Distribution and abundance of waterfowl and waterbirds relative to shellfish aquaculture
Shellfish aquaculture (primarily oysters) is a multi-million-dollar industry in Rhode Island that continues to increase. One of the potential conflicts of expanding aquaculture operations is spatial overlap with prime foraging and resting habitat for migratory waterfowl and other waterbirds. However, much remains to be learned about the effects of aquaculture operations on waterfowl and other waterbirds. In 2020, our lab and Rhode Island Department of Environmental Management Division of Fish and Wildlife initiated a collaborative project to address this need. This research is focused on areas where aquaculture operations were either in existence or potentially could be developed and involves conducting year-round land-based bird counts at 60+ sites across Rhode Island’s coastal ponds and Narragansett Bay. Initial findings from this study suggest that the potential for bird-aquaculture conflict likely varies seasonally, depending on species migration chronology. Ongoing objectives of this project include:
- Evaluate the distribution and abundance of waterfowl and other waterbirds in relation to aquaculture.
- Characterize the annual changes in abundance and distribution of waterfowl and waterbirds in coastal ponds and Narragansett Bay.
- Evaluate the abundance of waterfowl and waterbirds before and after the establishment of aquaculture sites.
- Provide a decision support tool for Rhode Island Division of Fish and Wildlife to use when commenting on future aquaculture permit applications.
Effects of shellfish aquaculture disturbances on American Black Ducks
Shellfish aquaculture (primarily oysters) is a multi-million-dollar industry in Rhode Island that continues to increase. Several species of waterfowl and other waterbirds use waters in Rhode Island where aquaculture presents a potential conflict. For example, our research group demonstrated that American black ducks (Anas rubripes) prefer habitats that are better suited for aquaculture. However, it is uncertain whether future aquaculture development in areas best suited for aquaculture will displace individuals that occupy these areas, or if they will tolerate the disturbance and continue to occupy such spaces. Therefore, our lab and Rhode Island Department of Environmental Management Division of Fish and Wildlife initiated a collaborative project to quantify the ways in which aquaculture directly affects the space use, movements, and energetics of American Black Ducks. We will deploy backpack style GPS-GSM transmitters on American Black Ducks during the winter and establish pseudo-aquaculture farms in areas highly used by tagged birds to evaluate individuals’ responses to aquaculture disturbance. The specific objectives of this research are to:
- Quantify the importance of inland water sources to American Black Ducks responding to the presence of pseudo-aquaculture farms.
- Determine the extent to which the presence of pseudo-aquaculture farms influences American Black Duck space use and energetic costs.
- Assess the functional responses in habitat selection of American Black Ducks exposed to pseudo-aquaculture farms.
Recent Waterfowl Research
Comprehensive approaches to unraveling the movement ecology of waterfowl throughout the annual cycle
Waterfowl that occupy seasonally available habitats cope with annual fluctuations in resource availability by undertaking regular annual migrations between winter and breeding sites. Investigating the movement ecology and space use of waterfowl across the annual cycle can reveal patterns in waterfowl behavior, phenology, and distributions to inform conservation and management strategies. Further, comprehensive approaches that incorporate multiple data sources improve our ability to address basic and applied questions to inform waterfowl management. Our lab collaborated with the Rhode Island Department of Environmental Management Division of Fish and Wildlife to integrate data from individual-borne tracking devices, spatiotemporally extensive surveys, high resolution remotely sensed environmental data, and implicit isotopic signatures to investigate the movement ecology and space use of 3 species of waterfowl (American Black Duck [Anas rubripes], Atlantic Brant [Branta bernicla hrota], and Greater Scaup [Aythya marila]) that share a common estuarine wintering area in Rhode Island, USA. This project provided evidence that:
- The extent to which proximity to aquaculture influenced habitat selection of American Black Ducks depended on factors specific to individuals’ primary non-breeding sites but American Black Ducks across sites consistently selected for areas better suited for aquaculture (i.e., areas of potential future development) relative to areas poorly suited for aquaculture (i.e., areas less likely to be developed). The continued expansion of aquaculture into preferred American Black Duck habitats will increase American Black Duck interactions with aquaculture and therefore needs to be considered in the decision-making process for siting future aquaculture leases.
