Species Status Assessments

Many of Hawai‘i’s forest birds have shown significant declines in the past 200 years, with many currently listed as endangered species. Multiple threats have been identified as contributing to declines, including disease, invasive species, habitat loss, and decreased survivorship and productivity caused by introduced predators. Demographic and ecological studies are needed to determine how...

Loss of wetlands, invasive plants, and non-native predators pushed Hawaii’s waterbirds to the brink of extinction by the early 1900s, although population numbers have improved somewhat in recent decades with conservation efforts. Nonetheless, all Hawaiian waterbirds have global population sizes estimated around or below below 2,000 individuals, making them still highly vulnerable to extinction...

The Challenge Over the last two decades, the Eastern migratory population of monarch butterflies has declined by about 80%, leading many scientists to consider how to best conserve and rebuild monarch populations. Conservation efforts can be challenging to design and execute because of the multi-generational migration of monarchs that spans North America. Conservationists must consider many...

WERC wildlife biologist Dr. Kristin Berry has more than forty years of experience studying Agassiz’s desert tortoise. As the lead on several USGS projects, Dr. Berry continues to lend her expertise to investigating the status, genetics, and behavior of Agassiz’s tortoise populations in the Mojave Desert.

The Challenge: The Akeke’e (Loxops caeruleirostris) and the Akikiki (Oreomystis bairdi), two species of Hawaiian honeycreeper, are critically endangered bird species endemic to high elevation ohia forests on the Hawaiian island of Kauai. Both species have suffered severe population declines and range contractions in recent decades. Akeke’e are currently thought to number ca. 950 wild individuals...

The Challenge: The Canada Goose Branta canadensis was historically a highly migratory species. However, this species has recently established resident populations in urban, suburban, and agricultural areas in many parts of the U.S., including the Chesapeake Bay region. The enormous success of these populations has led to consideration of this species as a nuisance, largely due to its excessive...

Populations of amphibians have been declining around the world (Stokstad 2004). The US Geological Survey is working to understand the extent and causes of such declines via the Amphibian Research and Monitoring Initiative (ARMI). We are conducting research in support of this program in the Midwest Region of ARMI. Our offices and laboratories are at the Upper Midwest Environmental Sciences Center...

Invertebrate communities provide food for several economically and ecologically important fish and waterbird species in coastal estuaries. Scientists at the WERC San Francisco Bay Estuary Field Station specialize in studying foraging ecology of waterbirds and fishes, general food web dynamics across estuaries, and the effects of habitat restoration and other factors on waterbird prey availability.

Adult sea lamprey abundance in Lake Erie increased during the past decade, exceeding pre-control levels and causing extensive mortality on some strains of stocked lake trout (Markham 2015). Control agents speculate that this increase may be due to an uncontrolled larval sea lamprey population in the St. Clair River because other known sources of larval sea lampreys are regularly treated with...

It is (relatively) easy to construct complex hierarchical models for analysis of the North American Breeding Bird Survey (BBS), but deciding which model best describes population change is difficult. We are developing methods for model selection for BBS and other important survey data sets, and using them to refine our estimates of population change from this important survey.

The boreal forest in the northeastern United States and eastern Canada contains most of the breeding range of the American black duck ( Anas rubripes ). We collaborate with scientists from the U. S. Fish and Wildlife Service to design and analyze waterfowl surveys in this large and often inaccessible area.

Designing and analyzing large-scale animal surveys is an important focus of our research. Although we conduct research into analysis methods for many surveys, the primary focus of this project is to conduct analyses and develop web-based summaries of data from the North American Breeding Bird Survey (BBS).