and a 

northern long-eared 

bat (right).

Opposite page 

(top): Butterwort 

is an arctic disjunct 

plant that grows in 

the rocky crevices 

of Isle Royale’s Lake 

Superior shoreline.
that affects this bat and others during their long winter to protect the plant and animal species that reside in 

hibernation. the national parks, but we have little control over what 

happens to these species once they leave our boundaries. 

For moose, the island serves as a refuge from a multitude 

of stressors (including warming temperatures and —Paul Brown

brainworm) that are causing populations to decline 

across much of the Great Lakes region (Dybas 2009). 

So while mainland moose have been steadily declining 

in recent years, Isle Royale moose have been steadily 

increasing. 

Sometimes Isolation Isn’t Enough

In our increasingly connected world, even islands may 

not continue to be effective refuges. We do what we can 

27

•

•

•

Isle Royale’s wolf and moose populations have fluctuated through time in response to winter ticks 

and harsh winters (for moose) and disease and genetic issues (for wolves). Data from the Wolves 

and Moose of Isle Royale web page (www.isleroyalewolf.org/)

 Noteworthy:

Islands are dynamic ecosystems that are influenced by the size 

of the island and its distance from the mainland. 

This isolation can significantly hinder the success of some 

plant and animal populations while helping others. 

Isle Royale is a refuge for unique plants and animals, but the 

specter of climate change may affect what species are found 

there in the future.
Park Program

Mississippi National River and Recreation Area (Minnesota)

The Cleaner That Isn’t So Clean

28

Your family has enjoyed a 

wonderful day at the park. 

There is no running water, 

but you brought along a large bottle 

of antibacterial handwash. 

It’s come in handy for the kids, especially 

the one that grabbed a frog and then wanted 

to grab a hamburger! But did you read the 

label on that handwash? Are you familiar 

with triclosan, a common ingredient in some 

antibacterial products?

Triclosan is an antibacterial product 

developed in the 1960s and introduced 

for use in health care facilities in 1972; it 

has since been added to a wide variety of 

household products. It is most commonly 

found in liquid antibacterial hand and 

dish soaps, but is also used in toothpaste, 

deodorant, fabric, kitchenware, and 

cosmetics. An estimated 96% of triclosan 

from consumer products goes down the 

drain, much of it eventually reaching 

wastewater treatment plants (see page 9). 

Treatment plants are not designed to remove 

triclosan, so it remains in treated water that is 

discharged into the environment (Buth et al. 

2010).

What Are the Risks?

You might think, “it’s a hand-cleaner; 

what could be so bad about it?” First, as 

triclosan moves through the wastewater 

treatment process, it is exposed to sunlight 

and chlorine, which can transform it into 

potentially harmful dioxins and other 

carcinogens, some of which can persist in 

our environment (Buth et al. 2010). Once 

in the environment, triclosan can directly 

impact aquatic organisms by interfering 

with thyroid and reproductive systems, 

disrupting endocrine function, and affecting 

neural development (Chalew and Halden 

2009, Martin 2011). It has also been 

shown to disrupt muscle function in mice 

(Cherednichenko et al. 2012) and interfere 

with fetal development in sheep (James et al. 

2010).

Humans can be exposed to triclosan through 

skin contact, ingestion of contaminated 

drinking water, or inhalation (Food and 

Water Watch 2009, Minnesota Department 

of Health 2010). It has been found in the 

urine of 75% of Americans over the age of 

five (Calafat et al. 2008, Martin 2011), breast 

milk (Allmyr et al. 2006), and blood (Allmyr 

et al. 2008). Higher overall levels are found 

in the bodies of people who use triclosan 

products. 

Triclosan’s effects on humans are unclear, 

but triclosan exposure can lead to allergy 

susceptibility in humans (Savage et al. 2012) 

and present risks to healthy fetal development 

in pregnant women (Woodruff et al. 2011). 

In addition, the Minnesota Department 

of Health (2010) recommends against 

using antibacterial products in most home 

applications because they may contribute to 

the emergence of resistant strains of bacteria.
Status and Trends

In the bottom sediments of Lake Pepin—a 

naturally occurring lake approximately 

60 miles downstream from Saint Paul, 

Minnesota—the amount of triclosanderived dioxins has increased by 200% 

to 300% since 1963. Dioxins are highly 

toxic, and this increase is consistent with 

the increased use of triclosan since its 

introduction into household products. 

Levels of all other dioxins have decreased 

by 73% to 90% (Buth et al. 2010). 

Triclosan-derived dioxins represent as 

much as 31% of the total mass of dioxins 

in Lake Pepin sediment (Buth et al. 2010). 

The U.S. Geological Survey found that 58% of 

U.S. streams contain triclosan, including the metro 

Mississippi River (Kolpin et al. 2002). Amounts are also 

increasing in several Minnesota lakes (Anger et al. 2013).

What You Can Do

Consumers who are concerned about the 

potential impacts of triclosan can: (1) follow the 

recommendations of both the Minnesota Department 

of Health and the American Medical Association by 

avoiding triclosan products for personal or household 

use; (2) look for triclosan in the ingredients list or “Drug 

Facts” box of over-the-counter drugs or personal care 

products; and (3) wash hands with soap and warm water, 

which the Centers for Disease Control and Prevention 

(2012) suggest is the best way to remove germs. If soap 

and water are unavailable, clean your hands with a hand 

29

•

•

•

sanitizer that contains at least 60% alcohol. Alcoholbased hand sanitizers do not contain triclosan.

The Future

In 2014, partially in response to attention brought to this 

issue by Russell and Weller (2013), Minnesota passed 

legislation banning the sale of triclosan-containing 

consumer products. The law goes into effect on January 

1, 2017, but some manufacturers have already announced 

plans to phase out the use of triclosan in their consumer 

products (Thomas 2012). Until similar actions are taken 

elsewhere, consumers need to be diligent in watching 

what they buy and what they send down the drain. 

—Lark Weller and Trevor Russell

The amount of triclosan-derived dioxins (red bars) in sediments at the bottom of 

Lake Pepin has increased by 200% to 300% since 1963, while all other dioxins 

(blue bars) have decreased (Buth et al. 2010).

 Noteworthy:

Triclosan is an antibacterial product used in a wide 

variety of household items. 

Triclosan is present in 75% of Americans over the age of 

five. 

