Publications
These publications showcase the significant science conducted in our Science Centers.
Filter Total Items: 16785
Waterfowl mortality factors
The objectives of waterfowl management in North America involve population size and harvest. Any management action intended to influence population size must do so through one of four demographic variables: reproduction, mortality, immigration, and emigration. Mortality is especially important because hunting can be strongly influenced by management.
Authors
J. D. Nichols
A coded tracking telemetry system
We describe the general characteristics of an automated radio telemetry system designed to operate for prolonged periods on a single frequency. Each transmitter sends a unique coded signal to a receiving system that encodes and records only the appropriater, pre-programmed codes. A record of the time of each reception is stored on diskettes in a micro-computer. This system enables continuous mo
Authors
P.W. Howey, W.S. Seegar, M.R. Fuller, K. Titus
Aerial tracking of radio-marked white-tailed tropicbirds over the Caribbean Sea
We radio-marked nesting white-tailed tropicbirds at Culebra National Wildlife Refuge, Puerto Rico, and tracked them from a Cessna 182 during flights over the open sea. Locations of the birds were determined using standard aerial telemetry techniques for side-facing Yagi antennas. We used strut-mounted, 4-element Yagi antennas connected to a switchbox and scanning receiver. By recording bearing
Authors
M.R. Fuller, H.H. Obrecht, C.J. Pennycuick, F.C. Schaffner
Telemetry location error in a forested habitat
The error associated with locations estimated by radio-telemetry triangulation can be large and variable in a hardwood forest. We assessed the magnitude and cause of telemetry location errors in a mature hardwood forest by using a 4-element Yagi antenna and compass bearings toward four transmitters, from 21 receiving sites. The distance error from the azimuth intersection to known transmitter lo
Authors
D.S. Chu, B. A. Hoover, M.R. Fuller, P.H. Geissler
Falcons
Four species of Falco occur in the northeastern United States. The gyrfalcon is a rare winter visitor. The peregrine falcon federally listed as endangered, is a migrant and through reestablishment is breeding and wintering locally throughout the northeast. The merlin is a migrant and uncommon winter bird. The American kestrel breeds, winters, and migrates in the northeast. A 22-year analysis
Authors
L.S. Schueck, M.R. Fuller, W.S. Seegar
Buteos
Red-tailed, red-shouldered, and broad-winged hawks nest throughout the 11 northeastern states, and red-tailed, red-shouldered, and rough-legged hawks winter in this region. Historical and present ranges of these species are similar, although red-shouldered and broad-winged hawk ranges now have more vacant patches at a local and regional level. Only the red-shouldered hawk is of special concern o
Authors
K. Titus, M.R. Fuller, D.F. Stauffer, J.R. Sauer
The impact of eastern equine encephalitis virus on efforts to recover the endangered whooping crane
The whooping crane (Grus americana), although never abundant in North America, became endangered primarily because of habitat modification and destruction. To help recovery, a captive propagation and reintroduction program was initiated at the Patuxent Wildlife Research Center (PWRC) in 1966. However, in 1984, 7 of 39 whooping cranes at PWRC died from infection by eastern equine encephalitis (EE
Authors
J. W. Carpenter, G.G. Clark, D.M. Watts
Considerations for monitoring raptor population trends based on counts of migrants
Various problems were identified with standardized hawk count data as annually collected at six sites. Some of the hawk lookouts increased their hours of observation from 1979-1985, thereby confounding the total counts. Data recording and missing data hamper coding of data and their use with modern analytical techniques. Coefficients of variation among years in counts averaged about 40%. The a
Authors
K. Titus, M.R. Fuller, J.L. Ruos
Lead contamination of golden eagles Aquila chrysaetos within the range of the California condor Gymnogyps californianus
Blood samples were taken from 66 golden eagles from June 1985 to January 1986 and analyzed for their lead content. Thirty-nine percent had blood lead levels greater than 0.2 ppm, indicating exposure to environmental lead. Within the exposed group, 3 had blood levels exceeding 0.6 ppm and one exceeded 1.0 ppm. These data suggest that lead, probably in the form of shot, bullets, or bullet fragmen
Authors
P.H. Bloom, J. M. Scott, O. H. Pattee, M. R. Smith
Current status of the Puerto Rican parrot conservation program
No abstract available.
Authors
G.D. Lindsey, M.K. Brock, M.H. Wilson
Turkey vulture and California condor
Populations of turkey vultures in the western states appear stable, with no evidence of recent significant changes in distribution. Turkey vultures occupy a variety of habitats, nest in diverse situations and utilize a wide variety of carrion. Consequently, no particular limiting factor is likely to have a major effect on the total population. California condor numbers, in contrast, have contin
Authors
O. H. Pattee, S.R. Wilbur
Bald eagle and osprey
Bald eagles nested in all nine western states during recent years (about 19% of known U.S. population in 1982). The known numbers of nesting pairs in the west increased substantially in the last 10 years and totaled 584 in 1986. Much of the increase was due to more intensive survey efforts, but most biologists cite examples of new palrs establishing nesting territories. In contrast, productivity w
Authors
C. J. Henny, R.G. Anthony