Patuxent Wildlife Research Center Research Articles

Adverse effects of acid rain on the distribution of the Wood Thrush Hylocichla mustelina in North America.

Research into population declines of North American bird species has mainly focused on the fragmentation of habitat on the breeding or wintering grounds [Robinson, S. K., Thompson, F. R., Donovan, T. M., Whitehead, D. R. & Faaborg, J. (1995) Science 267, 1987-1990]. In contrast, research into declines of European species has mainly focused on intensification of agriculture [Donald, P. F., Green, R. E. & Heath, M. F. (2001) Proc. R. Soc. London Ser. B 268, 25-29] and the role played by the atmospheric deposition of pollutants, in particular, acid rain [Graveland, J. (1998) Environ. Rev. 6, 41-54]. However, despite widespread unexplained declines of bird populations in regions of heavy wet acid ion deposition [Sauer, J. R., Hines, J. E. & Fallon, J. (2001) The North American Breeding Bird Survey Results and Analysis 1966-2000 (Patuxent Wildlife Research Center, Laurel, MD)], no North American studies have presented evidence linking such widespread terrestrial bird declines to acid rain. To address the question of the role played by acid rain in population declines of eastern North American songbird species, we combine data from several sources. We use a multiple logistic regression model to test for adverse effects of acid rain on the Wood Thrush, while controlling for regional abundance, landscape-level habitat fragmentation, elevation, soil pH, and vegetation. We show a strong, highly significant, negative effect of acid rain on the predicted probability of breeding by this species, and interactions with elevation, low pH soils, and habitat fragmentation that worsen these negative effects. Our results suggest an important role for acid rain in recent declines of some birds breeding in the eastern United States, particularly in high elevation zones with low pH soils, and show the need to consider other large-scale influences, in addition to habitat fragmentation, when addressing bird population declines.

RESOURCES: Wildlife Crossing

Every June, birders across the country polish their binoculars, lace up their boots, and head off to count birds. The results from the Breeding Bird Survey, an annual event since 1966, reveal changes in bird populations across the country. Ornithologists can access and analyze the findings of surveys through 1999 at the Web site of the U.S. Geological Survey's Patuxent Wildlife Research Center in Laurel, Maryland.

Do polychlorinated biphenyls contribute to reproduction effects in fish-eating birds?

Environmental Toxicology and ChemistryVolume 20, Issue 6 p. 1149-1151 Letter to the Editor Do polychlorinated biphenyls contribute to reproduction effects in fish-eating birds? Thomas W. Custer, Thomas W. Custer U.S. Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, WisconsinSearch for more papers by this authorChristine M. Custer, Christine M. Custer U.S. Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, WisconsinSearch for more papers by this authorRandy K. Hines, Randy K. Hines U.S. Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, WisconsinSearch for more papers by this authorSteve Gutreuter, Steve Gutreuter U.S. Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, WisconsinSearch for more papers by this authorKenneth L. Stromborg, Kenneth L. Stromborg U.S. Fish and Wildlife Service, Green Bay, WisconsinSearch for more papers by this authorP. David Allen, P. David Allen U.S. Fish and Wildlife Service, Green Bay, WisconsinSearch for more papers by this authorMark J. Melancon, Mark J. Melancon U.S. Geological Survey, Patuxent Wildlife Research Center, Laurel, Maryland, USASearch for more papers by this author Thomas W. Custer, Thomas W. Custer U.S. Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, WisconsinSearch for more papers by this authorChristine M. Custer, Christine M. Custer U.S. Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, WisconsinSearch for more papers by this authorRandy K. Hines, Randy K. Hines U.S. Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, WisconsinSearch for more papers by this authorSteve Gutreuter, Steve Gutreuter U.S. Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, WisconsinSearch for more papers by this authorKenneth L. Stromborg, Kenneth L. Stromborg U.S. Fish and Wildlife Service, Green Bay, WisconsinSearch for more papers by this authorP. David Allen, P. David Allen U.S. Fish and Wildlife Service, Green Bay, WisconsinSearch for more papers by this authorMark J. Melancon, Mark J. Melancon U.S. Geological Survey, Patuxent Wildlife Research Center, Laurel, Maryland, USASearch for more papers by this author First published: 04 February 2010 https://doi.org/10.1002/etc.5620200602Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume20, Issue6June 2001Pages 1149-1151 RelatedInformation

