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Birds Across Time: An Assessment of Historic and Current Waterfowl
Surveys within Nisqually National Wildlife Refuge
by
Heather N. Tucker
A Thesis
Submitted in partial fulfillment
of the requirements for the degree
Master of Environmental Studies
The Evergreen State College
July 2013
©2013 by Heather N. Tucker. All rights reserved.
This Thesis for the Master of Environmental Studies Degree
by
Heather N. Tucker
has been approved for
The Evergreen State College
by
_____________________________
Dr. Ralph Murphy, Ph.D.
Member of the Faculty
_____________________________
Date
ABSTRACT
Birds Across Time: An Assessment of Historic and Current Waterfowl
Surveys within Nisqually National Wildlife Refuge
Heather N. Tucker
Nisqually National Wildlife Refuge lies at the southern tip of the Puget Sound in
western Washington State. This estuary is not only an important wintering and
breeding site for local, resident waterfowl species but also acts as a stop-over site
for birds migrating both north and south along the Pacific Flyway. Since the
establishment of Nisqually NWR in the mid-1970’s, biologists and volunteers
alike have been monitoring waterfowl presence and behavior using a variety of
different survey methods. This thesis project sought to create a comparable
database using two of those survey types, aerial and ground waterfowl surveys
both performed by United States Fish and Wildlife. This research project also
analyzed the historical waterfowl trends that occurred before the estuary’s
restoration in 2009, and explored preliminary trends using a post-restoration
dataset collected by United State Geological Survey. Through these analyses,
qualitative descriptions of pre- and post-restoration conditions were created. This
research also explored the benefits and limitations of waterfowl surveys in
general. Overall, the data indicates that historical waterfowl trends were stable,
and trends since the estuary restoration have also remained steady. Many years of
continued data collection will be needed to fully assess the effects that the
restoration and other exogenous factors have had on Nisqually River estuary
waterfowl trends.
TABLE OF CONTENTS
1.
INTRODUCTION AND BACKGROUND
1
1.1
OVERVIEW
1.2
WHAT IS AN ESTUARY?
1.3
NISQUALLY NATIONAL WILDLIFE REFUGE
1.4
THE ESTUARY RESTORATION AND ITS IMPORTANCE TO
AVIFAUNA
16
1.5
AN OVERVIEW OF WATERFOWL
1.6
RESEARCH OBJECTIVES
2.
RESEARCH METHODS
2.1
SURVEY METHODS
2.1.1
ANNUAL AERIAL AND GROUND SURVEYS
2.1.2
MONTHLY HIGH-TIDE SURVEYS
2.2
METHODS OF DATA ANALYSIS
3.
RESULTS AND DISCUSSION
3.1
AERIAL AND GROUND WATERFOWL SURVEYS
3.2
MONTHLY HIGH-TIDE SURVEY
4.
CONCLUSION
4.1
SUMMARY OF RESULTS
4.2
PRE- AND POST-RESTORATION HABITAT CONDITIONS
4.3
IDENTIFYING AND ACCOUNTING FOR SOURCES OF ERROR
4.4
SUGGESTIONS FOR FUTURE RESEARCH
4.5
FINAL THOUGHTS
1
2
7
19
25
26
26
28
30
34
34
34
41
44
45
49
50
54
55
iv
LIST OF FIGURES AND TABLES
Figures:
Figure 1: Nisqually National Wildlife Refuge
Figure 2: Pacific Flyway
5
8
Figure 3: Nisqually Dike Construction
10
Figure 4: Aerial Photograph of the Nisqually Dike
12
Figure 5: Aerial Photograph of Nisqually NWR in November 2009 Following the
Dike Removal
12
Figure 6: Aerial Photograph of Nisqually NWR in January 2011 Following the Dike
Removal
13
Figure 7: Nisqually Estuary Restoration
15
Figure 8: Avifauna Utilizing Nisqually National Wildlife Refuge
Figure 9: Northern Pintail (Anas acuta)
17
22
Figure 10: Canada Goose (Branta canadensis)
23
Figure 11: American Wigeon (Anas americana)
24
Figure 12: Historical USFWS Ground and Aerial Waterfowl Survey Map and Flight
Path of Nisqually NWR
31
Figure 13: Current USFWS Ground and Aerial Waterfowl Survey Map and Flight
Path of Nisqually NWR
32
Figure 14: USGS Monthly High-Tide Survey Map of Nisqually NWR
33
Figure
15:
Total
(Aerial Survey)
35
Observed
Waterfowl
Abundance
Over
Time
Figure
16:
(Ground Data)
Observed
Waterfowl
Abundance
Over
Time
Total
36
Figure 17: Total Observed
(Aerial Data)
38
Waterfowl
Guild
Abundance
Over
Time
Figure 18: Total Observed
(Ground Data)
39
Waterfowl
Guild
Abundance
Over
Time
v
Figure
19:
(Aerial Data)
Total
40
Observed
Waterfowl
Abundance
by
Species
Figure
20:
(Ground Data)
Total
41
Observed
Waterfowl
Abundance
by
Species
Figure
21:
Total
(Monthly Data)
42
Observed
Waterfowl
Abundance
Over
Figure
22:
Total
(Monthly Data)
43
Observed
Waterfowl
Abundance
by
Figure
23:
(Monthly Data)
Percent
44
Observed
Waterfowl
by
Time
Species
Guild
Tables:
Table 1: Nisqually NWR Waterfowl Species
20
vi
ACKNOWLEDGEMENTS
I would like to express my appreciation to multiple people without whom this
thesis could not have been completed. First, I would like to thank United States
Geological Survey and Nisqually National Wildlife Refuge for allowing me the
invaluable opportunity to intern, work and study with them. Thank you to my USGS
crew for their support, field work excellence, data entry/QAQC, and friendship. Thank
you to my supervisors Kelley and Isa for showing me never-ending support during the
duration of this thesis journey. Thank you to my thesis advisor, Dr. Ralph Murphy and
the rest of the faculty and staff at TESC for their never-ending guidance and
encouragement. Thank you to my husband, Nick, for motivating me to continue my
education. I also thank my pets for making sure that I took breaks…to pet them and
distribute treats. I thank my parents, family and friends for their endless support
throughout my entire life and especially in completing my graduate studies. Last but
certainly not least, I would like to thank the incredible wildlife who have inspired my
career path and given me the determination to see this project through to the very end.
vii
1.
INTRODUCTION AND BACKGROUND
The 2009 tidal marsh restoration at Nisqually National Wildlife Refuge (NWR or
Refuge) in Olympia, Washington reestablished natural estuarine processes to a humanaltered ecosystem. This ecological reestablishment created multiple research
opportunities, which included an assessment of the effects of the restoration on endemic
bird species. From this arose the need to analyze the historical avian data whose
collection began not long after the establishment of the Refuge. However, the lack of
compiled and synthesized pre-restoration survey data as well as less than two years of
post-restoration data made assessing any fluctuations in avian presence, abundance or
distribution difficult to impossible. The purpose of this research seeks to change that,
focusing specifically on waterfowl species. The term waterfowl in this study includes all
species classified as diving ducks, dabbling ducks, geese or swan.
1.1
OVERVIEW
This research had four main objectives. The first objective is to compile
Nisqually NWR legacy, pre-restoration waterfowl data into a comparable database.
Second, it assesses Nisqually NWR waterfowl trends through analyses of survey data
from three different survey methods used over a period of more than three decades.
Third, this thesis seeks to provide qualitative descriptions of pre-restoration and current
post-restoration conditions of Nisqually NWR. The fourth objective discusses the
1
benefits and limitations of both pre and post-restoration waterfowl surveys and each
specific methodology used in this research.