- Land-based surveys and GPS telemetry produce species distribution models (SDMs) for Rhode Island’s nonbreeding American Black Duck, Atlantic Brant, and Greater Scaup that differ in predictive performance and precision. Differences in data sampling schemes and space use patterns among species affected the predictive performance of SDMs, especially for those based on GPS telemetry data. Moreover, integrating information from both datasets did not improve predictive performance or precision of SDMs for any species. We demonstrated that estimates of precision can substantially influence confidence in predicted SDMs and help determine which SDMs to use for making management decisions.
- Spring migration strategies differ among Rhode Island’s nonbreeding American Black Duck, Atlantic Brant, and Greater Scaup. Atlantic Brant and Greater Scaup demonstrated more energy-minimizing spring migration strategies while American Black Ducks demonstrated more time-minimizing strategies. Therefore, conservation and management efforts at migratory stopover sites might have more influence on Atlantic Brant and Greater Scaup energetics and breeding activity than American Black Ducks.
- Integrating telemetry data and stable isotope (δ2H) signatures produced refined estimates of Greater Scaup breeding and molt origins. Further, the breeding season phenology and distributions of Greater Scaup we documented do not align well with the timing or stratification of important breeding waterfowl surveys. For waterfowl species that breed in remote habitats that are logistically challenging to access, the integration of telemetry and feather isotope information as we outlined provides a promising approach for delineating breeding and molting origins for distinct non-breeding subpopulations to quantify migratory connectivity. This approach, when applied to larger samples, could effectively inform waterfowl monitoring programs and address conservation challenges for high latitude breeding migratory birds.
Eastern Wild Turkey Movement Ecology in Rhode Island
The Eastern Wild Turkey was extirpated from Rhode Island by the late 1800s; however, restoration efforts in the 1980s and 1990s successfully reestablished a self-sustaining population. Today, turkeys are widely distributed across the state and appear to be healthy, occupying both urban and rural landscapes. To better understand the factors influencing turkey populations in Rhode Island, the University of Rhode Island and Rhode Island Department of Environmental Management and have initiated a collaborative research project. From December through March in 2026 to 2028, graduate students will capture 180 turkeys (120 females and 60 males) and mark them with GPS transmitters. The overarching goals and implications of this research are to:
- Evaluate gobbling chronology in relation to nesting phenology to help managers evaluate the extent to which the spring turkey hunting season overlaps with the nesting and brood-rearing periods
- Describe nesting phenology and evaluate nest site selection and nest survival to prioritize habitat for conservation actions and provide insight into population trends to guide bag limits
- Describe brooding phenology and evaluate habitat selection and brood survival to prioritize habitat for conservation actions and provide insight into population trends to guide bag limits
- Evaluate turkey movement ecology in rural and urban landscapes to understand how turkeys use the landscape during the breeding season and determine the extent to which rural/urban turkeys are part of the harvestable turkey population
- Describe seasonal changes in resource selection in rural and urban landscapes to understand how turkeys use the rural and urban landscapes across the annual cycle and apply this to prioritize habitat for conservation actions
- Compile data into an integrated population model to estimate turkey population growth rates in Rhode Island to evaluate how changes in vital rates (e.g., nest success, brood survival, and adult survival) would affect turkey abundance
Long term Songbird Monitoring
Long-term banding datasets allow us to distinguish between true population declines or increases from short-term variability driven by weather or annual conditions. Bird banding stations provide important demographic data on age, sex, survival, and recruitment needed to identify whether declines are driven by reduced productivity, low survival, or altered migration timing. Most importantly stations that have been operated successively for many years can reveal changes in migration timing, stopover duration, and age structure that are strongly tied to warming temperatures and altered seasonal cues. Additionally, recapture rates, body condition, and stopover duration offer insights into how habitat loss, fragmentation, and management practices affect birds through time.