UNUSUAL LEG MALFORMATIONS IN SCREECH OWLS FROM A SOUTH CAROLINA SUPERFUND SITE

In 1995, the discovery of leg malformations in several screech owl (Otis asio) nestlings and in their female parent at a Department of Energy (DOE) Superfund site in South Carolina prompted an investigation into the nature of the observed abnormalities. Surviving nestlings and the female parent were transferred to a captive screech owl breeding colony at the USGS Patuxent Wildlife Research Center, Laurel, MD. The malformed female parent and her offspring were each mated with normal owls from the colony for 3 yr. Matings of the malformed female produced five malformed and six normal owls; all owls produced by matings of normal offspring were normal. Malformed offspring were euthanized when it became apparent that their physical distress precluded survival under normal conditions of colony care. Euthanized owls were necropsied and examined for skeletal development. Detailed descriptions of eight malformed owls are presented. Results of the matings indicated that the leg malformations were caused by a genetic trait in the female parent that was heterozygous dominant. The characteristic was lethal except in occasional mild manifestations and resembled an extreme form of a dominant abnormality previously described for domestic fowl called duplicate polydactyly. Other reports of skeletal abnormalities in wild birds and potential environmental causes of genetic mutations at the DOE Superfund site are presented. Other studies performed at the DOE Superfund site do not implicate elevated (above background) ionizing radiation from 137Cs, the dominant radionuclide where the owls were captured, as the cause of the mutation. The cause of this genetic abnormality remains unknown.

Editorial - A Good Story Ruined by the Facts?

Editorial: A Good Story Ruined by the Facts… Frederick W. Stoss SUNY University at Buffalo, USA On Friday, March 16, 2001, the same email message from several prestigious and trustworthy sources was sent under the subject: USGS Scientist fired over Arctic National Wildlife Refuge maps. The message contained the URL to a March 15 story running in the Los Angeles Times describing in journalistic prose the same account of the e-mail's message. A lengthy letter from the mapping specialist about his firing was included at the end of the email message. Initial transmissions of the message were coming from researchers who had solid reputations for their research and policy actions over decades. Other origins of the message included professional associations who had worked on countless issues with many previous administrations. Reputable scientists, trusted associations, noted individuals, a newspaper story, and the first- hand account of the unjustly dismissed scientist. This was REAL news! At the core of this issue was the posting of maps of caribou calving areas in the Arctic National Wildlife Refuge on the Web site of the (Department of Interior) U.S. Geological Survey's Geospatial Technology Activities at the Patuxent Wildlife Research Center . Given the sensitivity of the issues surrounding drilling for oil in the Arctic National Wildlife Refuge (ANWR) and the general anti-environmental rhetoric flowing around President George W. Bush's administration, many people thought this story was the smoking gun. It was described as the extent to which the Bush Administration would go to thwart attempts to prevent tapping the oil resources in ANWR. Soon cries of Foul! Outrage! Censorship! accompanied the message as it was forwarded on to environment, ecology, natural resources, library, and other discussion lists around the world. Scientists began to comment, while routing the original story on to colleagues, that this was an affront to all scientists doing research under the auspices of the federal government. Federal scientists questioned whether their integrity as scientists was going to be compromised to support political rather than scientific principles. And they had proof-positive with these messages that a new policy of threats and intimidation was just around the corner. This story spread on the Internet like a wild fire. It was the story that so many people wanted to believe. It was the story that so many people cited as exactly how our environment and the scientists who study it were going

Species Richness of the Campopleginae and Ichneumoninae (Hymenoptera: Ichneumonidae) Along a Latitudinal Gradient in Eastern North American Old-Growth Forests

We ran 10 Malaise traps along a latitudinal gradient in five old-growth forests: San Felasco Hammock, FL (30° N, 82° W); Tall Timbers Research Station, FL (31° N, 84° W); Hitchiti Experimental Forest, GA (33° N, 84° W); Patuxent Wildlife Research Center, MD (39° N, 77° W), and Shaw Woods, Ontario (46° N, 77° W). Of 18,791 ichneumonid wasps collected, 1,487 campoplegines and 4,494 ichneumonines were sorted to 241 species (95 species of Campopleginae and 146 of Ichneumoninae). Campoplegine species richness was highest at the Georgia site: San Felasco (20 species), Tall Timbers (32), Hitchiti (49), Patuxent (35), and Shaw Woods (12). Ichneumonine species richness was highest at the Maryland site: San Felasco (47), Tall Timbers (30), Hitchiti (44), Patuxent (68), and Shaw Woods (37). The results confirm reported trends that peak North American ichneumonid species richness lies at midlatitudes. However, they document greater biodiversity in the southern states and a broader peak than previously reported.

