Burhou, Alderney

12 – 14 June

 Burhou is the single most important breeding colony for Lesser Black-backed Gull in the Channel Islands – with c 1,000 pairs in most recent years (including 2010). As such it is a critical site to the current gull research projects being undertaken in the Bailiwick of Guernsey.

 Catherine and Paul Veron were able to visit Burhou, along with Jen Stockdale, the Ecologist for the Alderney Wildlife Trust (AWT), over the weekend of 12 – 14 June 2010. Given the recent highly variable weather we were fortunate to be able to land and carry out the research. Catherine and Paul flew up from Guernsey, arriving in Alderney at 11.20, where Jen kindly picked them up and took them to the supermarket to buy food for the trip.

 At  14.30 Roland Gauvain took us over to Burhou in Sunrise – the AWT’s RIB. It was a fast crossing over a relatively quiet sea – accompanied by many flights of Northern Gannets making their way back to the gannetries of Les Etacs and Ortac.

 After settling in to the hut on Burhou we set about trying to catch some adult Lesser Black-backed Gulls – the primary purpose of the trip. After a completely blank start in the colony just to the east of the hut, we got better at it! This area is quite thinly populated this year – much less so than in recent years. As this area is one of the closest to the main Puffin colony where some nests in close proximity to the puffins are destroyed it is possible that the gulls have finally got the message and moved further west across the island.  Certainly the main colonies to the west of the hut – all the way out to the west end looked well-populated, and Jen had the previous week made a very encouraging count of just over 1,000 nests in this large Lesser Black-backed Gull colony.

 In common with elsewhere in the Bailiwick, the LBBGs on Burhou appear to be a week-10 days earlier with their nesting than in 2009. The previous week Jen had seen the first few chicks just beginning to chip out of their eggs. During our visit the vast majority of nests still contained eggs, but there were a good number of chicks only a few days old. I was concerned that the prolonged heavy rain at the end of the previous week may have taken a heavy toll of very young chicks, but there was little evidence of this on the ground.

 We finished catching adult Lesser Black-backed Gulls three hours before dark, by which time we had colour ringed 19 new adults – including one bird which had been ringed as a chick on Burhou in 2000. We also recorded five colour ringed gulls – four LBBGs (including a bird ringed in the winter at Gloucester landfill, which is breeding on Burhou) and three adults ringed on the islet in 2009. The other was a Herring Gull ringed by Jamie Hooper as a chick on Pleinmont Cliffs, Guernsey in 2004.

 After a thoroughly encouraging start to our work we retired to the hut for supper and an early night. The weather held well, and Saturday dawned a near perfect day for the trapping – dry, but not too warm. After breakfast we began to catch gulls at 0700 and worked our way around the island, working for 10 hours to trap a further 56 adults – including four more which had been metal-ringed as chicks on Burhou in July 2000 (one) and 2003 (three). We also caught one of the adults colour ringed on Burhou in June 2009 (at the west end).

 We made a brief trip across to Little Burhou to help Jen with her gull counts. Here we recorded 99 Lesser Black-backed Gulls, 23 Herring Gulls and 17 Great Black-backed Gulls. A Great Cormorant nest with small chicks could be seen, and there were several nests in the central ridge with large chicks. However, we maintained our focus on the gulls and did not ring the Shag or Cormorant chicks.

 Tiredness eventually set in before we reached the end of the main colony, but everyone worked exceptionally hard to ensure safe catches and the recording of full data for the gulls. It was very good to see all birds in excellent condition and only natural food was regurgitated by the caught birds – indicating that the colony is continuing to feed on natural food. The most commonly observed prey items were sandeels, with several instances of squid/cuttlefish. Fishermen in Guernsey have commented on the abundance of small sandeels this spring/summer and this seems to be reflected in the food being taken by several seabirds – including Lesser Black-backed Gulls and European Shags.

 After refreshments and a short rest we set out to record some more colour ringed gulls, and enjoyed good success finding nine more Burhou-ringed adult LBBGs, and a couple of Guernsey-ringed  Herring Gulls.

 During the night it rained several times, and our last day dawned with stiff, cold north-easterly wind and frequent rain showers. Clearly we could not continue to catch adult LBBGs in such conditions so we used the remainder of our time to make a complete gull count of the main island – arriving at totals of 1,429 LBBG, just over 100 Herring Gulls and 28 Great Black-backed Gulls. We then recorded a few more colour rings – including another Gloucester-ringed Lesser Black-backed Gull, which is breeding on Burhou.

 Although a little curtailed by poor weather on our last morning, this had been a very successful and valuable trip, with much excellent gull data obtained. We were able to colour ring another 74 adult Lesser Black-backed Gulls, and take 23 colour ring observations on Burhou (including two LBBGs that had been ringed in winter in Gloucester by the Severn Estuary Gull Group and which are clearly CI breeding birds).

 I was also thrilled to record 16 of the 67 adults colour ringed in 2009 (several of which had been reported from France, Spain or Portugal over the intervening winter) and one of the four colour ringed in 2008. Given its long grass and the location of some of the sub-colonies Burhou is not a particularly easy place to obtain cr sightings – so this was a good effort. Thanks to Jen for taking her telescope over!

 In addition we trapped five LBBGs that had originally been metal ringed as chicks on Burhou – some a decade earlier in July 2000, and we read another two metal rings with the telescope (both birds ringed as chicks on the island in 2005).

 A Peregrine was the only raptor seen on the island this visit.

 Roland picked us up in Sunrise on cue at 1120 on Monday morning and we returned through pretty choppy seas. Roland then ran Catherine back to the airport for her lunchtime flight home, while I spent a leisurely afternoon walking around the north end of Alderney, before catching my 16.50 flight back to Guernsey.

 My sincere thanks to Catherine and Jen - both of whom worked tirelessly to obtain some really good data for the gull studies. Thanks also, as ever, to the AWT manager Roland Gauvain for transporting us to and from the island.

 

PKV

15 June 2010