Recent analysis have used data from these stations to compare trends to Breeding Bird Surveys (BBS), long term trends in songbird populations between stations and to quantify migratory weather.
Kingston Wildlife Research Station
- The KWRS banding station has been run continuously since 1958, making it one of the longest running stations in North America
- KWRS is run collaboratively between the University of Rhode Island and Audubon Society of Rhode Island
- Banding stations serve as critical field-based training, with young professionals gaining expertise in bird handling, identification, and ethical monitoring. KWRS is a valuable teaching asset for URI with students in the natural resources discipline volunteering at the station.
Block Island Banding Station
- The Block Island Station is run as a migration station when staffing allows. Uniquely located 12 miles offshore of mainland Rhode Island this is an incredibly important stopover for a variety of species, not just songbirds.
- This station is particularly important in our studies of migration physiology, migration direction and departure timing of songbirds.
Studying shorebird ecology throughout the Atlantic Flyway
- Understand and quantify the importance of conserving a network of small sites to support shorebird populations
- Assess potential risks of offshore wind energy development to shorebirds at the Atlantic Flyway scale
- Determine the importance of horseshoe crab eggs as a food source to shorebirds in New England, and estimate shorebird abundance at Monomoy NWR and Napatree Conservation Area during northbound migration.
We are working to better understand the ecology of Ruddy Turnstone (Arenaria interpres) and Red Knot (Calidris canutus) during northbound migration in New England. In recent years, large numbers of these species have been observed using coastal habitats in New England. In spring 2024 we initiated a study in collaboration with Manomet, Mass Audubon, and the USFWS to:
Canada
- Quantify the abundance of Ruddy Turnstone and Red Knot in southern New England during northbound migration
- Assess northbound migratory pathways to better understand potential risks of wind development in the Gulf of Maine using the Motus Wildlife Tracking Network
- Characterize the invertebrate community and horseshoe crab egg abundance at 2 important sites for shorebirds- Monomoy NWR and Napatree Conservation area
- Estimate shorebird diet at both study sites, and determine the importance of horseshoe crab eggs as a food source for shorebirds in New England
One of the biggest areas being explored on the Atlantic coast for offshore wind energy development is the Gulf of Maine, but data are lacking about how this may impact migrating shorebirds. In fall 2023 we initiated a study in partnership with CWS and Mount Allison University to track migrating shorebirds tagged in southwest Nova Scotia. This area is known to support thousands of shorebirds each year, and would offer a relatively short distance across the Gulf of Maine for migrant shorebirds. The goals of this work are to:
- Determine which species of shorebirds are most likely to cross the Gulf of Maine during migration, and estimate the proportion of birds that may be exposed to risk of offshore wind energy development
- Determine flight pathways across the Gulf of Maine for as many shorebird species as possible to inform wind turbine placement and minimize potential risk
- Quantify the departure conditions for multiple species of shorebirds departing the region during migration
Brazil
Northbound migration pathways of migrant shorebirds remains a large knowledge gap. Further, Brazil is exploring multiple offshore wind energy development areas along the coast and little is known about the potential risks this may pose shorebirds. In partnership with Aquasis, CWS, Mount Allison University, and USFWS, we aim to better understand local movements and migratory pathways of multiple shorebird species at the Banco dos Cajuais, a regionally important site for shorebirds in northeast Brazil. Our goals include:
- Assess local movements of multiple species of conservation concern including Semipalmated Sandpiper, Ruddy Turnstone, Red Knot, and Short-billed Dowitcher using the Motus Wildlife Tracking System
- Assess northbound migratory pathways using nanotags, satellite and GPS tags to better understand potential risks of offshore wind energy development to multiple shorebird species in the Atlantic Flyway
- Determine connectivity with staging and breeding areas for shorebirds using the Banco dos Cajuais during the non-breeding season
Forest Management
Forestry Work
Still more than half forested, Rhode Island has extensive and varied woodlands surrounding Narragansett Bay that contribute to the state’s economy, environmental benefits, and quality of life. The URI Forestry Extension implements and supports a range of forestry extension activities to support private forest owners in caring for their forests to protect and improve forest health, wildlife habitat and water quality. Some of these include:
- Rhode Island Woods
- URI hosts a website to provide the public with information about Rhode Island forestry and wildlife issues, and to help forest owners plan activities on their properties. The website provides lists of loggers and forestry businesses, as well as information about local plants and animals, state regulations related to forestry and wildlife, and the current price of timber. Rhode Island Woods was developed in collaboration with several other partners.