Effects of the mosquito larvicides temephos and methoprene on insect populations in experimental ponds

AbstractThe nontarget effects of Abate® 4E (44.6% temephos) at 0.054 kg of active ingredient (a.i.) per 1 ha and of Altosid® Liquid Larvicide (5% methoprene) at 0.011 kg a.i./ha were investigated in 18 experimental ponds (average area, 202 m2; maximum depth, 0.7 m) at Patuxent Wildlife Research Center, Laurel, Maryland, USA. Ponds were sprayed three times at 3‐week intervals. Six ponds were sprayed with Abate, six with Altosid, and six with distilled water. Two insect‐emergence traps per pond collected for 7 d and were then harvested 1 d before each spray and 13 to 14 days afterward. A repeated measures analysis of variance (ANOVA) revealed significant reductions in Shannon diversity, equitability, and numbers of individuals, species, and families in the Abate ponds relative to controls. Significant reductions also occurred in Ephemeroptera, Odonata, Diptera, Chironomidae, and Chaoborus sp. Hester‐Dendy samplers were installed before spray one and harvested 16 d after spray three. Based on one‐way ANOVA, Shannon diversity, equitability, and number of Ephemeroptera and Chironomidae were significantly reduced in the Abate ponds. Emergence data indicate only isolated cases with significant reductions in the Altosid ponds relative to controls, and the Hester‐Dendy data indicate no significant differences between the Altosid and control ponds.

Evolving dispersal: where to go next?

Habitat destruction and global climate change are two major threats to the persistence of ecosystems. The probability that a species survives such changes depends on its ability to track environmental shifts, either by moving between patches of habitat or by rapidly adapting to local conditions. This explains why the evolution of dispersal has become an integrative topic of paramount importance in evolutionary and behavioral ecology, as demonstrated by a recent conference * ‘The evolution of dispersal: causes, consequences and mechanisms at the individual, population and community level’, was held in Roscoff (France) in April 1999. The meeting was supported by NSF and CNRS, and was organized by Etienne Danchin (University of Paris, France), Jean Clobert (University of Paris), Andre Dhondt (Cornell University, USA) and Jim Nichols (Patuxent Wildlife Research Center, USA). *‘The evolution of dispersal: causes, consequences and mechanisms at the individual, population and community level’, was held in Roscoff (France) in April 1999. The meeting was supported by NSF and CNRS, and was organized by Etienne Danchin (University of Paris, France), Jean Clobert (University of Paris), Andre Dhondt (Cornell University, USA) and Jim Nichols (Patuxent Wildlife Research Center, USA).. A wide panel of researchers, who highlighted the recent major advances and the most promising lines of future research, were present at this meeting.

Fifty-year trends in a box turtle population in Maryland

A survey conducted in 1995 investigated long term declines reported in a population of box turtles Terrapene carolina monitored each decade since 1945 in bottomland hardwood forest at the Patuxent Wildlife Research Center, Maryland. Methods duplicated past surveys in most respects, but were supplemented by radiotelemetry and a survey of dominant vegetation. Seventy different turtles were found on the 11.8 ha study area, a decline of >75% since peak populations were recorded in 1955. Searchers were less efficient in 1995 than in 1945–1975 for a variety of possible reasons. Among turtles recorded, approximately equal numbers persisted from each of the past five decades, with some individuals surviving >70 years. A sex ratio strongly favoring males was first recorded in 1975 and continued in 1995, but juveniles and subadults were found in greater proportion in 1995 than in any other survey. Six of nine radio-marked turtles left the bottomland study area and migrated to the adjoining bluffs to hibernate, suggesting more extensive movements and perhaps less stable home ranges than formerly thought. Age structure of trees indicated a gradual change to more shade-tolerant species. Examination of rates of change from survey data suggested that major losses probably resulted from changes in hydrology that exacerbated flooding in 1972, with recovery only beginning in 1995 and perhaps limited both by repeated flood events and successional changes in the forest. Slow recovery from losses may indicate that populations of this species would respond poorly to exploitation. ©

