Distribution and Reproductive Status of Grassland Birds with respect to Condition of Grassland Habitat in Virginia
Amy L. Meehan and Carola A. Haas
The most precipitous declines in populations of songbirds in the eastern U.S. have been xhibited not by forest interior migrants, but by species that breed in grassland or shrubland habitats, according to data from Breeding Bird Survey routes. Many of these species were native to the extensive pine savannas that occupied much of the southeastern coastal plain and to the open habitat that occurred in the Shenandoah Valley. In the summer of 1996 we began preliminary field work to determine the breeding status in Virginia of several species of grassland bird, including upland sandpiper, Bachman's sparrow, and Henslow's sparrow. We documented presence of upland sandpiper and Bachman's sparrow in the state during the breeding season. We began work on a more common grassland species, the grasshopper sparrow, to determine the usefulness of a reproductive index to assess site quality.
Premigratory Movements of a Neotropical Migratory Species: the Wood Thrush
Jorge H. Vega, Carola A. Haas, and Dean F. Stauffer
Despite the recent attention given to declining populations of Nearctic-Neotropical migrant birds, little information is available regarding movements and habitat use during the period immediately after breeding but before fall migration. During May-October of 1993 to 1995, we used radiotelemetry to obtain information about the premigratory movements of wood thrush in Quantico Marine Corps Base, Virginia. The field work involved searching for and monitoring of wood thrush nests, mist-netting birds, radio-tracking wood thrushes, performing behavioral observations, and sampling vegetation.
We captured, radio-tagged and monitored the movements of 71 adults and 42 fledgling wood thrushes. At an average age of 32 days post-hatching, fledglings dispersed average distances of over 1500 m. After dispersal most fledglings were found (1) in second growth and sapling stands at the edge of forested areas, (2) in open-canopy Virginia pine (Pinus virginianus) forest with heavy understory of young deciduous trees, and (3) in a deciduous forest defoliated by gypsy moth (Lymantria dispar). Most young joined flocks of juveniles whereas a few of them remained solitary. On 38 occasions, 15 fledglings performed exploratory movements up to 6 km. Most fledglings left the Marine Base in September at an average age of 81 days post-hatching.
Adult wood thrushes completed their breeding activities by early August. Thirty stayed at the Marine Base for molting until late September or early October. Of these, 15 molted in the same area where they nested and 15 moved an average of 2015 m from their nesting sites. In general, molting sites differed from nesting sites in having less canopy cover, fewer large trees (dbh >38 cm), more pines, more saplings, and more vegetation in the understory.
This study shows that the forces behind the selection of dispersal and molting sites are complex and that individual variability further complicates the problem. Yet it is evident that, for the wood thrush, the ecological processes operating during the nesting period are different from those operating during the postreproductive period. Our results suggest that a conservation strategy that focuses on identifying and protecting habitat during the breeding season, although important, is incomplete at best if events and needs during the postreproductive period are not considered.
This study has been supported by the Legacy Program of the U.S. Department
of Defense, the Natural Resources Program of Quantico, and the Smithsonian
Conservation and Research Center.
Nutritional Value of Waterfowl and Shorebird Foods in Atlantic Coastal Impoundments
Chesapeake Bay and the Atlantic Coastal Sounds historically supported
some of the highest densities of wintering waterfowl in North America.
This region is also one of the most important migratory stopovers for shorebirds
in the Western Hemisphere. Traditional foods of wintering waterfowl and
migrating shorebirds in the mid-Atlantic include submerged aquatic vegetation
and horseshoe crab eggs, respectively. Recent declines in both food sources
have lead managers to seek alternative means to provide food for these
species. The goal of this project is to evaluate production of waterfowl
and shorebird foods in moist soil impoundments in response to common management
practices such as water level manipulation and discing. Food abundance
and quality will be assessed in relation to the distribution of vegetation
types. This will provide managers of moist-soil impoundments with the capability
of evaluating food production of impoundments on a nutritional basis, using
a rapid, qualitative assessment of plant community composition and successional
stage. Further, our goal is to aid managers in temporal and spatial location
of physical disturbances, to optimize production of nutritionally balanced
waterfowl and shorebird foods.
