Publications

Multistate mark-recapture methods provide an excellent conceptual framework for considering estimation in studies of marked animals. Traditional methods include the assumptions that (1) each state an animal occupies is observable, and (2) state is assigned correctly at each point in time. Failure of either of these assumptions can lead to biased estimates of demographic parameters. I...

Five lagoonal salt marsh areas, ranging from 220 ha to 3,670 ha, were selected from Cape Cod, Massachusetts to the southern DelMarVa peninsula, Virginia, USA to examine the degree to which Spartina marsh area and microhabitats had changed from the early or mid- 1900s to recent periods. We chose areas based on their importance to migratory bird populations, agency concerns about marsh...

During extreme drought conditions, mussel survival and habitat conditions were monitored weekly at nine locations representing a gradient in stream size in the lower Flint River basin, Georgia, USA. Cumulative unionid mortality ranged from 13 to 93% among sites, and was associated with low flow velocity (below 0.01 m/s) and dissolved oxygen concentrations below 5 mg/L. Species...

A sense of urgency attends the study of species of concern, like the Cerulean Warbler (Dendroica cerulea). Sharpened by Robbins et al. (1992) and Hamel (1992), such concern prompted the U.S. Department of the Interior, Fish and Wildlife Service (USFWS) to commission a status assessment of the Cerulean Warbler (Hamel 2000a). Shortly after the status review was published, a petition (Ruley...

The Shenandoah salamander (Plethodon shenandoah), known from isolated talus slopes on three of the highest mountains in Shenandoah National Park, is listed as state-endangered in Virginia and federally endangered under the U.S. Endangered Species Act. A 1999 paper by G. R. Thurow described P. shenandoah-like salamanders from three localities further south in the Blue Ridge Physiographic...

Contamination of the environment from atmospheric deposition during the twentieth century is pervasive even in areas ostensibly considered pristine or remote from point sources. In this study, Pb concentrations in a 210Pb-dated peat core collected from the Okefenokee Swamp, GA were used to assess historical contaminant input via atmospheric deposition. Lead isotope ratios were determined...

Orchid Meadows is a long-term wetland research and monitoring site on the Coteau des Prairie in extreme east-central South Dakota, USA. It is a 65-ha Waterfowl Production Area with numerous temporary, seasonal, and semi-permanent wetlands. Ground water and surface water have been monitored at the site from 1987 to 1989 and from 1993 to the present. Vegetation has been monitored since...

In community-level ecological studies, generally not all species present in sampled areas are detected. Many authors have proposed the use of estimation methods that allow detection probabilities that are 1 and that are heterogeneous among species. These methods can also be used to estimate community-dynamic parameters such as species local extinction probability and turnover rates...

The decline of the American black duck (Anas rubripes) has been attributed to competition from mallards (A. platyrhynchos) that led to exclusive use of fertile wetlands by mallards. Data from annual breeding waterfowl surveys provide instantaneous, single observations of breeding pairs, which are used to estimate breeding population size and evaluate the condition of habitat. Data from...

No abstract available.

State-dependent strategies (SDSs) are the most general form of harvest policy because they allow the harvest rate to depend, without constraint, on the state of the system. State-dependent strategies that provide an optimal harvest rate for any system state can be calculated, and stochasticity can be appropriately accommodated in this optimization. Stochasticity poses 2 challenges to...

No abstract available.