02 May 2014
Following the first visit to the Great Cormorant colony on Lihoumel, Lihou Island on 16 April 2014, we knew we had to return on the current set of spring tides to check on the success of egg hatching and to ring chicks before they are too large and mobile. Chris Mourant, Jamie Hooper and Paul Veron crossed the causeway at 13.45 and headed straight to Lihoumel.
On the way it was encouraging to see good numbers of gulls settled down on nests incubating eggs on the south side of Lihou. Jamie had recently erected the signs to inform the public of the need to keep back from the seabird nesting areas.
On Lihoumel we expected to see a thriving colony with double figures of growing Cormorant chicks, but as soon as we climbed onto the islet it was very obvious that the colony had suffered serious predation by an apparently large population of Brown Rats. Nests that contained eggs on our previous visit were now empty and the one nest that had four tiny chicks now had just one surviving chick (which we ringed).
A total of 15 Great Cormorant nests was counted (five of which were empty). Only three nests had any youngsters, with the other seven containing between one and four eggs. Given the encouraging signs last time this was a very disappointing outcome. Jamie estimated a population of perhaps 40+ rats from the active burrows on the islet. Given the success in significantly reducing the rat population on Lihou through a programme of baiting over the previous two winters, the rat population on Lihoumel was a surprise. It will of course be very easy for these rats to return to Lihou. Chris and Jamie discussed getting some baiting on Lihoumel as a priority.
Only six European Shag nests were counted (all with eggs)...a reduction from previous years, which may reflect the growing Great Cormorant colony in recent years, and also the current levels of rat predation. At least two Great Black-backed Gull nests with three eggs were found on the islet.
As is usual the adult Great Cormorants had already returned to their nests on Lihoumel by the time we stepped back onto Lihou. We erected the ropes to keep people on the paths in this area, and then completed a circuit of the island.
The gull colony in the gully to the north of the Venus Pool looked stronger than in recent years, with gulls spreading up the slope towards the path. The next rocky beach was also very strong with encouraging numbers of nesting Herring Gulls. Most appeared to be sitting on complete clutches of eggs, and several nests were right up to the edge of the beach, so that people could wander up to the nests themselves. We agreed it would be an excellent idea to get this area roped just to keep people a few metres back from the edge of the beach.
A Common Buzzard was hunting over the island as we moved to the northern beaches, which again looked encouraging for nesting gulls. One hopes they can repeat the success of the 2013 breeding season.
Finally…we managed to read nine colour rings on Herring Gulls and two on Lesser Black-backed Gulls producing some very valuable data for the gull research currently underway in the Islands.
06 May 2014