Long-Term Movement Patterns for Seven Species of Wading Birds

-We obtained banding and recovery records from 1914 through 1994 for seven species of wading birds from the Bird Banding Laboratory, United States Geological Survey, Patuxent Wildlife Research Center. We analyzed these data to evaluate differences in dispersal distance and frequency of dispersal movement among species. All records were from birds banded as juveniles and recovered at least five months later between March and July, which is the breeding season in most regions of North America. Focusing on recoveries during the breeding season reduced the chance that movements were related to migration rather than dispersal. When an individual was banded and recovered in the same ten-minute block of latitude and longitude, a movement distance of zero km was recorded. The frequency of zero-distance records provides an indication of breeding site fidelity for each species at a spatial resolution of ten minutes. Our results showed that mean dispersal distance was greatest for the Little Blue Heron (Egretta caerulea; 1148 km) followed by Glossy Ibis (Plegadis falcinellus; 1142 km), Tricolored Heron (Egretta tricolor 1019 km), Great Egret (Casmerodius albus; 909 km), Snowy Egret (Egretta thula; 837 km), Great Blue Heron (Ardea herodias; 758 km), and White Ibis (Eudocimus albus; 545 km). Species which dispersed large distances also exhibited fewer zero-distance records, indicating greater movement frequency. The White Ibis has been classified as a nomad, at one end of a continuum defined by low breeding site-fidelity and several life history traits associated with unpredictable foraging habitat. We found that White Ibises were indeed recovered at new locations the majority (76%) of the time but that the other six species of wading birds we examined were even more likely to move to different sites during subsequent breeding seasons. Movement distance and site fidelity will both likely affect whether a response to habitat restoration is due to immigration or local reproduction. Although an increase in total birds using a restored habitat may be an indication of increased habitat quality, caution should be used in inferring population changes without understanding reproduction, mortality, and movement of individuals using restored habitats. Received 20July 1999, accepted 8 September 1999.

Investigation into semen characteristics of naturally-fertile pairs in vitro and their correlation with fertility in Florida Sandhill crane

Semen characteristics of naturally fertile pairs and their correlation with fertility of eggs in Florida sandhill crane (Grus canadensis pratensis) were examined. Six pairs were used in this experiment, and all of them that had bred before were housed in open individual pens. These pairs were isolated physically each other but not visually and audibly. Semen was collected twice (Tuesday morning and Friday afternoon) from February 26 to June 4, 1993. The standard methods at Patuxent Wildlife Research Center were used collecting and evaluating the semen and spermatozoa, and incubating the eggs. There were statistically individual variations (p<0.05) about successful collecting attempts, semen volume, semen concentration, spermatozoon’s motility, spermatozoon’s number per collection, live spermatozoon’s number, male’s response to semen collection, and morphology of spermatozoa except the giant cell. There was a significantly (p<0.05, correlation coefficient was (0.73 or (1.00) negative correlation between fertility of eggs and, the multiple value of semen (sperm) characteristics of naturally fertile pairs in Florida sandhill crane.