Minnesota has passed the nation’s first legislation to ban 

triclosan in consumer products.
Park Program

Pictured Rocks National Lakeshore (Michigan) 

Beech Bark Disease Affects

More Than Just Trees

30

T he northern hardwood forest 

is home to the red-shouldered 

hawk and northern goshawk, 

both of whom are nest specialists 

that need the interior of mature 

northern hardwood forests with a 

closed canopy for nest sites. 

Beech bark disease—a two-part “disease 

complex” involving a beech scale insect 

followed by two species of fungi (Ehrlich 

1934)—is killing beech trees across the 

Northeast and Midwest, and at Pictured 

Rocks National Lakeshore. The loss of nest 

trees, increased competition from other 

hawks and owls exploiting the open forest, 

and a loss of prey species can all lead to 

declining populations of red-shouldered 

hawks (a State threatened species) and 

northern goshawks (a species of Special 

Concern in Michigan).

Nesting

One way beech bark disease affects redshouldered hawks and northern goshawks 

is by killing nest trees. Like other raptors, 

both red-shoulders and goshawks require 

a sturdy tree with appropriate branching 

that will support their large nests. They 

typically nest near the bottom of the high 

leafy canopy, which provides protection from 

wind, rain, and late season snows. Due to 

past logging practices, American beech are 

sometimes the only suitable trees available 

to nesting hawks. An infected tree loses its 

protective leafy cover as it slowly dies. This 

loss of cover exposes incubating adults, 

eggs, and then chicks to sun, wind, rain, and 

cold temperatures, all of which introduce 

unnecessary stress to the birds and can 

ultimately kill the developing embryos or the 

hatched chicks.

Competition and Predation

As beech trees die, gaps form where beech 

trees once stood and the closed canopy forest 

becomes more open. As the forests open 

up, red-tailed hawks can move deeper into 

the forest and, if given the chance, will kill 

the smaller red-shouldered hawks or push 

them out by taking over nest sites (Craighead 

and Craighead 1969). This happened once 

before, in Michigan’s Lower Peninsula as it 

was cleared for farming in the 19th century 

(Craighead and Craighead 1969). Now, due 

to beech bark disease, history may repeat 

itself, as we are seeing more red-tailed hawks 

and fewer red-shouldered hawks in the park.

Though it is unclear if northern goshawks 

are increasing or if our ability to find their 

nests has improved, this larger forest raptor 

is also susceptible to predation. Like redtailed hawks, great horned owls will infiltrate 

farther into an open forest and prey on 

both nestling and adult goshawks and redshouldered hawks (Craighead and Craighead 

1969, Curnutt 2009). An owl is suspected 

Above: A beech tree 

infected with beech 

bark disease (left). 

An adult northern 

goshawk (right).

Opposite page 

(bottom): A redshouldered hawk 

nest is exposed to 

extreme heat after 

beech bark disease 

kills the tree and the 

leafy canopy is lost.
to have killed an adult 

northern goshawk and 

preyed on its nest in 2014—

the first such incident 

documented in the park.

Food Production

The death of beech trees 

also causes a significant 

decline in the production of 

beech nuts, or mast. Beech 

nuts are an extremely 

important food for 

many animals including 

chipmunks, red squirrels, 

ruffed grouse, and blue 

jays—animals that also 

happen to be some of the 

preferred prey of redshouldered hawks and 

goshawks. One study in 

central Appalachia found 

that survival of the ruffed 

grouse population depends 

strongly on mast crops, 

particularly beech and oak 

(Tirpak et al. 2006). Another (Rosemier and Storer 2010) 

found that the abundance of white-footed mice and deer 

mice in Michigan’s Upper Peninsula was related to the 

production of beech seeds the previous autumn. They 

also found a correlation between eastern chipmunk 

abundance and the presence of beech, and that small 

mammals (deer mice, eastern chipmunk, and red-backed 

voles) preferred American beech seeds over those from 

31

•

•

•

sugar maples. 

Losing beech trees will have a profound effect on seedeating birds and small mammals, and those effects 

will ripple throughout the food web, all the way to the 

woodland raptors.

—Cindy Heyd

Seen from the air (2012), a dark brown, S-shaped line of dead beech trees along the southern edge of the Beaver 

Basin Wilderness gives a sense of the devastation beech bark disease is inflicting in the park’s forests. The purplishbrown dots north and east of the ridgeline (left side of the photo; group of three largest indicated by yellow arrow) 

are also dead beech trees. Inset map shows the location of this ridge in the park. 

 Noteworthy:

Beech bark disease—a two-part “disease complex” involving a beech scale 

insect followed by two species of fungi—is killing beech trees throughout 

Pictured Rocks National Lakeshore. 

Interior forest hawks are especially vulnerable because suitable nest sites are 

lost, there is increased competition with and predation by other raptors, and 

the small mammals they prey on are affected. 

The loss of beech nuts reduces the amount of food available for small 

mammals.
Park Program

Sleeping Bear Dunes National Lakeshore (Michigan) 

Sharing the Beach

With Piping Plovers

32

high-pitched peep-lo

called out over the beach 

announces the return of 

piping plovers each spring. 

Piping plovers are small migratory shorebirds 

with three distinct breeding populations in 

the United States, one of which is found on 

beaches in the Great Lakes region. Great 

Lakes piping plovers nest on wide, sparsely 

vegetated beaches with a fair amount 

of cobble and gravel. They were once 

considered common around the Great Lakes, 

but increasing development and recreational 

use of coastal beaches greatly reduced their 

available habitat, resulting in significant 

population declines (Cuthbert et al. 2014). 

Only 17 nesting pairs remained in the 

region by the 1980s, all of them in Michigan. 

Subsequently, the piping plover was listed as 

federally endangered in 1986.

Taking Action in a Variety of Ways

One-third of the Great Lakes piping plover 

A

population nests at Sleeping Bear Dunes, 

so we have an important role in a multifaceted species recovery program that 

includes monitoring, protection, education, 

and research. We work with the U.S. Fish 

and Wildlife Service and other agencies, 

universities, private institutions, and a 

network of citizen volunteers to help the 

piping plover reach the primary recovery 

goal of 150 nesting pairs in the Great Lakes 

region, with 100 of them in Michigan. 

Sharing the Beach

Our work begins each year with a search for 

nests along park beaches. Where nests are 

found, those beaches are closed to limit the 

potential for disturbance by humans and 

their pets. Adult plovers that are frequently 

scared off their nests will abandon that nest, 

or the unprotected eggs will fail to hatch 

because of frequent exposure to heat, cold, 

or rain. 

