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

Abstract

1. 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.

2. 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).

3. 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.

4. 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.

5. 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.