Collection of waterfowl data began in 1975, not long after the Refuge’s
establishment one year prior. The data analyzed in this research is derived from prerestoration aerial (February 1984 to January 2009) and ground-based waterfowl surveys
(February 1998 to November 2008) as well as pre and post-restoration monthly high-tide
surveys (October 2009 to January 2011). These specific datasets were selected as oppose
to the entire historical dataset because they employed clearly defined methods and field
observations by trained biologists and volunteers. This allows for a more sound final
analysis than if each of the complete datasets, 1975-2011, were used.
1.2
WHAT IS AN ESTUARY?
The Environmental Protection Agency (EPA) describes estuaries as some of the
most dynamic, nutrient-rich of all nature’s ecosystems. Estuaries are comprised of a
complex patchwork of habitats that can include combinations of salt marsh, freshwater
marsh, river delta, open grasslands, riparian woodlands/wooded swamp, sea grass beds,
tidal pools, mangrove forests, reefs, rocky shores, sandy beaches, open water, open
mudflats or upland habitats whether forested or open (Harvey 1998). They can also be
referred to as a firth, mouth, delta, bay, lagoon, harbor, inlet, sound, or embouchure.
Popular sources define estuaries as semi-enclosed bodies of water that act as a transition
zone between riverine and stream mouths with that of oceanic environments. They are
subject to influx of both marine waters as well as fresh, riverine water and sediment. The
2
infusion of saltwater and freshwater distributes high levels of nutrients into both the
water column and benthic sediment. These high nutrient levels allow estuaries to be
counted as some of the most productive ecosystems in the world. Such productivity can
be measured by the amount of organic energy exported to estuaries and coastal
environments (Odum 1961).
Estuaries are also known for their natural cleansing abilities (Mitsch and
Gosselink 2000). Upland water drainage carries sediments, nutrients, and other
pollutants to estuaries. As the water flows through wetlands such as swamps and salt
marshes, much of the sediments and pollutants are filtered out. This filtration process
creates cleaner water, which benefits both the health of marine life and humans. Wetland
plants and soils also act as natural buffers between the land and ocean, absorbing flood
waters and storm surges. Salt marsh grasses and other estuarine plants also help prevent
erosion and stabilize shorelines. This protects upland habitat as well as valuable real
estate from storm and flood damage.
Estuarine biodiversity has often been referred to as a “biological supermarket”
due to the ability to support of complex, intricate food webs. Thousands of species of
birds, mammals, fish, and other wildlife depend on estuarine habitats as places to find
shelter, feed, and reproduce. Because they are so biologically productive, estuaries
provide ideal areas for migratory birds to rest and re-fuel during their long journeys.
Many marine organisms, including most commercially-important such as threatened and
endangered species of fish, depend on estuaries at some point during life-cycle
3
development. Due to the reliance on the sheltered spawning places provided by estuaries,
they are often called the "nurseries of the sea."
Along the southern shores of the Puget Sound in western Washington State lays
one such ecosystem: the Nisqually River estuary. Also referred to as the Nisqually Delta,
this unique locale is the site of the largest estuary restoration project in the Pacific
Northwest (Figure 1, pp 5). Due to the plethora of nutrients and microorganisms it
provides, this diverse landscape supports native plants and over 300 species of wildlife
that include birds, mammals, reptiles, amphibians and fish (fws.gov 2012). This includes
the Endangered Species Act (ESA) threatened Nisqually Fall Chinook salmon
(Oncorhynchus tshawytscha), an important cultural symbol for the local Nisqually Indian
Tribe as well as the Bald Eagle (Haliaeetus leucocephalus), the national emblem of the
United States.
Restoration and protection of estuaries are critical actions that have been at the
forefront of recent ecological management practices. One reason for this is an estuary’s
suite of biological resources and services such as those just discussed. Another reason is
their aesthetic contribution. Communities residing around estuaries utilize them for
spiritual and cultural enjoyment. Another reason is their provision of measureable
commercial commodities in the form of tourism, fisheries and recreational activities
(boating, fishing, swimming, and bird-watching to name a few) all while acting as a
prime locations for education and scientific study. Each of these factors is considered
immeasurable those who benefit from them.
4
Figure 1: Nisqually National Wildlife Refuge
(Source: U.S. Fish and Wildlife Service)
The top figure represents the relative location of Nisqually National Wildlife Refuge within Washington State, while
the bottom figure defines the Refuge’s boundaries and specific location within the Nisqually River delta.
5
The economy of many coastal areas is based on the natural beauty and bounty of
estuaries. When those natural resources are imperiled, so too are the livelihoods of those
who live and work in estuarine watersheds. Over half the U.S. population lives in coastal
areas, including along the shores of estuaries. According to a 2007 study, coastal
watershed counties provided 69 million jobs and contributed $7.9 trillion to the Gross
Domestic Product. Coastal counties are growing three times faster than counties
elsewhere in the nation (National Ocean Economics Program, 2009).
Unfortunately this increasing concentration of people upsets the natural balance of
estuarine ecosystems and imposes increased pressures on their vital natural resources.
What happens on the land indirectly affects the quality of the water and health of the
organisms that live in an estuary. Excessive nutrients, runoff, marine debris, pathogens,
metals, invasive species and atmospheric deposition can cause ecosystem disturbances
including but limited to eutrophication and algal blooms. This in turn leads to animal
illness and die-off, fish kills, brown and red tides, and even human sickness. This
highlights the final reason described by the Coastal and Estuarine Research Federation.
They estimate that 80% of tidal marshes in the Puget Sound have been degraded or
destroyed over the past 150 years. These anthropogenic actions combined with the threat
of rapid global climate shift compromise any remaining estuaries including the wellbeing of fauna and flora that inhabit them. It is for these reasons that Nisqually NWR
and the recent restoration that took place is critical to the overall health of the ecosystem
and the wildlife that inhabit it, as the primary purpose of the restoration was to provide
6
shelter and food resources to the various ecologically, economically and culturally
important Nisqually salmon species.
A secondary example of the importance of the Nisqually Delta is a major noncoastal resting and feeding area for over 275 species waterfowl migrating between the
Skagit Flats and Columbia River within the Pacific Flyway (fws.gov 2012). The
Nisqually NWR provides thousands of acres of resting and nesting grounds for not only
migrating waterfowl but also songbirds, gulls, shorebirds, raptors and wading birds. The
Pacific Flyway stretches from the Arctic Circle down the Pacific coast to Central
America. Waterfowl migrating within the Pacific Flyway begin arriving in the Nisqually
Delta in September with some remaining throughout the winter months (Figure 2, pp 8).
1.3
NISQUALLY NATIONAL WILDLIFE REFUGE
Nisqually National Wildlife Refuge is managed by United States Fish and Wildlife
Service. It is located just off of Interstate-5 in Thurston and Pierce Counties between the
cities of Olympia and Tacoma, Washington. Refuge boundaries lie within the Nisqually
Delta on the west side of the Nisqually River, adjacent to the neighboring Nisqually
Indian Tribe lands. In 1845, James McAllister and his family settled Medicine Creek,
now known as McAllister Creek. By 1852, he had begun developing the land by
damming the creek and building a sawmill.
7
Figure 2: Pacific Flyway
(Source: USFWS)
The above figure represents the Pacific Flyway, one of four major North American avian migration flyways
8
In December 1854, the land became the site of an Indian treaty. Taking place at a
grove of trees along the east bank of McAllister Creek, it was the first-ever Indian treaty
to take place in Washington Territory. The agreement ensured fishing, hunting, and
gathering rights for the surrounding tribes. Members of the Nisqually Tribe still exercise
these rights to this day, fishing for various salmon species in Refuge waters.
