**Intermountain West Coordinated Bird Monitoring Program**

**Design of the Aquatic Bird Survey**

Jonathan Bart and Ann Manning

March 1, 2006

(*NOTE: The permanent IWCBM web site address is given in this document
but at present \[4 Mar 2006\] the web site is still under development;
it may be found at http://iwcbm.dev3.fsr.com*/)

**Contents**

[Executive Summary 2](#executive-summary)

[Introduction 2](#introduction)

[Conceptual Approach 3](#conceptual-approach)

[Management Issues to be Addressed
4](#management-issues-to-be-addressed)

[Vision and Goals 6](#vision-and-goals)

[Objectives 6](#objectives)

[Survey Area 6](#survey-area)

[Focal Species 7](#focal-species)

[Parameters to be Estimated 8](#parameters-to-be-estimated)

[Accuracy Targets 8](#accuracy-targets)

[Sampling Plans and Documentation 8](#sampling-plans-and-documentation)

[Sampling Frame 8](#sampling-frame)

[Site Descriptions 9](#site-descriptions)

[Overview 9](#overview)

[Detailed description of contents 10](#detailed-description-of-contents)

[Examples 11](#examples)

[Design of Site-specific Sampling Plans
14](#design-of-site-specific-sampling-plans)

[Mapping suitable habitat 14](#mapping-suitable-habitat)

[Selecting survey locations 15](#selecting-survey-locations)

[Methods for Large Areas 19](#methods-for-large-areas)

[Describing the sampling plan 20](#describing-the-sampling-plan)

[Data Management 21](#data-management)

[Literature Cited 22](#literature-cited)

[Appendix: Focal Species and Seasons of Occurrence
24](#appendix-focal-species-and-seasons-of-occurrence)

# Executive Summary

Numerous organizations and individuals in the intermountain west are
collaborating to implement an Intermountain West Coordinated Bird
Monitoring (IWCBM ) program. The program has four parts: a new Aquatic
Bird Survey, an improved Terrestrial Bird Survey, a data management
system, and a series of analytic tools. A description of the IWCBM is
available on the IWCBM home page,
[http://greatbasin.nbii.gov/iwcbm/]{.underline}. This report describes
the Aquatic Bird Survey. See the IWCBM homepage for reports on the other
parts of the program.

The broad goal of the Aquatic Bird survey is to increase the efficiency
of monitoring programs for aquatic birds in the IW. Numerous management
issues will be addressed by the program including identifying species at
risk, helping to design and refine management programs, and document
progress toward population goals. The program covers the Rocky Mountains
and the Intermountain West region (to the Cascades and Sierra Nevadas)
and all aquatic species that occur often enough in the IW to warrant
monitoring. The design involves delineation of regions and
identification of all areas that are important for aquatic birds. Groups
of aquatic birds (i.e., waterfowl, waterbirds, shorebirds) using each
site are identified. Information about existing surveys and the
difficulty of initiating new surveys is compiled and used to decide
which surveys should be given highest priority in the future.
Descriptions of each important site, and of each survey at each site,
are prepared. A home page and a database are being established to help
implement the program. Periodic progress reports will be issued that
summarize recent activities in the program.

# Introduction

Monitoring programs -- whether long-term to assess status and trends or
short-term, conducted as part of a management program -- play a key role
in avian conservation. The recently completed State Comprehensive
Wildlife Conservation Plans in the IW highlight this need; all of them
contain commitments to monitor bird populations. Population targets for
bird conservation are also becoming more important and will lead to
increased pressure to obtain accurate estimates of current population
size and to implement programs to provide reliable information on
progress towards achieving the targets. Thus monitoring programs for
birds have always been a critical component of avian conservation
programs, but their importance is even greater now due to recent events.

Despite the importance of rigorous monitoring programs, many efforts at
present are incomplete and uncoordinated and are thus of less value to
managers than they might be. For example, hundreds of surveys of aquatic
birds are made every year in the IW. Yet most of the data collected are
not contributed to any central repository and many of the data sets are
being lost each year. Furthermore, in the past no comprehensive design
declaring goals, objectives, and methods has existed. As a result, even
if the data collected could be assembled in one place, it would be
difficult to produce regional estimates of distribution, abundance,
trends, or to address specific management issues.

The problems referred to above are being addressed by the Intermountain
West Coordinated Bird Monitoring (IWCBM) program, a cooperative effort
to assist State and federal agencies in the intermountain west by
increasing the efficiency of their bird monitoring efforts. Funding is
provided by the Intermountain West Joint Venture, the Department of
Defense, the Great Basin Information Project of the USGS NBII program,
and the USGS Forest and Rangeland Ecosystem Science Center. In-kind
contributions are being made by the many participants. The IWCBM Program
has four major components at present:

1\. Aquatic Bird Survey

2\. Terrestrial Bird Survey

3\. Data management system

4\. Analytic tools

Information about the IWCBM program is available at the IWCBM homepage,
<http://greatbasin.nbii.gov/iwcbm/>. The IWCBM program is an
implementation of the larger Coordinated Bird Monitoring (CBM) effort
(Bart and Ralph 2005, Bart 2005), described at
[http://greatbasin.nbii.gov/cbm/]{.underline}.

A substantial amount of work on developing conservation goals, and
methods to achieve them, has been completed on aquatic birds in North
America and within the IW. National conservation plans for shorebirds,
waterbirds, and waterfowl have been completed for the US and Canada
(Brown et al 2001, Kushlan et al. 2002, NAWMP 2004, Rich et al. 2004).
Regional plans for the IW have been completed for waterbirds (Ivey and
Herziger 2005) and shorebirds (Oring et al. 2004). The Aquatic Bird
Survey is intended to implement the recommendations in the regional
shorebird and waterbird plans.

This report describes the proposed IW Aquatic Bird Survey in detail. It
will be reviewed by managers and biologists who work on aquatic birds
and ultimately will serve as a reference for selecting and describing
sites, designing surveys, and submitting or retrieving data to the
central data base.

## Conceptual Approach

The Aquatic bird survey will be used to address many issues.
Consequently, it is difficult to design the survey around one or two
carefully specified objectives. Instead, the implementation process
proposed here involves describing the broad purpose of the survey,
creating the infrastructure needed for the survey, choosing a small
number of specific goals (long- or short-term term), and then launching
the survey (Table 1). The

Table 1. Approach for initiating the IW Aquatic Bird Survey

1\. Describe general purpose of the survey

2\. Create the needed infrastructure

Focal area and species

Sites to be covered

Site descriptions

Current and potential surveys

Data management system

Organizational support

3\. Choose specific management issues to address

4\. Implement the survey for those issues

primary assumption implicit in this approach is that creating a solid
foundation for the survey, which will support work on numerous different
management issues, will be more efficient, in the long run, than
designing the survey to address only one or a few specific management
issues.

