Seasonal home range dynamics and sex differences in habitat use in a threatened, coastal marsh bird

Abstract

A comprehensive understanding of spatiotemporal ecology is needed to develop conservation 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, resident 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.

Home‐ranges of tropical Red‐capped Larks are influenced by breeding rather than vegetation, rainfall or invertebrate availability

“…Similar to our results, home-ranges in birds have been shown to vary with breeding status, some species reportedly showing an increase in home-range with breeding (Jahn et al 2010, Kolts & McRae 2017, others a decrease (Willey & Van Riper Iii 2014, Morganti et al 2017, and some show no variation between (Winiarski et al 2017). The need to defend nest-sites, coupled with nest attendance and chick provisioning, may constrain movement of breeding Red-capped Larks to areas closer to their nests.…”

Quantitative acoustic differentiation of cryptic species illustrated with King and Clapper rails

“…Intraspecific and within‐individual variation occurs with kek note structure and calling rates in response to external stimuli (Massey & Zembal, ; L. L. Stiffler, & K. M. Schroeder, personal observations). During the breeding season, unpaired males use the repeated kek call for mate advertisement as well as in territorial displays when paired (Kolts & McRae, ; Meanley, ; Zembal & Massey, ).…”

“…L. Stiffler, & K. M. Schroeder, personal observations). During the breeding season, unpaired males use the repeated kek call for mate advertisement as well as in territorial displays when paired (Kolts & McRae, 2017;Meanley, 1969;).…”

“…The refuge includes 550 ha of impoundments managed for overwintering waterfowl, as well as extensive natural marshes subject to prescribed burn (Rogers, Collazo, & Drew, 2013). King rails are the only species of long-billed rail breeding at the site, and detailed study of King Rail ecology and behavior has been ongoing at Mackay Island NWR for the last 7 years (for further information about the study population, see Clauser & McRae, 2016;Clauser & McRae, 2017;Kolts & McRae, 2017). Recordings were made using a Song Meter SM4 (Wildlife Acoustics) at 44.1 kHz and 16 bit.…”

Importance and effectiveness of correction methods for spatial sampling bias in species with sex‐specific habitat preference

“…Even if the differences in habitat preferences between sexes for Capercaillie were small in this study, many other species show more differentiated habitat use, which could affect model accuracy more strongly. This was observed in mark-recapture studies (McKnight & Ligon, 2017) and telemetry studies (Kolts & McRae, 2017). While systematic protocols are more robust to differences TA B L E 5 Spearman correlation coefficient calculated between predicted maps of sex-specific model and prediction from generic models for Capercaillie between sexes, their use is unlikely to solve the entire problem of biased detectability.…”