We use displays, media, and on-site 

programming to provide beach users, 

school groups, and the general public with 

information about piping plovers. These 

efforts go a long way in helping visitors 

to understand why some park beaches 

are closed in early summer. Plovers begin 

migrating south in mid-July, so beaches are 

reopened once nesting and chick-rearing is 

completed.

Nests are monitored throughout the breeding 

season. When eggs are laid, we place a 

small cage, or nest exclosure, over each nest 

to protect the birds and their eggs from 

predators. The mesh size of these exclosures 

is large enough for plovers to move through, 

but it prevents predators from taking adults, 

eggs, or chicks. Foxes, gulls, and crows are 

often attracted to areas where beach-goers 

have left behind food and garbage, but 

they also find their prey by watching the 

movements of adult plovers that have been 

scared off their nests. Additionally, the 

Above: Once nests 

are located, park 

staff close sections 

of beach during 

the plover nesting 

season (left). A 

newly-hatched 

piping plover wears 

colored leg bands 

(right). 

Opposite page 

(bottom): Plover 

nests are wellcamouflaged among 

the sand and gravel.
merlin (a small falcon) is thought 

to be responsible for the loss of 

approximately 30 adult piping plovers 

since 2005, along with an unknown 

number of chick deaths (Cuthbert et 

al. 2014). 

After eggs hatch and young leave the 

nest, we capture adult plovers and 

their young and place color-coded 

bands on their legs. These bands 

allow us to identify individual birds 

from year to year so that we can track 

its age, measure its nesting success, 

and determine what migration routes and 

wintering sites it uses. This information 

guides our management strategies. For 

example, we now know that consistent use 

of exclosures increases hatching success and that chicks 

who hatch earlier are more likely to survive to fledging 

(Saunders et al. 2014).

One exciting component of our species recovery efforts 

is a captive rearing program in partnership with the 

Detroit Zoo. When a nesting adult is preyed upon or 

otherwise abandons a nest, the abandoned eggs are 

collected and sent to any one of a network of zoo 

keepers across the country. The eggs are incubated and 

hatched, and the young are fed and carefully monitored 

until they are ready for release back into the wild. Seven 

chicks were captive-reared and released in 2015.

What the Future Holds

Our combined efforts have contributed to a steady 

increase in the Great Lakes region from 13 pairs in 

33

•

•

•

Recovery efforts have lifted the Great Lakes piping plover population from 14 pairs in 1984 

to 75 in 2015. One-third of the Great Lakes piping plover population nests at Sleeping 

Bear Dunes National Lakeshore.

1984 to 75 breeding pairs in in 2015. Yet, the population 

remains well below the recovery goal. The potential 

loss of beach habitat due to climate change-induced 

fluctuations in lake level is one threat, but a bigger 

concern is the unforeseen random event such as a severe 

storm or disease outbreak. Such events are especially 

threatening to sites like Sleeping Bear Dunes, where 

plovers are abundant and nest density is high, because a 

catastrophic event would affect a larger proportion of the 

population at one time.

Until the population is large enough to sustain 

natural losses and hazards, intensive monitoring and 

conservation strategies will be necessary to ensure every 

spring is accompanied by a high-pitched peep-lo. 

—Sue Jennings and Kevin Skerl

 Noteworthy:

There were 17 pairs of piping plovers nesting in the Great Lakes 

region—all of them in Michigan—when the shorebird was first listed as 

endangered in 1986. 

The primary recovery goal for the Great Lakes population is to have 

150 nesting pairs in the Great Lakes region, with 100 of them in 

Michigan. 

In 2015, there were 75 breeding pairs in the region, one-third of which 

nested on beaches at Sleeping Bear Dunes National Lakeshore.
Park Program

St. Croix National Scenic Riverway (Wisconsin and Minnesota) 

It Takes a Fish

to Grow a Mussel

34

I

f you are an animal that can 

live for 80 years or more, if you 

only move 10 feet during your 

lifetime, and if you gather food by 

filtering water, you do not respond 

very well to the loss of your home or 

the declining quality of water from 

which you feed. 

Such is the case for many of the mussels that 

are native to our country’s rivers. The St. 

Croix National Scenic Riverway boasts over 

40 species of native freshwater mussels (more 

than any other river outside the southeastern 

United States), among which are five federally 

endangered species with colorful names like 

the Higgins eye, winged mapleleaf, snuffbox, 

sheepnose, and spectaclecase. 

Above: Higgins eye 

mussels.

Opposite page 

(bottom): A winged 

mapleleaf displays 

her glochidia-filled 

lure to attract a host 

fish.

An Incredible Find

In the mid-1980s, a park naturalist asked 

a private mussel researcher to identify a 

shell for him. The researcher was thrilled to 

report that it was a winged mapleleaf—the 

first evidence that the species was in the St. 

Croix River! A number of surveys ensued 

to determine how many mussels there were 

and where they were living (Doolittle 1988). 

Regular population monitoring followed, 

and NPS biologists continue to assist the 

U.S. Army Corps of Engineers in their 

assessments of mussel communities at two 

locations in the river.

Simply monitoring was not enough, so in 

the late 1990s, the Upper Mississippi Basin 

Mussel Coordination Team began working to 

improve conditions for the survival of these 

important river dwellers. One of our projects 

was to develop rearing techniques for several 

of the threatened, endangered, or special 

concern species. 

It Takes a Fish...And a Matchmaker

There is an important connection between 

mussels and fish. For mussels to reproduce, 

they use fish as a host for their developing 

larvae (called glochidia). Some mussels use 

more than one host fish species. Winged 

mapleleaf mussels in the St. Croix River use 

only one—the channel catfish. So our first 

step was to identify and then raise the host 

fish.

When an adult mussel is ready to release 

her glochidia, she uses different types of 

lures to attract the host. Some produce 

small glochidia-filled packets that look like 

tasty insects a fish might want to eat. Others 

produce flaps that look like minnows, 

complete with eye spots, tails, and fins. 

Several species troll “lures” behind them that 

wave in the current like fish bait. Using her 

lure, a female mussel attracts a fish in close, 

then transfers the glochidia to it by inducing 

a bite from the fish or simply squirting the 

glochidia onto it. The glochidia latch onto 

the gills or fins of the unsuspecting host and 

stay there for a period of weeks or months, 

drawing nutrients from the fish’s blood to 
develop their own internal organs.

Our second step, once we raised the 

fish, was to find female mussels at 

the right time to donate their young, 

and to put the two together so that 

the mussels could transfer their 

glochidia to the appropriate host 

fish. 