This document addresses topics 1 and 2 in Table 1, particularly the
management issues to be addressed, the focal area and species, and sites
to be covered. It also discussed procedures for writing site and survey
descriptions and briefly describes the emerging data management system
and organizational support. A series of progress reports will be
prepared describing results of the surveys of current and potential
support and progress on items 3 and 4 in Table 1.

## Management Issues to be Addressed

Design of any monitoring program should begin with careful consideration
of the management issues to be addressed (Coordinated Bird Monitoring
Working Group 2004, Salafsky and Margoluis 2003). This is difficult with
long-term surveys because they will be used for many purposes, some of
which are not even foreseeable when the survey is initiated.
Nonetheless, describing broad categories of problems to be addressed,
along with any specific issues that can be identified, is useful because
it helps avoid building in features of the survey that will later turn
out to be problematic.

An analysis of management issues that a proposed continental survey for
secretive marshbirds will help address was completed recently (Bart
2006). Although it was focused on just one group of aquatic birds and on
a region larger than the IW, its conclusions apply well to the IWCBM
Aquatic Bird Survey. The abstract is reprinted below:

> *The program to survey secretive marshbirds in North America will help
> identify species at risk, set harvest rates, design and evaluate
> management and conservation issues, and document progress towards
> population goals. The program to monitor secretive marshbirds will
> also help us understand the species' habitat, and other environmental
> relationships and will provide a measure, along with many other
> monitoring programs, of whether society is living in a manner that is
> sustainable for the long-term. These programs, more than some other
> long-term monitoring programs, will help managers address local
> issues. Experience with other long-term programs indicates that the
> program will also help us address many other issues that are difficult
> to foresee at present.*

Another recently completed report (Altman et al. 2006) analyzed the new
State Wildlife Action Plans to identify recommendations on management
issues that monitoring can help address and that will be best addressed
using a regional approach. The abstract from this report is reprinted
below:

> *We examined 10 State Wildlife Action Plans from the Intermountain
> West to determine the highest priority bird species, habitats, and
> conservation and management issues; and to identify monitoring
> programs to support those priorities that will best be implemented
> through regional rather than State-specific approaches. Our review
> resulted in the following common themes for priority bird monitoring
> needs: 1) determination of status and trends for high priority but
> poorly known species; 2) determination of the effects of water level
> management and availability; and 3) the effects of anthropomorphic
> activities in riparian areas, grasslands, and sagebrush-juniper
> habitats. This synthesis points to four regional-based efforts that
> would help States meet their monitoring needs and efficiently carry
> out their Action Plans: 1) initiation of a coordinated aquatic bird
> survey; 2) initiation of status and trend monitoring for poorly
> monitored landbird species; 3) development of models to predict how
> birds will respond to specific changes in their environment; and 4)
> development of a regional bird monitoring data management system to
> support these efforts.*

The general management issues, which the IW Aquatic Bird Survey will
help address, may be categorized as follows:

1\. Identifying species at risk

2\. Setting harvest limits

3\. Designing and evaluating management programs

4\. Documenting progress towards population goals

5\. Investigating basic biology

6\. Helping managers address local issues

For more discussion of specific questions, under each of these headings,
see Bart (2006).

## Vision and Goals

The vision and goals for the IW Aquatic Bird Survey are consistent with
the regional waterbirds and shorebirds plans, corresponding statements
in the IWCBM program, and with the views expressed above. The vision for
the IW Aquatic Bird Survey is

> *A comprehensive, efficient monitoring program for aquatic birds in
> the intermountain west that helps people manage and conserve aquatic
> birds and the environments on which they depend.*

The goals of the IW Aquatic Bird Survey are to:

1.  Describe distribution and abundance of aquatic species in the IW

2.  Identify relationships between species and habitat types

3.  Estimate population trends

4.  Develop an infrastructure to address specific short-term management
    issues

# Objectives

## Survey Area

The survey area for the IWCBM program is the intermountain west portion
of the US (Fig. 1). The area coincides closely with the IW Joint
Venture. The main difference is that the IWCBM area includes southern
Arizona and southeastern California whereas these areas are not within
the IW Joint Venture. These areas were included at the request of
biologists from Arizona and California. The survey area includes most of
the area in the Western Working Group, the eleven western States, but
areas in the extreme east and west of these States are not within the
Aquatic Bird Survey area. The excluded areas are much different
ecologically than the IW. Biologists from those areas, however, have
expressed interest in initiating their own CBM programs and we hope that
they will do this.

> . Fig. 1. Study area for the IWCBM Project including BCS numbers (and
> BC R numbers). Black line is the IW Joint Venture boundary

![](media/image1.jpeg){width="5.466666666666667in"
height="3.7395833333333335in"}

## Focal Species

Focal species for the Aquatic Bird Survey were selected using the
general criterion that we should ideally monitor any species we would
try to conserve if we knew the species was declining. Using this
criterion, we identified 85 aquatic species, 23 shorebirds, 27
waterfowl, and 35 waterbirds, common enough in at least one State and
season to warrant monitoring (Table 1). The numbers per State varied
from 65 to 75. Surveys during the breeding season would provide
information on 67 species, surveys during the migration period would
provide information on all 85 species, and surveys during winter would
provide information for 72 species. A detailed list is provided in the
Appendix.

Table 1. Aquatic species judged to warrant monitoring in the IW.

  ------------- ------ ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- -----
  Inititative   West   WA    OR    ID    MT    WY    CA    NV    UT    CO    AZ    NM

  Shorebirds    23     16    18    16    22    21    18    16    17    21    16    20

  Waterfowl     27     26    26    23    24    24    25    22    23    23    22    23

  Waterbirds    35     25    30    26    26    24    32    29    29    28    30    28

  All species   85     67    74    65    72    69    75    67    69    72    68    71
  ------------- ------ ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- -----

## Parameters to be Estimated

As noted above under Goals, the survey will be used to address numerous
management issues. The parameters used can be classified as follows:

1\. Density and population size

2\. Trend in population size

3\. Measures of habitat associations

4\. Responses to environmental change

As more experience is gained with the program and issues it can address,
it will become possible to formulate these parameters more precisely
(for example by defining, species, areas, and periods of greatest
interest).

