Seasonal variation in the sex and age composition of the woodcock bag in Denmark

Abstract

The Eurasian woodcock is a highly valued game bird in Western Europe from which c. 2.7 million individuals are harvested annually from an estimated population of 20–26 million birds. The population size and status remains uncertain due to the cryptic behaviour and widespread and solitary occurrence of woodcock, on breeding and wintering areas, making reliable population surveys difficult. Hunting bag records provide age ratios amongst bagged birds, but sex ratios remain poorly known because of the sexually monomorphic nature of this species. We used DNA analysis to determine sex ratios amongst 327 shot woodcocks from two hunting seasons in Denmark (1 October–31 January, 2012/13 and 2013/14). Based on bag totals, age ratios and sex ratios, juvenile females constituted 37%, juvenile males 27%, adult females 16% and adult males 20% of the annual woodcock bag. The female bias was related to a significant deviation from parity in the sex ratio amongst juvenile birds in October, although no such deviation was found at other times or amongst adults. Compared to limited data from other European countries, our data suggest that autumn migration of woodcock involves an initial wave of juvenile females followed by juvenile males and adults, and perhaps that males stay further north in Europe than females during autumn and winter. This migratory pattern would suggest that postponing the opening of the hunting season could reduce the hunting bag on reproductively valuable females in this polygamous species.