The fish are not harmed by this 

semi-parasitic relationship, and 

in addition to being a “mussel 

nursery,” they help young mussels 

to disperse by giving them rides to 

different parts of the river. Once the 

mussels are old enough, they drop 

off the fish and begin living as adults on the 

river bottom, but only if they land on a suitable 

area. To ensure successful dispersal, we placed 

the glochidia-laden fish in cages in appropriate 

reaches of the river, then monitored the growth of the 

newly free–living mussels for several months. 

Success and Challenges

Using these methods, we have helped raise thousands 

of Higgins eye mussels in the last 10 years. Winged 

mapleleaf mussels have proven more challenging; we 

have only been able to raise and recover a few dozen 

over this same period. But in 2014, we found hundreds 

of winged mapleleaf mussels that were released during 

our first propagation effort in 2005, suggesting we might

indeed be able to raise these animals in the wild.

35

•

•

•

Our propagation efforts are especially important to 

mussel populations in the St. Croix River because their 

survival is threatened by non-native zebra mussels 

and Asian carp as well as habitat loss. But even worse 

is that survival and reproduction of native mussels 

are hampered by chemicals and microplastics from 

personal care products (see pages 8 and 28), caffeine, and 

pharmaceuticals that pass through wastewater treatment 

plants. Mussels can continue to thrive if we are diligent 

in keeping the invasive species out, and if we are mindful 

of what we wash down the drain. We can grow mussels, 

but it takes a clean river to keep them alive, and that is 

something everyone can help to achieve.

—Byron Karns

Estimated number of winged mapleleaf mussels in the Interstate Study Area, St. Croix 

River, derived from number of mussels observed in square-meter quadrats. Data from 

multiple sources and summarized by U.S. Fish and Wildlife Service (2015).

 Noteworthy:

The St. Croix River is home to more than 40 species of native mussels––

more than any other river outside the southeastern United States. 

The NPS is involved in monitoring, propagation, restoration, and research 

of native mussels. Successes include a colony of hundreds of endangered 

winged mapleleaf mussels thriving in the river. 

Threats to native mussels include the invasions of nonnative zebra mussels 

and black carp, the loss of habitat, and the decline of water quality.
Park Program

Voyageurs National Park (Minnesota) 

Mercury Contamination: 

Improvements on the Horizon?

36

Voyageurs National Park, like 

most of the upper Midwest, 

lies in a mercury-sensitive 

landscape where mercury deposited 

from the atmosphere is transformed 

to methylmercury that accumulates 

to dangerously high levels in fish and 

wildlife. 

Many of the lakes in Voyageurs are listed 

as impaired by the U.S. Environmental 

Protection Agency and are subject to 

Minnesota Department of Health fish 

consumption advisories. Anglers spend 

over 700,000 hours per year fishing in the 

park, with walleye and northern pike being 

the most frequently harvested species 

(Kallemeyn et al. 2003). Considering that 

these predatory fish are known to accumulate 

high levels of mercury and are frequently 

eaten by humans, mercury contamination 

of park lakes is a public health concern in 

addition to being an ecosystem health issue.

Scientists at Voyageurs National Park have 

been monitoring mercury in the park’s lakes 

for over a decade, working with the Great 

Lakes Inventory and Monitoring Network, 

the U.S. Geological Survey, the University 

of Wisconsin–La Crosse, the University of 

Minnesota–Duluth, the Minnesota Pollution 

Control Agency, the Science Museum of 

Minnesota, and others to determine where 

the mercury comes from and how it moves 

through the food web. This work has revealed 

that the majority of mercury contamination 

in this region comes from human sources 

such as coal fired power plants and industrial 

boilers (Evers et al. 2011), and that natural 

chemical processes that occur in wetlands 

play a role in changing this mercury to 

methylmercury.

Methylmercury is the most toxic form of 

mercury and the cause of our concern for 

fish and other aquatic organisms (Wiener 

et al. 2006). Inorganic mercury falls into 

lake water as rain, snow, or dust, where 

sulfate-reducing bacteria living in the bottom 

of the lake transform it into organic and 

highly toxic methylmercury—a process 

known as methylation. We have found that 

methylmercury has contaminated all levels of 

the aquatic food web including invertebrates, 

fish, fish-eating birds such as common 

loons and bald eagles, and even terrestrial 

songbirds that eat aquatic insects.

Dams artificially control water levels in Rainy 

Lake and the Namakan Reservoir. Studies 

have established a link between annual 

water level fluctuations and the pulse of 

methylmercury that enters the aquatic food 

web in these two lakes (Sorensen et al. 2005, 

Larson et al. 2014). Large fluctuations in 

water levels release methylmercury when the 

bottom sediments and associated wetlands 

are exposed and re-flooded. 

Above and opposite 

page (bottom): 

Fishing for northern 

pike is a popular 

activity at Voyageurs, 

but people need 

to be aware of the 

health risks posed 

by eating fish 

contaminated with 

mercury.
Reasons for Optimism

A recent publication 

(Brigham et al. 2014) 

shows that mercury 

contamination of 

some interior lakes at 

Voyageurs is decreasing 

in concert with 

decreasing amounts of 

mercury being deposited 

in northern Minnesota 

from the atmosphere. 

We believe this is related 

to better controls on 

emissions from coalfired power plants and 

waste incinerators. A 

similar decline in mercury 

levels was documented in bald 

eagles nesting in and around 

Wisconsin’s Apostle Islands 

National Lakeshore (Dykstra 

et al. 2010).

Through our monitoring and future work, we aim to 

provide dam operators with water level management 

options that would decrease mercury contamination in 

these large lakes that are popular fishing destinations. 

Moreover, continued efforts to control emissions 

through cleaner energy sources, regulation, and 

improved technologies can slowly decrease the levels of 

mercury in the aquatic systems, which will benefit fish, 

wildlife, and people.

—Ryan Maki and Bill Route

Mercury levels in northern pike from 15 lakes at Voyageurs National Park, 1986–1999 (historical) and 2001–

2002. Dashed line shows the level at which the U.S. Environmental Protection Agency considers a fish to be 

unsafe for human consumption (0.3 micrograms/g). Solid line shows the level at which mercury begins to affect 

a fish’s ability to reproduce. Data from Knights et al. (2005).

37

Noteworthy:

• Mercury contamination in park lakes is high enough to harm fish 

and wildlife and require fish consumption advisories for people. 

Monitoring results show that mercury contamination is 

decreasing, which may be related to regional emission controls. 

It may be possible to further reduce contamination of the aquatic 

food web by modifying the way dams artificially control water 

levels in park lakes.

