Thomas O'Shea, PhD (Former Employee)

Among the 45 species of bats that occur in the United States (U.S.), 34 species regularly occur in western regions of the country. Many of these “western” species choose roost sites in crevices or cavities. Herein we provide an introduction to the biology of bats that roost in cavities and crevices and assess the challenges and opportunities associated with monitoring their populations...

Bats are ecologically and economically important mammals. The life histories of bats (particularly their low reproductive rates and the need for some species to gather in large aggregations at limited numbers of roosting sites) make their populations vulnerable to declines. Many of the species of bats in the United States (U.S.) and territories are categorized as endangered or threatened...

No abstract available.

The West Indian manatee (Trichechus manatus) is endangered by human activities throughout its range, including the U.S. Atlantic coast where habitat degradation from coastal development and manatee deaths from watercraft collisions have been particularly severe. We radio-tagged and tracked 78 manatees along the east coast of Florida and Georgia over a 12-year period (1986-1998). Our...

This overview has three related objectives. First, it provides simple documentation, descriptive summaries, and anecdotal accounts that demonstrate the extent to which maiming, and likely pain and suffering, occur in wild manatees as a result of strikes by boats. The chapter calls attention to the issues wounding raises for policy makers and managers involved with implementing boat speed...

Bats are significant components of mammalian diversity and in many areas are of management concern. However, little attention has been given to bats in urban or prairie landscapes. In 1997 and 1998, we determined species richness, relative abundance, roosting habits, and echolocation activity of bats at Rocky Mountain Arsenal National Wildlife Refuge (RMA), the largest urban unit in the...

Rocky Mountain Arsenal (RMA) National Wildlife Area, near Denver, Colorado, is a Superfund site contaminated by past military and industrial uses, including pesticide manufacturing. From an ecosystem standpoint, the most critical contaminants at RMA are certain cyclodiene insecticides and metabolites, p,p′-DDE, p,p′-DDT, arsenic, and mercury. Bats are important ecosystem components that...

This working group did not divide into subgroups, and its report consists of a unified document in a format somewhat different than those of the other working groups. The group considered four major topics: (1) projected "new" contaminants of future concern; (2) future trends with contaminants currently known to be issues for marine mammals; (3) future needs to improve and insure...

Prompted by concern about declining bat populations in the southwestern United States, we surveyed for changes in populations between 1972 and 1997 at a study area in central Arizona. We duplicated earlier searches of ancient Indian dwellings and crevices in surrounding cliffs for diurnally roosting bats during the time of year when maternity colonies should have been present, and...

The population dynamics of large, long-lived mammals are particularly sensitive to changes in adult survival. Understanding factors affecting survival patterns is therefore critical for developing and testing theories of population dynamics and for developing management strategies aimed at preventing declines or extinction in such taxa. Few studies have used modern analytical approaches...

Recent development of age-determination techniques for Florida manatees (Trichechus manatus latirostris) has permitted derivation of age-specific data on reproduction and survival of a sample of 1212 carcasses obtained throughout Florida from 1976–1991. Population viability analysis using these data projects a slightly negative growth rate (−0.003) and an unacceptably low probability of

Growth layers were observed in histological preparations of bones of known-age, known minimum-age, and tetracycline-marked free-ranging and captive Florida manatees (Trichechus manatus latirostris), substantiating earlier preliminary findings of other studies. Detailed analysis of 17 new case histories showed that growth-layer group (GLG) counts in the periotic bone were consistent with...