In 1904, 2,350 acres of the Nisqually River estuary were purchased by Seattle
lawyer Alson L. Brown and his wife, Emma. A crew of 30 men and a horse-drawn scoop
built the original 6.44 km (4 mile) dike that prevented marine tidal inundation inside the
designated area. The dike took three years to construct, and an additional three years was
needed to dry and leach salts from the area (Figure 3, pg. 10). In 1910, the dike was
reinforced ending the conversion of the delta into land for farming purposes. The main
agricultural practices included cattle grazing and raising crops. The farm also raised
chickens and hogs, ran a dairy, as well as maintained a general store and housing for the
farm’s crew.
Brown lost the farm after World War I, but it continued to operate under
subsequent owners who rebuilt an even higher dike, as well as a cross-dike at McAllister
Creek (fws.gov 2012). In 1919, the title was transferred to P.B. Truax, C.D. Clinton, and
Robert Olden. Then in 1952, the land switched ownership again to Bruce Pickering who
leased the land to dairy farmers for a short period of time (Farris 1974).
9
Figure 3: Nisqually Dike Construction
(Source: WA State Historical Society)
The above figure depicts a crew building the Nisqually dike in 1904.
In 1970, the Nisqually River Task Force was created to assist in the preservation
and protection of the Nisqually River Delta. The group consisted of federal, state and
local governments, natural resource business representatives, the Nisqually Indian Tribe,
landowners and citizen activists. In 1987, each of these groups came together to create
the Nisqually River Management Plan which provided recommended policies and
implementation guidelines. The management plan also provided balanced stewardship of
the area’s economic resources, natural resources, and cultural resources.
10
In 1971, in recognition of the significance of the natural ecosystem, the U.S.
Department of the Interior designated the estuarine portion of the Nisqually River Delta
as a National Natural Landmark. The Nisqually River Task Force recommended in 1972
that the delta be set aside as a National Wildlife Refuge (nisquallyriver.org). Then in
February 1974, in recognition of the area’s unique fish and wildlife resources, the Brown
Farm property and tidelands were acquired for inclusion in the National Wildlife Refuge
System and became Nisqually National Wildlife Refuge (Nisqually NWR
Comprehensive Conservation Plan 2005).
The Nisqually estuary restoration began in 1996 with the reintroduction of tidal
flow to nine acres of land east of the Nisqually River by the Nisqually Indian Tribe in
partnership with landowner, Ken Braget. This parcel, along with the rest of the Braget
Farm was later acquired by the Nisqually Indian Tribe in 2000 and is cooperatively
managed by the USFWS. Additional restoration action taken by the Tribe included the
8.5 hectare (21 acre) Phase I marsh in 2002, followed by the 40.5 hectare (100 acre)
Phase II marsh in 2006. This earlier work culminated with the removal of the Brown
Farm dike on the Nisqually NWR in October of 2009, allowing marine waters of the
Puget Sound to infiltrate 308 hectares (762 acres) of land for the first time in over 100
years (Figures 4-6, pp 12-13). The area surrounding the Nisqually NWR headquarters
remained diked to inhibit flooding of the Nisqually headquarters, maintenance building,
educational center and visitor center.
11
Figure 4: Aerial Photograph Prior to the Removal of the Nisqually Dike
(Source: Nisqually NWR)
Figure 5: Aerial Photograph of Nisqually NWR in November 2009 Following the Dike Removal
(Source: Nisqually NWR)
12
Figure 6: Aerial Photograph of Nisqually NWR in January 2011 Following the Dike Removal
(Source: Nisqually NWR)
The three figures above (4-6) represent time lapsed, aerial pictures of the Nisqually NWR dike. Figure 4 shows the
dike before its removal in 2009. Both Figure 5 & 6 shows the dike remnants following its removal in 2009 and 2011
respectively.
This restoration was part of the Refuge’s Comprehensive Conservation Plan,
providing long-term guidance for management decisions, to set forth goals, objectives
and strategies needed to accomplish refuge purposes and identify and Service’s best
estimate of future needs. The USFWS took habitat restoration into consideration when
developing the CCP. The objectives of the CCP are to protect the Nisqually NWR
resources and to contribute toward the goals of the Refuge. An excerpt of the CCP goals
is as follows:
13
To conserve, manage, restore, and enhance native habitats and
associated plant and wildlife species representative of the
Puget Sound lowlands.
To support recovery and protection efforts for Federal and
State threatened and endangered species, species of concern,
and their habitats.
To provide quality environmental education opportunities
focusing on fish, wildlife, and habitats of the Nisqually River
Delta and watershed.
To
provide
quality
wildlife-dependent
recreation,
interpretation, and outreach opportunities to enhance public
appreciation, understanding, and enjoyment of fish, wildlife,
habitats and cultural resources of the Nisqually River Delta
and watershed.
An unaltered marsh within the Nisqually Delta, known as the Reference Marsh,
has served as a benchmark for post-restoration monitoring performed by United States
Geological Survey (USGS) and the Nisqually Indian Tribe. The restoration increased not
only tidal marsh habitat but also the natural quality of the Nisqually NWR for public use
and compatibility with National Wildlife Refuge System policies and guidelines
(Nisqually NWR Comprehensive Conservation Plan 2005). USGS (Western Ecological
Research Center, Coastal Marine Geology, and Western Fisheries Research Center),
along with the Tribe and Nisqually NWR are continuing to lead monitoring and research
efforts to track the biological and physical changes as a result of the restoration (Figure 7,
pp 15).
14
Figure 7: Nisqually Estuary Restoration
(Source: Jennifer Cutler, Nisqually Indian Tribe)
The above is a map of the Nisqually delta and each of the trails, habitats and tasks associated with its 2009
restoration. This reintroduced 762 acres to Puget Sound tides after 100 years. This combined with earlier
restorations conducted by the neighboring Nisqually Indian Tribe, restored approximately 900 acres of
estuarine habitat.
15
1.4
THE ESTUARY RESTORATION AND ITS IMPORTANCE TO
AVIFAUNA
Estuarine ecosystems provide valuable amenities to fish, wildlife, and humans
alike. The restoration of the Nisqually estuary to its historical salt marsh state was
important for multiple reasons. Those reasons include the economic, aesthetic,
recreational and ecological value to both the surrounding communities and the wildlife
that inhabit the delta. This protected ecosystem also holds a cultural significance for
those in the surrounding community including Native Americans groups such as the
Nisqually Indian Tribe and other stakeholders.
Further reasoning supporting the importance of the restoration is the rich
biodiversity that wetlands sustain. Due to the fact that salt marshes and open mudflats
are washed by the changing tides of Puget Sound, rich nutrients are distributed to a
variety of vegetation and invertebrates that reside in the mudflats and sediment. In turn,
other species living within the Nisqually Estuary are provided a food resource. This
includes the ESA listed Nisqually Fall Chinook salmon as well as the waterfowl that are
the focus of this research project: diving ducks, dabbling ducks, geese, swan. Estuaries
also provide migratory, breeding as well as overwintering grounds for multiple waterfowl
species such as the Common merganser (Mergus merganser) and Cackling geese (Branta
hutchinsii) (Figure 8, pp 17).
16
Figure 8: Avifauna Utilizing Nisqually National Wildlife Refuge
(Source: Nisqually NWR)
The above photo shows an example of the diversity of avian species that utilize Nisqually NWR.
The science of habitat restoration is relatively new with literature first emerging in
the 1990’s (Kusler and Kentula 1990; Marble 1992). Wetland restoration specifically
began to emerge in the literature with a study of tidal wetland restoration by Zedler
(1988) and also tidal salt marsh restoration by Broome et al (1990) among others.
However, the decline of wetlands has also been documented, as many regard wetlands as
more of a wasteland than an area essential to the survival of various species. Puget
Sound saltwater wetland habitat loss due to diking, draining, filling and development are
estimated to be more than 73% (estuaries.org 2009).
