|Mother Carey and her chickens (from the Biodiversity Heritage Library|
in their version of Ornithological Miscellany, Volume II, part VI
While the staff on Skomer are charged with the task of performing population census' of breeding seabirds on the island, the European storm petrel hasn't been included in these survey since the last full island count was performed back in 2004, lead by a previous warden, Juan Brown. However this year is the year that we repeat the census.
"So why the long wait?" you may ask. Well, as mentioned above, these birds still hold some of their historic mystery. For one thing, they are nocturnal visitors to their breeding places, spending their days far out to sea, which makes them extremely difficult to observe on land. The fluttering of a small winged shape in the darkness is often all that you will see if you spend any time in a colony, and the only real opportunity to see them up close is if they are caught for ringing. Further to this, the sites in which they breed are often difficult to access, and the nests are hidden deep amongst loose rocks and scree, completely hidden. This leaves us with the challenge of censusing a seabird which we cant see!
|European storm petrel, caught for a ringing study. Photo by Jason Moss|
There are ways of achieving this seemingly impossible task however. Fortunately, while storm petrels may be difficult to see, they are rather prone to making plenty of noise when they hear the call of their own kind, responding either with a soft hiccupping 'ter-chik, ter-chik', or a rolling purr.
So, equipped with hard hats, MP3 players and white paint markers, we have been spending many hours searching all known and accessible sites around Skomer, trying to systematically locate as many storm petrel nest sites as we possibly can, whilst also performing 10 repeat visits to two known breeding colonies, in order to obtain a correction factor for the island (any survey of a site will always produce an underestimate of the actual population, as the birds don't respond every single time. Applying a correction factor, obtained by surveying a site repeatedly to get a maximum number of active sites, can help give a more realistic island population).
|Playing the call of a storm petrel into a suitable nesting site. Photo by Alastair Wilson|
|Knee-pads are a must! Photo by Alastair Wilson|
|One of the benefits of the census is that it takes you some little-visited, and often |
beautiful sites, like the Mew Stone boulders. Photo by Alastair Wilson
|The birds tend to favour areas of loose substrate piled amongst larger boulders, |
nesting within the gaps formed there. Photo by Alastair Wilson
|Happy surveyors after another visit to Toms House (Alastair, Jane and Jason). |
Photo by Alastair Wilson.
We aren't quite finished yet, but an early look at the numbers shows that the total number of responses is slightly lower than in the previous census in 2004. However, there is still a fair bit of number crunching to be done yet for these mysterious seabirds, and the final results will be published at the end of the season.