## Accuracy Targets

The landbird and shorebird initiatives have adopted quantitative
accuracy targets for trend estimates at large spatial scales: 80% power
to detect a 50% decline occurring during no more than 20 years, using a
two-tailed test, a level of significance of 0.10 (shorebirds) or 0.15
(landbirds) and acknowledging effects of potential bias (Brown et al.
2001, Rich et al. 2004). Bart et al. (2004) describe the rationale for
this target. The waterbirds initiative has adopted a similar -- though
less fully specified -- accuracy target: "detect greater than a 50%
change over 10 years or 3 generations" (Kushlan et al. 2002). While
these targets seem reasonable, more experience will be needed before we
can assess the feasibility of achieving them for aquatic birds in the
IW. Accuracy targets have not been set for the other parameters, and
this should probably be done in the context of specific management
issues. Guidelines for developing quantitative accuracy targets for
short term projects have been provided by Bart et al. (2005).

# Sampling Plans and Documentation 

## Sampling Frame 

"Bird Conservation Sub-regions" (BCSs) were defined throughout Canada
and the US by intersecting a Bird Conservation Regions (BCR) map with a
States map (Fig. 1). Small polygons were deleted and boundaries were
smoothed to make them easier to locate on the ground. The resulting BCSs
permit aggregating results to either the BCR or State level and to any
larger level that uses these sub-divisions. Within each BCS, we
identified important areas for any of the focal species at any time of
year. These areas were numbered sequentially. We refer to them below as
"designated areas". Many designated areas are specific sites like a game
management area or a National Wildlife Refuge. Others area larger areas
such a region of playa lakes. In many BCSs, substantial numbers of birds
are widely distributed. In such cases, after identifying the discrete
sites and regions we defined a final designated area as including all
other parts of the BCS.

A series of reports, one for each of the Intermountain (and all other
contiguous) States, was prepared to help in the process of identifying
designated areas. Each report contains one section for each BCS in the
State. Within each BCS, aquatic species that occur within the State, in
sufficient numbers to warrant survey efforts, are identified and the
seasons of occurrence are recorded. Preliminary lists of designated
areas are also provided. The reports for the IW States are posted on the
IWCBM home page (<http://greatbasin.nbii.gov/iwcbm/>). Reports for all
contiguous States are posted on the CBM home page
(<http://greatbasin.nbii.gov/cbm/>).

A Site Monitoring Plan is prepared for each designated area. The Plan
consists of a "site description" which provides general information
about the site or stratum useful in preparing the specific surveys. It
is followed by detailed descriptions of how to carry out each survey at
the site. For example, at the Boise River designated site in Idaho, the
State conducts a secretive marsh bird survey, a survey of the great blue
heron rookery, and a general water bird survey. Their "Boise River
Monitoring Plan" (in prep.) has the following sections: site
description, secretive marsh bird survey, great blue heron rookery
survey, waterbirds survey. Below, guidelines are provided for preparing
the site description and designing and describing each of the surveys.

## Site Descriptions

### Overview

Maps of each site are prepared and information useful in designing
surveys for the focal species is presented using the following headings:

1\. Boundaries and ownership

2\. Focal species using the site and timing of use

3\. Location of type 1 (good) and 2 (fair) habitat within the site

4\. Access to type 1 and 2 habitat and visibility of the birds

5\. Past and current surveys

6\. Potential survey methods

a\. Description

b\. Selection bias

c\. Measurement error and bias

7\. Needed pilot studies

Up to three types of habitats are described for each focal species or
group of focal species at each site. Type 1 habitats include the
regularly-used areas that should be sampled using a well-defined
sampling plan. Type 2 habitats include areas used sparingly by the focal
species. Type 2 habitat will not be surveyed as often or with rigorously
defined methods, but will be surveyed less formally every few years to
document continued low use by the focal species. Type 3 habitats (all
other areas within the site) receive virtually no use by the focal
species during the study period and will not be surveyed as part of the
monitoring program.

Site descriptions have been prepared for most or all designated areas in
Nevada, Idaho, Montana, Utah, Colorado, and are being prepared for
several other States particularly in the northeast US and the
Intermountain West. Most of the descriptions were incorporated into
State "Coordinated Bird Monitoring Plans" which contain descriptions of
the major monitoring efforts and proposed new programs as well as the
site descriptions. All of them are accessible at the IWCBM home page,
<http://greatbasin.nbii.gov/iwcbm/>.

### Detailed description of contents

*1. Boundaries and ownership* -- This is a brief description of who owns
the land. If special permission or permits are needed to access the
site, note this. Include local contact names and phone numbers, if
appropriate. Briefly describe the habitat at the site.

*2. Focal species using the site and timing of use* -- Identify which of
the focal species are found at the site. Observers should record
information regarding the timing or season of use (e.g., spring
migration) and estimated numbers of birds using the site, if known.

*3. Location of Type 1 and 2 habitat within the site* - Describe Type 1
and Type 2 habitat boundaries within the site. It may be useful to group
species into functional groups (e.g., migrating shorebirds, secretive
marsh birds).

*4. Access to Type 1 and 2 habitat and the visibility of the birds* --
Describe access to the site, including observation points, boat access
and permission requirements. If complete access is possible, note this.
Describe problems with seeing all birds during a survey, if any. If
visibility is different for different species note this (e.g., large
waders are easily detected, but distances are too great to accurately
identify small shorebirds).

*5. Past and current surveys* -- Briefly describe past or current
surveys at the site. Provide survey means, if available; however, do not
spend a lot of time analyzing the data.

*6a. Potential survey methods: description* -- Discuss the survey
methods appropriate for each species or functional group at the site and
recommend the best method(s). Consider access, visibility and past
survey results in your recommendation. Consider differences in survey
methods among seasons, if appropriate. Bear in mind, however, that the
final decision regarding the season for monitoring will be made at a
larger scale. Consider when during the day surveys should be conducted.
In general, all surveys in a site should be made during a single period.
Timing of surveys is especially important at tidal sites but may be
important at other sites due to the sun or other factors. Note that if
the number of birds present varies rapidly, as is often the case with
tidal areas, then the survey period should be brief. Otherwise,
surveyors may gradually learn when surveys will yield the highest counts
and may be tempted to visit at these times.

*6b. Potential survey methods: selection bias* -- Discuss the potential
for selection bias in the proposed survey methods. If the entire site
can be surveyed completely, there is no selection bias and "not
applicable" can be entered. If only a portion of the site can be
sampled, discuss reasons why the accessible area may not be
representative of the total site. Provide recommendations for minimizing
potential selection bias.