Numts: A Challenge for Avian Systematics and Population Biology

CONFER, J. L. AND K. KNAPP. 1981. Golden-winged Warblers and Blue-winged Warblers: The relative success of a habitat specialist and a generalist. Auk 98:108-114. FICKEN, M. S., AND R. W. FICKEN. 1968. Territorial relationships of Blue-winged Warblers, Goldenwinged Warblers, and their hybrids. Wilson Bulletin 80:161-172. GILL, F. B. 1980. Historical aspects of hybridization between Blue-winged and Golden-winged warblers. Auk 97:1-18. GILL, F. B. 1997. Local cytonuclear extinction of the Golden-winged Warbler. Evolution 51:519-525. GILL, F. B., AND W. E. LANYON. 1964. Experiments on species discrimination in Blue-winged Warblers. Auk 81:53-64. GILL, F. B., AND B. G. MURRAY, JR. 1972. Discrimination behavior and hybridization of the Bluewinged and Golden-winged warblers. Evolution 26:282-293. HANDS, H. M., R. D. DROBNEY, AND M. R. RYAN. 1989. Status of the Golden-winged Warbler in the northcentral United States. United States Fish and Wildlife Service, Twin Cities, Minnesota. HILL, N. P., AND J. M. HAGAN III. 1991. Population trends of some northeastern North American landbirds: A half-century of data. Wilson Bulletin 103:165-182. HOLMES, R. T., T. W. SHERRY, AND F. W. STURGES. 1986. Bird community dynamics in a temperate deciduous forest: Long-term trends at Hubbard Brook. Ecological Monographs 50:201-220. LITVAITIS, J. A. 1993. Response of early successional vertebrates to historic changes in land use. Conservation Biology 7:866-873. MURRAY, B. G., JR., AND F. B. GILL. 1976. Behavioral interactions of Blue-winged and Golden-winged warblers. Wilson Bulletin 88:231-254. RAPPOLE, J. H., AND M. V. McDoNALD. 1994. Cause and effect in population declines of migratory birds. Auk 111:652-660. SAUER, J. R., J. E. HINES, G. GOUGH, I. THOMAS, AND B. G. PETERJOHN. 1997. The North American Breeding Bird Survey home page, version 96.3. Patuxent Wildlife Research Center, Laurel, Maryland. SCHEIDER, F. 1959. Warblers in southern New York. Kingbird 9:13-19. SMITH, C. R., D. M. PENCE, AND R. J. O'CONNOR. 1993. Status of Neotropical migratory birds in the northeast: A preliminary assessment. Pages 172-188 in Status and management of Neotropical migratory birds (D. M. Finch and P. W. Stangel, Eds.). United States Forest Service General Technical Report RM-229, Newton Corner, Massachusetts. WILL, T. C. 1986. The behavioral ecology of species replacement: Blue-winged and Golden-winged warblers in Michigan. Ph.D. dissertation, University of Michigan, Ann Arbor. WITHAM, J. W, AND M. L. HUNTER, JR. 1992. Population trends of Neotropical migrant landbirds in northern coastal New England. Pages 85-95 in Ecology and conservation of Neotropical migrant landbirds (J. M. Hagan III and D. W Johnston, Eds.). Smithsonian Institution Press, Washington, D.C.

Efficacy of eastern equine encephalitis immunization in whooping cranes.

An epizootic of eastern equine encephalitis (EEE) at the Patuxent Wildlife Research Center (PWRC), Laurel, Maryland (USA), in 1989 provided an opportunity to determine if EEE immunization protected whooping cranes (Grus americana). Based on seroconversion of 31% of sympatric hatch-year sandhill cranes, Grus canadensis, and a previous 35% case fatality rate in whooping cranes, 17 (37%) of the 46 susceptible whooping cranes should have been exposed to virus and six should have died. As there were no deaths in these birds, the EEE vaccination program appeared to be efficacious in this whooping crane population.

Watershield Use by Ring-Necked Ducks

During 1993-94 and 1994-95 the amount of watershield {Brasenia schreberi) in selected Maryland wetlands was determined to see if any relationship existed between the amount of watershield on a wetland and the number of ring-necked ducks {Aythya collaris) observed on that wetland. Data were collected for two years from eight different wetlands on the Patuxent Wildlife Research Center in Laurel, Maryland. Results indicate that there was no significant correlation between the amount of watershield in a wetland and the number of ring-necked ducks observed on that wetland.

An epizootic of Tanaisia bragai in a captive population of Puerto Rican plain pigeon (Columba inornata wetmorei).