- USDA Northeast Climate Hub
- URI is one of 14 land grant universities participating in the Northeast Climate Hub of the U.S. Department of Agriculture (USDA), which delivers science-based knowledge and practical information to farmers and forest managers about adapting to climate change. URI shares information about climate adaptation approaches with landowners through various outreach events, and collaborates with Hub members in the development of new adaptation approaches. URI has been involved in a variety of projects with the Northeast Hub.
- The Rhode Island Woodland Partnership (RIWP)
- URI is a founding member of RIWP, a collaboration among foresters, landowners, conservationists, and professionals who represent public agencies, small businesses, and non-profit organizations. Partnership members share a common goal of advancing the stewardship and long-term protection of Rhode Island’s woodlands to benefit the local economy, ecological values, and community enjoyment and health. We welcome additional partners.
- Rhode Island Coverts Project
- Outreach Events for Landowners: URI organizes several trainings for private landowners about forestry and wildlife, including the annual Rhode Island Coverts Program, a training for forest landowners about forest management practices that can make wildlife healthier, more diverse and abundant. The project has trained landowners from across the state through this workshop, which focuses on forest ecology and stewardship, wildlife management and land conservation.
The Rhode Island Coverts Project is an education program designed to help forest landowners and stewards promote the development of critical wildlife habitats using sound forest management practices that can make wildlife healthier, more diverse and abundant. Coverts or thickets are patches of young forest or shrublands created though forest management. The project has trained landowners from across the state through its workshops that focus on forest ecology and stewardship, wildlife management, and land conservation.
- Conduct research on key issues related to the promotion of early successional habitat:
- Current status and recent trends of early successional habitat;
- Experience to date in promoting early successional habitat in RI;
- Impact of forest management interventions on populations of key wildlife species;
- Strengthen cooperative extension programs involved in forest management and wildlife conservation by disseminating the results of research related to the first project objective. This is a collaborative project with RI DEM, Dr. Pete August, Dr. Thomas Husband, Dr. Bill Buffum, Christopher Riely and colleagues at NRCS.
Forest Management and Wildlife
American Woodcock Work
Early successional habitats consisting of young regenerating forest, old fields, shrublands, meadows and grasslands have been identified as a specific management concern in the northeast U.S. However, the habitat needs of many other wildlife species are quite different and include those that depend on older intact forests with certain tree and understory plant species, freshwater wetlands and salt marshes. Proactive planning efforts to identify landscape priorities and habitat goals to meet the needs of wildlife and develop focus areas are needed. Any state-wide conservation plan for Rhode Island must consider wildlife associated with young-forest habitats and how to manage such habitat over time to maintain adequate amounts in the best locations and patch sizes, but also must consider wildlife that depend on different habitats.
