Movements and activity patterns of the light-footed clapper rail

We monitored 54 individually color-banded light-footed clapper rails (Rallus longirostris levipes) (9 were harnessed for radio telemetry) to determine movements, home range, and activity patterns. Resightings over 3 years indicated a strong site tenacity. Maximum distances between locations for a given rail were generally 95%) was done during daylight hours. To check for nighttime activity, fixes were taken on 4 rails every 2-3 hours through 1 night each. Of our total tracking effort, 37% of locations were obtained in the first 4 hours of daylight, followed by 19, 26.9, and 16.5%, respectively, in consecutive 4-hour time blocks. Position fixes were taken every 15-30 minutes. Rails under visual observation yielded more fixes/unit of time, whereas rails roosting through high tides did not change position and, therefore, were not checked as often. Tracking stations were situated along the edge of the marsh, 15-50 m apart. The telemetered rails were within 50 m of the observer. The presence of an observer did not appear to affect a rail's behavior because rails were habituated to human activity (e.g., biking, jogging, class tours, boating, driving, and picnicing). Two or more readings were taken within 515 minutes, to determine a single location for a telemetered rail by triangulation. The data were entered into a computer that converted our compass readings to Cartesian coordinates. The program discarded fixes with >3 readings that crossed >5 m apart. A graphics plotter displayed the spread of fixes for a rail on maps of approximately 1:1,719-1:4,132 scale. Movements and range were measured on these maps with a digital planimeter and calipers. Home ranges were calculated using minimum convex polygons. We assessed activity patterns based on visual observations of the 4 most frequently observed telemetered rails and the mate of 1 of them. We quantified vocalizations by counting each bout of calling by each rail as 1 vocalization. We sexed rails by observing the behavior of m ted pairs. Also, the females of mated pairs were always smaller than the males. This size difference was corroborated by the measurement of 100 museum skins, measurements of 12 rails subsequently observed mating, and measurements of 5 birds later found dead and examined by laparotomy. Birds referred to by sex, herein, are only those observed mating or later dissected.