Regulation of body reserves in a hunted wader: Implications for cold‐weather shooting restrictions

Abstract

Severe winter weather can reduce avian energetic reserves. At such times, reducing disturbance, and therefore energy expenditure, through science‐based policy is crucial to mitigating negative impacts on survival. We used allometric equations to examine the energy reserves of Eurasian woodcock Scolopax rusticola, a popular quarry species across most of Europe, in relation to time of winter, location and temperature. We used data from 221 dissected birds, shot in Britain in two winters (2013/14, 2014/15), and 1,689 live birds captured during six consecutive winters (2010/11 to 2015/16). Woodcock are able to store large amounts of energy as fat in mid‐winter and increase energy reserves as night air temperature drops to below 0°C, provided the ground thaws during the day. In the event of cold weather in Britain, the mean potential flight distance of woodcock, based on mobilizable energy estimates of shot birds, is 860 km. If they do not move away, woodcock could withstand frozen conditions without feeding for a mean of 6 days. Synthesis and applications. To reduce the effects of cold weather on Eurasian woodcock S. rusticola, shooting should be restricted before energy reserves are depleted. Current policies vary across Europe, but our results suggest that restrictions should come into force sooner, after 4 days of continually frozen ground at inland sites. Restrictions should cover large regions and remain in operation for 7 days after the end of the cold spell.

Spring migration phenology of Eurasian Woodcocks tagged with GPS-Argos transmitters in Central Europe

“…The large variance is most likely caused by the combined effect of individual condition (nutrition, motivation) and weather factors (wind direction and speed). The values nevertheless correspond to those published in the international literature (Sánchez-García et al 2018). Such performances are not considered extraordinary in similar species, e.g., Great Snipes (Gallinago media) were able to cover distances of 4,300-6,800 km in 48-96 h during autumn trans-Sahara migration (Klaassen et al 2011), or the Bar-tailed Godwit (Limosa lapponica) capable of crossing the whole Pacific Ocean (Gill et al 2009).…”

“…According to the calculation based on their registered bodyweight (Boos et al 2005, Sánchez-García et al 2018, the Woodcocks we tagged were predicted to be able to cover a distance of about 400-1,100 km in one flight without risking their survival. However, to use fat reserves and migrate quickly to be the first to arrive at the breeding ground is not necessarily the best strategy in stochastic environmental conditions in spring.…”