12/13 July 2008

With the winds lighter than forecast, Sophie and I flew out to Alderney at 0830 confident of getting across to Burhou to fit the Lesser Black-backed Gull chicks with colour rings. With no other ringers able to make the trip, we envisaged a very hard day’s work searching the bracken for the chicks.

Roland Gauvain and Lyndsey Pyne kindly picked us up from the airport and drove us out to the Alderney Wildlife Trust (AWT) field centre at Essex Castle. Here Roland picked up the boat (Nomad) and we went straight to the harbour. As the forecast was for a moderate breeze Roland had arranged for a qualified boatman (Tim) to take us over to Burhou. We were all loaded and on our way by 1030. Although the sea was slight-moderate there were still some rollers crossing the Swinge.

As soon as Sophie and I had settled into the hut, and grabbed a bite to eat we set off to the West End of the island to start searching for the gull chicks. I had not done this on Burhou since 1994, but with my new colour ringing project underway I was really keen to try to get at least 100 rings fitted. I knew that previous teams had ringed c 300 Lesser Black-backed Gull chicks at this time of year several times in the previous decade, and was therefore hopeful of a good result. However, once Sophie and I began to search through the bracken at the West End, we knew that the gulls were in big trouble this year. Far from the usual picture of many large gulls hiding in the bracken, or wandering at the edge of the colony all we could find were empty nests or nests still containing eggs (several which were just hatching).

A careful search of the whole of the West End colony resulted in our finding only three well grown L B B Gull chicks (which we duly fitted with colour rings). We located another 30-40 nests with eggs or tiny chicks. It was also very noticeable that there were no Herring Gull chicks visible on the Island. Again by this time of year these gulls should have been very visible on the beaches and in the air. As it was we only found one well-grown Herring Gull chick on the North End of the Island.

At first I speculated that perhaps a fierce storm earlier in the season could have drenched the exposed West End colony and caused breeding failure. However, when the picture was the same across the whole island this seemed like a less probable explanation for the desperately poor breeding season. Somewhat disheartened we retuned to the hut after a largely fruitless two hour search. After a brief rest we searched the colony around the hut, but with the same very poor results. The beaches along the north held only one Herring Gull chick, and a second chick that was too young to identify.

The L B B Gull adults that were still sitting on eggs/small young returned to their nests very quickly, but it soon became obvious that the majority of adult gulls on the island were spending large parts of the day loafing on the grass. They were not busy feeding chicks, and for the duration of our stay we saw no chicks wandering the edges of the colonies as is usually the case by mid July.

Having checked all the gull colonies, and confirmed the same picture it can only be concluded that the gulls on Burhou have had a disastrous breeding season in 2008. Whether the relatively few pairs which are still sitting on eggs or tiny young can raise these successfully this late in the season is not (yet) known, but even if most are successful the recruitment into the population from 2008 is going to be minimal.

The shags on the island had failed earlier in the summer, and no young could be found on the main island. We could not cross to Little Burhou because of the neap tide. The Puffin raft in the bay in front of the hut contained c 160 birds during the early evening, with several birds seen flying ashore with beaks full of sandeels.

With the gull work cut short by a lack of chicks we had time on our hands, so we went to examine the area where a predator had recently been killing and eating Storm Petrels. Unfortunately, we found wings from another seven or eight birds and a pellet, indicating that the predation problem is continuing. The next day we found the wings of another three or four petrels at the West End of the island. We photographed the remains and collected them to take back to Roland. In all more than 20 Storm Petrels have now been found dead on the Island this summer.

Other birds found dead on the island, which had been predated, included several Feral Pigeons and two Oystercatchers. When we left the island on Sunday we saw a Feral Pigeon being struck in mid-air by one of two hunting Peregrines. One of the falcons hit the bird, which then dropped like a stone with the second falcon chasing after it. I think this was an adult Peregrine teaching a fledged youngster hunting skills. Whatever, the presence of at least two Peregrines on Burhou may be considered a “mixed blessing”…especially if these birds are found to be hunting on moonlight nights! In this context it is important to establish the facts and confirm what is hunting the Storm Petrels. Hopefully the remote camera being set up by AWT will solve the mystery.

After a restful Sunday morning, Sophie and I were picked up by Roland in Nomad at 1230 pm.  We swapped over with Mel and Bill who were arriving to undertake their next Puffin survey counts.

The very poor breeding season for Lesser Black-backed Gulls must be cause for concern. If this is the result of a natural phenomenon, and is short-lived, it will not impact too greatly on the population. However, the situation should be monitored in the years ahead, and if repeated priority should be given to identifying the causes and (if possible) trying to improve the productivity of the Lesser Black-backed Gulls. Burhou has, historically, been a stronghold in the Channel Islands for this species…even more so over the past decade. While there has been success in other Channel Islands gull colonies this year, the birds on Burhou have largely failed to produce young this year.

Our thanks to Roland for his hard work and great assistance in making sure that we could visit Burhou to continue work on the Lesser Black-backed Gulls.