Publications

Density, age-specific survival, timing of breeding and molting, and movements of the Omao or Hawaiian Thrush (Myadestes obscurus) were studied at four sites on the island of Hawaii. Mean monthly density (birds/ha) was 3.23 +- 0.57, 1.07 +- 0.33, 3.23 +- 0. 16, and 3.74 +- 0.36 at Kau Forest, Hamakua. Keauhou Ranch, and Kilauea Forest study areas, respectively. Annual survival of juvenile...

No abstract available.

Because count data collected in many bird surveys are only an index to population size, factors that can influence the counts must be identified and incorporated into analyses. Observer quality is often ignored in analyses of population changes from survey data, but observers differ in methods and capabilities and, hence, tend to count different numbers of birds. We assess the...

We studied populations of the endangered Akepa (Loxops coccineus coccineus) and Hawaii Creeper (Oreomystis mana) at four sites on the island of Hawaii. Mean monthly density (? SL) of Akepa was 5.74 t 0.87, 1.3? 0.41, 0.96 -? 0.13, and 0.76 ? 0.12 Akepa/ha at Kau Forest, Hamakua, Keauhou Ranch, and Kilauea Forest study areas, respectively. Hawaii Creepers were found at densities of 1.68...

The timing of breeding and molting was studied in six species of Hawaiian honeycreepers with differing food habits on the Island of Hawaii. The availability of nectar was highly seasonal, whereas insect abundance was relatively constant throughout the year. All six species of honeycreeper had extended breeding and molting periods with peak breeding between April and July and peak molting...

Population densities for small mammal and arthropod populations can be estimated using capture frequencies for a web of traps. A conceptually simple geometric analysis that avoid the need to estimate a point on a density function is proposed. This analysis incorporates data from the outermost rings of traps, explaining large capture frequencies in these rings rather than truncating them...

This study examines the effects of operational use of pesticides on avian species inhabiting apple orchards in Pennsylvania Mourning dove (Zenaida macroura) and American robin (Turdus migratorius) nests were monitored in three organic and three conventional apple orchards during 1990 and 1991 In 1991 we surveyed the avian communities of these orchards by using line transects...

Reproductive success and contaminant levels in 1986 and 1987 were compared between Barn Swallows nesting at selenium-contaminated Martin Lake, Texas, USA, and swallows nesting at a reference site. Nests were initiated about the same time or earlier at Martin Lake than at the reference site and clutch size was similar between the two locations. Nest success was significantly higher at...

From 1977–1978 to 1990, concentrations of polychlorinated biphenyls (PCBs) and most organochlorine pesticides declined in eggs of red-breasted mergansers (Mergus serrator) nesting on islands in northwestern Lake Michigan. Total PCBs decreased 60% (from 21 ppm in 1977–1978 to 8.5 ppm in 1990) and p,p′-DDE decreased 66% (from 6.5 to 2.2 ppm). Dieldrin decreased only 16% (from 0.82 to 0.69...

No abstract available.

Population viability analyses for a number of endangered species have incorporated a metapopulation approach. The risk assessments of these viability analyses have indicated that some extant populations should be subdivided into numerous subgroups with exchange of individuals among them in order to reduce the chance of catastrophic loss of the species. However, routine application of a...

We determined the current range of the desert tortoise (Gopherus agassizii) based on the available latest data from government agencies, the literature, and our experience. We developed the first detailed range map of this species and summarized information about habitat preferences. New records of occurrences were incorporated, and some peripheral localities of questionable authenticity...