Woodcock habitat selection data and scripts

Description

Data tables and habitat selection modelling analysis scripts for GPS tracking data for 43 non-breeding Eurasian woodcock (Scolopax rusticola) in Ireland.

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Fieldwork was undertaken at six locations in Ireland, in counties Cavan, Cork, Kerry and Tyrone, over the course of three consecutive winter seasons: 2019-20, 2020-21 and 2021-22. Two fieldwork sites were used per season, one of which was ‘hunted’ and the other ‘not hunted’. Between 12 and 36 woodcocks were tagged with ‘very high frequency’ (VHF) radio transmitters (5.5g glue-on model; Perdix Wildlife Supplies, UK) at each site, with a total of 168 birds tagged with VHF transmitters that included a mortality indicator, across the six sites. ). Of these, 69 (42 adults, 27 juveniles) were additionally mounted with GPS loggers. Tagging took place in the month of December each season: season 1 (2-15 December); season 2 (3-17 December); season 3 (16-22 December). Birds were mainly captured at night in open habitats, using a bright torch and hand-net, although some were captured using mist nets as they flew over fields at dusk. The age of each bird was determined as juvenile or adult using wing feather characteristics and moult status. The VHF transmitter produced a single VHF pulse every 1.6 seconds (bandwidth 149-151MHz), and included a ‘mortality indicator’, which presented as a repeated double VHF pulse after 18 hours of the tag experiencing no movement. Tags were fitted with a small piece of cotton gauze and attached using cyanoacrylate glue to a small area of feathers and skin on the birds’ backs, positioned over the front of the synsacrum. This unobtrusive method of attachment was temporary, and tags would eventually have been discarded as a result of the birds’ moult or preening action. During season 1 & 2, tags were pre-programmed using Pinpoint Host software (Lotek Wireless Inc., UK, version 2.15.4.0) to take a GPS locational data four times per day; two nocturnal (04:00 and 21:00) and two diurnal (09:00 and 15:00). During season 3, tags were programmed to take an additional four locations per day, resulting in eight locations in a 24 hour period; four nocturnal (00:00, 04:00, 06:00 and 21:00), three diurnal (09:00, 12:00 and 15:00) and one which transitioned from nocturnal through dusk to diurnal as the season progressed (18:00). At least once per week through each winter season, sites were revisited in attempts to re-locate each tagged bird via VHF telemetry, monitoring their activity status and approximate location. If a mortality indicator was detected, attempts were made to find and retrieve the tag and record the status of the bird and cause of death if possible or appropriate. When tags had been discarded, or went ‘missing’ either due to birds permanently emigrating from the sites or tag failure, birds were removed from the study, or ‘censored’. Where GPS tags had not been retrieved before the 15th February of each season, we attempted to recapture each bird either using mist nets at dusk, or a torch and hand net at night. Upon recapture of a bird, the GPS logger was retrieved before immediate release.

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