Ed Tooth, RSPB Scotland's Black Grouse Project Officer, explores some of the outcomes of this years black grouse lek monitoring season under the Galloway Glens Landscape Partnership.
Black Grouse lek monitoring
The beginning of June marked the end of the first black grouse lek monitoring season under the Galloway Glens Landscape Partnership (GGLP). Firstly, I would like to say a huge thank you to the team of volunteers that helped with the surveys this year. Their dedication and commitment to some shockingly early mornings meant that we could cover all the sites that I wanted to target, and far beyond anything that I could have managed on my own. Collectively they contributed over 100 hours of their time! Volunteers are an integral part of RSPB Scotland and the Galloway Glens Landscape Partnership, and without them there would be no way we could deliver our conservation, restoration, outreach and education programs.
So, for the results. Interpreting black grouse data can be difficult for a few reasons. Firstly, because of the constantly changing landscape of the Forest Park, the leks tend to move around. What we achieved this year was to cover historical and potential new sites to ensure we weren’t missing anything. As a result, we found 3 new leks! Secondly, with a dedicated project like this, I can focus my time on ensuring that all sites are covered. Without dedicated surveyors, this is not always possible, so survey effort and intensity can vary between years and could affect the number of leks found.
However, we have data that is reliable back to 2001, which can provide an excellent insight into how the birds are doing. Over that period and within the southern and central part of the GGLP area where my work is focused, the mean number of lekking males was 15. This year, we found a minimum of 13 lekking males, so nearly bang on average for the 18-year period 2001-2019. This also represents an increase from 9 the previous year, and an increase on the 5-year mean from 11. So, this is good news, right?
At first glance, it is good news for two reasons. Firstly, there is no obvious decline this year, which is always nice to see; as the summer last year was so dry (perhaps a little too dry), this is what we would hope. Secondly, as mentioned above, the long-term trend indicates that these populations have remained stable for the last 18 years.
However, as recently as 2011 there were 30 lekking males in the area as populations began to increase dramatically in 2006 (see the graph below) off the back of a productive few breeding seasons. By 2013, numbers had dropped to just 6. This could be attributed to poor weather, but it is also likely that the habitat needed to support a healthy population isn’t there. We also know, from casual records from the 1960s, that there were single leks in the area that held 30 birds. It is also worth remembering that across the wider Galloway Forest Park, numbers are in steep decline and we eagerly await the results of the surveys from there