Current Projects


Conservation science is at the core of what we do at Great Hollow. Our researchers and collaborators conduct applied studies of biodiversity in Connecticut and beyond to better understand human impacts to the environment, and provide science that can help guide management decisions and public policy. We specialize in integrating the fields of animal ecology, physiology, and toxicology to investigate the effects of introduced species, land use change, and pollution on wildlife and habitats.  We take a highly collaborative approach to research, pooling and leveraging the skills and resources of partners across academia, government, and non-governmental organizations to most effectively and efficiently approach questions of common interest. Below are some of the projects we are currently working on.

Using Citizen Science to Predict the Spread of the Spotted Lanternfly in Connecticut

Project Lead: Tara Ewers

In 2014, an insect previously undocumented in the U.S. was reported for the first time in Pennsylvania. Native to China and parts of South Asia, the spotted lanternfly (Lycorma delicatula) had already invaded South Korea and Japan a decade before, damaging thousands of agricultural acres along the way. Just four years later, Connecticut had its first reported sighting of this invasive species. Spotted lanternflies are capable of decimating vineyards through their feeding habits. The threat to grape growers comes at a time when the state’s wine tourism industry is booming. Using citizen science data from iNaturalist, this project seeks to understand the spatiotemporal spread of the spotted lanternfly in the U.S. and predict when this species will make its way into Connecticut’s vineyards.

Effects of Japanese Barberry on Forest Songbird Habitat Quality and Diet Composition

Project Lead: Dr. Chad Seewagen

Since its introduction from Asia in the late 1800s, Japanese barberry has become one of the most widespread non-native invasive plants in Northeastern forests, and like most other non-native invasive plants, is assumed to diminish habitat quality for forest wildlife. Yet, surprisingly few studies have actually investigated the effects of Japanese barberry on the wildlife that inhabits invaded areas. Great Hollow is conducting an integrative assessment of the effects of Japanese barberry on breeding habitat quality for forest songbirds, using the ovenbird as a model. The first stage of this research examined food abundance and the physiological condition of ovenbirds in breeding territories with either extensive or little to no Japanese barberry coverage, and was published in 2019 in the journal Conservation Physiology. We are now investigating differences in ovenbird diet composition between highly or minimally invaded areas of forest, using carbon and nitrogen isotope analysis.  The goal of this research is to allow for more science-based decision making among land managers and conservation practitioners who are grappling with Japanese barberry invasions across the Northeast.

Effects of Japanese Barberry on Invertebrate Food Webs

Project Leads: Drs. Chad Seewagen, Robert Clark, Wales Carter

Non-native plants can negatively affect the abundance and diversity of foliage-dwelling and leaf litter invertebrates. These invertebrates play an important role in forest nutrient cycling and are a critical food source for birds and other wildlife at higher trophic levels. We conducted a study to compare invertebrate biomass, diversity, and community composition on invasive Japanese barberry to that of native plants in the forest understory and leaf litter. We found that branch-dwelling and leaf-litter arthropod communities in invaded areas are significantly different from, and less species-rich than, those where native vegetation is still dominant, although overall biomass does not differ. The study was published in 2019 in Environmental Entomology and can be read here. We are now using stable isotope methods to investigate whether these differences in arthropod community composition driven by barberry invasions alter the diet composition of woodland insectivores, using the ovenbird as a model.

Host Plant Effects on Insect Nutritional Quality and Plant-Insect-Bird Trophic Interactions

Project Leads: Drs. Robert Clark and Wales Carter

Plant species differ greatly in the abundance, richness, and diversity of insects they support, with non-native, invasive plants often representing the lowest-quality hosts. This can have cascading effects up the food web, beginning with insectivores, like birds. What is not well-understood, however, is how the quality of insects as food for birds might also vary across different species of host plants. Through a bird exclusion experiment involving 10 woodland plant species (6 native and 4 non-native), Great Hollow is currently investigating (1) prey selection of insectivorous birds across plant species, (2) differences in energy density between the insect taxa eaten most and eaten least by birds, and (3) differences in insect energy density across host plant species. The results of this research are intended to help inform habitat management efforts that aim to benefit insectivorous birds by supporting intact, robust communities of insect prey.