Annals of the New York Academy of SciencesVolume 653, Issue 1 p. 202-205 An Epizootic of Tanaisia bragai in a Captive Population of Puerto Rican Plain Pigeon (Columba inornata wetmorei) A. B. ARNIZAUT, A. B. ARNIZAUT Department of Natural Resources San Juan, Puerto Rico 00906 Department of Biology University of Puerto Rico-Humacao Campus Humacao, Puerto Rico 00791 P.O. Box 1553, Luquillo, Puerto Rico 00773.Search for more papers by this authorL. HAYES, L. HAYES Southeastern Cooperative Wildlife Disease Study Athens, Georgia 30602Search for more papers by this authorG. H. OLSEN, G. H. OLSEN Patuxent Wildlife Research Center Laurel, Maryland 20708Search for more papers by this authorJ. S. TORRES, J. S. TORRES Caguas Veterinary Hospital Caguas, Puerto Rico 00726Search for more papers by this authorC. RUIZ, C. RUIZ Department of Natural Resources San Juan, Puerto Rico 00906 Department of Biology University of Puerto Rico-Humacao Campus Humacao, Puerto Rico 00791Search for more papers by this authorR. PÉREZ-RIVERA, R. PÉREZ-RIVERA Department of Biology University of Puerto Rico-Humacao Campus Humacao, Puerto Rico 00791Search for more papers by this author A. B. ARNIZAUT, A. B. ARNIZAUT Department of Natural Resources San Juan, Puerto Rico 00906 Department of Biology University of Puerto Rico-Humacao Campus Humacao, Puerto Rico 00791 P.O. Box 1553, Luquillo, Puerto Rico 00773.Search for more papers by this authorL. HAYES, L. HAYES Southeastern Cooperative Wildlife Disease Study Athens, Georgia 30602Search for more papers by this authorG. H. OLSEN, G. H. OLSEN Patuxent Wildlife Research Center Laurel, Maryland 20708Search for more papers by this authorJ. S. TORRES, J. S. TORRES Caguas Veterinary Hospital Caguas, Puerto Rico 00726Search for more papers by this authorC. RUIZ, C. RUIZ Department of Natural Resources San Juan, Puerto Rico 00906 Department of Biology University of Puerto Rico-Humacao Campus Humacao, Puerto Rico 00791Search for more papers by this authorR. PÉREZ-RIVERA, R. PÉREZ-RIVERA Department of Biology University of Puerto Rico-Humacao Campus Humacao, Puerto Rico 00791Search for more papers by this author First published: June 1992 https://doi.org/10.1111/j.1749-6632.1992.tb19647.xCitations: 10 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume653, Issue1Tropical Veterinary Medicine: Current Issues and PerspectivesJune 1992Pages 202-205 RelatedInformation

Captive breeding and reintroduction of the endangered masked bobwhite

AbstractEfforts to restore the endangered masked bobwhite (Colinus virginianus ridgwayi) to its former range have required 1) habitat acquisition, restoration, and preservation; 2) captive propagation; and 3) reintroduction of captive‐bred stock. In its role to recover the masked bobwhite, the Patuxent Wildlife Research Center (U.S. Fish and Wildlife Service) has refined captive breeding techniques; provided captive‐produced stock for release; conducted field research on the distribution, limiting factors, and habitat characteristics of this species; and developed release methods. Techniques for the husbandry and captive management, breeding, artificial incubation and hatching of eggs, and rearing of young of the masked bobwhite have been developed. Successful reintroduction techniques for the masked bobwhite have included prerelease conditioning and/or cross‐fostering of captive‐reared masked bobwhite chicks to a wild‐caught, related, vasectomized bobwhite species and their release to the wild as family units. In addition, the establishment by the U.S. Fish and Wildlife Service of the Buenos Aires National Wildlife Refuge in 1985 has further enhanced the potential for establishing a self‐sustaining population of the masked bobwhite in the U.S. Through continued releases and active management of habitat, therefore, it is believed that the masked bobwhite can become permanently established at the refuge to ensure its continued survival in the wild.

Relationship between Age and Mass Among Female White-Tailed Deer during Winter and Spring

Journal Article Relationship between Age and Mass Among Female White-Tailed Deer during Winter and Spring Get access L. David Mech, L. David Mech U.S. Fish and Wildlife Service, Patuxent Wildlife Research Center, Laurel, MD 20708U.S. Forest Service, North Central Forest Experiment Station, 1992 Folwell Avenue, St. Paul, MN 55108 Search for other works by this author on: Oxford Academic Google Scholar Ronald E. McRoberts Ronald E. McRoberts U.S. Fish and Wildlife Service, Patuxent Wildlife Research Center, Laurel, MD 20708U.S. Forest Service, North Central Forest Experiment Station, 1992 Folwell Avenue, St. Paul, MN 55108 Search for other works by this author on: Oxford Academic Google Scholar Journal of Mammalogy, Volume 71, Issue 4, 7 December 1990, Pages 686–689, https://doi.org/10.2307/1381808 Published: 07 December 1990 Article history Received: 07 October 1988 Accepted: 30 November 1989 Published: 07 December 1990