However, the value of wetlands is now recognized as a benefit to humans and
other species and is protected under the Federal Water Pollution Control Act. According
17
to the USDA, President George Bush Sr. implemented the No Net Loss Policy during his
1988-1992 presidential term. "No net loss" is the government's overall policy goal
regarding wetland preservation. The goal of the policy is to balance wetland loss due to
economic development with wetlands reclamation, mitigation, and restorations efforts, so
that the total acreage of wetlands in the country does not decrease. The goal is to allow it
to remain constant or increase. To achieve the objective of no net loss, the federal
government utilizes several different environmental policy tools which legally protect
wetlands, provide rules and regulations for citizens and corporations interacting with
wetlands, and incentives for the preservation and conservation of wetlands.
Waterfowl ecology and management has also been studied by many scientists,
including Johnsgard (1965), Bellrose (1978), Owen and Black (1990), Baldasarre and
Bolen (1994) among others. In 1989, Weller examined management techniques for
wetland enhancement, creation and restoration. This research gave special consideration
to preserving natural landscapes, functional values and encouragement of waterfowl
utilization. A study in British Columbia by Hirst and Eastope (1981) found that the
number of American wigeon (Anas americana) observed in agricultural fields exhibited a
strong correlation with adjacent estuaries and the amount of standing water in the fields.
Hickman and Mosca (1991) looked at improvement of quality habitat in support of
migratory waterfowl and nesting bird species and in 1999, Weller studied more intensely
the relationship between waterfowl and wetlands.
18
The function and value of wetlands and the wildlife in which they provide for has
catalyzed the conservation and preservation of remaining wetlands. It has also prompted
the restoration of already degraded, altered and destroyed areas. Corrective practices
backed by protective legislation are becoming more and more critical as the human
population continues to increase and sprawl. As this encroachment continues, it threatens
the livelihood of important wildlife habitat such as estuaries.
1.5
A BRIEF OVERVIEW OF WATERFOWL
Waterfowl are important both ecologically and economically. Not only are they
an important part of biological webs worldwide, but they also attract an array of birdwatchers, photographers, naturalists and others who enjoy viewing or photographing
them in their natural habitats. They draw in hunters as they are a popular game species.
This in turn provides revenue during hunting season, contributes to the local and regional
economies and tourist industry.
There have been multiple waterfowl species sighted within Nisqually NWR with
occurrences ranging from common to rare (Table 1, pg. 20). According to Simenstad and
Watson (1983), there are 59 bird species common to Pacific Northwest estuaries. When
utilizing a migration route stopover site like Nisqually NWR, waterfowl species are
known to feed on the following, depending upon species: small fish and fish eggs,
various species of worm and mollusks, small crustaceans, grasses and weeds, algae and
aquatic plants, frogs, salamanders and other amphibians, aquatic and terrestrial insects,
seeds and grain, and small berries or fruits (Sibley 2000).
19
Table 1: Nisqually NWR Waterfowl Species
The table below lists each of the observed waterfowl species name, code used in analyses and type within
Nisqually NWR
Common Name
Species Code
Type
American Green-winged Teal
AGWT
Dabbler
American Wigeon
Barrow's Goldeneye
Brant
Bufflehead
Blue-winged Teal
Cackling Goose
AMWI
BAGO
BRAN
BUFF
BWTE
CACK
Dabbler
Dabbler
Geese
Diver
Dabbler
Goose
Canada Goose
Canvasback
CAGO
CANV
Geese
Dabbler
Cinnamon Teal
Clark's Grebe
Common Goldeneye
Common Loon
Common Merganser
CITE
CLGR
COGO
COLO
COME
Dabbler
Diver
Dabbler
Diver
Diver
Eared Grebe
Eurasian Wigeon
Gadwall
Greater Scaup
Greater White-fronted Goose
Harlequin
EAGR
EUWI
GADW
GRSC
GWFG
HARD
Diver
Dabbler
Dabbler
Diver
Geese
Dabbler
Horned Grebe
HOGR
Diver
Hooded Merganser
Lesser Scaup
Long-tailed Duck
Mallard
Mute Swan
HOME
LESC
LTDU
MALL
MUSW
Diver
Diver
Dabbler
Dabbler
Swan
Northern Pintail
NOPI
Dabbler
Northern Shoveler
NSHO
Dabbler
Oldsquaw
Pied-billed Grebe
Red-breasted Merganser
Redhead
OLDS
PBGR
RBME
REDH
Dabbler
Diver
Diver
Dabbler
Ring-necked Duck
Ring-necked Grebe
Ruddy Duck
Snow Goose
RNDU
RNGR
RUDU
SNGO
Dabbler
Diver
Dabbler
Geese
Surf Scoter
SUSC
Diver
Trumpeter Swan
Tundra Swan
Western Grebe
Wood Duck
White-winged Scoter
TRUS
TUSW
WEGR
WODU
WWSC
Swan
Swan
Diver
Dabbler
Diver
20
The onset of season rainfall that occurs on an annual basis and begins in the early
Fall signals the arrival of waterfowl migrating south along the Pacific Flyway. The
Nisqually Delta and watershed is important for resting and foraging of waterfowl during
strenuous migrations (Dahl 1991). For some species, Nisqually NWR is the end of their
journey and they utilize the Refuge as nesting and rearing grounds for young. Waterfowl
migration along the Pacific Flyway begin arriving in Nisqually in late September, and
many remain throughout the winter and into the spring, while other resident birds stay
throughout the year. They travel between the estuary and flooded agricultural or grass
fields as well as wetlands on and off the Refuge. Those off-Refuge sites are primarily
found south of I-5, on nearby farmland (Nisqually NWR Comprehensive Conservation
Plan 2005).
Species such as Pied-billed Grebes (Podilymbus podiceps), Cinnamon Teal (Anas
cyanoptera) and Canada Geese (Branta canadensis) have been observed nesting in
Nisqually NWR. Both Canada and Cackling Geese (Branta hutchinsii) are common
species found in the winter. However, the most prevalent species seen within Nisqually
NWR have historically been American Wigeon, Mallard (Anas platyrhynchos), Northern
Pintail (Anas acuta) (Figure 9, pp 22) and American Green-winged Teal (Anas crecca),
all of which are dabbling waterfowl. It must be noted, that although waterfowl are
among the most abundant birds seen within Nisqually NWR, species from all other avian
foraging guilds have been sited utilizing all that the estuary has to offer.
21
Figure 9: Northern Pintail (Anas acuta)
(Source: National Audubon Society)
The above figure represents a Northern Pintail drake, a common dabbling duck species observed in Nisqually.
It is well-known that disturbance from human activities cause temporary changes
in waterfowl behavior and locally affect temporal and spatial distribution of migratory
and wintering species. To some extent however, birds can compensate for such
disturbance by altering their behavior and habituating around these human activities.
One example of this could potentially be the effect of hunting season on these waterfowl
as disturbance from gunshots could cause the birds to flush. Fall through spring hunting
is widely practiced throughout the world, although few studies have been conducted
investigating the effects on waterfowl. Little is known though about how anthropogenic
disturbance influences large-scale dispersion and population dynamics of waterfowl
(Madsen 2008).
22
Seven different species of goose and swan have been sighted on the Refuge such
as Cackling geese and Canada geese (Figure 10). Other species might include Trumpeter
Swan (Cygnus buccinator) and Black Brant (Branta bernicla). Geese and swans can be
identified by their large, heavy bodies and long necks. They feed by grazing or by
tipping-up when swimming. They can be found in large flocks and are known for their
loud calls (Sibley 2000).
Figure 10: Canada Goose (Branta canadensis)
(Source: National Geographic Society)
The above photograph depicts a Canada goose hen with her ten goslings as they swim.
Dabbling ducks are among the most common waterfowl species seen within
Nisqually NWR and include 11 different species. The most common of species within
this guild are Mallard, American Wigeon (Figure 11, pp 24), Northern Shoveler,
23
American Green-winged Teal and Northern Shoveler (Anas clypeata). These species are
known for their foraging behavior of dabbling their bills in the water and tipping forward.