- The American Woodcock is an iconic gamebird long associated with early successional forests of the northeast. Past research in the McWilliams lab has contributed to aspects of migratory strategy, habitat selection and informed management plans in the state to not only provide habitat for American Woodcock but other early successional species. Our group has been working with woodcock since the early 2010s and have collaborated closely with RI DEM to carry out numerous projects. A few of these projects are listed here:
- Habitat selection of male and female woodcock that breed in southern New England
- Identifying other co-occurring bird species that may benefit from habitat management for woodcock, a proposed umbrella species
- Developed a forest management tool for land managers to utilize when planning forest cuts to create the greatest possible benefit for woodcock and co-occurring species
- Leverage a 9 year tracking data set of male and female woodcock to create a statewide map quantifying woodcock likelihood of selection. This map was then validated using a reciprocal transplant experiment which showed that woodcock assess the surrounding habitat in a way consistent with the likelihood of selection map allowing us to quantify woodcock habitat as high or low quality.
- Identifying the breeding system in woodcock using data across the breeding range in collaboration with the Eastern Woodcock Migration Research Cooperative
- Nesting ecology of female woodcock in eastern North America and;
- Post-breeding survival of male woodcock in managed forests of southern New England.
- Currently we are studying woodcock diet using stable isotope analysis as well as home range differences between breeding and post-breeding periods. This portion of the study aims to
- determine if male woodcock home range size and diurnal coverts differ between sites designated as high or low quality as well as determine seasonal differences
- determine if diets of male woodcock differ among sites designated as high or low quality as well as between breeding and post-breeding using stable isotope analysis.
Umbrella Species Work
- Early-successional forest has declined in the region and in the state, and so have the species that depend on it. Management targeted to increase American Woodcock habitat can also benefit co-occurring species.
- Evaluate the efficacy of American Woodcock as an umbrella species for two early successional forest associated songbirds by assessing reproductive metrics at sites that differ in their quality for woodcock based on the likelihood of selection map. We found that management for woodcock can benefit a generalist species like the Eastern Towhee with increased density of males raising nestlings being in better condition at fledging at high quality sites for woodcock. However, an early successional forest specialist like the Prairie Warbler while occurring in greater densities at high quality sites for woodcock, was parasitized frequently by cowbirds, leading to overall poor condition at fledging. This potentially leads to low reproductive success across the state, especially due to the landscape context the surrounds their habitat, with fragmentation and cowbird feeding areas increasing access to early successional breeders.
- Assess habitat selection and reproductive metrics of a co-occurring early successional species, the Eastern Whip-poor-will to identify how forest management could improve populations.
Effects of Offshore Wind Energy Development on waterbirds
The State of Rhode Island invested > $10 million dollars in baseline monitoring of natural resources including sea ducks and in the development of the RI Ocean SAMP (Special Area Management Plan) that will guide offshore development including wind farms. Since 2008, we (Dr. Peter Paton and Dr. McWilliams) have collaborated on research documenting the distribution and abundance of birds for the RI Ocean SAMP project. This collaborative research expanded to include an assessment of potential effects of land-based wind energy development on birds and bats, as well as the following objectives related to offshore wind energy development:
- Used existing data from the RI Ocean SAMP to develop spatially explicit models that identified the key biotic and abiotic factors that affect the abundance and distribution of sea ducks in Rhode Island nearshore and offshore waters,
- Applied these spatially explicit models to predict affects of global climate change on sea duck abundance and distribution,
- Estimated seasonal changes in population size of sea duck species and applied these population models to harvest management plans, and
- Collected additional data on the movement patterns of selected sea ducks in relation to biotic and abiotic factors to test the spatially explicit models developed from existing data and to better inform decisions about extent and placement of offshore wind power as well as inform existing survey data (e.g., Atlantic flyway sea duck survey, USFWS). This is a collaborative project with RI DEM, and colleagues at USGS, BOEMRE, and RI CRC.
Physiology Work
Physiological Ecology of Songbirds
- Evaluate new nondestructive methods for measuring body composition dynamics in songbirds;
- Study the nutritional ecology and physiology of songbirds during migration; and
- Use stable isotopes to test contemporary hypotheses about the effect of diet quality and fasting on the metabolic routing of dietary nutrients in songbirds.