Foraging Ecology of Ruffed Grouse in Relation to Forage Availability and Secondary Plant Compounds in the Southern Appalachians.
Ruffed grouse (Bonasa umbellus) densities are lower in the Southern Appalachians than in more northerly parts of their range. We have shown that winter subsistence foods of grouse in the South have higher levels of tannins than foods in the North and the southern grouse must spend more time foraging in winter to meet nutritional requirements. This increased time foraging likely increases susceptiblity to predation. The availability of low tannin herbaceous foods is probably a critical determinant of grouse abundance in the Southeast. Studies on nest predation indicated about 20% of nests were predated and nest predation was not density dependent.
Brittle antlers in mule deer (Odocoileus hemionus) from the US Air Force Academy at Colorado Springs, Colorado.
Patrick F. Scanlon and Luz M. Borrero-Yu
During the past several years an undetermined number of mule deer (Odocoileus hemionus) from the US Air Force Academy at Colorado Springs, Colorado, have shown antler fractures and tooth lesions. The availability of antlers for the study is very limited since these populations are managed for hunting purposes. Teeth and bone are being used as surrogates of antlers to study elementcontents of the tissues and bone strength. Results indicated that the concentrations of fluoride found in bone and teeth of this population of mule deer are higher than those found in deer populations from two other areas in Colorado (Game Management Units in Northwestern Colorado and Piñon Canyon Maneuver Site in Southeastern Colorado). Fluoride content of bone and tooth tissues were considerably greater than those of deer species from reference sites in other areas where fluoride contamination was a problem. Fluoride is an element that has been associated with brittle bones and tooth lesions in humans, cattle, sheep, elk and rodents. The tooth lesions associated with ingestion of high concentrations of fluoride vary from white spots to lack of formation and mineralization of the tooth enamel. The tooth lesions found in mule from Colorado Springs were more severe than those found in the two other collection sites.
To determine other possible causes of brittle antlers other elements
such as lead, boron cadmium, selenium, mercury, calcium, and phosphorous
are currently being measured. Also tests are being conducted to determine
the resistance of bone to breakage in shear force tests.
Distributions of large carnivore and their interactions with agricultural land use in Colombia.
Luz M. Borrero-Yu, Patrick F. Scanlon and J.A. Parkhurst
During the past decade anecdotal data on land-owner complaints in Colombia indicate that Andean Bears Tremarctos ornatus are destroying crops and that Andean Bears, Pumas Puma concolor and Jaguars Panthera onca are attacking and killing livestock. An informal sample survey of government officials conducted between July 28 and August 2, 1996, indicated that complaints from farmers were reported in Antioquia, Bolívar, Cundinamarca, Quindio, Boyacá, Valle and Putumayo, i.e. 7 of 32 departments into which the country is divided.
In an attempt to document and identify the types of problems that large carnivores are producing in Colombia that might limit long term survivial of these species in Colombia the present research project will conduct interviews and surveys among government officials managing natural resources and farmers from affected areas. Through the survey process it would be possible to identify the the location, extent, and impacts of the damage caused by large carnivores. The study will also identify how different of stakeholders perceive, tolerate or otherwise react to damage caused by large carnivores. It will be also possible to determine the stakeholders' knowledge and attitudes toward presence and management of large carnivores. By identifying the type and location of existing interactions and the accompanying stakeholder attitudes toward these interactions, management, mitigation and education programs can be developed. The proposed study will generate valuable baseline information for the conservation of large carnivores in Colombia, and will suggest a protocol to identify and manage future conflicts between these species and agricultural land use.
Current distributions of the three species of carnivores in Colombia will be inferred from the information provided by government officials and farmers in surveys on damage and presence/absence of the species. Distribution data obtained from the interviews and surveys will be compared with information available through literature and other records as a means to detect possible changes in the distributions of the three large carnivores in Colombia.