•

•
Monitoring In Action

38

Using remote recording units 

(“frog loggers”; top left) we are 

monitoring amphibians in all nine 

Network parks. In 2015, one of the 

recorders along the Mississippi River 

detected calling cricket frogs, an 

endangered species in Minnesota 

(cricket frog sonogram at left, frog 

above right).

Network and Midwest Region staff are collaborating on 

projects funded by the Great Lakes Restoration Initiative 

to map the bottom of Lakes Superior and Michigan 

within park boundaries at Apostle Islands, Isle Royale, 

Pictured Rocks, and Sleeping Bear Dunes. Imagery from 

Munising Bay and the southern part of Pictured Rocks 

(top right) show that the lake is not just a flat blue feature 

on the map. This information is being used to help locate 

historical artifacts (mostly shipwrecks), understand sand 

movement along nearshore areas, and identify important 

fish habitat. We are also collaborating on a study of lake 

currents and water chemistry in Lake Michigan near 

Sleeping Bear Dunes and in Lake Superior near the Apostle 

Islands using monitoring stations that are anchored to the 

lake bottom (bottom right). 
39

In concert with our contaminants 

monitoring program, Bayfield High 

School students studied water chemistry, 

isotopes in eagle blood (far right), and, 

with a Northland College professor, 

different parts of the Lake Superior food 

web. For the food web study, students 

collected water, zooplankton (near 

right), and fish near eagle nests in the 

Apostle Islands. These studies help us 

understand how contaminants move 

through the food web up to bald eagles. 

Students developed their own research 

questions and presented the data at 

regional and national student science 

competitions.

Monitoring contaminants in fish and dragonflies at Grand Portage, 

Indiana Dunes, Isle Royale, Pictured Rocks, Sleeping Bear Dunes, 

and Voyageurs was carried out by scientists from the University 

of Wisconsin–La Crosse. Dragonfly larvae were collected with dip 

nets (left). These fascinating insects (below) proved to be an ideal 

sentinel because the average concentration of methylmercury found 

in dragonflies that burrow in lake bottom sediments was positively 

correlated with average methylmercury concentrations in unfiltered 

lake water and, in some cases, with average mercury concentrations in 

prey fish and game fishes from the same lakes (Haro et al. 2013). Thus, 

data from dragonflies can be extrapolated to tell us something about 

the larger environment. Plus, they are easier to collect than fish, allow 

us to study lakes that have no fish, and collection and identification is 

easily taught, so they are well-suited to citizen volunteer monitoring 

programs. As a result, in 2012, eleven national parks across the 

country participated in a pilot study of mercury in dragonflies. More 

than 300 dragonfly larvae samples were collected from 25 sites by 

about 200 citizen scientists (Nelson et al. 2015). For more information, 

visit www.nature.nps.gov/air/Studies/air_toxics/dragonfly/
Literature Cited

40

Allison, T.D. 2006. Canada yew and white-tailed deer 

at the Apostle Islands: Summary of research to-date 

with recommendations for continued monitoring and 

management. Great Lakes Inventory and Monitoring 

Network Report GLKN/2006/04. National Park Service, 

Ashland, Wisconsin. Available at https://irma.nps.gov/

App/Reference/Profile/642068/. 

Allmyr, M., F. Harden, L.L. Toms, J.F. Mueller, M.S. 

McLachlan, M. Adolfsson-Erici, and G. SandborghEnglund. 2008. The influence of age and gender on 

triclosan concentrations in Australian human blood 

serum. Science of the Total Environment 393(1): 

162–167.

Allmyr, M., M. Adolfsson-Erici, M.S. McLachlan, and G. 

Sandborgh-Englund. 2006. Triclosan in plasma and 

milk from Swedish nursing mothers and their exposure 

via personal care products. Science of the Total 

Environment 372(1): 87–93.

Anger, C.T., C. Sueper, D.J. Blumentritt, K. McNeill, D.R. 

Engstrom, and W.A. Arnold. 2013. Quantification of 

triclosan, chlorinated triclosan derivatives, and their 

dioxin photoproducts in lacustrine sediment cores. 

Environmental Science and Technology 47(4): 1833–

1843.

Bowerman, W.W., J.P. Giesy, D.A. Best, and V.J. Kramer. 

1995. A review of factors affecting productivity of 

bald eagles in the Great Lakes region: Implications 

for recovery. Environmental Health Perspectives 103: 

51–59.

Brigham, M.E., M.B. Sandheinrich, D.A. Gay, R.P. Maki, 

D.P. Krabbenhoft, and J.G. Wiener. 2014. Lacustrine 

responses to decreasing wet mercury deposition rates—

Results from a case study in northern Minnesota. 

Environmental Science and Technology 48(11): 6115–

6123. 

Buth, J., P. Steen, C Sueper, D. Blumentritt, P. 

Vokelans, W. Arnold, and K. McKneill. 2010. Dioxin 

photoproducts of triclosan and its chlorinated 

derivatives in sediment cores. Environmental Science 

and Technology 44: 4545–4551. 

Calafat, A.M., X. Ye, L.Y. Wong, J.A. Reidy, and L.L. 

Needham. 2008. Urinary concentrations of triclosan in 

the U.S. population: 2003–2004. Environmental Health 

Perspectives 116(3): 303–307. 

Centers for Disease Control and Prevention. 2012. 

Handwashing: clean hands save lives. Available at 

www.cdc.gov/handwashing/. 

Chalew, T.E., and R.U. Halden. 2009. Environmental 

exposure of aquatic and terrestrial biota to triclosan 

and triclocarban. Journal of the American Water Works 

Association 45(1): 4–13. 

Cherednichenko, G., R. Zhang, R.A. Bannister, V. 

Timofeyev, N. Li, E.B. Fritsch, W. Feng, G.C. Barrientos, 

N.H. Schebb, B.D. Hammock, K. G. Beam, N. 

Chiamvimonvat, and I.N. Pessah. 2012. Triclosan 

impairs excitation-contraction coupling and Ca2+ 

dynamics in striated muscle. Proceedings of the 

National Academy of Sciences of the United States of 

America 109(35): 14158–14163. Available at 

 www.pnas.org/content/109/35/14158.

Craighead, J., and F. Craighead, Jr. 1969. Hawks, Owls 

and Wildlife. Dover Publications, Inc., New York. 

Curnett, J. 2009. Conservation assessment for northern 

goshawk (Accipiter gentilis) in the western Great 

Lakes region. USDA Forest Service, Eastern Region, 

Milwaukee, Wisconsin.

