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231 records · Page 13Linked to original sources
USGS1994

Distribution and abundance of birds wintering in Maryland, 1988-1993

A winter bird survey was conducted throughout Maryland, primarily by volunteers, during the 6 winters of 1988 to 1993 between the dates of 10 Jan and 10 Feb. The state of Maryland is covered by 1231 blocks (9.5 sq. miles each), each comprising one-sixth of the standard U.S.G.S. 7.5 minute topographic quadrangle, and 548 of these blocks (44.5%) were surveyed for winter birds. Blocks were chosen in a systematic pattern with eventually almost every other block in the state having been surveyed as of Feb, 1993. Volunteers conducted each 4-hour survey by walking a 4-6 mile route chosen by the volunteer to sample habitats in proportion to their availability in the block. Surveys began around sunrise (~7:30 a.m.) and all birds seen or heard during the 4 hours were recorded on data sheets. The data were then used to create maps representing the distribution and relative abundance of each species of wintering bird found in at least 10 blocks in the state.

Maryland Birdlife↗
USGS1978

The breeding bird atlas of Montgomery and Howard Counties, Maryland

A pilot Breeding Bird Atlas was initiated during 1971 in Montgomery County. A second atlas was begun during 1973 in Howard County. The Montgomery project was completed in 1973 and the Howard project in 1975......A total of 138 species were recorded for the two counties (129 confirmed, 7 probable, 2 possible). Montgomery County had 135 species recorded (122 confirmed, 9 probable, 4 possible) and Howard County had 127 species (110 confirmed, 7 probable,10 possible)......Thirty-two species were found in all 5-km blocks and eight were found in all 5-krn and 21/2-km blocks. Two species were confirmed in all blocks.......There were 11 new Montgomery County breeding records and eight new Howard County records. Nine species were found only in Montgomery County and two only in Howard County. Twelve species were confrmed in Montgomery County but not in Howard; five were confirmed in Howard County but not in Montgomery. Ninety-eight species were confirmed on active nests in Montgomery County and 85 in Howard County.

Maryland Birdlife↗
USGS1973

Sea birds wintering off Maryland shores, 1972-73

During the winter of 1972-73, studies were conducted to determine the status and distribution of pelagic species of birds occurring at sea as far as 38 miles east of Ocean City, Md. The wintering off-shore avifauna was found to be impressively rich in variety of species and numbers of individuals. Sightings included Fulmar and Skua, both first sight records for Maryland. Large alcids, especially Razorbills, were observed in unprecedented numbers and on five of the seven trips undertaken. Thick-billed Murre was sighted once and Dovekie, once. A Pomarine Jaeger was a mid-winter first for Maryland. Black-legged Kittiwakes were sighted on all seven trips, with age ratios consistently averaging about three adults to one immature. Likewise, Gannets were observed on all seven trips, 7.5 adults to one immature. Iceland Gulls were seen twice and Black-headed Gulls on three trips. Evidence of a definite migration was noted on Nov. 19, as Gannets were observed flying south in a narrow band, four miles wide, five to nine miles east of Ocean City, and Black-legged Kittiwakes, likewise, were heading south in a steady stream no closer than 14 miles east of Ocean City. Data accumulated from December through March suggest most pelagics occurring in Maryland waters during this period were truly wintering and not transients. This report is concerned primarily with the true pelagics normally found well away from the sight of land and does not dwell on those 'sea birds' commonly seen in immediate coastal waters.

Maryland Birdlife↗
USGS2014

Chromic and iron oxides as fecal markers to identify individual whooping cranes

The whooping crane ( Grus americana ) is listed as endangered under the IUCN Red List, the United States Endangered Species Act, and the Canadian Species at Risk Act (BirdLife International 2012, CWS and USFWS 2007). A major focus of recovery efforts for this endangered species is reintroduction to establish new populations (CWS and USFWS 2007). Captive populations are critical as a source of individuals for reintroduction efforts and also serve as insurance populations. Currently, there are a total of 157 whooping cranes held in captive breeding centers across North America, with the largest at the USGS Patuxent Wildlife Research Center (PWRC) in Laurel, Maryland. Birds produced in this facility are currently being released as part of efforts to establish the Eastern Migratory Population (EMP, Urbanek et al. 2005) and in an effort to establish a non-migratory population in Louisiana. In the past decade, PWRC has produced and released annually an average of 18 birds into the wild; however, reproductive performance of birds at this facility is lower than desired. PWRC had a 60% fertility rate for eggs laid from 2000 through 2010 (J. N. Chandler, personal communication, 2011). Furthermore, reproductive onset in this captive population appears to be delayed compared to wild populations. In wild populations, reproductive onset (production of sperm and eggs) normally occurs ~5 years of age in both males and females, ~2 years after initial pair formation occurs (Ellis et al., 1996), while some females in the EMP have laid eggs earlier than 5 years of age (Converse et al. 2011). However, PWRC females in some cases do not start to lay eggs until 7 years of age (Mirande et al. 1996). Currently, the PWRC population consists of a total of 74 whooping cranes, including 22 pairs. Six of these pairs (27%) are consistently infertile (i.e., no production of fertile eggs) and 3 other pairs (14%) have low fertility (30- 45% fertility in eggs laid), which is variable from year to year. Six pairs (27%) are recently formed and have not produced eggs, and so have unknown fertility. This leaves only 7 pairs (33%) which contribute maximally to PWRC’s chick production (J. N. Chandler, personal communication, 2011). Because of the challenges occurring within this captive colony, PWRC and Smithsonian National Zoo have initiated a joint research project to identify potential underlying causes of poor reproduction in captive whooping cranes.

Conference Paper↗