Survival of White-Tailed Deer Fawns in Relation to Maternal Age

Journal Article Survival of White-Tailed Deer Fawns in Relation to Maternal Age Get access L. David Mech, L. David Mech U.S. Fish and Wildlife Service, Patuxent Wildlife Research Center, Laurel, MD 20708U.S. Forest Service, North Central Forest Experiment Station, 1992 Folwell Ave., St. Paul, MN 55108 Search for other works by this author on: Oxford Academic Google Scholar Ronald E. McRoberts Ronald E. McRoberts U.S. Fish and Wildlife Service, Patuxent Wildlife Research Center, Laurel, MD 20708U.S. Forest Service, North Central Forest Experiment Station, 1992 Folwell Ave., St. Paul, MN 55108 Search for other works by this author on: Oxford Academic Google Scholar Journal of Mammalogy, Volume 71, Issue 3, 28 August 1990, Pages 465–467, https://doi.org/10.2307/1381963 Published: 28 August 1990

Estimation of Recruitment from Immigration Versus In Situ Reproduction Using Pollock's Robust Design

Recruitment to animal populations can occur through both immigration and in situ reproduction. These two components of recruitment are conceptually distinct and lead to different mechanistic models of population dynamics. We describe a capture—recapture design that can be used to obtain separate estimates of two recruitment components. We then illustrate the use of our method and estimators with capture—recapture data from a population of Microtus pennsylvanicus at the Patuxent Wildlife Research Center in Maryland.

Summer-Fall Survival of American Woodcock in Maine

We estimated summer-fall (15 Jun-20 Oct) survival for 32 adult and 96 fledged young American woodcock (Scolopax minor) radiotagged in eastern Maine during 1982-84 using single-interval, multipleinterval, and nonparametric (product-limit) methods. Single-interval survival estimates were 0.90, 0.88, 0.57, and 0.73 for adult males, adult females, young males, and young females, respectively. Multiple-interval survival estimates (0.93, 0.88, 0.63, and 0.71) and product-limit estimates were similar (0.92, 0.90, 0.60, and 0.69). Within each age class, male and female period survival was not significantly different for any method. However, point estimates of survival for young females exceeded those of young males by 0.08-0.16. Regardless of sex, adults exhibited higher summer-fall survival (range = 0.89-0.92) than young woodcock (range = 0.64-0.68). Age-specific variation in survival was caused by different predation rates that may be related to age-specific differences in mobility. The survival rates sustained by young woodcock during our study were similar to 4-month rates derived from annual survival estimates that assume constant mortality throughout the year. The high summer-fall survival estimates exhibited by adult woodcock suggest that most of their annual mortality occurs during another season. J. WILDL. MANAGE. 54(1):97-106 Because of the long-term decline of American woodcock in the eastern United States (Tautin et al. 1983) the U.S. Fish and Wildlife Service (USFWS) implemented woodcock harvest restrictions in 1985. Changes in habitat conditions, through forest succession and urbanization, are believed largely responsible for the decline (Dobell 1977, Coulter and Baird 1982, Dwyer et al. 1983). However, the exact mechanisms that have resulted in lower recruitment or survival remain largely unexamined. To define the relationship between woodcock survival and habitat conditions, information is needed on timeand causespecific mortality factors. Estimates of annual survival for American woodcock relied on return rates of breeding birds (Sheldon 1956, 1967), life tables (Godfrey 1974), or band recoveries from hunters (Martin et al. 1969, Krohn et al. 1974, Dwyer and Nichols 1982). Analysis of band recoveries is least biased with the development of band-return and markrecapture models (Brownie et al. 1978). However, precise estimates of annual survival of woodcock are difficult to obtain because of the large sample sizes required by banding models (Dwyer and Nichols 1982). Fortunately, application of more rigorous statistical methods used in conjunction with radio-telemetry data permit relatively unbiased time-specific survival estimates from studies of free-ranging animals (Mayfield 1961, 1975; Trent and Rongstad 1974; Ri gleman and Longcore 1983; Cowardin et al. 1985; Heisey and Fuller 1985; Kirby and Cowardin 1986; Kurzejeski et al. 1987; Pollock et al. 1989). Our objectives were to estimate ageand sex-specific survival of American woodcock from June to October and compare survival estimates among 3 statistical methods with differing assumptions on survival constancy within the study period. We acknowledge C. M. Bunck, S. R. Winterstein, and G. L. Hensler for statistical consultation and thank G. L. Storm, T. J. Dwyer, M. A. Howe, C. M. Bunck, J. R. Sauer, R. H. Yahner, and W. M. Tzilkowski for thoughtful reviews of the manuscript. Support was providby the Patuxent Wildlife Research Center, the Moosehorn National Wildlife Refuge, the Pennsylvania Cooperative Wildlife Research Unit, the Ruffed Grouse Society, and the National Rifle Association.