*6c. Potential survey methods: measurement error and bias* -- Discuss
the potential for measurement error and bias in your proposed survey
methods. If most of the birds present at the time of the survey are
counted, then measurement error and bias will be minimal. If many birds
may be missed because of poor visibility or access problems, then
measurement error and bias are important considerations. Discuss ways to
minimize error and/or bias, if known.

*7. Needed Pilot Studies* -- Identify what information is needed before
a sampling plan could be devised for the site. If all the information
requested above is available, then a pilot study is not needed for the
site.

### Examples 

1\. Lake Lowell -- Deer Flat NWR, Idaho

Fig. 2. Map of Lake Lowell and Deer Flat NWR, Idaho.

![](media/image2.jpeg){width="3.8520833333333333in"
height="2.722916666666667in"}

*Boundaries and ownership:* This site encompasses Lake Lowell and the
surrounding shoreline inside Deer Flat National Wildlife Refuge. It is
administered by the USFWS. Habitats include open water in the middle of
the lake and marsh along the sides of the lake. Open mudflats are found
primarily at the SE end of the lake and the NE lower embankment when the
lake water level is low. Contacts: Greg Kaltenecker, Idaho Bird
Observatory, 208-377-1440 or Refuge Manager, 208-467-9278

*Focal species:* Most aquatic focal species are found at this site.

*Location of Type 1 and Type 2 habitat:* Location of birds varies with
the water level and season.

Table 2. Definition of type 1 and 2 habitat for Lake Lowell-Deer Flat
NWR, Idaho.

+-----------------+----------------------------------------+-----------+
| Functional      | Type 1 Habitat                         | Type 2    |
| Group           |                                        | Habitat   |
+-----------------+----------------------------------------+-----------+
| waterbirds      | open water & emergent vegetation       | none      |
+-----------------+----------------------------------------+-----------+
| large waders    | breeding colonies, emergent vegetation | rest of   |
|                 |                                        | shoreline |
+-----------------+----------------------------------------+-----------+
| secretive marsh | water\'s edge, except during very low  | none      |
| birds           | water                                  |           |
+-----------------+----------------------------------------+-----------+
| waterfowl       | open water, edges during breeding      | none      |
|                 | season                                 |           |
+-----------------+----------------------------------------+-----------+
| shorebirds      | exposed mudflats at SE tip & at NW     | rest of   |
|                 | lower                                  | shoreline |
|                 |                                        |           |
|                 | embankment during spring/fall          |           |
|                 | migration                              |           |
+-----------------+----------------------------------------+-----------+
| gulls and terns | all areas                              | none      |
+-----------------+----------------------------------------+-----------+

*Access to Type 1 and Type 2 habitat and visibility of the birds:* Open
water can be accessed by boat and marshes can be accessed by canoe.
There are seven access points from the roads and there is a patrol road
along the SE side of the Lake. Visibility is good for open water or
exposed mudflat counts by boat or from access points. Visibility is
poorer in emergent vegetation but can be improved by using a canoe for
access.

*Past and current surveys:* Refuge staff conduct mid-winter waterfowl
counts by small plane. Idaho Bird Observatory conducts Bald Eagle
nesting surveys (mean = 2 nests/year) and colony counts for Great Blue
Herons (mean = 20-25 nests/year).

*Potential survey methods, description:*

> a\. Nest searches for grebes and other waterbirds nesting in the
> emergent vegetation in small colonies. A canoe is necessary for
> access.

b\. Colony counts for nesting Great Blue Herons and Double Crested
Cormorants

> c\. Census for waterfowl on the open water using a boat. Late summer
> or winter counts may be better than breeding season counts, as
> waterfowl are more easily detected during this period.
>
> d\. Area searches for migrating shorebirds from observation points
> near Type 1 habitat.
>
> e\. Systematic sample, probably including the use of playback calls,
> for secretive marsh birds using a canoe to access marshes
>
> f\. Census gulls and terns during waterfowl counts?

*Potential survey methods, selection bias:* Not applicable unless a
systematic sampling approach is taken for the secretive marsh birds.

*Potential survey methods, measurement error and bias:*

a\. Error and bias are negligible for nest searches and colony counts

> b\. Error and bias are probably negligible for area searches for
> migrating shorebirds, although this needs field verification
>
> c\. Error and bias are negligible for waterfowl counts in late summer
> or winter, but could be relatively high during the breeding season
> because of cryptic nesting birds
>
> d\. Error and bias are unknown for secretive marsh birds
>
> e\. Error and bias are negligible for gulls and terns if a census is
> possible.

*Needed pilot studies:*

Few needed. This is a good site to test protocols for groups of species.
A site visit is recommended to assess the error associated with making
counts from observation points for migrating shorebirds.

2\. Bear River NWR, Utah (shorebirds only)

Fig. 3. Map of Bear River NWR, Utah.

![](media/image3.png){width="4.772222222222222in"
height="3.790277777777778in"}

*Boundaries and Ownership:* This site is the entire NWR and is
administered by the U.S. Fish and Wildlife Service. Bear River NWR is a
large, important area for shorebirds; however the habitat changes
dramatically due to management regimes and flood events that remove
vegetation.

*Focal species and timing*: Most shorebird focal species in Utah use
this site during spring and/or fall migration. Species include: AMAV,
BNST, GRYE, LEYE, MAGO, LBDO, WESA, WIPH.

*Location of Type 1 and 2 habitat:* Much of the refuge is Type 1 habitat
during some years or seasons, although there may be areas of Type 2 or 3
habitats. More work is needed to identify all Type 1 habitats.

*Access to Type 1 and 2 habitat and visibility of birds:* Visibility is
often low and access to all areas of the refuge is questionable.

*Past and current surveys:* This area was surveyed on the Great Salt
Lake Water bird Survey (areas 27, 29a, and 29b). Area 29b was along the
refuge road and had low numbers (\<10) of focal species. Means/survey
(\>10) for focal species for areas 27 and 29a were WIPH -- 3684, WESA --
4619, LBDO -- 3510, MAGO -- 4938, GRYE -- 11, and LEYE -- 12. Tens of
thousands of AMAV and thousands of BNST were also counted.

*Potential survey method, description:* Potential survey methods cannot
be determined until the location and extent of all type 1 habitat is
identified and the issues of visibility and access are addressed.

*Potential survey method, selection bias:* If all of the Type 1 habitat
on the Refuge cannot be accessed, the potential for selection bias
exists. Selection bias could be minimized if a sampling plan is
implemented where a small, random sample of the inaccessible Type 1
habitat is surveyed each year.

*Potential survey method, measurement error and bias:* The potential for
measurement error and bias exists in those areas where visibility is
poor. A double sampling approach to estimate detection rates may be
appropriate for assessing measurement error.