Impacts of Forest Disturbance on Spring Wildflowers and their Seed-Dispersing Ant Mutualists

Project Lead: Dr. Robert Clark

Many plants produce fruits to attract birds or mammals to help disperse seeds. However, there is a relatively small group of plant species that uses ants for seed dispersal. These ant-dispersed plants, or ‘myrmecochores’, are primarily found in mature, second-growth forests and have short flowering periods in early spring. Trout Lily, Trillium, Dutchman’s Breeches, Corydalis, Spring Beauty, and Hepatica, for example, all rely on the ant species Aphaenogster for seed dispersal. There is some concern that forest fragmentation and other forms of disturbance may disrupt this important mutualism. Without spring ephemerals, Aphaenogaster may not get enough food to persist in forests, and without Aphaenogaster, spring ephemerals will not be able to effectively reproduce. We are currently tracking long-term changes to spring ephemeral communities in Connecticut forests to see how this mutualism responds to environmental change. To this end, we have collected data on the density of ant-dispersed wildflowers at nine forests in Litchfield County, Connecticut that have varying degrees of disturbance. Following a 7-year removal experiment, we surveyed the relative abundance of the keystone mutualist Apheanogaster rudis compared to other non-seed dispersing ants at these locations. We are now analyzing the data from this study and preparing a manuscript for publication in a scientific journal. The results of this research will tell us if certain habitat management practices and forms of forest disturbance interfere with this important mutualistic interaction and whether these communities can recover over multiple growing seasons.

The effects of diet shifts from insects towards fruit on the energetic condition of autumn-migrant songbirds

Project Lead: Dr. Wales Carter

Migration is a heavily taxing period in the lives of songbirds, and acquiring sufficient energy and nutrients en route is crucial for migration success. Although many songbirds rely on insects during the breeding season, they shift to fruits in the fall, which has been proposed to support their ability to complete migratory journeys by both reducing foraging costs and providing a source of antioxidants. High levels of antioxidant consumption could be particularly useful for aiding recovery after long flights or prophylactically preventing oxidative damage to muscle during flight. Similarly, starting to consume fruits earlier in the migratory season could prevent longer-term declines in condition, particularly for species with particularly long migrations. However, the timing of diet shifts by fall migrants, and the relationship between antioxidant consumption and energetic condition, have received little study. Great Hollow scientists are using stable isotope analysis of feathers, red blood cells, and blood plasma to compare timelines of diet shifts between a long- and short-distance migrant (Swainson’s thrush and hermit thrush), and using histological analysis of fecal samples to relate the degree of recent fruit consumption to energetic condition. This research is being conducted in collaboration with Dr. Susan Pagano of the Rochester Institute of Technology, using samples generously collected for us by the Braddock Bay Bird Observatory in New York and Powdermill Avian Research Center in Pennsylvania.

Effects of Light Pollution on Bat Activity and Community Composition

Project Lead: Dr. Chad Seewagen

Populations of many bat species have suffered dramatic declines due to the outbreak of a disease known as white-nose syndrome. Bats are also facing a series of other threats from habitat loss, wind energy development, hibernaculum disturbance, and environmental contaminants. As nocturnal animals, bats may also be adversely affected by light pollution, but this has not been well-studied in North America. It is particularly unknown how contemporary, energy-efficient lighting technologies, like LED, affect bats. In collaboration with Dr. Amanda Adams of Bat Conservation International and Texas A&M University, Great Hollow is experimentally studying the effects of LED lighting on bats at our preserve. Using an experimental array of floodlights erected along the edge of our wetland and an acoustic bat recorder that detects the echolocation calls of bats, we have so far shown that LED light pollution significantly displaces some species, but not others, from illuminated areas. This results in a significant change in the species composition of the bat community. These findings were published in 2021 in the journal Ecology and Evolution, and will help natural resources managers better evaluate potential impacts to bats from new development projects that involve nighttime lighting. We subsequently published a follow-up experiment in Global Ecology and Conservation in 2023 that documented the distances up to which LED lights have these negative effects on bats, so the full footprint of disturbance from light pollution can be better understood.

Home Ranges and Movement Patterns of Wood Turtles

Project Lead: Dr. Chad Seewagen and John Foley

Great Hollow’s naturalist, John Foley has been consistently radio-tracking wood turtles at various sites in Fairfield County, CT and Putnam County, NY for the past several years. In collaboration with Dr. Suzanne Macey at the American Museum of Natural History and Columbia University undergraduate student, Jason Hagani, we have used these data to determine the home range sizes and area requirements of male and female wood turtles in our region, and examine annual fidelity to their hibernacula and core breeding season habitats. The findings of this research were published in 2021 in Chelonian Conservation and Biology. We plant to continue monitoring these turtles to obtain the long-term data needed to determine their survivorship in the face of threats from vehicle collisions, declining stream quality, and an abundance of synanthropic predators like raccoons.