Dabbling ducks will rarely dive while feeding. An interesting aspect of their behavior is
their ability to take-off in flight without running (Sibley 2000).
Figure 11: American Wigeon (Anas americana)
(Source: nisquallydeltarestoration.org)
The American wigeon, like those pictured above, are among the most common dabbling ducks species observed in
Nisqually NWR.
The most diverse species of waterfowl are diving ducks. Eleven different species
of diving ducks have been observed utilizing the Refuge, including Bufflehead
(Bucephala albeola), Common Merganser (Mergus merganser) and Surf Scoter
(Melanitta perspicillata). These species are known for diving underwater for food.
However, as some dabblers will also dive, some divers will also dabble. Divers are more
likely and better-able to dive due to their heavier bodies and higher wing loading. Wing
loading, combined with faster wing beats, allow them to fly faster than other waterfowl.
They are also known to run along the water’s surface before becoming airborne (Sibley
2000).
24
Avian monitoring efforts are maintained by biologists, technicians and volunteers
from both Nisqually NWR and USGS. Surveys are performed not only on the Refuge,
but also on the Nisqually Tribe’s Pilot, Phase I and Phase II sites. This research
however, only concerns observed avian data that has been collected within the boundaries
of Nisqually NWR using only data from 1984 to January 2011 was analyzed.
1.6
RESEARCH OBJECTIVES
The purpose of this thesis research is to assess decades of waterfowl data
collected throughout the history of Nisqually NWR and produce a database that can be
used to detect change in species frequency since the delta restoration in 2009. Analysis
began with February 1984 aerial survey data and ends with January 2011 monthly hightide survey data. Nisqually NWR waterfowl data analyses have occurred through
collection, organization, entry and quality control of historical Refuge aerial and groundbased waterfowl data, as well as current USGS monthly high-tide data separately.
The objectives of this research are:
a. Compile Nisqually NWR pre-restoration waterfowl data into a
standardized, comparable database;
b. Describe the spatial seasonality and abundance of waterfowl within
Nisqually NWR using pre-restoration aerial and ground-based waterfowl
survey data, as well as the preliminary results from ongoing USGS postrestoration monitoring efforts;
25
c. Provide a qualitative description of past and present conditions for
waterfowl;
d. Discuss the benefits and limitations of waterfowl surveys and each
specific methodology used.
Due to its premature nature, it is too early to determine the true effect the 2009
estuary restoration has had on waterfowl trends. Collection of current USGS monthly
high-tide waterfowl data has only been collected since the restoration in October 2009
and monitoring is expected to continue for as long as funding allows. Data collected
prior to and following restoration activities will greatly assist the evaluation of habitat
management actions conducted by Nisqually NWR and create a database for future
surveys to be incorporated and analyzed along with the data utilized in this research.
2.
RESEARCH METHODS
The following section details each of the three waterfowl surveys used for
analysis in this research. The ground and aerial waterfowl surveys were performed by
Nisqually NWR biologists from soon after the establishment of the Refuge in 1974.
Monthly high-tide surveys were performed by USGS, Refuge volunteers, and the author
since the estuary restoration in 2009.
2.1
SURVEY METHODS
This research focuses analyses on three waterfowl datasets within Nisqually
NWR. Two are historical aerial and ground-based waterfowl surveys performed by
26
Nisqually NWR staff. The third includes monthly high-tide surveys that take place on
foot as well as by boat and are performed by USGS biologists and crew. Certain surveys
targeted specific types of birds, while others may seek to record every species identified.
For example, the Nisqually NWR aerial surveys targeted mainly waterfowl while USGS
monthly high-tide surveys seek to record all bird species present within the survey area.
Avian identifications are made based upon auditory or visual sightings.
Tide height, time of day, season and weather conditions also factor into where,
when and if survey will be performed at that time as each of these factors greatly
influence avian activity. It is for these reasons that survey data can sometimes be
difficult to interpret and use, and surveys of different types provide information of
varying quality. Most bird surveys tend to provide incomplete coverage that miss
proportions of populations, so there are no definitive surveys for most species. Varying
surveyors and recorders for these surveys can also create variability, as skill and
observation levels also vary from person to person. For this research, a variety of
different biologists and trained volunteers have aided in the observation, identification
and recording of birds sighted during the various surveys (ground, aerial and monthly
high-tide) discussed in this research.
Another inconsistency is varying access to certain survey areas, vegetation that
blocks hidden species and changing site boundaries over time. However, some
consistencies within Nisqually NWR surveys includes the utilization of the same overall
area boundary and all surveys have been performed using visual aids such as binocular or
27
spotting scopes and each survey employed the master birding skills of Nisqually NWR
biologists and/or volunteers to help insure accurate identification of avian species
sighted.
2.1.1 AERIAL AND GROUND SURVEYS - NNWR
The purpose of the aerial and ground waterfowl surveys are to document the
species and number of waterfowl using Nisqually NWR. These surveys provide a guide
to assess wetland enhancement efforts and monitor habitat use. The aerial survey gives
the biologist and managers an overview of Nisqually NWR as well as surrounding areas.
Ground counts are conducted the same day in each location to supplement or cross-check
the aerial data for accuracy. These waterfowl surveys are conducted near the beginning
of each month starting in October and end in March or April. An annual mid-winter
count also takes place and usually occurs the first week or two of January. Waterfowl
surveys were conducted from 1974 through the present. The number of surveys varied
from year to year, ranging from zero (1980) to six surveys (1976, 1986, 1987 and 1989)
per season. Ground surveys were performed from 1998 to present. Gear utilized
includes binoculars and wildlife spotting scopes as well as means to record the data.
Aerial surveys are conducted in a fixed wing Cessna or Beaver float plane flying a
set flight path with an observer in the front passenger seat and often a second observer is
positioned behind the pilot. The front passenger looks right while the secondary biologist
riding behind the pilot surveys to the left. Data is recorded into either cassette recorder
28
or computer microphone recorder. Notes and observations are also recorded on a
standard data sheet. This included species, number observed and location of observation.
For this survey, the Refuge is divided into units. Unit 1 included McAllister Creek and
adjacent salt marsh habitats. Unit 2 included the Nisqually Flats, and the mudflats and
salt marsh areas just north of the dike. Unit 3 included all of the interior diked area,
consisting of grassland and freshwater wetland habitats. Unit 4 includes the Nisqually
River, tidal, higher marsh, and intertidal habitat east of the River on the Nisqually Tribe
sites, and the northeast corner of the Refuge. Unit 5 was a linear transect that extended
off Refuge property from the northwestern corner of the Refuge to Johnson Point (Figure
12 (historical map with flight path), 13 (current map used), pp31-32). This particular unit
will be omitted from analysis as they fall outside of the Refuge boundary.
Approximately 4 hours are needed to complete these aerial surveys.
Nisqually NWR ground counts follow a set route and are conducted by vehicle.
The count usually takes four hours or more to complete, and should not be started after
14:30 as it will be dark before the survey is complete. If necessary, the ground count is
conducted the next day near the time the aerial flight took place the previous day. Again,
a standard data sheet is used to record any observations made. Recordings are
transcribed to data sheet after the flight.
Ideal aerial count time would be midtide, when there is water covering the
mudflats, but not necessarily deep water. The Nisqually ground count however must take
29
place soon after the plane has finished the count, in the same day. This is because the
surveying plane may create disturbance causing the birds to flush. If this occurs during
or before the aerial count the aerial observation will not be similar. Coordination
between those conducting the ground count and aerial survey is critical.
