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E.L. Derleth

Publications and source records attributed to E.L. Derleth.

11 recordsLinked to original sources
USGS1990

American woodcock winter distribution and fidelity to wintering areas

We examined winter distribution and fidelity to wintering areas for the American Woodcock ( Scolopax minor ), which exhibits reversed, sexual size dimorphism. Band-recovery data revealed no difference in winter distributions of different age/sex classes for woodcock from the same breeding ares. Similarly, band recoveries from woodcock banded on wintering grounds revealed no difference in fidelity to wintering sites. Males may winter north of a latitude that is optimal for survival based on physiological considerations, but they gain a reproductive advantage if they are among the first to arrive on the breeding grounds. This may explain our results, which indicate males and females have similar distribution patterns during winter.

The Auk↗
USGS1989

Avian community response to small-scale habitat disturbance in Maine

The effects of small clearcuts (1 - 8 ha) on avian communities in the forest of eastern Maine were studied using point counts during spring 1978 - 1981. Surveys were conducted in uncut (control) and clear-cut (treatment) plots in three stand types: conifer, hardwood, and mixed growth. We used a mark-recapture model and its associated jackknife species richness estimator (N), as an indicator of avian community structure. Increases in estimated richness (N) and Shannon - Weaver diversity (H') were noted in the treated hardwood and mixed growth, but not in the conifer stands. Seventeen avian species increased in relative abundance, whereas two species declined. Stand treatment was associated with important changes in bird species composition. Increased habitat patchiness and the creation of forest edge are hypothesized as causes for the greater estimates of richness and diversity.

Maine↗
USGS1988

Demographic Characteristics of a Maine Woodcock Population and Effects of Habitat Management

A population of American woodcock (Scolopax minor) was studied on a 3,401-ha area of the Moosehorn National Wildlife Refuge in northeastern Maine from 1976 through 1985. During 1976-83, from 4 to 64 clearcuts were created each year, opening up large contiguous blocks of forest. A combination of mist nets, ground traps, nightlighting techniques, and trained dogs were used to capture and band 1,884 birds during the first 5 years. Capture and recapture data (totaling 3,009 observations) were used with both demographically closed and open population models to estimate population size and, for open population models, summer survival. Flying young, especially young males, represented the greatest proportion of all captures; analysis showed that young males were more prone to capture than young females. Male courtship began about 24 March each year, usually when there was still snow in wooded areas. Males ~2 years old dominated singing grounds during April each year, but this situation changed and first-year males dominated singing grounds in May. Singing males shifted from older established singing grounds to new clearcuts soon after we initiated forest management. Many males were subdominant at singing grounds despite an abundance of unoccupied openings. Three hundred adult females were captured and, except for 1978, the majority were ~2 years old. The year in which female homing rate was lowest(1979) was preceded by the year with the largest number of l-year-old brood female captures and a summer drought. Summer survival of young was lowest in 1978 and was attributed to summer drought. The year 1979 had an abnormally cool and wet spring, and was the poorest for production of young. Capture ratios of young-to-adult females obtained by nightlighting could be used to predict production on our study area. Closed population model estimates did not seem to fit either young or adult data sets well. Instead, a partially open capture-recapture model that allowed death but no immigration seemed to fit best. Only the number of males in the population changed significantly during the study. An increase from 88 males in 1976 to 156 in 1980 was attributed to habitat management. Singingmale surveys on our area detected little change in the number of singing males, but our independent population estimates from mark-recapture data showed a larger total male population by 1980. Annual density estimates for all age and sex classes ranged from 19 to 25 birds/l00 ha. A hypothesis on the breeding system of the American woodcock is presented as well as a discussion of management implications, including the importance of creating high-quality habitat on private lands.

Fish and Wildlife Research↗
USGS1987

A quick-catch corral trap for wintering canvasbacks

We designed a bait trap for wintering Canvasbacks (Aythya valisineria) that has proven more effective than conventional funnel or slot entrance traps for diving ducks. The unique feature of this trap is the corral entrance that presents unimpaired access to the bait and thus ease of entrance to the trap. Catches of 50-75 ducks have been made in a matter of minutes at prebaited sites.

Journal of Field Ornithology↗
USGS1985

An aerial photographic census of Chesapeake Bay and North Carolina canvasbacks

We used conventional 35-mm photography to conduct an aerial photographic census of canvasbacks ( Aythya valisineria ) throughout Chesapeake Bay (tidal Maryland and Virginia) and coastal North Carolina, 26-30 January 1981. Flock size and sex ratio characteristics were determined from examination of color transparencies of 165 canvasback flocks totaling over 95,000 birds. A sex ratio of 2.91 males/female was determined from 68,769 birds, 80% of the birds in 150 flocks. Sex ratio for the Atlantic Flyway was projected as 2.90 males/female. We recorded the greatest number of canvasbacks and the widest range of flock size in Maryland waters; the fewest canvasbacks and the smallest average flock size in Virginia; and the fewest but on average the largest flocks of canvasbacks in North Carolina. Sex ratio varied latitudinally in the flyway with a tendency for males to occupy more northern and females more southern latitudes in winter. Sex ratio (males/female) was highest in Maryland (3.98), slightly lower in Virginia (3.71), and lowest in North Carolina (1.70). Locally, sex ratio varied with flock size. In Chesapeake Bay, small flocks (<100 birds) had lower sex ratio (P < 0.05) than medium (100-1,000) or large (>1,000) flocks. By providing large- sample sex ratio information, as well as exact counts of birds, we conclude that low-level 35-mm aerial photography is the most efficient and accurate means of determining canvasback population status in eastern coastal habitats.

Maryland, North Carolina, Virginia↗
USGS1982

Woodcock brood ecology in Maine

Captures of 102 American woodcock (Philohela minor) broods, including 338 chicks, from 1977 to 1980 provided data on age-related production by breeding females and on growth and survival of chicks. Although broods of second-year females are smaller and hatch at slightly later dates and the growth of the chicks is slower than that of broods of after-second-year hens, we could detect no difference in survival of the chicks. Yearly variation in the sex ratio of fledged young was probably the result of selection for or against larger female chicks during different environmental conditions. Broodmates associate with each other throughout the summer, and there are differences in habitat preferences between young (1-5 days old) and older (> 5 days old) broods. Older broods prefer more open, mature forest stands with fewer trees per hectare.

Book chapter↗
USGS1982

Techniques for trapping, aging, and banding wintering canvasbacks

Techniques used to trap, band, and determine age of Canvasbacks during winter on Chesapeake Bay are presented. Canvasbacks were captured with welded-wire traps baited with corn. Two trap designs were used and traps and trapping techniques are described. Ducks were dipnetted from traps and held in modified poultry crates that provided seclusion and ventilation and allowed birds to dry unsoiled. Carney's (1964) wing plumage methodology was found most efficient in determining age of Canvasbacks during large-scale bandings. This technique was rapid and was easily taught to inexperienced personnel. In contrast, the cloacal technique could be performed efficiently only by experienced and skillful banders. Band wear was observed to vary widely on individual birds and rounding of bands was recognized as an important technique in extending band life. Bands were placed upside down on the tarsus so that wear along the upper edge would be less likely to destroy band numbers. In 5 winter seasons, over 17,000 Canvasbacks were captured. Mortality rate for the program was .3%.

Journal of Field Ornithology↗