*Needed pilot studies:* A pilot study is needed to classify all areas in
the site as Type 1, 2 or 3 habitats and to assess whether there are Type
1 areas that are inaccessible. If all Type 1 habitats cannot be
accessed, then a small, random sample of the inaccessible Type 1 habitat
should be surveyed each year. The ability of observers to count all
birds present, even in areas of low visibility, needs to be assessed. A
double sampling approach would provide this information.

## Design of Site-specific Sampling Plans

Once designated sites, for a given survey, are identified, decisions
must be made about which areas within the site will be surveyed. In many
sites, all accessible areas are covered on general aquatic bird surveys.
Some areas (e.g., many coastal marshes), however, are too large to
survey completely so sampling is needed. In addition, surveys for
secretive marsh birds involve selection of locations at which the point
counts are conducted. This section discusses ways to select survey areas
or points.

### Mapping suitable habitat

The first step is to prepare a map of the site or matrix stratum showing
the areas in which any of the focal species are believed to be present,
in non-negligible numbers, during the survey season. Many sources may be
used to delineate suitable habitat. The most comprehensive one, in the
United States, is the National Wetlands Inventory (NWI;
http://wetlandsfws.er.usgs.gov/) which covers much, though by no means
all, of the 48 contiguous States (Fig. 4). Their "Wetlands Mapper" may
be used to display the NWI (and other) data for any site they have
mapped, and a pdf file can be downloaded. The Mapper is slow, however,
and a better option is probably to download their digital data and use a
GIS to create the map.

While the NWI maps are of great value, they are several years old in
many regions and changes may have occurred in the distribution of
suitable habitat since they were prepared. Also, suitable habitat for
marsh birds may move around and preparing new maps each year may be
worthwhile. Other sources thus often must be used. Aerial photos and
satellite imagery, including sources now available on the internet
(e.g., Google Earth™ ), may be useful. State agencies may also have
useful images. For example, in Idaho images from the Tax Bureau are
being used (C. Moulton, pers. comm.). There is no need to standardize
vegetation categories or even map accuracy across regions. The goal at
this stage is simply to show the distribution of suitable habitat.

Fig. 4. Areas mapped by the National Wetlands Inventory

![](media/image4.png){width="0.9270833333333334in"
height="0.5715277777777777in"}

### Selecting survey locations

The next step is to decide which locations are suitable for conducting
surveys and to distribute survey locations evenly across this area. For
aerial surveys, ground-based surveys for all species, and surveys of
migrating shorebirds, large areas are usually accessible. For secretive
marshbird surveys, locations must be selected for the point counts. In
many sites, these locations must be on dikes, roads, marsh edges and
other linear features. Carey Lake WMA in Idaho (Fig. 5) provides an
example. The area was depicted on NWI imagery as having a lake in the
center of the site, but this area is now covered by dense emergent
vegetation, and only a narrow channel, accessible by canoe, is available
to surveyors. Thus survey locations were restricted to this channel.

Fig. 5. Selection of survey locations for a secretive marshbird survey
at Carey Lake WMA in Idaho.

![](media/image6.jpeg){width="3.847916666666667in" height="2.6375in"}

At other sites, habitat may occur in patches and placing survey
locations within these patches may be worthwhile. The Sterling WMA in
Idaho (Fig. 6) provides an example. Habitat in this WMA is more open
than in the Carey WMA, and surveyors can reach any point within it. The
habitat is quite variable between years, however, so it was decided to
make a new map each year, using aerial photographs or reconnaissance on
the ground, and to distribute the count locations so that they covered
the habitat as thoroughly as possible. Fig. 6 shows how survey locations
might be distributed if habitat occurred as depicted on the NWI imagery.

Fig. 6. Selection of survey locations for a secretive marshbird survey
at the Sterling WMA Idaho (color scheme is the same as in Fig. 5).

![](media/image7.jpeg){width="2.9868055555555557in"
height="3.4381944444444446in"}

In larger sites the surveyed area may cover a much smaller portion of
the area accessible to surveyors. In such cases, using a well-defined
sampling plan to select locations may be useful, though an alternative
is just to distribute the survey locations, or survey routes, evenly
across the site. Any well-defined sampling plan may be used to select
survey locations. Simple plans are generally sufficient. Three issues
are discussed below. Consulting a statistician for advice on design of
the sampling plan is recommended, especially for cases not covered by
the following brief discussion.

A first issue is whether to sub-divide the sampled population into
strata. Strata may be delineated so that sampling intensity can vary
between strata, so that separate estimates can be computed for each
stratum, or because different sampling plans will be used in different
strata. Many refuges are subdivided into impoundments or other units
which make natural strata and ensures that separate estimates will be
available for each unit. The strata should partition the suitable
habitat, i.e., every point in suitable habitat should be in exactly one
stratum.

A second issue is whether to use cluster sampling. Cluster sampling
occurs when a set of locations is selected and then a cluster of survey
plots or points is selected at each location. The BBS is a typical
example. Starting locations for survey routes are selected randomly and
then a cluster of 50 locations is selected in the vicinity of each
location. Cluster sampling usually yields less precise estimates than a
one-stage sample of the same size. This approach should therefore be
used primarily in cases where distributing locations evenly across the
site or stratum will lead to large travel costs with a resulting
decrease in sample size or increase in project costs.

In selecting the survey locations or clusters of locations, systematic
selection seems preferable to simple random selection to insure that the
area is covered evenly. As a practical matter, selection can probably be
made non-randomly by distributing the plots or points evenly (subject to
a minimum nearest neighbor distance for point counts) across the area
without reference to habitat quality (so "good" locations will be
neither favored nor avoided). Two more formal methods are described
below however. They may be useful when the sampled area is large
relative to the area surveyed and when suitable habitat is patchy.

In method one (Fig. 7) we assume that survey locations are restricted to
dikes, roads, wetland edges or other linear features and a series of
locations for point counts is needed. Assume that the minimum distance
between points is to be 0.4 km. A simple approach for selecting survey
locations is to number the segments sequentially, determine the length
(in km) of each segment, and add these lengths to get the total length.
Divide the total length by the number of stations that can be surveyed
to get the distance, *D* say, between stations. Then randomly select a
location within the interval 1 to *D* and place the first station at
this distance from the start of the first segment. If the suitable
habitat begins at the beginning of this segment, it may be worth
selecting a location between 0.2 and *D* to keep the surveyor at least
0.2 km (the half width of the survey circle) from the edge of the
habitat. Place subsequent stations at intervals of *D* or more if needed
to keep circles from over-lapping.