2.1.2 MONTHLY HIGH-TIDE BIRD SURVEYS - USGS
Monthly, high-tide surveys are a relatively new survey that began just before the
removal of the dike in the summer of 2009. As the name implies, they are performed
once a month during a high-tide window on a delta-wide basis. The surveys are usually
timed so that the high-tide window occurs during the morning to capture birds during
active foraging hours. During this particular survey, all species types are recorded
including their location and estimated abundances. A team of surveyors is sent to four
sites within the Nisqually NWR. Location within Nisqually NWR is determined from
predefined 250 meter by 250 meter grid system on a map (Figure 14, pp 33). For this
research however, the Tribe sites will be omitted and only Nisqually NWR data will be
analyzed due to time constraint. This survey is performed year-round.
30
Figure 12: Historical USFWS Ground and Aerial Survey Map and Flight Path of Nisqually NWR
(Source: Nisqually NWR)
The above map represents the area and units surveyed during ground and aerial waterfowl surveys before the 2009
Nisqually NWR dike removal, as well as the plane flight path taken during surveys (indicated in blue).
31
Figure 13: Current USFWS Ground and Aerial Survey Map and Flight Path of Nisqually NWR
(Source: Nisqually NWR)
The above map represents the area and units surveyed during ground and aerial and ground waterfowl surveys after
the Nisqually NWR dike removal and restoration
32
Figure 14: USGS Monthly High-Tide Survey Map of Nisqually NWR
(Source: Kelley Turner, USGS)
The above map represents the gridded area within Nisqually NWR that is surveyed during the Monthly High-Tide
Survey beginning after the removal of the dike in 2009.
33
2.2
METHODS OF DATA ANALYSIS
The data was represented graphically in the following ways:
3.
Overall avian abundance detected over time
Overall abundance by species over time
Percent waterfowl by guild
RESULTS AND DISCUSSION
The following section details the results from the analyses performed for each of
the three pre- and post-restoration survey types. The first section details the results from
the aerial and ground surveys performed by Refuge crews. The second section discusses
the results from post-delta restoration surveys led by USGS crews. It must be noted that
although the surveys are essentially recording the same type of data, the survey methods
for each differ and can therefore not be directly compared to one another.
3.1
AERIAL AND GROUND WATERFOWL SURVEYS
The first analysis examined change in total observed waterfowl abundance
patterns over time using aerial survey data from February 1984 to January 2009 (Figure
15, pp 35). The data indicates a slight decrease in waterfowl abundances over time.
However, when using the same analysis for the ground survey data, there is an upshift in
waterfowl sightings from a ground perspective (Figure 16, pp 36). Again, each of these
two survey methods are performed from separately and from a different perspectives and
cannot be directly compared. It should be noted that although the aerial survey provides
a different viewing perspective, the ground survey allows for not only visual sightings but
34
35
Figure 15: Observed Waterfowl Abundance Over Time (Aerial Data)
This figure represents the change in waterfowl abundance over time using aerial survey data from February 1984 through January 2009, and indicates a decrease in
abundance until 2003 when surveys were only performed in January.
36
Figure 16: Observed Waterfowl Abundance Over Time (Ground Data)
This graph represents the change in waterfowl abundance over time using ground survey data from February 1998 through November 2008. The data indicates an
upshift in waterfowl abundance over time.
audio identification as well. Ground surveys also allow for Unit 3 habitat penetration by
foot which provides a ground-level analysis of that particular unit. It is also difficult to
make inferences about which of these datasets is correct because neither are guaranteed
to capture the true waterfowl Refuge usage as presence and numbers can vary greatly
from day to day, hour to hour. In order to best evaluate this data in that way however, it
should be standardized for survey month, tides, number of observers, weather conditions,
etc. It should also be noted that after 2003, surveys were only conducted in January.
The next analysis explored each species’ total individual abundance using the
same aerial and ground survey datasets. From the aerial analysis, we see that American
wigeon, American Green-winged Teal and Mallard were the most abundant species
recorded (Figure 17, pp 38). When analyzing the ground data using the same method, we
see that American wigeon, Canada geese and Mallard are the most abundant (Figure 18,
pp 39). Please note that the species beginning with “UN” indicate unidentified species,
and that Cackling geese were not historically recognized as a separate species.
The avian abundances were then converted into percentages and analyzed based
on which waterfowl group made up the majority of waterfowl sightings. Dabblers were
by far the most prevalent followed by geese and swan and finally by diving ducks (Figure
19, pp 40). The same method was done using ground data (Figure 20, pp 40). This
analysis indicates that dabblers again yield that highest percent, but showed either an
increase in abundance or perhaps an increase in guild diversity as geese and swan make
up a larger percentage of a whole than observed during aerial surveys.
37
38
Figure 17: Observed Waterfowl Abundance by Species (Aerial Data)
The figure represents the total observed waterfowl using the aerial survey data from February 1984 to January 2009. American Wigeon were the
most commonly observed species, followed by Mallard and American Green-winged Teal.
39
Figure 18: Observed Waterfowl Abundance by Species (Ground Data)
The graph shows the total waterfowl abundance by species using ground survey data from February 1998 to November 2008. American Wigeon and
Canada Geese were the most commonly observed, followed by Mallard and Cackling Geese.
Figure 19: Percent Observed Waterfowl by Guild (Aerial Data)
The above graph shows the observed waterfowl by guild represented in percentages using aerial data from
February 1984 to January 2009. Dabbling ducks made up the largest proportion at 94%, followed by geese
and swan and finally divers.
Figure 20: Percent Observed Waterfowl by Guild (Ground Data)
This graph shows the observed waterfowl by guild represented in percentages using ground data from February 1998 to
November 2008. Again, dabbling ducks made up the largest proportion at 64%, followed by geese and swan and
finally divers.
40
3.2
MONTHLY HIGH-TIDE SURVEY
In analyzing the post-restoration monthly high-tide survey data, one analysis
performed examined total observed waterfowl abundance change over time. From this
analysis, we see that waterfowl numbers have remained relatively steady since the
restoration (Figure 21, pp 42). The data indicates that peak waterfowl abundance
occurred between September and March, which correlates with the migratory and
overwintering season. Within the overwintering period, there are variable abundances
between months. This could be due to a variety of factors including inclement weather
conditions such as freezing temperatures or simply that the waterfowl were utilizing
nearby resources and were not on the Refuge at the time of the survey. However, the
lack of survey data at this point makes it difficult to impossible to make sound inferences.
The second analysis performed looked at the total abundance of each species
individually. From this, it can be said that so far the most common waterfowl species
observed have been American Green-winged Teal. Other commonly observed species
include Cackling geese and American wigeon respectively. Mallard and Northern pintail
were also frequently sighted(Figure 22, pp 43). Any unidentified or hybrid species’
acronyms begin with “UN” or “HY”, respectively.
The final analysis performed explored each waterfowl guild as a percentage.
Dabbling ducks yielded the highest percentage, as seen in both the Refuge aerial and
ground waterfowl survey data results. The USGS dataset also observed geese and swan
contributing a large proportion of waterfowl presence at 30% (Figure 23, pp 44).
41
42
Figure 21: Observed Waterfowl Abundance Over Time (Monthly Data)
This figure represents the observed waterfowl abundance over time using monthly high-tide survey data from September 2009 to January 2011.
43
Figure 22: Waterfowl Abundance by Species (Monthly Data)
The above figure represents waterfowl abundance totals using September 2009 through January 2011 monthly high-tide survey data. American Green-winged Teal yielded
the highest abundance total followed by Cackling Geese, Mallard and Northern Pintail (change color to blue).
Figure 23: Percent Observed Waterfowl by Guild (Monthly Data)
This figure represents the proportion of waterfowl by guild using monthly high-tide survey data from September 2009
through January 2011. Dabblers make up the largest porportion at 69%, followed by geese and swan at 30%, and
finally divers at 1% (change colors to coordinate with aerial and ground analyses).
4.