Cuthbert, F., J. Rutter, and S. Saunders. 2014. Piping 

plover breeding biology and management in the Great 

Lakes. Unpublished report submitted to the U.S. Fish 

and Wildlife Service, East Lansing. Department of 

Fisheries, Wildlife, and Conservation Biology, University 

of Minnesota. St. Paul, Minnesota. 

 Doolittle, T.C.J. 1988. Distribution and relative abundance 

of freshwater mussels in the Saint Croix National 

Scenic Riverway. Unpublished report to the Natural 

Heritage and Nongame Research Program, Minnesota 

Department of Natural Resources. 

Drake, J., S. Menard, and D.F. Langendoen. 2011. 

Review of successional pathways and disturbances of 

forests in the Grand Portage National Monument Area. 

NatureServe, Arlington, Virginia.

Dybas, C.L. 2009. Minnesota’s moose: Ghosts of the 

northern forest? BioScience 59: 824–828. Available at 

http://bioscience.oxfordjournals.org/content/59/10/824.

full.pdf.

Dykstra, C.R., W.T. Route, M.W. Meyer, and P.W. 
41

 Rasmussen. 2010. Contaminant concentrations in bald 

eagles nesting on Lake Superior, the upper Mississippi 

River, and the St. Croix River. Journal of Great Lakes 

Research 36: 561–569. 

Edlund, M.B., J. Ramstack, D. Engstrom, J. Elias, and B. 

Moraska Lafrancois. 2011. Biomonitoring using diatoms 

and paleolimnology in the western Great Lakes national 

parks. Natural Resource Technical Report NPS/GLKN/

NRTR—2011/447. National Park Service, Fort Collins, 

Colorado.

Edlund, M.B., J.E. Almendinger, D.R. Engstrom, X. Fang, 

J. Elias, and U. Gafvert. 2014. Modeling the effects 

of past climate change on lakes in Isle Royale and 

Voyageurs national parks. Natural Resource Technical 

Report NPS/GLKN/NRTR—2014/909. National Park 

Service, Fort Collins, Colorado. Available at http://

science.nature.nps.gov/im/units/glkn/publications.

cfm?tab=2&MonitorLake=open#MonitorLake. 

Ehrlich, J. 1934. The beech bark disease, a Nectria disease 

of Fagus, following Cryptococcus fagi (Baer.). Canadian 

Journal of Research 10: 593–692.

Evers, D.C., J.G. Wiener, C.T. Driscoll, D.A. Gay, N. Basu, 

B.A. Monson, K.F. Lambert, H.A. Morrison, J.T. Morgan, 

K.A. Williams, and A.G. Soehl. 2011. Great Lakes 

mercury connections: The extent and effects of mercury 

pollution in the Great lakes region. Report BRI 2011-

18, Biodiversity Research Institute, Gorham, Maine. 

Available at http://glc.org/files/docs/Mercury-FINALmediumresolution.pdf. 

Fisichelli, N.A., S.R. Abella, M.P. Peters, and F.J. Krist, 

Jr. 2014a. Climate, trees, pests, and weeds: Change, 

uncertainty, and biotic stressors at Grand Portage 

National Monument. Unpublished brief, National Park 

Service Forest Vulnerability Project.

Fisichelli, N.A., S.R. Abella, M.P. Peters, and F.J. Krist, 

Jr. 2014b. Climate, trees, pests, and weeds: Change, 

uncertainty, and biotic stressors in eastern U.S. national 

park forests. Forest Ecology and Management 327: 

31–39. 

Food and Water Watch. 2009. What’s lurking in your 

soap? The trouble with triclosan. Available at www.

foodandwaterwatch.org/factsheet/what-is-lurking-inyour-soap/.

Gafvert, U. 2009. Grand Portage National Monument 

preliminary soil survey. Natural Resource Technical 

Report NPS/GLKN/NRTR—2009/188. National Park 

Service, Fort Collins, Colorado.

GLKN (Great Lakes Network). 2013. Blue-green algae 

create temporarily toxic waters. Unpublished resource 

brief. National Park Service, Ashland, Wisconsin. 

Available at http://science.nature.nps.gov/im/units/glkn/

publications.cfm?tab=0. 

Haro, R.J., S.W. Bailey, R.M. Northwick, K.R. Rolfhus, 

M.B. Sandheinrich, and J.G. Wiener. 2013. Burrowing 

dragonfly larvae as biosentinels of methylmercury in 

freshwater food webs. Environmental Science and 

Technology 47(15): 8148–8156.

Hop, K., S. Lubinski, J. Dieck, S. Menard, J. Drake, and 

D. Faber-Langendoen. 2010. National Park Service 

Vegetation Inventory Program: Grand Portage National 

Monument, Minnesota. Natural Resource Report. NPS/

GLKN/NRR—2010/200. Natural Resource Program 

Center, Fort Collins, Colorado.

Host, G.E. 2011. Vegetation characterization and pine 

regeneration strategies for the Grand Portage National 

Monument. Final report to the National Park Service 

and the Great Lakes Northern Forest Cooperative 

Ecosystem Studies Unit. Natural Resources Research 

Institute Technical Report NRRI/TR-2011/12. University 

of Minnesota–Duluth, Duluth, Minnesota.

Howell, A.H. 1936. Description of a new red squirrel from 

Isle Royale, Michigan. Occasional Papers of the Museum 

of Zoology, Number 338. University of Michigan, Ann 

Arbor, Michigan.

James, M.O., W. Li, D.P. Summerlot, L. Rowland-Faux, 

and C.E. Wood. 2010. Triclosan is a potent inhibitor 

of estrodial and estrone sulfonation in sheep placenta. 

Environment International 36: 942–949.

Kallemeyn, L.W., K.L. Holmberg, J.A. Perry, and B.Y. 

Odde. 2003. Aquatic synthesis for Voyageurs National 

Park. Information and Technology Report USGS/BRD/

ITR––2003-0001. U.S. Geological Survey, Columbia 

Environmental Research Center, International Falls 

Biological Station, International Falls, Minnesota. 

Available at www.cerc.usgs.gov/pubs/center/pdfdocs/

ITR2003-0001.pdf.
42

Literature Cited (continued)

Knights, B.C., J.G. Wiener, M.B. Sandheinrich, J.D. 

Jeremiason, L.W. Kallemeyn, K.R. Rolfhus, and 

M.E. Brigham. 2005. Ecosystem factors influencing 

bioaccumulation of mercury from atmospheric 

deposition in interior lakes of the Voyageurs National 

Park, Minnesota. Unpublished final report to the 

National Park Service for Project No. 02-01, Fort Collins, 

Colorado.