Fig. 7. Hypothetical area showing placement of survey locations using
"Method One" (see text).

A. Segments B. Segment lengths

![](media/image8.jpeg){width="3.3722222222222222in"
height="1.7909722222222222in"}

C. Calculations for interval and starting point

  ----------------- ---------- --------------------------------- ---------
  Total length      45.9       Distance between stations         2.3

  N stations        20         Random start                      0.8
  ----------------- ---------- --------------------------------- ---------

D. Calculations for starting points D. Survey locations

![](media/image9.jpeg){width="3.375in" height="1.8888888888888888in"}

In method two (Fig. 8) we assume that all parts of the sampled
population may be reached by surveyors. A simple approach in such cases
is to partition the area into bands, randomly select a point between the
two bands and then establish parallel lines at this point. These lines
can then be treated as the "segments" in the approach described
immediately above, and the same process can be followed to select the
points. The needed distance between survey stations and survey lines is
the square root of *A*/*n* where *A*=area and *n* = the number of
stations. An alternative to this approach is to use a GIS routine to
randomly select points, but with the restriction that they be no closer
together than 0.4 km. As noted above, however, this approach can result
in considerable clumping of points and large areas with few or no survey
points. The systematic approach described above avoids this problem.

> Fig. 8. Example of "Method Two" for selecting survey point locations
> (see text). Only the final result is shown.

![](media/image10.jpeg){width="4.944444444444445in"
height="2.827777777777778in"}

In many sites, some areas will be difficult or impractical to reach. If
they are impractical to reach they are just excluded from the sampled
area. If they are only difficult to reach, then some consideration may
be given to assigning them to a separate stratum and sampling that
stratum at low intensity.

A final question is how to select times for the survey when points are
surveyed more than once. Recommendations vary on whether to survey in
the same order each time or vary the order. Rotating times, as is
usually done in point count studies of terrestrial systems, has the
advantage of covering the statistical population (all places at all
times) more evenly and of facilitating within-site comparisons because
contrasts are more likely to be balanced with respect to survey times.
This approach, however, may be more difficult to schedule than simply
repeating the route in the same order each time. Whatever approach is
followed it should be well documented so future surveyors can continue
the same method.

### Methods for Large Areas

Less experience has been accumulated with sampling plans for large areas
than with small areas so guidelines at present are tentative. Two broad
approaches may be distinguished however. The first approach applies when
suitable habitat is concentrated in a relatively small number of sites
such as lakes and reservoirs. They may be too numerous for surveyors to
visit all of them, but it still may be feasible to enumerate them. A
random or systematic sample of the desired size may then be selected and
the sampling plan for selected units may be developed following the
guidelines above.

When suitable habitat is too extensive and patchy to enumerate or
delineate then the best approach is probably to delineate large areas
such as blocks 20 km on a side or townships. A systematic sample of
these areas may then be selected. Within the selected units, the
guidelines above may be followed. Often, stratification and/or cluster
sampling will be useful. Skagan and Bart (2005) followed this approach
in designing surveys for migrant shorebirds in the Dakotas. A systematic
sample of townships was selected and then one driving route was randomly
selected in each selected township. All suitable habitat within 200 m of
the road, along the route, was surveyed. In a survey for secretive marsh
birds, the habitat along the route might first be mapped and then a
systematic sample of points, at which counts would be made, would be
selected within suitable habitat. If the habitat was too patchy to map,
then the sample of points might be selected without first delineating
suitable habitat. This would cause some points to be in non-suitable
habitat, but 0s would just be entered for these locations and the
surveyor could pass immediately to the next point so little time would
be lost. The main disadvantage of this approach, compared to delineating
suitable habitat, is that the within-cluster variance would be high due
to numerous 0s.

BCS 51, southern Idaho, provides an example of the methods discussed
above. Biologists have identified 36 designated areas about half of
which have been surveyed. The rest will be surveyed during the next
several years. A new sampling plan will then be developed with lower
sampling intensity. This may be accomplished by assigning many of the
sites to a single designated area and then selecting a sample of them
for coverage. Alternatively, they may all be retained as separate
designated areas but only be surveyed every 2-3 years. In addition, 37
lakes \>300 acres have identified and defined as one designated areas. A
sample of them will be selected for surveys. NWI data is available for
only a part of this BCS but it, along with other information, can
probably be used to delineate strata with more and less wetlands. For
example, the southwest portion (Owyhee uplands) has very few wetlands
whereas the eastern portion has more wetlands. It thus might be
reasonable to delineate "high" and "low" density sampling units (e.g.,
townships). The townships could thus be partitioned into three
designated areas: lakes \>300 acres, high density units, low density
units. A sample from each of these groups would then be selected and
surveyed. Selected units might be further stratified so that efforts
were concentrated in the better areas. Surveys might be along randomly
selected driving routes.

### Describing the sampling plan

The plan used to select survey locations at each site should be
documented and information needed to aggregate results across sites (see
next section) should be recorded. The information needed is:

1\. Map showing site and survey locations

2\. BCS

3\. Site number and name

4\. Years that the information applies to

5\. Area of the target population within the site

6\. Description of survey locations

a\. Stratum and/or cluster if applicable

b\. Latitude and longitude

c\. Area of the survey circle covered by the target population

7\. Advice on conducting the survey

An example is shown in Fig. 9.

Fig. 9. Example of the data needed for each site.

  ---------------------------------------------------- ------------------
  A. Site description                                  

  Bird Conservation Sub-region                         51

  Number                                               3

  Name                                                 Smith Falls

  Area of target population (km^2^)                    65
  ---------------------------------------------------- ------------------

  ----------- -------- ------------ ----------- -------- ------------ ------------
  B. Survey                                                           
  locations                                                           

  Cluster     Number   Latitude     Longitude   Area     Prop. in the Area in the
                                                Circle   target       target
                                                         population   population

  1           1        48.9503      -116.5512   0.50     1.0          0.50

  1           2        48.9512      -116.5480   0.50     1.0          0.50

  1           3        48.9537      -116.5453   0.50     0.5          0.25

  2           1        48.9561      -116.5422   0.50     0.1          0.05

  2           2        48.9573      -116.5395   0.50     0.8          0.40

  2           3        48.9588      -116.5362   0.50     1.0          0.50
  ----------- -------- ------------ ----------- -------- ------------ ------------

C. Notes on conducting the survey

# Data Management

A comprehensive data management system, modeled on work being done at
the Cornell Laboratory of Ornithology and elsewhere around the world, is
being developed for the IWCBM project. It is described in the IWCBM
overview and in "Data Management System for the IWCBM Program" available
at <http://greatbasin.nbii.gov/iwcbm/>. In brief, a "distributed,
federated approach" is being used in which data owners maintain their
data, taking responsibility for entry, error checking, and storage, but
they also participate in defining core variables and subsets of data
that will be contributed to a central repository and thus made available
to all collaborators and to others. Analytic tools are also being
developed for such common tasks as predicting bird abundance in
specified locations and estimating trends. The USGS Forest and
Rangelands Ecosystem Science Center, in cooperation with the NBII Great
Basin Information Project, are hosting the site.

