Expanding black grouse range
Males were successfully translocated into three formerly occupied sites in the Yorkshire Dales. © Dave Mason
KEY FINDINGS
Released males have established new leks, which have attracted females to settle and breed. Fourteen new leks have been established attended by 44 males in 2015. Seven new 10x10-km grid squares have been recolonised, contributing to the delivery of range expansion targets.
Philip Warren Frances Atterton Matteo Anderle David Baines
Black grouse were once widespread in England, but have declined over the past 150 years largely owing to habitat changes. In 1998, 773 males remained and were mainly confined to the North Pennines in northern England. Owing to their recent declines they have been red-listed as a species of high conservation concern and were a ‘Priority Species’ of the UK Government’s Biodiversity Action Plan with its own Species Action Plan (SAP) to restore both numbers and range. The English SAP targets were (i) to stem or reverse the decline in numbers to 800 males recorded in 1995/6 by 2005, and (ii) in the long term (20 years) increase the range to its 1988-91 extent of 61 10x10 kilometre (km) grid squares occupied by displaying males in spring. Following the instigation of a range of conservation measures, numbers increased to 1,029 males in 2006, thus achieving the first set target. However, range increased only from 37 to 42, 10x10-km grid squares and the delivery period for achieving the target was extended to 2030. The conservation effort subsequently focused on expanding range. Suitable,
formerly occupied habitats were present adjacent to or beyond the southern fringe of the existing range in the Yorkshire Dales. Natural range expansion was considered to be limited by juvenile males, which move only short distances (up to 1km), whereas females disperse up to 19km (mean 9.3km). These findings, confirmed by field observa- tions, suggested that yearling females may disperse into suitable habitat where few or no males are present. To stimulate sustained range expansion, we started a male translocation programme
into three formerly occupied sites in the Yorkshire Dales, following a successful pilot study at a site within the existing range. By translocating males we aimed to increase range through encouraging males to establish leks in formerly occupied sites, which would then attract dispersing females to settle and go on to breed. The degree of success was evaluated in (a) the short-term (one to three years post-release) using radio-telemetry to assess settling patterns, behaviour and survival of translocated individ- uals, and (b) the longer-term (one to nine years post-release) through annual lek surveys to assess the persistence of established leks through successful breeding and their contri- bution to the range expansion target. Three release sites were chosen beyond the southern edge of the male range in the
Yorkshire Dales, but were within the perceived dispersal distance of females, and where habitats were considered suitable and generalist predators were controlled. Between 2006 and 2010, 17 males were released at Mossdale, and a further 18 and 27 respec- tively in Coverdale and Nidderdale (see Figure 1) between 2011 and 2014. Males were caught at night, fitted with radio-transmitters and released immediately at the new sites.
50 | GAME & WILDLIFE REVIEW 2016
www.gwct.org.uk
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