Kolpin, D.W, E.T. Furlong, M.T. Meyer, E.M. Thurman, 

S.D. Zaugg, L.B. Barber, and H.T. Buxton. 2002. 

Pharmaceuticals, hormones, and other organic 

wastewater contaminants in U.S. streams, 1999–2000: 

A national reconnaissance. Environmental Science and 

Technology 36: 1202–1211.

Lafrancois, B.M., S.C. Riley, D.S. Blehert, and A.E. 

Ballmann. 2011. Links between type E botulism 

outbreaks, lake levels, and surface water temperatures 

in Lake Michigan, 1963–2008. Journal of Great Lakes 

Research 37: 86–91.

Larson, J.H., R.P. Maki, B.C. Knights, and B.R. Gray. 

2014. Can mercury in fish be reduced by water level 

management? Evaluating the effects of water level 

fluctuation on mercury accumulation in yellow perch 

(Perca flavescens). Ecotoxicology 23(8): 1555–1563.

Marra, P.P., L.A. Culp, A.L. Scarpignato, and E.B. Cohen. 

2014. Full annual cycle climate change vulnerability 

assessment for migratory birds of the upper Midwest 

and Great Lakes region. The Smithsonian Conservation 

Biology Institute, Migratory Bird Center, Washington, 

D.C. Available at www.migratoryconnectivityproject.

org/climate-change-vulnerability. 

Martin, A. 2011. Antibacterial chemical raises safety 

issues. New York Times (August 19). Available at 

www.nytimes.com/2011/08/20/business/triclosan-anantibacterial-chemical-in-consumer-products-raisessafety-issues.html.

Matthews, S., R. O’Connor, L.R. Iverson, and A.M. Prasad. 

2004. Atlas of climate change effects in 150 bird 

species of the eastern United States. General Technical 

Report NE-318. USDA Forest Service, Northeastern 

Research Station, Newtown Square, Pennsylvania.

Minnesota Department of Health. 2010. Triclosan 

exposure and toxicity summary. Available at www.health.

state.mn.us/divs/eh/risk/guidance/dwec/sumtriclosan.pdf.

NABCI (North American Bird Conservation Initiative, U.S. 

Committee). 2010. The state of the birds 2010 report 

on climate change: United States of America. U.S. 

Department of the Interior, Washington, D.C. Available 

online at www.stateofthebirds.org/2010. 

NABCI (North American Bird Conservation Initiative, U.S. 

Committee). 2011. The state of the birds 2011 report 

on public lands and waters. U.S. Department of the 

Interior, Washington, D.C. Available online at www.

stateofthebirds.org/2011.

Nelson, S.J., H.M. Webber, and C.M. Flanagan Pritz. 

2015. Citizen scientists study mercury in dragonfly 

larvae: Dragonfly larvae provide baseline data to 

evaluate mercury in parks nationwide. Natural Resource 

Report NPS/NRSS/ARD/NRR—2015/938. National Park 

Service, Fort Collins, Colorado. Available at www.

nature.nps.gov/air/Studies/air_toxics/dragonfly/.

NPCA (National Parks Conservation Association). 

2009. Climate change and national park wildlife: A 

survival guide for a warming world. National Parks 

Conservation Association, Washington, D.C. Available 

at www.npca.org/resources/1847-climate-change-andnational-park-wildlife-risk-and-opportunity. 

NPS (National Park Service). 2014. Harvestable species 

plan and environmental assessment, Apostle Islands 

National Lakeshore. Apostle Islands National Lakeshore, 

Bayfield, Wisconsin. Available at www.nps.gov/apis/

learn/management/hwp.htm.

Prasad, A.M., L.R. Iverson., S. Matthews., and M. Peters. 

2007. A climate change atlas for 134 forest tree species 

of the eastern United States [database]. USDA Forest 

Service, Northern Research Station, Delaware, Ohio. 

Available at www.nrs.fs.fed.us/atlas/tree.

Räikkönen, J., J.A. Vucetich, R.O. Peterson, and M.P. 

Nelson. 2009. Congenital bone deformities and the 

inbred wolves (Canis lupus) of Isle Royale. Biological 

Conservation 142:1025–1031.

Rodman, A., S. Droege, R. Grundel, and J. Rykken. 2015. 

Bees on the brink—Survey of bee species in vulnerable 

habitats at Isle Royale National Park. Resource brief 

and species list available at https://irma.nps.gov/App/

Reference/Profile/2221656. 
Literature Cited (continued)

43

Rosemier, J.N., and A.J. Storer. 2010. Assessing the 

responses of native small mammals to an incipient 

invasion of beech bark disease through changes in 

seed production of American beech (Fagus grandifolia). 

American Midland Naturalist 164: 238–259.

Route, W.T., C.R. Dykstra, P.W. Rasmussen, R.L. Key, 

M.W. Meyer, and J. Mathew. 2014a. Patterns and 

trends in brominated flame retardants in bald eagle 

nestlings from the upper Midwestern United States. 

Environmental Science and Technology 48: 12516–

12524.

Route, W.T., R.E. Russell, A.B. Lindstrom, M.J. Strynar, 

and R.L. Key. 2014b. Spatial and temporal patterns in 

concentrations of perfluorinated compounds in bald 

eagle nestlings from the upper Midwestern United 

States. Environmental Science and Technology 48: 

6653–6660.

Russell, T.A., and L. Weller. 2013. State of the river report: 

Water quality and river health in the Metro Mississippi 

River. National Park Service–Mississippi National River 

and Recreation Area and Friends of the Mississippi River, 

St. Paul, Minnesota. Available at www.stateoftheriver.

com.

Sanders, S. 2008. Implementation of a long-term 

vegetation monitoring program at Grand Portage, 

National Monument. Great Lakes Inventory and 

Monitoring Network Report GLKN/2008/07. National 

Park Service, Ashland, Wisconsin.

Sauer, J.R., J.E. Hines, J.E. Fallon, K.L. Pardieck, D.J. 

Ziolkowski, Jr., and W.A. Link. 2014. The North 

American Breeding Bird Survey, results and analysis 

1966–2013. Version 01.30.2015. USGS Patuxent 

Wildlife Research Center, Laurel, Maryland. Online at 

www.mbr-pwrc.usgs.gov/bbs/specl13.html.

Saunders, S., D. Findlay, T. Easley, and T. Spencer. 2011. 

