Current Projects


Biological research is at the core of what we do at Great Hollow. Our researchers and collaborators conduct conservation-driven 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 multiple partners across academia, government, and non-governmental organizations to most effectively and efficiently approach scientific studies of common interest. Below are some of the projects we are currently working on.

Effects of Japanese Barberry on Forest Songbird Breeding Habitat Quality

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. We are examining food availability and the diet composition and physiological condition of ovenbirds in breeding territories that have either extensive or little to no Japanese barberry coverage. The results of this study will allow for more science-based decision making among land managers and conservation practitioners who are grappling with Japanese barberry invasions.

Effects of Japanese Barberry on Invertebrate Food Webs

The effects that non-native plants may have on the abundance and diversity of foliage-dwelling and leaf litter invertebrates are surprisingly poorly understood. Invertebrates play an important role in forest nutrient cycling and are a critical food source for birds and other wildlife higher up in the food web. We are working with Dr. Robert Clark at Washington State University to compare invertebrate biomass, diversity, and community composition on Japanese barberry to that of native plants in the forest understory and leaf litter. This will provide important information with consequences for the management of highly invasive plant species of Connecticut’s forests.

Impacts of Light Pollution on the Foraging Activity of Bats

Populations of many bat species are in dramatic decline 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 turbine collisions, chemical pollution, and light pollution. As nocturnal creatures, bats may be adversely affected by the abundance of artificial lighting in our cities and towns, along our roads, and around our homes, but this has not been well-studied in North America. In collaboration with Dr. Amanda Adams at Texas A&M University, Great Hollow is conducting an experiment on the effects of L.E.D. lighting on bat activity at our preserve. Using an array of lights erected along the edge of the wetland at the southern end of the preserve and an acoustic bat recorder that detects the echolocation calls of bats and identifies them to species, we are able to compare bat activity levels on nights with and without the lights turned on. The findings of this experiment will help natural resources managers to evaluate potential impacts to bats from new development projects that involve nighttime lighting. Read an article on our research in the newsletter of the American Wildlife Conservation Foundation here.

Home Ranges and Movement Patterns of Wood Turtles

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 are using 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. Continued monitoring of these turtles will also provide long-term data needed to determine their survivorship in the face of threats from vehicles, water pollution, and an abundance of synanthropic predators like raccoons. Check out a recent conference poster of the project’s findings here.

Effects of Mercury Pollution on the Migratory Behaviors of Songbirds

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 (see 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 recently published in the Journal of Ornithology and represents the first study of the effects of mercury pollution on the migratory behavior of birds.

Evaluating the Quality of an Urban Estuary as Migratory Shorebird Stopover Habitat

Great Hollow’s executive director, Chad Seewagen, studied the stopover biology of migratory songbirds in New York City parks for many years to investigate the quality of urban forests as stopover sites for long-distance migrants in need of places to rest and quickly refuel along their journeys. Now, in collaboration with Dr. Susan Elbin and Kaitlyn Parkins at New York City Audubon, and Dr. David Mizrahi at New Jersey Audubon, Great Hollow is initiating a study of the refueling rates, stopover duration, and possibly diet composition of semi-palmated sandpipers in Jamaica Bay, New York City to evaluate the ability of this heavily urbanized estuary to meet the resource requirements of migrating shorebirds using it as a stopover site. By comparing these parameters between shorebirds stopping over in Jamaica Bay to those in a non-urban reference site in the Delaware Bay estuary, we will be able to see how Jamaica Bay stacks up and what role it appears to be playing in the intercontinental migrations of shorebirds, many species of which have experienced dramatic population declines in recent decades. Changes in the availability and quality of stopover habitat are suspected to be one of the primary drivers of these declines, highlighting the importance of identifying and protecting key stopover sites in the conservation of migratory shorebirds.

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

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. 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.

Population Monitoring of the New England Cottontail at Great Hollow Nature Preserve

The rare and declining 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 and the like, the New England cottontail is currently known to occur in only 104 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 of our preserve to collect fecal pellets for genetic analyses, and have confirmed the presence of New England cottontails. 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.