Spatio-Temporal Effects of Land-Use Changes in Savanna Wildlife Areas of Kenya
Enos E. Esikuri and Dean F. Stauffer
The National Parks and Reserves of Kenya are able to support large numbers and varieties of wild animals because of the vast unprotected wildland areas that surround them. However, as human population grows (at 3.8% , Kenya has one of the highest growth rates in the world) and permanent agriculture increases, the land-use structure in these nonpark areas becomes less
favorable to wildlife foraging, migration, and conservation options. Increased cultivation in these savanna wildlife does not only affects habitat suitability for wildlife, but also increases the potential for negative interactions between wildlife and private landowners. Incidents of wildlife damaging agricultural resources or threatening public safety are not uncommon. The dynamics of such interactions can significantly affect the way local people perceive wildlife and whether or not they support conservation actions.
It is against such a backdrop that this study is conceived in order to assess: 1) land use change patterns and rates in time and space using remote sensing technology, 2) how those changes affect wildlife habitat suitability in nonpark areas, and 3) how those changes translate into wildlife-damage hazards for landowners living adjacent to National Parks and Reserves. Amboseli Basin is used as the case study, while the African elephant is used as the evaluation species due to its high visibility and unselective-generalist feeding behavior. Field data collection commenced in March, 1996 and will continue until July, 1997.
This work is supported by grants from the World Wildlife Fund, the Rockefeller
Foundation, and The World Bank.
Large-scale Relationships of Birds to Habitat Patterns
Mark E. Penhollow and Dean F. Stauffer
Historically, work to determine wildlife-habitat relationships has been conducted at a site-specific level for single species. Models were developed that allowed the prediction of the population response of a species to changes in various habitat characteristics such as tree density or canopycover. However, it is difficult to develop such models for all species, and the shift to ecosystem management requires that we understand the relationship of all species to their habitats at a scale larger than that of a species home range.
This study was initiated to develop empirically-based models of how bird communities respond to variation in forested landscapes. Data were collected at 20 50 to 70-ha sites on Quantico Marine Corps Base in northeastern Virginia. We developed models that related total bird density, speciesrichness, and diversity to landscape patterns. We found that the best predictors of bird diversity were the number of different forest patches per unit area (a positive relationship) and theamount of hardwood forest present (a negative influence). The relative abundance of individual bird species was most often related to the number of different forest stand types, the amount of high- contrast edge between forest types, and the amount of mixed pine/hardwood forest present. We used this information to provide models that can be used to assess potential impacts of forest management practices on songbirds.
This work is supported by the National Biological Service and Quantico Marine Corps Base
Relationship of Home Range Size, Movement, and Survival of Ruffed Grouse to Landscape Level Habitat Variables
Todd M. Fearer and Dean F. Stauffer
The ruffed grouse (Bonasa umbellus) is one of the most popular game birds of North America. Much of the grouse's native range occurs in areas where aspen is an important component of the forest, and it is widely documented that forest stands containing aspen (Populus spp.) are very important to ruffed grouse for both food and cover. Little research has been done onruffed grouse populations occurring outside the native range of aspen, such as those in the Mid-Atlantic region, and the factors limiting these populations are poorly understood. In recent years, there is a growing concern that ruffed grouse populations are declining in this region. Since there is a general lack of knowledge of ruffed grouse ecology in the Southeast, developing successful management plans to counter these declines are problematic at best.
Several management recommendations for ruffed grouse stress the importance of providing and maintaining the proper mixture of landscape level habitat characteristics, such as the size, spatial arrangement, and availability of different habitat types and forest age classes in the landscape. However, few studies suggest what size or configuration these habitats should have in the landscape relative to each other. The purpose of this project is to determine the relationship of size and configuration of landscape level habitat types to ruffed grouse home range size, movement, and survival. Landscape level habitat selection by individual grouse will be examined at three study sites in Virginia. We hope to identify trends in landscape level habitat types that increase the survival of adult and juvenile birds and maintain a healthy grouse population over a given area. This projection is being conducted in conjunction with the Appalachian Cooperative Grouse Research Project.
This work is supported by the Virginia Department of Game and Inland Fisheries, the U.S. Fish and Wildlife Service, The U.S. Forest Service, and the Ruffed Grouse Society.
