| Popis: |
Nine female woodcock (Philohela minor) were radio-tagged in central Pennsylvania before fall migration to monitor premigratory and migratory movements. Within 15 days of departure, 5 of the birds moved 0.8 to 8.0 km from their normally used area, but the remaining 4 did not move. In 1973 five marked woodcock began migration between 30 November and 8 December. In 1974, four birds departed between 18 and 29 November. Departures coincided with high pressure centers approaching from the north and west or low pressure centers retreating to the north and east, or both. Eight of the 9 woodcock departed 2.5 or more hours after sunset and at least 7 left before midnight. Two hatching-year birds were tracked for up to 201 km SSW of the study area during 2 nights. Their air speeds (mean -+s) were 36 +2 and 45 -+ 3 km/h. J. WILDL. MANAGE. 40(1):91-95 During 1973 and 1974 nine female woodcock were radiotracked to document their movements before and during fall migration. This paper presents results dealing with their premigratory movements, time and weather conditions at departure, and data obtained on a portion of the migratory flights of two woodcock. Details of woodcock migration such as departure times, rate of travel, and altitude and distance of flights have not been documented. Although information is available from banding studies (Glasgow 1958, Martin et al. 1970, Mendall and Aldous 1943, Sheldon 1967), the potential to acquire details from banding records is limited. Radiotelemetry appears to be an appropriate technique to obtain specific information and has been employed successfully with woodcock (Dunford and Owen 1973, Godfrey 1974, Owen and Morgan 1975, Wenstrom 1973). We acknowledge the assistance of J. S. Lindzey and J. W. Artmann for critically reviewing the manuscript, W. W. Cochran for technical advice, and S. Smith and the late J. M. Cox who piloted the aircraft and made other helpful contributions throughout the study. Reference to trade names does not imply endorsement of commercial products by the U.S. Government. MATERIAL AND METHODS Woodcock were captured on 3 roosting fields within the 2,614-ha Pennsylvania State University Experimental Forest in Huntingdon County, Pennsylvania. They 1 A contribution of the Pennsylvania Cooperative Wildlife Research Unit, supported by the Pennsylvania Game Commission, The Pennsylvania State University, the U.S. Fish and Wildlife Service, and the Wildlife Management Institute. Unit Paper No. 186. Authorized for publication on 5/12/75 as Paper No. 4864 in the Journal series of the Pennsylvania Agricultural Experiment Station. This work was supported by the U.S. Fish and Wildlife Service, Contract No. 14-16-0008-791 with the Pennsylvania Game Commission. 2Present address: Migratory Bird and Habitat Research Laboratory, U.S. Fish and Wildlife Service, Laurel, Maryland 20811. ' Present address: U.S. Environmental Protection Agency, Region III, 6 and Walnut Streets, Philadelphia, Pennsylvania 19106. J. Wildl. Manage. 40(1):1976 91 This content downloaded from 40.77.167.32 on Fri, 13 May 2016 06:23:21 UTC All use subject to http://about.jstor.org/terms 92 FALL MIGRATION OF FEMALE WOODCOCK * Coon et al. were captured by nightlighting (Rieffenberger and Kletzly 1967) and were aged and sexed (Martin 1964), weighed, banded, and equipped with radio transmitters. Each bird was recaptured 2 or 3 times at about 24-day intervals to record its weight and general condition and to attach a transmitter with fresh batteries. A transmitter (SM-1, AVM Instrument Company, Champaign, Illinois) weighing between 4.5 and 6.0 g with battery and harness was attached to each of 4 hatchingyear females (HYF) and 5 after-hatchingyear females (AHYF). Transmitters were attached either by a rubber harness (Godfrey 1970) or by gluing to the skin. The glued transmitters were held also by two wires (Cochran 1972:41). We placed glued transmitters on three of nine birds, and each bird began migration with the transmitter in place. The duration of attachment was not determined, although this attachment previously had held at least 23 days on a test bird. Movements of radio-marked birds were monitored with a radio receiver (LA-12, AVM Instrument Company, Champaign, Illinois) and yagi-type receiving antenna. Both hand-held and truck-mounted units were used. The most intensive monitoring periods were between sunset and midnight, and at sunrise. The daily fixes for each bird were recorded on maps. Two fixedwinged aircraft and a mobile ground unit were used to locate and monitor birds during migration. Aerial tracking methods followed those described by Cochran (1972). Flight speeds were calculated by the method of Allen (1939). RESULTS AND DISCUSSION Seven birds were first captured between 21 September and 17 October, and one was captured on 6 November. These 8 woodcock carried transmitters an average of 47 days before migration. The 9th bird, captured on 10 May, had been radio-tagged 199 days before it migrated. It weighed 186 g when captured and 190 g when last handled on 5 November. The average weight of the 9 females at first capture was 195 -? 13 g (mean 1 SD). After 40 -20 days, weights of 7 of the birds averaged 204 --9 g. Godfrey (1974:73) also reported slight weight gains of 4.5 -5.5 g in 6 radio-tagged males after 20.4 ? 3.1 days. Premigratory Movements Before migration the nine woodcock were most active and made local movements primarily at dusk and dawn. This behavior was consistent with previous documentation (Dunford and Owen 1973, Krohn 1971, Sheldon 1961). Daily radio locations indicated that all birds remained within an 0.8-km2 area near their capture site until 15 days prior to migration. Within this 15-day period, 5 of the 9 woodcock made singular evening flights that ranged from 0.8 to 8.0 km outside their normally used areas. Two HYF birds flew 6.1 to 8.0 km, and 3 AHYF birds flew 1.0 to 1.6 km. Two of the five returned periodically to their original capture area. The remaining four of the original nine (two HYF and two AHYF) continued to use the area where captured. Migration Departures In 1973 the five radio-marked females departed on four different nights between 30 November and 8 December. The four birds in 1974 also migrated on four separate nights between 18 and 29 November (Table 1). At least 8 of the 9 woodcock did not depart on migratory flights during the usual activity period at sunset, but left 2.5 J. Wildl. Manage. 40(1):1976 This content downloaded from 40.77.167.32 on Fri, 13 May 2016 06:23:21 UTC All use subject to http://about.jstor.org/terms FALL MIGRATION OF FEMALE WOODCOCK Coon et al. 93 Table 1. Fall migration departure data for nine radio-equipped female woodcock in central Pennsylvania. Wind Temp. ( C) a Cloud BaroBird Departure Departure Sunset cover Speed metric no. Ageb date time (EST) (EST) High Low (%) Direction (km/h) pressure 580 AHY 30 Nov 1973 2030-052 |
