Seasonal home range dynamics and sex di�erences in habitat use in a threatened, coastal marsh bird

A comprehensive understanding of spatiotemporal ecology is needed to develop con- servation strategies for declining species. The king rail (Rallus elegans) is a secretive marsh bird whose range historically extended across the eastern United States. Inland migratory populations have been greatly reduced with most remaining populations inhabiting the coastal margins. Our objectives were to determine the migratory status of breeding king rails on the mid-Atlantic coast and to characterize home range size, seasonal patterns of movement, and habitat use. Using radiotelemetry, we tracked individual king rails among seasons, and established that at least a segment of this breeding population is resident. Mean (±SE) home range size was 19.8 ± 5.0 ha (95% kernel density) or 2.5 ± 0.9 (50% kernel density). We detected seasonal variation and sex differences in home range size and habitat use. In the nonbreeding season, resi- dent male home ranges coincided essentially with their breeding territories. Overwintering males were more likely than females to be found in natural emergent marsh with a greater area of open water. Females tended to have larger home ranges than males during the nonbreeding season. We report for the first time the use of wooded natural marsh by overwintering females. Brood-rearing king rails led their young considerable distances away from their nests (average maximum distance: ~600 ± 200 m) and used both wooded natural and impounded marsh. King rails moved between natural marsh and managed impoundments during all life stages, but the proximity of these habitat types particularly benefitted brood-rearing parents seeking foraging areas with shallower water in proximity to cover. Our results demonstrate the importance of interspersion of habitat types to support resident breeders. Summer draining of impounded wetlands that are seasonally flooded for wintering waterfowl allows regrowth of vegetation and provides additional habitat at a critical time for wading birds

Seasonal home range dynamics and sex diî€erences in habitat use in a threatened, coastal marsh bird

A comprehensive understanding of spatiotemporal ecology is needed to develop con- servation strategies for declining species. The king rail (Rallus elegans) is a secretive marsh bird whose range historically extended across the eastern United States. Inland migratory populations have been greatly reduced with most remaining populations inhabiting the coastal margins. Our objectives were to determine the migratory status of breeding king rails on the mid-Atlantic coast and to characterize home range size, seasonal patterns of movement, and habitat use. Using radiotelemetry, we tracked individual king rails among seasons, and established that at least a segment of this breeding population is resident. Mean (±SE) home range size was 19.8 ± 5.0 ha (95% kernel density) or 2.5 ± 0.9 (50% kernel density). We detected seasonal variation and sex differences in home range size and habitat use. In the nonbreeding season, resi- dent male home ranges coincided essentially with their breeding territories. Overwintering males were more likely than females to be found in natural emergent marsh with a greater area of open water. Females tended to have larger home ranges than males during the nonbreeding season. We report for the first time the use of wooded natural marsh by overwintering females. Brood-rearing king rails led their young considerable distances away from their nests (average maximum distance: ~600 ± 200 m) and used both wooded natural and impounded marsh. King rails moved between natural marsh and managed impoundments during all life stages, but the proximity of these habitat types particularly benefitted brood-rearing parents seeking foraging areas with shallower water in proximity to cover. Our results demonstrate the importance of interspersion of habitat types to support resident breeders. Summer draining of impounded wetlands that are seasonally flooded for wintering waterfowl allows regrowth of vegetation and provides additional habitat at a critical time for wading birds

Seasonal home range dynamics and sex di?erences in habitat use in a threatened, coastal marsh bird