Dynamics of body composition in small migratory songbirds
The dynamics of body composition influences nutrient requirements which then interact with resource availability to determine length of stopover at sites along the migration route, the pace of migration, and ultimately the success and survival of individuals. The increase in body mass in birds during migration has been commonly assumed to be composed of fat and no protein. More recent studies suggest that the reserves in birds may be composed of protein as well as fat. However, these more recent results come almost entirely from studies of large-bodied shorebirds and waterfowl that migrate long distances.
Changes in body composition across individuals in a population rarely provide accurate estimates of body composition changes within individuals. The solution to this problem is to repeatedly measure the protein and fat content of individual birds using nondestructive techniques. We completed the first cross-validation study that simultaneously uses two different techniques (TOtal Body Electrical Conductivity [TOBEC] and isotope dilution) to independently estimate lean and fat mass of small songbirds during their migration. These independent estimates of body components are a prerequisite for determining the lean-mass proportion of body-mass gains and losses in field-caught wild passerines.
We extended this work to studies of songbirds during spring migration as they cross the Negev Desert in Israel (supported by US-Israel Binational Science Foundation). This research explores the thermoregulatory physiology of small migrating passerine birds during the process of refueling at stopovers. We tested the hypothesis that birds enter rest-phase hypothermia to reduce nighttime energy expenditure and increase fuel accumulation rate. As many small passerines switch from a normally insectivorous to a frugivorous diet while migrating, we are also testing the hypothesis that the fatty acid composition of the birds’ diets during stopover influences their use of rest-phase hypothermia, and hence their daily energy expenditure.
Nutritional Ecology of Birds During Migration
Despite the obvious importance of stopover sites for recovery of stored energy and nutrients, the ecology and physiology of birds at stopover sites during migration is one of the least studied topics in bird migration. Ecological studies at stopover sites suggest an interaction between diet, body composition, and digestive features in small migratory birds during recovery of body mass has great importance.
- In addition, we studied songbird preferences for specific dietary fatty acids and how fatty acid composition of birds affects performance during migration. Theoretically, selectively feeding on long-chain unsaturated fatty acids may be advantageous because such fatty acids may be absorbed and/or metabolized more efficiently than saturated fats into a bird’s fat depots. We tested this hypothesis by offering songbirds in different physiological states choices between diets that vary only in their fatty acid composition. Additionally, we studied how dietary fatty acids influence fatty acid composition of fat depots in birds, the energetics of activity, and its ecological implications. During my sabbatical at the Max Planck Institute for Ornithology (Germany) in 2005, I was able to demonstrate for the first time that birds with more polyunsaturated fat stores expended less energy during a simulated migratory flight (6-hrs continuously flying in a wind tunnel) than birds with more monounsaturated fat stores. This research has led to successive NSF grants for the last 10+ years that focus on how fat quality matters for migrating songbirds.
Alternatively, the gut-limitation hypothesis suggests that the initially slow rate of mass gain at stopover sites occurs because birds lose digestive tract tissue and hence function during fasting, and rebuilding of the gut takes time and resources and itself restricts the supply of energy and nutrients from food. This hypothesis is supported by studies that show reduced gut size after fasting in mammals and chickens and by a few studies on migratory songbirds that show food intake and gut function are reduced after fasting. We tested these two hypotheses (gut- or nutrient-limitation) by measuring food intake, digestive features, and body composition of birds before and after a fast, and during recovery of body mass in birds after a fast.
- Ecological field studies at stopover sites have revealed two interesting patterns related to replacement of used energy and nutrients.
- First, many insectivorous songbirds switch to feeding primarily on fruits during migration. This dietary switch from insects to fruits has been proposed as an energy-conservation strategy in that abundant fruits are less energetically expensive to obtain compared to insects. Fruits may be nutritionally adequate if only fat reserves must be replenished. However, fruits may be inadequate if birds must replenish both fat and protein reserves during migration because, in general, fruits contain relatively little protein. A basic understanding of the nutritional adequacy of particular diets requires understanding which endogenous stores are used and how exogenous nutrients in particular diets are routed during recovery of endogenous stores.