# Literature Cited

Altman, R., D. Casey, and J. Bart. 2006. Bird monitoring priorities in
the new State Wildlife Assistance Plans. Manuscript submitted to Great
Basin Birds.

Bart, J., K.P. Burnham, E.A. Dunn, C.M. Frances and C.J. Ralph. 2004.
Goals and strategies for estimating trends in landbird abundance.
Journal of Wildlife Management 68:611-626.

Bart, J. 2005. Monitoring the abundance of bird populations. Auk.
122:15-25.

Bart J. Guidelines for designing short-term bird monitoring programs.
2005. Pp. 985-992 in C. J. Ralph and T. D. Rich, editors. Bird
Conservation Implementation and Integration in the Americas: Proceedings
of the Third International Partners in Flight Conference. 2002 March
20-24; Asilomar, California; Volume 2. Gen. Tech. Rep. PSW-GTR-191.
Albany, CA: Pacific Southwest Research Station, Forest Service, U.S.
Department of Agriculture; 643 p.

Bart, J. 2006. Management Issues to be Addressed by the Secretive
Marshbird Monitoring Program. Unpublished manuscript.

Brown, S., C. Hickey, B. Harrington, and R. Gill (editors). 2001. United
States Shorebird Conservation Plan, 2^nd^ edition. Manomet Center for
Conservation Sciences, Manomet, Massachusetts, USA.

Ivey, G.L. and C.P. Herziger. 2005. Intermountain West Waterbird
Conservation Plan-A plan associated with the Waterbird Conservation for
the Americas initiative. Version 1.0. U.S. Fish and Wildlife Service,
Portland, Oregon.

Kushlan, J.A., M.J. Steinkamp, K.C. Parsons, J. Capp, M.A. Cruz, M.
Coulter, I. Davidson, L. Dickson, N. Edelson, R. Elliot, R.M. Erwin, S.
Hatch, S. Kress, R. Milko, S. Miller, K. Mills, R. Paul, R. Phillips,
J.E. Saliva, B. Sydeman, J. Trapp, J. Wheeler, and K. Wohl. 2002.
Waterbird Conservation for the Americas: The North American Waterbird
Conservation Plan, Version 1. Waterbird Conservation for the Americas,
Washington, D.C., U.S.A.

NAWMP. 2004. The North American Waterfowl Management Plan --
Strengthening the biological foundation. NAWMP, Washington DC.

Oring, LW, L. Neel, and KE Oring. 2004. Intermountain West Regional
Shorebird Plan. Version 1.0. US Shorebird Conservation Plan. Unpublished
manuscript. US Fish and Wildlife Service, Washington, D.C.

Rich, T.D., C.J. Beardmore, H. Berlanga, P.J. Blancher, M.S.W.
Bradstreet, G.S. Butcher, D.W. Demarest, E.H. Dunn, W.C. Hunter, E.E.
Inigo-Elias, J.A. Kennedy, A.M. Martell, A.O. Punjabi, D.N. Pashley,
K.V. Rosenberg, C.M. Rustay, J.S. Wendt, and T.C. Will. 2004. Partners
in Flight North American Landbird Conservation Plan. Cornell Laboratory
of Ornithology, Ithaca, N.Y.

Salafsky, N., and R. Margoluis. 2003. What conservation can learn form
other fields about monitoring and evaluation. BioScience 53:120-122.

Schmidt, P. 2006. U.S. NABCI Committee takes a lead on monitoring. The
All-Bird Bulletin, January 2006. US Fish and Wildlife Service,
Washington, D.C.

# Appendix: Focal Species and Seasons of Occurrence

Species judged to warrant monitoring in the IW. Entries provide the
primary seasons of occurrence for each species in each State (b=breeding
season, m=migration, w=winter).

  -------------------- ---------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- --------
  **Species**          **West**   **WA**   **OR**   **ID**   **MT**   **WY**   **CA**   **NV**   **UT**   **CO**   **AZ**   **NM**

  Common Loon          mw         mw       mw                                  mw       m        m                           

  Horned Grebe         mw         mw       mw                                  mw       mw       m        w        w         

  Eared Grebe          bmw        bmw      bmw      bm       bm       bm       bmw      bmw      bm       bmw      bmw      bmw

  Pied-billed Grebe    bmw        bmw      bmw      bmw      bmw      bm       bmw      bmw      bmw      bmw      bmw      bmw

  Red-necked Grebe     bmw        mw       mw       b        b                 mw                                            

  Clark\'s Grebe       bmw        mw       bmw      bm       bm       bm       bmw      bm       bm       bm       bmw      mw

  Western Grebe        bmw        bmw      bmw      bm       bm       bm       bmw      bm       bm       bm       bmw      mw

  American White       bmw        m        bm       b        b        bm       mw       bm       bm       bm       mw       mw
  Pelican                                                                                                                   

  Brown Pelican        bmw                                                     bmw                                 w         

  Double-crested       bmw        bmw      bmw      bm       bm       bm       bmw      bmw      bmw      bm       bmw      mw
  Cormorant                                                                                                                 

  Least Bittern        bmw                 m                                   bmw                                 bmw      m

  American Bittern     bmw        bmw      bmw      bm       bm       bm       bmw      bmw      bm       bm       mw       mw

  Black-crowned        bmw        bm       bmw      bm       bm       bm       bmw      bmw      bmw      bm       bmw      bmw
  Night-Heron                                                                                                               

  Green Heron          bmw        bmw      bmw                                 bmw      mw       bm       b        bmw      mw

  Cattle Egret         bmw        mw       mw       mw       mw       mw       bmw      mw       bmw      mw       bmw      mw

  Snowy Egret          bmw                 bmw      bm       m        m        bmw      bm       bm       bm       bmw      bm

  Great Egret          bmw        mw       bmw      m                          bmw      bmw      bm       m        mw       bmw

  Great Blue Heron     bmw        bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw

  White-faced Ibis     bmw                 bm       bm       m        bm       mw       bm       bm       bm       mw       bm

