In early February, Patuxent scientists, Deborah Cowman and Donald Sparling, working with Laura McConnell (USDA), will begin controlled laboratory studies designed to answer questions raised in field experiments regarding amphibian declines in the Sierra Nevada Mountains. Atmospheric chemists have documented the atmospheric transport of pesticides applied in the Central Valley, CA to high elevation habitats in the Sierras. Cowman and Sparling hypothesize that these pesticides are contributing to the overall decline of Sierra Nevada amphibian populations, including those of the mountain yellow-legged frog. Mountain yellow-legged frog (Rana muscosa) populations are seriously low. The southern populations of the mountain yellow-legged frog were listed as an endangered species in August 2002, and the northern populations are currently candidates for listing.

Mountain yellow-legged frog (Rana muscosa)

John Seginak Continues Outreach Lectures about Wildlife at Georgia High School and at the University of Georgia

USGS Patuxent scientist John Seginak, of the Athens (Georgia) Field Station, presented lectures at Madison County (Georgia) High School on January 30 and 31. This is the 8th year Mr. Seginak has been requested to lecture at the school. Topics included responsible deer management schemes, and their influence on herd/habitat condition, neotropical migrants, and other avian/mammalian populations. Also, lectures regarding physiological characteristics as indicators of herd condition and habitat quality of ungulate species were given. Mr. Seginak will also present these lectures at 2 large hunting clubs, Pine Hill and Plantation, in February.

John will also lecture at the University of Georgia in February. For the 9th straight year, he will give presentations in the Wildlife Management Techniques class, now being taught by Professor Sara Schweitzer. Topics will include those mentioned above, plus lectures on radio telemetry uses, methods, and techniques.

Patuxent's Hahn one of Authors of  "Geographic variation in cowbird distribution, abundance, and parasitism"

Morrison, M. L. and D. C. Hahn. 2002. Geographic variation in cowbird distribution, abundance, and parasitism. Pages 65-72 in T. Luke George and David S. Dobkin, editors. Effects of habitat fragmentation on birds in western landscapes: contrasts with paradigms from the eastern United States. Studies in Avian Biology 25:270 pp.

Abstract: We evaluated geographical patterns in the abundance and distribution of Brown-headed Cowbirds (Molothrus ater) and in the frequency of cowbird parasitism, across North America in relation to habitat fragmentation. We found no distinctive parasitism patterns at the national or even regional scales, but the species is most abundant in the Great Plains, the heart of their original range, and least common in the southeastern U.S. This situation is dynamic, because both the Brown-headed and two other cowbird species are actively expanding their ranges in the southern U.S. We focused almost entirely in this paper on the Brown-headed Cowbird, because it is the only endemic North American cowbird, its distribution is much wider, and it has been much more intensively studied. We determined that landscape is the most meaningful unit of scale for comparing cowbird parasitism patterns as, for example, in comparisons of northeastern and central hardwood forests within agricultural matrices, and suburbanized areas versus western coniferous forests. We concluded that cowbird parasitism patterns were broadly similar within all landscapes. Even comparisons between prominently dissimilar landscapes, such as hardwoods in agriculture and suburbia versus coniferous forest, display a striking similarity in the responses of cowbirds. Our review clearly indicated that proximity of feeding areas is the key factor influencing presence and parasitism patterns within the landscape. We considered intensity of landscape fragmentation from forest-dominated landscapes altered in a forest management context to fragmentation characterized by mixed suburbanization or agricultural development. Our review consistently identified an inverse relationship between extent of forest cover across the landscape and cowbird presence. Invariably, the variation seen in parasitism frequencies within a region was at least partially explained as a response to changes in forest cover. The most salient geographic aspect of cowbirds` response to landscape fragmentation is the time since fragmentation occurred. Eastern landscapes generally experienced 200 years ago the development and fragmentation that western landscapes experienced less than 75 years ago. Consequently, there is a broad east-west contrast in which more numerous human settlements and smaller unbroken forest stands are found in the East, a difference that permits cowbirds to be more pervasive and ubiquitous. The locality of suitable feeding areas is a hallmark trait of the cowbirds` strategy in exploiting specific forest fragments. Host abundance influences parasitism patterns only secondarily at the landscape scale. These two limiting factors come into play differently in different landscapes. For example, cowbird abundance in unbroken forested landscapes are limited primarily by the availability of foraging areas rather than by host density, whereas cowbirds are limited primarily by host availability in landscapes that are extensively fragmented with feeding areas.

