Fall survival, movements, and habitat use of American woodcock in ...
Fall survival, movements, and habitat use of American woodcock in ...
Fall survival, movements, and habitat use of American woodcock in ...
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2003 Field Season Report · February 2004 7tarsus lengths were measured. All captured <strong>woodcock</strong> were fitted with U. S. Fish <strong>and</strong>Wildlife Service alum<strong>in</strong>um leg b<strong>and</strong>s, <strong>and</strong> birds that weighed >140 g also were equippedwith 4.5 g transmitters (Advanced Telemetry Systems, Inc., model A2480 with athermister mortality switch). Transmitters were attached us<strong>in</strong>g livestock tag cement <strong>and</strong>a wire harness around the belly <strong>of</strong> the bird (McAuley et al. 1993).Signals <strong>of</strong> radio-marked <strong>woodcock</strong> were monitored daily until all birds had leftthe study area. If transmitters were <strong>in</strong> mortality mode, we homed <strong>in</strong> on the signal torecover the transmitter <strong>and</strong> any rema<strong>in</strong>s <strong>of</strong> the <strong>woodcock</strong>. When the bird or transmitterwas found, we exam<strong>in</strong>ed the carcass, site, <strong>and</strong> transmitter to determ<strong>in</strong>e the ca<strong>use</strong> <strong>of</strong> deathor whether the transmitter had slipped <strong>of</strong>f. Necropsies will be conducted on all carcassesfor which the ca<strong>use</strong> <strong>of</strong> death was not obvious. Miss<strong>in</strong>g <strong>woodcock</strong> were searched for withan airplane about once per week as weather <strong>and</strong> aircraft schedules allowed. Birds locatedby air were subsequently re-located on foot to determ<strong>in</strong>e a more precise location <strong>and</strong> tocheck their status.SurvivalSurvival estimates were calculated for the period correspond<strong>in</strong>g to the hunt<strong>in</strong>gseasons <strong>in</strong> 2001, 2002, <strong>and</strong> 2003 for all study areas us<strong>in</strong>g the Kaplan-Meier procedurewith the staggered entry design (Pollock et al. 1989). The hunt<strong>in</strong>g season periods were22 September – 5 November <strong>in</strong> 2001, 21 September – 4 November <strong>in</strong> 2002, <strong>and</strong> 20September – 3 November <strong>in</strong> 2003. Beca<strong>use</strong> short-term behavioral or <strong>survival</strong> effects mayresult from capture <strong>and</strong> adjust<strong>in</strong>g to the transmitter, we subtracted the first 3 exposuredays from all <strong>woodcock</strong> <strong>in</strong>cluded <strong>in</strong> the sample <strong>use</strong>d to estimate <strong>survival</strong> (Krementz et al.1994, Krementz <strong>and</strong> Berdeen 1997). Woodcock that were miss<strong>in</strong>g, slipped their