Expanding the range of black grouse Lyrurus tetrix in northern England - can wild females be successfully translocated?

Abstract

The range of black grouse Lyrurus tetrix in northern England was expanded by translocating males beyond the species' currently occupied distribution between 2006 and 2014. Translocation of wild males resulted in the establishment of new leks, attraction of females and successful breeding. To determine whether females could also be translocated to supplement the few present, 24 were moved and released in 2013 and 2014. Following release, 20 females survived to nest in their first spring on average 1.7 km from the release point. Annual survival by females over the first two years following release averaged 0.81 (0.63-0.90, 95% CL), comparable to that of resident birds in the core northern England range. Females exhibited fidelity to their breeding areas, with distance between nest locations in consecutive years averaging 0.2 km. Of the 35 nests monitored, 71% hatched chicks. Brood survival averaged 28% and the proportion of females with broods was 20%. Clutch size, egg volume, nest and brood survival were all comparable with estimates from birds from studies in northern England. Chicks reared per female averaged 0.3 (±0.1 SE), lower than resident birds from four sites in northern England. Post-translocation lek attendance varied between nine and 12 males. When attempting to expand black grouse range into formerly occupied areas, our study demonstrated that wild females translocated into areas where males had previously been released, settled, survived well and exhibited a propensity to breed.