James Silvey, our nature recovery officer, takes a look at why one small island is so important for one of Scotland's rarest insects.
Small reserves for small creatures
Great yellow bumblebee on red clover. Credit: Neil Cowie
Does size matter? When it comes to protecting ecosystems then the answer is probably yes. There’s no doubt that if you want to conserve populations of capercaille, pine marten and potentially even lynx in Scotland then you need huge areas to do it. Our largest reserve, Forsinard Flows covers nearly 200km² and the Cairngorms Connect partnership (RSPB Scotland, SNH, Forestry Commission Scotland and Wildlands ltd) covers over 600km² of ancient woodland, peatlands and rugged mountain landscapes.
When we talk about species though, specifically smaller species like insects, then size is relative and suddenly a 200km² reserve can be scaled down to a single pond capable of sustaining entire populations. In this sense some of our smallest reserves can be hugely important for the species that live in them and over the last three years the tiny island of Copinsay in Orkney has really stood out for me.
Copinsay. Credit: Charlie McMurray
Copinsay is a small island (<60ha) and lies 2km off the east coast of mainland Orkney. Once home to a small farming community the islands only residents are now the thousands of seabirds that breed along the coast and cliffs and, perhaps unusually for a seabird island, a thriving population of bumblebees.
Bumblebees probably arrived on the island soon after it was first cultivated as the hay meadows the farmers needed for their livestock would have provided plenty of flowers and nesting opportunities for the bees. The island is now home to six species of bumblebee including a very special resident, the great yellow bumblebee.
Great yellow bumblebee on red clover. Credit: Colin Campbell
Despite this charismatic species having the title of Scotland’s rarest bumblebee on Copinsay it is fairly common with a survey in August 2016, recording 119. Elsewhere in Orkney you may be lucky to see even one great yellow over an entire day so why are they so easy to spot on Copinsay? Firstly Copinsay has 8ha of fantastic great yellow habitat filled to bursting with the flowers that the bees love. Secondly the island is so small that the bees are concentrated into a fairly small area meaning that on any one trip it is possible to see a high proportion of the total population. Despite this over three years of surveys on reserves across Orkney, it is Copinsay that has easily stood out as RSPB Scotland’s best site for bees.
Given that large areas of Orkney are now intensively farmed for beef and dairy cattle these small areas are becoming increasingly important for the species that rely on them. What Copinsay does show us is that it’s not necessarily size that matters but quality.