Great Lakes national parks in peril: The threats of 

climate disruption. The Rocky Mountain Climate 

Organization, Denver, Colorado, and the Natural 

Resources Defense Council, New York, New York.

Saunders, S.P., T.W. Arnold, E.A. Roche, and F.J. Cuthbert. 

2014. Age-specific survival and recruitment of piping 

plovers in the Great Lakes region. Journal of Avian 

Biology 45: 437–449.

Savage, J.H., E.C. Matsui, R.A. Wood, and C.A. Keet. 

2012. Urinary levels of triclosan and parabens are 

associated with aeroallergen and food sensitization. 

The Journal of Allergy and Clinical Immunology 130(2): 

453–460. Available at www.jacionline.org/article/

S0091-6749(12)00779-8/abstract.

Sizer, M., and L. Johnson. 2014. 2014 deer browse 

and pellet survey, Apostle Islands National Lakeshore. 

Unpublished report submitted to Apostle Islands 

National Lakeshore, Bayfield, Wisconsin.

Slavick, A.D., and R.A. Janke. 1987. The vascular flora of 

Isle Royale National Park. The Michigan Botanist 26(3).

Smith, D. 2007. White-tailed deer population increase 

and response by understory saplings and shrubs in 

the Apostle Islands National Lakeshore: Final Report. 

Unpublished report submitted to Apostle Islands 

National Lakeshore, Bayfield, Wisconsin.

Sorensen, J.A., L.W. Kallemeyn, and M. Sydor. 2005. 

Relationship between mercury accumulation in youngof-the-year yellow perch and water-level fluctuations. 

Environmental Science and Technology 39: 9237–9243.

Talsness, C.E. 2008. Overview of toxicological aspects 

of polybrominated diphenyl ethers: A flame-retardant 

additive in several consumer products. Environmental 

Research 108: 158-167.

Thomas, K. 2012. Johnson and Johnson announces 

new safety plan. Rochester Post Bulletin (August 16). 

Available at http://postbulletin.com/news/stories/display.

php?id=1505396.

Tirpak, J.M., W.M. Giuliano, C.A. Miller, T.J. Allen, S. 

Bittner, D.A. Buehler, J.W. Edwards, C.A. Harper, W.K. 

Igo, G.W. Norman, M. Seamster, and D.F. Stauffer. 

2006. Ruffed grouse population dynamics in the central 

and southern Appalachians. Biological Conservation 

133: 364–378.

USEPA (U. S. Environmental Protection Agency). 2008. 

National rivers and streams assessment 2008–2009. 

Technical Report EPA/841/R-16/008. Washington, 

DC. Available at www.epa.gov/national-aquaticresource-surveys/nrsa.
44

Literature Cited (continued)

USEPA (U.S. Environmental Protection Agency). 2015. 

Contaminants of emerging concern. Water: Science 

and Technology. Available at http://water.epa.gov/

scitech/cec/.

USEPA (U. S. Environmental Protection Agency). 2016. 

Polychlorinated biphenyls (PCBs)—Basic Information. 

Available at www3.epa.gov/epawaste/hazard/tsd/

pcbs/.

U.S. Fish and Wildlife Service. 2003. Final recovery 

plan for the Karner blue butterfly (Lycaeides melissa 

samuelis). U.S. Fish and Wildlife Service, Fort Snelling, 

Minnesota. 

U.S. Fish and Wildlife Service. 2015. Winged mapleleaf 

(Quadrula fragosa) 5-year review: Summary and 

evaluation. U.S. Fish and Wildlife Service, Twin Cities 

Field Office, Bloomington, Minnesota. Available at 

www.fws.gov/midwest/endangered/clams/wima/pdf/

WMMU5YearReview2015.pdf.

White, M.A., and G.E. Host. 2003. Historic disturbance 

regimes and natural variability of Grand Portage 

National Monument forest ecosystems. Unpublished 

report submitted to Grand Portage National 

Monument (PO# P6150-0100002), Grand Portage, 

Minnesota.

iener, J.G., B.C. Knights, M.B. Sandheinrich, J.D. 

Jeremiason, M.E. Brigham, D.R. Engstrom, L.G. 

Woodruff, W.F. Cannon, and S.J. Balogh. 2006. 

Mercury in soils, lakes, and fish in Voyageurs National 

Park (Minnesota): Importance of atmospheric 

deposition and ecosystem factors. Environmental 

Science and Technology 40: 6261–6268.

oodruff, T.J., A.R. Zota, and J.M. Schwartz. 2011. 

Environmental chemicals in pregnant women in the 

United States: NHANES 2003–2004. Environmental 

Health Perspectives 119(6): 878–885. Available at 

www.ncbi.nlm.nih.gov/pmc/articles/PMC3114826/.

ota, A.R., L. Linderholm, J.S. Park, M. Petreas, T. Guo, 

M.L. Privalsky, R.T. Zoeller, and T.J. Woodruff. 2013. 

Temporal comparison of PBDEs, OH-PBDEs, PCBs, and 

OH-PCBs in the serum of second trimester pregnant 

women recruited from San Francisco General Hospital, 

California. Environmental Science and Technology 

47(20): 11776–11784.

W

W

Z

A view from the 

Empire Bluff Trail, 

Sleeping Bear Dunes 

National Lakeshore.
The National Park Service (NPS) preserves unimpaired the natural and cultural resources and 

values of the National Park System for the enjoyment, education, and inspiration of this and future 

generations. The NPS cooperates with partners to extend the benefits of natural and cultural 

resource conservation and outdoor recreation throughout this country and the world. 

The Great Lakes Inventory and Monitoring Network serves nine parks in Minnesota, 

Wisconsin, Michigan, and Indiana by conducting long-term monitoring of the highest-priority 

vital signs, with a goal of improving park management through greater reliance on scientific 

knowledge. We are one of 32 such networks across the country, encompassing nearly 300 national 

park units with significant natural resources. 

The National Park Service celebrates its 100th birthday on August 25, 2016. Our Centennial goal 

is to connect with and create the next generation of park visitors, supporters, and advocates. 

One way of making those connections is by telling the stories of what we do in the National Park 

Service and how it connects with the public we serve. 

To order copies of this report, or for more information about our monitoring programs:

National Park Service

Great Lakes Inventory and Monitoring Network

2800 Lakeshore Drive East, Ashland, Wisconsin 54806

715.682.0631

http://science.nature.nps.gov/im/units/glkn/

www.facebook.com/npsglkn
EXPERIENCE YOUR AMERICA TM

National Park Service

U.S. Department of the Interior