Cooperative Allegheny Bear Study
Cale L. Godfrey, Jennifer C. Higgins, Kristine L. Higgins, Christopher W. Ryan, Michael R. Vaughan, and Dennis D. Martin (Virginia Department of Game and Inland Fisheries)
The Cooperative Allegheny Bear Study is a large scale, long-term research project designed to provide critical management information on Virginia's exploited or hunted black bear population. The goal of the research is to develop an understanding of the population dynamics of the hunted black bear population, which will enable wildlife managers to evaluate and predict population trends and to effectively manage the population.
Two hundred and fifty-six bears were captured 394 times during three summers on the northwestern study area 85 bears were captured and 137 times during 2 summers on the southwestern study area; more than 100 bears were equipped with radio transmitters. Bears equipped with radio collars are routinely tracked to determine survival rates and causes of mortality, habitat use, and movement and distribution patterns. All females are tracked to their dens in winter to determine reproductive success. The information collected will permit us to calculate reproductive and survival rates and population growth rates. In addition, several indices to population abundance are being tested to determine how best to monitor Virginia's black bear population.
This research is a cooperative venture with the Virginia Department
of Game and Inland Fisheries, Virginia Tech, and the U. S. Forest Service.
Twelve separate agencies have provided funding for the research. Genetics
of Black Bear Populations in the Southeastern United States
Daniel A. Miller, Barbara A. Lubinski, Jennifer C. Allen, John W. Kasbohm, Eric M. Hallerman, and Michael R. Vaughan
The American black bear originally was distributed throughout nearly all of eastern North America. However, bear populations were reduced significantly as land was cleared and developed for human activity. Population decline was especially strong for the Louisiana subspecies of black bear leading to its listing as a threatened species, and for the Florida black bear considered as warranting listing under the Endangered Species Act. During the listing process, questions were raised about the validity of classifying the Louisiana and Florida black bears as distinct subspecies, leading to a study of their population genetics. DNA fingerprinting was used to measure genetic relatedness of 30 populations of black bears across the southeastern United States. Results showed that translocations of black bears form Minnesota to Louisiana in the 1960s had little or no impact on Louisiana black bear populations. Genetic similarity of Louisiana and Florida subspecies of black bears suggested that separate subspecies designations may not be justified. However, both Louisiana and Florida populations of black bears are distinct from other populations in the southeastern United States. These findings will support informed management of black bear populations in the Southeast.
Funding is provided by the U.S. Fish and Wildlife Service and the National
Council of the Paper Industry for Air and Stream Improvement (NCASI)
Black Bear Reproductive Physiology and Natural Regulation
Black bears breed in the summer and delay implantation of the fertilized egg until sometime in late fall or early winter. Beyond that, little is known about black bear reproductive physiology and therole of the reproductive strategy in natural regulation of bear populations. One theory, known as the "blastocyst resorption hypothesis", suggest that if an impregnated female could assess hernutritional condition and determine she is incapable of successfully raising an offspring, she could abort the fertilized egg before implanting it in the uterus and wait until conditions are better, thus regulating population growth. This idea also implies she is in poor nutritional condition because of overpopulation. This research tests the blastocyst resorption hypothesis and investigates various aspects of black bear reproductive physiology.
Adult female black bears, captured by the Virginia Department of Game and Inland Fisheries as nuisance bears, are brought into captivity in late summer and held overwinter in a bear holding facility at Virginia Tech. Every 10 days from October through March the captive bears are immobilized to have their blood drawn and be weighed. At this time we take measures of body fat by bioelectrical impedance and with ultra-sound monitors. Beginning in December, we also use ultra-sound to monitor for pregnancy and measure fetal development. After birth, cub growth rates are measured. Captive bears are returned to the wild in mid-May when their cubs are big enough to follow them.
Research results indicate that bears actually implant the fertilized egg within the first two weeks of December and that gestation time is about 60 days. Further, bears implant the fertilized eggs regardless of their nutritional condition, which is contrary to the prediction of the blastocyst resorption hypothesis. However, bears in poor nutritional condition use other methods of terminating cubs prior to starting lactation.
This on-going research is financed by the Virginia Department of Game
and Inland Fisheries and Virginia Tech.
Last edited June 2000