Effects of Mercury Exposure on the Behavior and Endurance Physiology of Migrating Songbirds

Project Lead: Dr. Chad Seewagen

Mercury is a global pollutant and a powerful neurotoxin that has become increasingly widespread in the environment as a result of a two- to three-fold increase in atmospheric emissions over the past 200 years. The threats of mercury pollution to fish-eating wildlife and other top predators have been well-documented, but it has recently become apparent that animals at lower positions in food webs, like songbirds, can also accumulate harmful levels of mercury. However, it is largely unknown at what level mercury begins to cause adverse effects in songbird species. We also know next to nothing about how mercury exposure might affect the ability of birds to migrate long distances. In collaboration with Drs. Chris Guglielmo, Yolanda Morbey, and Yanju Ma at the University of Western Ontario, Great Hollow scientists radio-tagged and tracked yellow-rumped warblers of differing blood mercury levels during their spring migration to investigate the effect of mercury on migration behavior and orientation. The study was published in 2019 in the Journal of Ornithology and represents the first study of the effects of mercury pollution on the migratory behavior of birds. In the second phase of this work, we are now investigating the effects of mercury on key regulators of energy metabolism in yellow-rumped warblers to determine whether exposure to mercury pollution can hinder the long-distance flight abilities of migratory birds.

Birds as a Potential Dispersal Mechanism of the Asian Long-horned Tick

Project Lead: Dr. Chad Seewagen

The Asian long-horned tick is an invasive species that was first discovered in the U.S. in 2017 and has now been documented in at least 8 states, including Connecticut and New York. In its native range in Asia, the tick is a vector of hemorrhagic fever and Japanese spotted fever in humans, and is a devastating pest of livestock. It is currently unknown what threat the Asian long-horned tick presents to people, domestic animals, or wildlife in the U.S., or how far and fast it will spread. Its rapid spread through the eastern U.S. so far, however, indicates that migratory birds might be a primary mechanism by which the Asian long-horned tick is moved around. Birds are a common host of Asian long-horned ticks in Asia, but it is unknown whether North American bird species represent suitable hosts. In collaboration with Dr. Neeta Connally at Western Connecticut State University, Great Hollow is surveying various species of migratory and resident birds at our nature preserve for the presence of ticks during spring migration and the summer breeding season to investigate whether birds carry Asian long-horned ticks, and if so, what species of birds and birds associated with what habitat types are the most common hosts. Preliminary findings of this work were presented at the 2020 conference of the Entomological Society of America and can be viewed here. Great Hollow also works with Dr. Connally to monitor temporal trends in the abundance of black-legged ticks (the vector of Lyme disease) in western Connecticut.

New England Cottontail Population Estimation and Monitoring at Great Hollow Nature Preserve

Project Leads: Dr. Chad Seewagen and John Foley

The New England cottontail is the only native rabbit species of the northeastern United States. Not to be confused with the introduced and invasive eastern cottontail that is ubiquitous to suburban backyards, the New England cottontail is currently known to occur in only about 100 sites across its geographic range, from southern New York and Connecticut to Maine. Nearly identical, the two species can only be reliably distinguished from one another by DNA. For the past three winters, the Connecticut Department of Energy and Environmental Protection (DEEP) and Great Hollow researchers have been conducting standardized transect surveys at our preserve to collect fecal pellets for genetic analyses, and have confirmed the presence of New England cottontails in multiple locations. Great Hollow Nature Preserve is one of only 58 sites in the state of Connecticut in which the species is known to occur. Now, we are working with the University of New Hampshire to genotype the DNA extracted from the fecal pellets in order to distinguish different individual rabbits from one another and estimate the size of the New England cottontail population at Great Hollow. We’re also exploring opportunities to study the rabbits in more detail and manage that area of our preserve to enhance habitat conditions for New England cottontails while discouraging their invasive competitor, the eastern cottontail. Stay tuned for more!

Additional Projects

In addition to the above projects that are being lead by Great Hollow, our staff also frequently collects data for, or otherwise supports projects that are lead by researchers at other institutions. Such projects to which Great Hollow is currently contributing include:

Black Bear Distribution and Land-cover Associations in the Lower Hudson Valley (Project Lead: Budd Veverka, Mianus River Gorge)

Black-legged Tick Population Monitoring in Western Connecticut (Project Lead: Dr. Neeta Connally, Western Connecticut State University Tick Lab)

Connecticut Bird Atlas Project (Project Leads: Dr. Chis Elphick, UConn and Dr. Min Huang, CT Department of Energy & Environmental Conservation)

Motus Wildlife Tracking System

Past Projects

Please visit our Publications page to see the results of all of our previous research projects.

Funding Sources

Grants in support of some of our past and current projects have been generously provided by the following:

American Wildlife Conservation Foundation

Connecticut Department of Energy and Environmental Protection

Connecticut Ornithological Association

Eastern Bird Banding Association

Environmental Professionals’ Organization of Connecticut

Friends of the Great Swamp

Robert F. Schumann Foundation

USDA Natural Resources Conservation Service