A comprehensive understanding of spatiotemporal ecology is needed to develop con- servation strategies for declining species. The king rail (Rallus elegans) is a secretive marsh bird whose range historically extended across the eastern United States. Inland migratory populations have been greatly reduced with most remaining populations inhabiting the coastal margins. Our objectives were to determine the migratory status of breeding king rails on the mid-Atlantic coast and to characterize home range size, seasonal patterns of movement, and habitat use. Using radiotelemetry, we tracked individual king rails among seasons, and established that at least a segment of this breeding population is resident. Mean (±SE) home range size was 19.8 ± 5.0 ha (95% kernel density) or 2.5 ± 0.9 (50% kernel density). We detected seasonal variation and sex differences in home range size and habitat use. In the nonbreeding season, resi- dent male home ranges coincided essentially with their breeding territories. Overwintering males were more likely than females to be found in natural emergent marsh with a greater area of open water. Females tended to have larger home ranges than males during the nonbreeding season. We report for the first time the use of wooded natural marsh by overwintering females. Brood-rearing king rails led their young considerable distances away from their nests (average maximum distance: ~600 ± 200 m) and used both wooded natural and impounded marsh. King rails moved between natural marsh and managed impoundments during all life stages, but the proximity of these habitat types particularly benefitted brood-rearing parents seeking foraging areas with shallower water in proximity to cover. Our results demonstrate the importance of interspersion of habitat types to support resident breeders. Summer draining of impounded wetlands that are seasonally flooded for wintering waterfowl allows regrowth of vegetation and provides additional habitat at a critical time for wading birds

Oceanographic and demographic mechanisms affecting population structure of snow crabs in the northern Bering Sea

Snow crabs Chionoecetes opilio are quite productive at suitable temperatures, but can also be abundant in water cold enough to depress settlement of larvae, growth, and reproduction. In much of the northern Bering Sea, bottom water temperatures are below -1°C for most or all of the year. Crab pelagic larvae prefer to settle at temperatures above 0°C, so we found high densities of juveniles only where intruding warm currents deposited larvae in localized areas. After settlement, maturing crabs appeared to exhibit ontogenetic migration toward deeper, warmer water. Cold temperatures excluded key predators, but decreased fecundity by restricting females to small body size (with associated small clutches) and to breeding every 2 yr. Migration to warmer water may allow females to breed annually and to encounter more adult males needed to fertilize subsequent clutches. Because older males also emigrate, remaining adolescent males probably inseminate newly maturing females. Without localized intrusion of warmer currents, snow crabs might not persist at high densities in such cold waters. However, they are currently very abundant, and export many pelagic larvae and adults

A Video Seafloor Survey of Epibenthic Communities in the Pacific Arctic including Distributed Biological Observatory Stations in the Northern Bering and Chukchi Seas

Two separate efforts to characterize epibenthic communities in the northern Bering and Chukchi seas using video imagery from a drop camera system have now been completed. In the initial phase in 2008, we acquired video imagery from the USCGC Healy while drifting on station during the multidisciplinary Bering Sea Program and used cluster analysis and non-metric multidimensional scaling to identify epibenthic assemblage types and associated sediment characteristics based upon along-track epifaunal counts. We also quantified the areal density of easily recognizable organisms such as brittle stars (Ophiura sp.) and sea stars, which were abundant and easily identified. While sampling was not extensive enough to rigorously compare the density of epifauna with trawling data available from prior years, our observations confirmed the characteristics of epifaunal communities sampled through much more labor-intensive trawling. Densities of epifauna that could be readily enumerated were of the same order of magnitude in both types of observations. During the second phase in 2016 and 2017 of video observations from the CCGS Sir Wilfrid Laurier, we improved the quality of imagery, and obtained seafloor video footage from each station in the internationally coordinated sampling grid in the Distributed Biological Observatory (DBO). This grid lies in the productive waters of the northern Bering and Chukchi seas. Quantitative analysis was not undertaken in this second phase, but the imagery confirms the presence of specific organismal community assemblages that can be related to environmental factors such as sediment grain size and water mass identity that are available from other project data collected during the Bering Sea and DBO projects. For example, sandier sediments typically had diverse epifaunal communities including filter feeders as significant community components. In muddier sediments, deposit feeders such as brittle stars predominated. All the second phase video footage has been posted in both abbreviated form on the video-sharing website youtube.com, and longer (10 min per station) versions are freely downloadable from a Google Drive server. Future videography may help identify changes in epibenthic diversity and community composition and could be successfully evaluated with crowd-sourced citizen science and/or more traditional scientific documentation