CONCLUSION
The following sections detail the results from each of the three waterfowl surveys
analyzed in this research; pre-restoration aerial and ground waterfowl surveys, and postrestoration monthly high-tide surveys. Also described in these sections is a description of
pre and post-habitat restoration habitat conditions to provide a written demonstration of
how greatly the restoration altered the ecosystem. Finally, this section details suggestions
for future research that have arisen as a result of both the restoration and this thesis
research.
44
4.1
SUMMARY OF RESULTS
For aerial surveys occurring from February 1984 to January 2009, the months
yielding the highest average observed waterfowl abundance were October and
November. During this particular survey, the top three most commonly observed
waterfowl species included Mallard, American wigeon and American Green-winged
Teal. For ground surveys occurring from February 1998 through November 2008, the
months with the greatest average waterfowl abundance were November through March.
During this survey, the most commonly observed waterfowl species included Mallard,
American wigeon and Canada (Cackling) geese. Monthly high-tide surveys occurring
from October 2009 through January 2011, no peak average waterfowl abundance month
has yet to be recorded due to a limited amount of survey years. The three most
commonly observed waterfowl species during this time period were American wigeon,
Canada geese, Cackling geese and American Green-winged Teal. For monthly high-tide
surveys, Canada geese and Cackling geese were identified as two separate species due to
change in distinction in taxonomic classification.
For each type of survey conducted, the overall dominant waterfowl foraging guild
was dabbling ducks. The American wigeon, also a dabbling duck, was the most common
waterfowl species observed for each of these surveys. Peak waterfowl use of the Refuge
spanned from the months of September through March. When considering that
waterfowl begin south-bound waterfowl migration during the fall months and return in
the spring, the peak months for waterfowl abundance within Nisqually National Wildlife
45
Refuge correlates with general Pacific Flyway migration patterns. According to spatial
distribution analyses conducted using aerial and ground surveys, Unit 4 of the Refuge
yielded the highest number of waterfowl with dabbling ducks as the most common
foraging guild identified. Post-restoration data needs to be collected for many more years
to be able to generate the power of analysis needed to detect change due to the
restoration.
From the research, it became very clear that there are both benefits and limitations
to each survey type. There are also limitations to any bird survey in general, as birds
vary in size from large to very small and difficult to see. Many are also extremely well
camouflaged and all have the ability to fly and move about a survey area. This often
leads to double-counting or even completely missing a sighting of certain small-bodies or
species that are well-hidden and camouflaged. Such inconsistencies affect how results
are recorded and analytically interpreted.
The limitations of aerial surveys are the distance and speed at which surveyors
have to count and identify bird species. Also included in aerial limitations is the expense
of the flight itself. Inclement weather can inhibit a survey from taking place and also
flying in general holds risks for any pilots and surveyors who partake in it. It is also
more difficult to observe certain species, especially smaller waterfowl that are too minute
or too well-hidden to be seen and recorded. Low flying aircraft can also cause the birds
to flush and fly out of the survey area. Benefits include having a better view of survey
areas with few physical obstructions by which to potentially block bird sightings. The
aerial surveys are also able to be completed in a shorter amount of time. Shorter survey
46
time can also help prevent the possibility of overcounting as they are less likely to move
about the survey area. Maneuvering around high tides is also not an issue during this
survey as it is when performed by foot.
There are also both benefits and limitations to ground and monthly high-tide
surveys, as these are both terrestrial methods of surveying. Some limitations include
visibility issues caused from high vegetation such as cattails or reed canarygrass
(Phalaris arundinacea). For some of the units, there are also accessibility issues that
inhibit the length and time that area can be surveyed due to threat of a rising tide.
Limited staff can also lead to lengthy surveys which could in turn lead to double counting
if the birds move about the survey area. There are also variable tide levels and survey
times that must coincide in order for a survey to take place. Tides must be incoming and
in the morning in order to capture optimal activity and behavior, as avian species are
typically most active during the morning. However, there are also benefits. These
include the slower pace of the surveys allowing for more accurate identification of
species, and increase the likelihood of seeing the smaller species that might be difficult or
impossible to see from an aerial survey. Audio identification is also used a great deal in
bird surveys, as it is often said that the majority of bird identification occurs from a bird
call rather than a sighting. These audio identifications are impossible by plane but are
very commonly used in terrestrial surveys.
It is also important to note that there are not only general inconsistencies related
to bird surveys, but also inconsistencies that vary throughout an individual month. To
47
highlight the variability in observed monthly abundances, three ground waterfowl
surveys with similar survey conditions including tide height and time of day were
selected. These surveys occurred in January 1999. Survey 1 yielded 2229 birds, survey
2 yielded 6089 birds, and survey 3 yielded 895 birds. Though conditions were similar,
each survey yielded very different total waterfowl abundances. This speaks to the
“snapshot” nature of waterfowl surveys in which on a particular date and time, the
number of birds observed can be very different and not necessarily reflect the true
population numbers utilizing the site.
The above-mentioned highlights one of the primary difficulties in these types of
waterfowl surveys in which the target animals have the ability to fly and move readily
throughout the survey area. Refuge and USGS biologists have often noted birds flying
south across Interstate-5 during surveys. It is believed that one way to try to account for
this is to conduct more surveys throughout the month to better capture waterfowl use on
the site. For many years, Refuge biologists tried to do exactly that, by conducting two to
three surveys per month. This was thought to allow for a better understanding of
waterfowl populations on the site as compared to once a month surveys. It is now
understood that multiple surveys are not always useful as the previous example of
variability within a single month shows. Performing multiple surveys each month also
requires more resources, personnel, and time which make surveys at this level of intensity
difficult to maintain.
48
There are many limitations to performing any wildlife survey. But from this
research we see that to perform a survey in which the species has the ability of flight as a
means of movement makes surveying such species much more difficult. But despite
these limitations, we also see many benefits as well as necessity to monitor their numbers
and behaviors. The most important of these is that with any sound scientific survey,
despite difficulties or limits, it is better to have limited survey abilities and data than no
survey or data collection at all.
4.2
PRE- AND POST-HABITAT RESTORATION CONDITIONS
From this research we can see that based on historical waterfowl numbers, the
majority of waterfowl were dabbling ducks. This indicates that ecosystem conditions at
Nisqually NWR were likely much drier prior to the restoration than of its natural
estuarine state. This was in part due to construction of the dike that inhibited tidal
influence, and also the addition of soil to the land to make it more suitable for agricultural
purposes. Historical habitats consisted primarily of grasslands and riparian habitat
suitable for certain waterfowl and other types of birds. These specific types of waterfowl
included dabblers as mentioned before, but also geese and swan. Each used the area for
purposes that included foraging, resting or waiting out the winter season. Beyond the
dike and along the Nisqually River, diving waterfowl were also provided some suitable
habitat and opportunities to forage.
After the removal of the dike, the habitat composition shifted. Due to this
restoration, the amount of wetland habitat greatly increased. This increase created more
49
opportunity for diving ducks to feed. Although the amount of wetland susceptible to tide
fluctuation expanded its range within Refuge boundaries, some upland habitats such as
grasslands, riparian and forested habitat also remained allowing for continued geese,
swan and dabbling ducks presence. From current waterfowl numbers, we see that
dabblers are still the dominant foraging guild. Those numbers are expected to remain
high based on the amount suitable habitat the Refuge still provides them. However, it
could be predicted that the increase in tidally-influenced wetlands within Nisqually NWR
boundaries may at some point in the future cause diving duck numbers to increase as
well.
4.3
IDENTIFYING AND ACCOUNTING FOR SOURCES OF ERROR
As discussed in the previous section, most bird surveys tend to provide
incomplete coverage. They can either miss proportions of populations for various
reasons or even double count individual birds during the same survey. Therefore, there
are no definitive surveys for most species. It is for these reasons that survey data can
sometimes be difficult to interpret, and surveys of different types provide information of
varying quality.
