As many of you will have read here before we successfully eradicated brown rats from Ramsey in 1999/2000. Non-native to Ramsey this invasive species had been accidentally introduced via shipwrecks in the 1800's and caused havoc with our native seabird populations. Puffins and storm petrels became extinct and Manx shearwaters were reduced to very small numbers.
At the last full census in 2012, the Manx shearwater population had risen dramatically to 3,800 pairs from 850 in 1998 (next survey due in 2016). We are now undertaking tracking work on some of our birds using GPS and geolocator technology. This work is in conjunction with Oxford University who are also studying birds on Skomer, Rum, Copeland and Lundy. We are finding more and more out each year about this enigmatic seabird and the multi-colony work allows comparison between large and small sites and those that are well established compared with those recovering following the removal of predators. Not only is this work answering scientific questions but also provides a direct conservation benefit by contributing data in the establishment of Marine Protected Areas.
There is plenty of available burrow space on Ramsey so our birds are choosing to occupy existing rabbit warrens. The warrens can be maze like at time as opposed to the relatively short, straight burrows that shearwaters dig for themselves. This makes life difficult when you are trying to remove birds from burrows to fit devices to. In order to establish a sub-colony we could more easily work on we installed nest boxes last year. These are based on a NZ design that we discovered on a visit there a few years ago. The closely related Hutton's and Fluttering shearwaters both readily use such nest boxes (used in NZ for establishing new colonies following eradication and translocation projects)
In common with most shearwater species Manx don't breed until they are 5 or 6 years old so we are not expecting instant results. However it is hoped that non breeding birds that return to the colony aged 2-4 years old will prospect the nest boxes and take up residence.
We have therefore been very encouraged to see exactly this happening over the past week. I placed small bracken twigs at the rear end of the pipes that form the tunnel entrance to see if any were knocked over (showing that a bird had gone in). 5 out of the 20 boxes had been visited last week. Birds have only been back in any significant numbers quite recently and non breeders are not at their peak yet so this is very good news. One also showed signs of being visited by the bird leaving a lovely 'calling card' in the form of a big streak of guano!
I set a trail camera up on one nest and it was visited on two consecutive nights - proof that it was shearwaters doing the visiting and not pesky rabbits! Watch this space for more news!
Manx shearwaters visiting nest boxes on Ramsey with one leaving a distinctive calling card!