Contact: Dr Caldwell Hahn, 301-497-5653

Experimental Lead Poisoning in Turkey Vultures, Cathartes aura James W. Carpenter, Oliver H. Pattee, Steven H. Fritts, Barnett A. Rattner, Stanley N. Wiemeyer, J. Andrew Royle, and Milton R. Smith

Abstract: Lead-induced mortality appears to have been a major factor in the decline of the California condor, Gymnogyps californianus. We orally dosed turkey vultures (Cathartes aura) with BB-sized lead shot from January 1988 through July 1988 to determine physiological response (delta-aminolevulinic acid dehydratase inhibition, erythrocyte protoporphyrin levels, anemia), diagnostic tissue lead concentrations (blood, liver, and kidney), and comparative sensitivity of this species. Two turkey vultures died and two became so intoxicated they were euthanized. Overall, responses of measured parameters were comparable to other species exposed to lead although there was considerable individual variation. Survival time (143-211 days), even with the large number of shot and constant redosing, was much longer than reported for other species of birds, suggesting considerable tolerance by turkey vultures to the deleterious effects of lead ingestion. Based on these observations, turkey vultures appear to be poor models for assessing the risk of lead poisoning to California condors or predicting their physiological response. KEY WORDS: California condors, Cathartes aura, endangered species, Gymnogyps californianus, lead poisoning raptors, turkey vultures.

Twedt one of Authors of  "Spring bird migration in Mississippi Alluvial Valley forests"

Wilson, R. R. and D. J. Twedt. 2003. Spring bird migration in Mississippi Alluvial Valley forests. American Midland Naturalist 149 (1):163-175.

Abstract: We surveyed forest songbirds during migration in bottomland hardwood forest stands and managed cottonwood (Populus deltoides) plantations in northeast Louisiana and west-central Mississippi between 24 March and 24 May 1996 and 1997. We detected more bird species in bottomland hardwood stands than in cottonwood stands. Within hardwood stands, we detected more individuals in stands subjected to uneven-aged timber harvest than in unmanaged stands. Early in migration, avian species composition was similar in both forest types, being comprised mainly of short-distance migrants. Bird species composition in these forest types became increasingly disparate as long-distance neotropical-nearctic migrants arrived. Ten bird species were characteristic of bottomland hardwood forests, whereas eight different species were characteristic of managed cottonwood plantations. Because these two forest types supported different bird communities, both forest types provide important inland stopover habitat during migration. Silvicultural management of bottomland hardwood forests that increases their understory vegetation will provide forested habitat for a more species rich and abundant population of songbirds during migration.

Hoffman Honored as one of Most Highly Cited Authors in field of Ecology/Environment for Journal Publications over Last Two Decades

Dr David Hoffman was honored by a letter of recognition and placement on the newly established website for the Institute for Scientific Information as one of the world’s most highly cited authors -- comprising less than one half of one percent of all publishing researchers in the field of Ecology/Environment for journal publications over the last two decades (1981-1999). Visit http://www.isihighlycited.com/  Three other Department of Interior scientists were identified, all from USGS. This freely accessible Web site provides research professionals working in a variety of occupations an invaluable tool to identify individuals, departments and laboratories that have made fundamental contributions to the advancement of science and technology in recent decades. ISIHighlyCited.com strives to reveal the face of research--the people behind the accomplishments in 21 broad subject categories in life sciences, medicine, physical sciences, engineering and social sciences. For over 40 years, ISI has indexed the world’s scholarly literature from a wide range of subjects in science and social science, and has collected cited references from many millions of articles. ISI's database contains millions of citation relationships, each one derived from one author’s reference to another. Accumulated across many years and millions of articles, this information becomes a statistically powerful resource for finding individual authors who have formed or changed the course of research in a subject.

Contact: Dr David Hoffman 301-497-5712

HiLites Contact: B.H. Powell, USGS Patuxent Wildlife Research Center, 301-497-5782

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