- A second interesting pattern apparent in field studies at stopover sites is that recovery of body condition after arrival at stopover sites is typically slow for 1 to 2 days and then much more rapid despite apparently abundant food resources. Although ecological conditions influence rate of recovery, birds exhibit the two-step recovery after fasting even when provided food ad libitum in the laboratory. Physiological mechanisms to explain the initial mass loss after arrival at a stopover site are largely unexplored, but two hypotheses have some support. The nutrient-limitation hypothesis suggests that the initially slow rate of mass gain occurs because birds utilize protein reserves during migration, and recovery of these protein reserves must occur first and is slow. Only after recovery of protein reserves can lipid reserves be repleted and, once initiated, this recovery of lipid reserves is faster. This hypothesis is supported by studies of migrating hummingbirds, domestic geese, and a few other birds.
Use of stable isotopes to investigate the metabolic routing of dietary nutrients
Plant physiological ecologists have used natural variation in stable isotope ratios to study photosynthesis, water balance, and nitrogen metabolism in plants. In contrast, animal physiological ecologists have made much less use of naturally occurring stable isotopes in their research despite its great potential. Recently, animal ecologists interested in migratory birds have used stable isotope ratios to reconstruct diets and to trace movements between breeding and wintering areas. However, all such work relies on important untested assumptions about the effect of physiological processes on the stable isotope ratios. We tested some of these key assumptions by using diets that have their protein and carbohydrate components uniquely labelled with stable isotopes to determine the effect of diet quality on the metabolic routing of dietary nutrients in small songbirds.
- We also conducted field studies of
- diet switching in free-living songbirds during migration by comparing patterns of stable isotopes in selected wild fruits and insects, and in the breath, blood, and feathers of birds; and
- habitat use of goslings in western Hudson Bay (Canada) by comparing stable isotope signatures of forage plants with that of certain tissues in goslings collected throughout growth.
This study is a collaborative project with Dr. Robert Rockwell (American Museum of Natural History), Dr. Evan Cooch (Cornell Univ.), and former graduate student Kris Winiarski and is part of the Hudson Bay Cooperative Research Project.
Avian Herbivores and the Importance of Body Size
Geese provide an interesting model for studying how avian herbivores circumvent the problem of combining the high energy demands of flight with the ecological limitations associated with eating leaves which are low in energy and nutrients and typically are high in fiber. Geese are an excellent group in which to study such issues of body size on ecology because species such as the Canada goose vary 7-fold in body size.
Highly selective feeding is one way geese escape some of the constraints associated with being a small avian herbivore. However, geese also show remarkable abilities to modulate digestive features (e.g., hydrolytic activity of digestive enzymes, nutrient uptake rates across gut membrane, size of the absorptive regions of the gut) in response to changes in diet quality and, as a result, they are able to maintain relatively high digestive efficiency on a wide range of diets. In addition, my past work has shown that geese are able to utilize dietary fiber by using microbial fermentation in their hindgut.
My studies of geese focus on the allometrics of metabolic rate, gut capacity, digestive physiology, and foraging strategy within and between species. I also conducted work in subarctic Canada on the nutritional and physiological ecology of gosling growth. The goal of the gosling growth study is to identify the effects of protein limitation and dietary fiber on growth rates of sympatric Canada and Snow geese. Information on growth rates and nitrogen requirements of Canada and Snow geese is particularly pertinent, yet inadequate. Increased numbers of Snow geese have caused widespread destruction of their preferred salt-marsh plants. In response to this habitat destruction, snow geese are now nesting or raising broods in areas traditionally used primarily by Canada geese. The consequences of this habitat shift include increased competition between goslings of Canada and Snow geese for limited nutrients. This study is a collaborative project with Dr. Robert Rockwell (American Museum of Natural History), Dr. Evan Cooch (Cornell Univ.), and graduate student Kris Winiarski and is part of the Hudson Bay Cooperative Research Project.