  Trumpeter Swan       bmw        mw       mw       mw       bmw      mw                w                                    

  Snow Goose           mw         m        mw       m        m        m        mw       m        mw       m        mw       mw

  Ross\'s Goose        mw         m        m                 m        m        mw                         m                 mw

  Canada Goose         bmw        bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw      mw       bmw

  Black-bellied        bm                                                                                          bm        
  Whistling-Duck                                                                                                            

  Wood Duck            bmw        bmw      bmw      bmw      bmw      bm       bmw      mw       mw       bmw      mw       mw

  Mallard              bmw        bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw

  Gadwall              bmw        bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw

  American             bmw        bmw      bmw      bmw      bmw      bmw      mw       mw       bmw      bmw      bmw      mw
  Green-winged Teal                                                                                                         

  American Wigeon      bmw        bmw      bmw      bmw      bmw      bmw      mw       bmw      bmw      bmw      mw       mw

  Northern Pintail     bmw        mw       bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw

  Northern Shoveler    bmw        bmw      bmw      bmw      bm       bmw      bmw      bmw      bmw      bmw      mw       bmw

  Blue-winged Teal     bmw        bm       bm       bm       bm       bm       bmw      bm       bm       bm       m        m

  Cinnamon Teal        bmw        bm       bm       bm       bm       bm       bmw      bm       bm       bm       bmw      bmw

  Canvasback           bmw        bmw      bmw      bmw      bm       bm       mw       bmw      bmw      bmw      mw       mw

  Redhead              bmw        bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw      mw       bmw

  Ring-necked Duck     bmw        bmw      bmw      bmw      bmw      bmw      bmw      mw       mw       bmw      mw       mw

  Greater Scaup        mw         mw       mw                                  mw                w                           

  Lesser Scaup         bmw        bmw      bmw      bmw      bm       bmw      mw       bmw      bmw      bmw      mw       mw

  Harlequin Duck       bmw        bmw      bmw      m        bm       bm       w                                             

  Barrow\'s Goldeneye  bmw        bmw      mw       mw       bmw      bmw      mw                mw       mw                mw

  Common Goldeneye     bmw        mw       mw       mw       bmw      bmw      mw       mw       mw       mw       mw       mw

  Bufflehead           bmw        mw       bmw      bmw      bmw      mw       mw       mw       mw       mw       mw       mw

  Common Merganser     bmw        bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw      mw

  Red-breasted         mw         mw       mw                                  mw       mw       mw       mw       mw       mw
  Merganser                                                                                                                 

  Hooded Merganser     bmw        bmw      bmw      mw       bmw      mw       mw       mw       mw       mw       mw       mw

  Ruddy Duck           bmw        bmw      bmw      bmw      bm       bm       bmw      bmw      bmw      bmw      bmw      bmw

  Virginia Rail        bmw        bmw      bmw      bm       bm       bm       bmw      bmw      bmw      bm       bmw      bmw

  Sora                 bmw        bm       bm       bm       bm       bm       bmw      bmw      bmw      bm       bmw      bmw

  Yellow Rail          bm                  bm                                                                                

  Black Rail           bmw                                                     bmw                        b        mw        

  Common Moorhen       bmw                                                     bmw      bmw      bmw               bmw      bmw

  American Coot        bmw        bmw      bmw      bmw      bm       bmw      bmw      bmw      bmw      bmw      bmw      bmw

  Sandhill Crane       bmw        m        bm       bm       bm       bm       bmw      bm       bm       m        mw       mw

  Black-bellied Plover mw         mw       mw       m        m        m        mw       m        m        m        m        m

  Snowy Plover         bmw        mw       bmw               m        m        bmw      bm       bm       bm       m        bm

  Piping Plover        m                                     m                                            m                  

  Killdeer             bmw        bmw      bmw      bmw      bm       bmw      bmw      bmw      bmw      bmw      bmw      bmw

  Mountain Plover      bmw                                   bm       bm       mw       m        m        bm       mw       bmw

  American Avocet      bmw        bm       bm       bm       bm       bm       bmw      bm       bm       bm       bmw      bm

  Black-necked Stilt   bmw        bm       bm       bm       bm       bm       bmw      bm       bm       bm       bmw      bm

  Willet               bmw                 bm       bm       bm       bm       mw       bm       bm       bm       m        m

  Greater Yellowlegs   mw         mw       mw       m        m        m        mw       m        m        m        mw       mw

  Lesser Yellowlegs    mw         m        m        m        m        m        mw       m        m        m        m        m

  Solitary Sandpiper   m          m        m        m        m        m        m        m        m        m        m        m

  Spotted Sandpiper    bmw        bmw      bmw      bm       bm       bm       bmw      bm       bm       bm       bmw      bmw

  Long-billed Curlew   bmw        bmw      bmw      bm       bm       bm       mw       bm       bm       bm       mw       bm

  Marbled Godwit       bmw        mw       mw       m        bm       m        mw       mw       m        m        m        m

  Least Sandpiper      mw         mw       mw                                  mw                                            

  Baird\'s Sandpiper   m                                     m        m                                   m                 m

  Pectoral Sandpiper   m                                     m        m                                   m                 m

  Upland Sandpiper     bm                  m                 bm       bm                                  m                 m

  Long-billed          mw         mw       mw       m        m        m        mw       m        m        m        mw       mw
  Dowitcher                                                                                                                 

  Short-billed         mw         m        m                 m        m        mw                                            
  Dowitcher                                                                                                                 

  Stilt Sandpiper      m                                     m        m                          m        m                 m

  Common Snipe         bmw        bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw      bmw      mw       mw

  Wilson\'s Phalarope  bm         bm       bm       bm       bm       bm       bm       bm       bm       bm       m        m

  Franklin\'s Gull     bm                  b        bm       bm       m                 m        bm       m                 m

  Ring-billed Gull     bmw        bmw      bmw      bm       bm       bm       mw       bmw      bmw      mw       mw       mw

  California Gull      bmw        bmw      bmw      bm       bm       bm       mw       bmw      bm       bm       mw       m

  Herring Gull         mw         mw       mw       mw       m        mw       mw       mw       mw       mw       mw       mw

  Caspian Tern         bmw        bm       bm       bm                bm       bmw      bm       m                 m         

  Forster\'s Tern      bmw        bm       bm       bm       bm       bm       bmw      bm       bm       bm       m        m

  Common Tern          bm                                    bm                                                              

  Least Tern           bm                                    b                 m                          m                 m

  Black Tern           bm         bm       bm       bm       bm       bm       bm       bm       bm       bm       m        m
  -------------------- ---------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- --------