Another inconsistency is varying access to certain survey areas. Rough terrain or
vegetation can be difficult to maneuver during surveys. Certain types of environmental
barriers and even tall, thick vegetation types such as trees can inhibit view and block
hidden species from being seen, especially among those species that are characteristically
more secretive. These factors may also alter food and habitat availability. One particular
plant species that has been known to cause visibility and mobility issues in the past is the
50
invasive reed canarygrass. Now that the outbreak of this exotic plant is for the most part
contained within Refuge boundaries, it will create little to no issues in the future.
Another issue discovered within the survey types used in this research included
changing site boundaries over time. While some consistencies within Nisqually NWR
surveys includes the utilization of the same overall area boundary, the units within the
Refuge boundary have shifted and all surveys have been performed using visual aids such
as binocular or spotting scopes and each survey employed the master birding skills of
Nisqually NWR biologists and/or volunteers to help insure accurate identification of
avian species sighted.
When surveying or monitoring wildlife populations, there is always a concern that
an individual or entire group will be double counted in the data. This issue occurs when
an individual or flock is recorded and then accidently counted a second time later in the
survey as it moves about the habitat. This occurrence is especially true for avian
populations as their size and ability to fly enables them to hide or move around with
relative speed and efficiency. It is often difficult to discern whether or not a particular
bird has been previously recorded as most individual birds do not possess characteristics
or phenotypic variability by which to distinguish them from other individuals. One way
to account for double counting is to note a bird or flock recorded while in flight as well as
the time and direction in which they are travelling. If s similar bird or group is seen
entering the survey area at a later time then it may be concluded that it is the same group.
Note-taking is also important when multiple groups are surveying separate areas at
51
different times. Collaboration between survey teams after the survey can help to
determine is any data was double counted between the groups of surveyors.
The issue of missing an individual or group present may also occur. A majority
of the time, avian presence is discerned based on auditory identification rather than a
visual sighting. If the bird or flock is in a dense habitat and not calling or singing, they
may not be recorded. Also, if they are immobile, small-bodied or well-camouflaged, they
may not be visually observed. It is for these reasons that a thorough examination of the
survey area must always take place.
Although maintaining consistent, specific surveyors when monitoring wildlife
populations is strived for, it is not always possible. There will not always be the same
skilled surveyor available for every survey, which could inhibit the quality of data
recorded. This might occur because different surveyors have varying skill levels for
audio and visual identification of birds. A variety of different biologists and trained
volunteers have aided in the observation, identification and recording of birds sighted
during the various surveys (ground, aerial and monthly high-tide) discussed in this
research. The best way to account for this is to maintain participation of a team of
observers with master-level skills in visual and vocal avian identification that are familiar
with survey protocol.
Hunting is also a potential source of disturbance while in season. Spanning from
October to January depending upon the targeted species, hunting season could have an
effect on waterfowl survey data recorded during these months. The fire from a shotgun
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or rifle has the ability to flush birds from an area, and was even recorded doing so in
some of the dataset notes in this project. Flushing of waterfowl because of gunfire could
force more birds into the safety of the Refuge, or could cause them to seek shelter
somewhere outside of the Refuge boundary. There is also the possibility that hunting has
little effect on waterfowl overall and have adapted to this type of recreation. Further
research is needed to reach a consensus. The best way to account for the possibility of
hunting disturbance during waterfowl surveys is to note any change in behavior that
might be seen as a result of nearby gunfire.
There are also other exogenous factors that could have an effect on waterfowl.
Such sources include visitor disturbance or necessary maintenance such as mowing that
may be occurring within the Refuge’s boundaries. Nearby boat, automobile, commercial
airport or military air traffic may also effect bird behavior and disrupt any potential for
audio identification of species.
Tide height, time of day, weather conditions and season also factor into where,
when and if survey will be performed at that time as each of these factors greatly
influence avian activity. Shifts in seasonal weather or climate may also affect bird
behavior and abundance from year to year creating anomalies within the data. Fog, frost
and storms may also have an effect on avian presence and surveyor ability to identify or
even participate in a survey.
Each of these factors can potentially affect the quality of the data. Some can even
prevent a survey from occurring altogether. Despite these possibilities, the benefits of
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performing these particular wildlife surveys are great, and even imperative in assessing
the overall health and management of their populations and habitats.
4.4
SUGGESTIONS FOR FUTURE RESEARCH
There are a variety of potential topics that can be derived from the basis of this
research. For example, this research could be utilized as a basis for furthering the same
Nisqually waterfowl studies in the future. Further study can provide a better
understanding of how the avian populations within Nisqually NWR have changed over
time. It can also provide a detailed description of how their populations have reacted to
the 2009 restoration as current post-restoration data is insufficient to come to an accurate
conclusion of the full effects the project has had. Approximately 5-10 years more data
would need to be collected to come to such an accurate consensus.
It may also be of interest to concentrate in-depth on changes in other avian groups
such as raptors, passerines and water birds in a study similar to this. When performing
the monthly high-tide bird survey, all avian species are recorded, and the dataset is not
just limited to waterfowl. One study in particular that may also be of interest is
comparing the trends of insectivorous birds to any trends discovered using benthic
invertebrate data also being collected from the Nisqually Delta. Invertebrate species are
known to be indicators of a healthy estuary and are an important food item for various
species of birds that utilize the estuary for foraging. Changes in vegetation dominance as
a result of the restoration and corresponding elevation changes might also be a subject
that could be compared to the waterfowl trends analyzed. Shifts in avian guild trends
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would also be interesting, as would analysis of trends from other avian surveys performed
at Nisqually such as point-count surveys and Christmas bird counts, as well as the avian
data collected from the Nisqually Tribal sites and Reference Marsh.
Disturbance from human activities could cause temporary changes in waterfowl
behavior and locally affect temporal and spatial distribution of migratory and wintering
species. To some extent however, birds can compensate for such disturbance by altering
their behavior and habituating around these human activities (Madsen 2008). One
example of this could potentially be the effect of hunting season on these waterfowl.
Fall, winter and spring hunting is widely practiced throughout the world, although few
studies have been conducted investigating the effects on waterfowl. Little is known
though about how anthropogenic disturbance influences large-scale dispersion and
population dynamics of waterfowl (Madsen 2008).
4.5
FINAL THOUGHTS
From this research, we have recognized the amount of survey work that needs to
be done to monitor the plants and wildlife that call Nisqually NWR home. We have also
identified the faults and deficiencies within these surveys. But with these sources of error
stands a simple truth: surveys are imperative to monitoring the overall health of wildlife
populations. The biologists, technicians and faithful volunteers of the Refuge are
continuing to make this happen so that the true effects of the restoration on waterfowl
populations can be accurately assessed.
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We also see from this research that despite the differences in survey types
spanning decades, one waterfowl guild stands out above the rest; dabbling ducks.
Included within this popular guild is the American Wigeon, the most prominent of the
dabbling duck species and poster child of Nisqually NWR itself. This particular species
likely stands out above the rest because of the availability of shallow waters present both
before the restoration due to seasonal rains, and following the restoration due to tide
fluctuation. These shallow standing waters allow for ample amounts of suitable feeding
habitat for both migrants and residential birds.
Finally, from this research we see the importance of suitable habitat for wildlife.
Even more so, we understand how an estuarine ecosystem such as the one at Nisqually
NWR supports an array of habitats and intricate food webs. One of the most notable
wildlife groups that utilize the resources provided by such an ecosystem includes birds,
specifically waterfowl. The Refuge is exactly what the name implies: a safe haven. It
provides food items, breeding grounds, shelter and a place to rest on a long migratory
journey. Nisqually NWR has provided this service for many decades, and will continue
to do so since its dramatic transformation back into its natural estuarine state.
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