The Humps, Herm

14 May 2014

As arranged the day before, Chris Morris and Sea Fisheries staff were very kindly taking members of the Guernsey Seabird Monitoring Team out today to commence the monitoring for the 2014 season. In view of the huge Seabird Wreck in February 2014,  which had resulted in c 37,000 dead/dying seabirds being found in the region (including >1,300 in the Channel Islands), coupled with the continuing protracted period of very high levels of seabird turbidity, we have serious concerns for the success of the 2014 seabird season (and beyond!).

With a gentle NW breeze, sunny and warm conditions and a slight sea we set off in Sea Fisheries’ Leopardess at 0900. The Guernsey Seabird Team on this occasion comprised Chris Mourant, Michelle Hooper, Phil Alexander and Catherine and Paul Veron. It was a swift crossing to Rosaire Steps, Herm, spotting a few Common Guillemots in the Little Russell on the way.

Once at Rosaire we enjoyed a cup of tea, before setting off in the RIB to The Humps via the east coast of Herm, where we were very pleased to count 11 Atlantic Puffins. With around half of the seabirds affected by the February Wreck being this species, it was a relief to know that this small colony on the Herm cliffs had not been wiped out. There are perhaps up to 20 pairs nesting on the cliffs, so a count of 11 on the sea at this time of year may indicate that the colony is largely intact.

No Common Terns were in the vicinity of Saddle Rock as we passed, although the usual lone Great Black-backed Gull pair was in its usual commanding position on the rock. With a falling tide we motored out to Grande Amfrocque first to complete a circuit of the islet and thus get some idea of seabird numbers. Three Atlantic Grey Seals were lazing on the rocks or in the water on approach.

Once again seabird numbers looked rather thin on this islet with few European Shag visible (perhaps 2-4 nests), along with at least four pairs of Great Black-backed Gulls and three pairs of Herring Gulls. One pair of Eurasian Oystercatchers appeared to be nesting. The oddest observation was of a lone Barnacle Goose (almost certainly a feral bird from the Marais Nord, Guernsey), which flew around Grande Amfrocque several times and landed at least twice!

The first signs of a strong hirundine passage today were also recorded with 15-20 Barn Swallows and House Martins flying over the rock. Many Barn Swallows were seen crossing the Big Russell throughout the day on what was clearly a very favourable day for northward migration.

Our next stop was Longue Pierre, but before landing on this islet we completed a circuit to count the Common Guillemots. This was very encouraging with at least 40 Common Guillemots on the east face, a dozen or so on the sea, and 20-30 on the west slopes under the boulders. Given the high mortality amongst guillemots in the Seabird Wreck, this was another very positive sign. The breeding population seems to be around normal (c 50 pairs). Several nesting Razorbills were also recorded, along with two pairs of Atlantic Puffin (one on a nest under a boulder). This was an excellent showing for auks on Longue Pierre. One of the Guillemots was “Bridled”. Catherine will make the necessary return for the UK Bridled Guillemot Survey, which is taking place this year.

Landing conditions were tricky with the falling tide and boulder fields, so we only landed three of the Team (Chris, Phil and Catherine). They quickly surveyed the islet. 28 European Shag nests were counted, 25 of which contained eggs or small pulli. 15 of the nests either had three eggs (or in one case each one pullus and two eggs and two pulli and a single egg, plus two nests with three pulli). Three nests had two eggs, while another two had three small chicks each. Five nests contained just a single egg, while three active nests were empty. While this is a modest number (the islet can have up to 50 pairs in some years), there must remain concerns about the viability of the nests, given the continued very cloudy state of the water. It will be very interesting to see how many further chicks hatch and fledge from this modest number of nests. It is at least encouraging that some shag are nesting this year, and that just over half the nests had clutches of three eggs.

30+ adult Great Black-backed Gulls were counted flying over the islet and the team located four nests (two with complete clutches of three eggs, and two with two eggs).  A full sweep of the islet was not carried out to the west where the majority of the nests are located. The verdant vegetation of Tree Mallow makes it hard to locate gulls nests on both Longue Pierre and Godin. However, there are always many more adults on these islets than indicated either from the nests we record or the chicks that we ring later in the summer. One dead adult Great Black-backed Gull was found (no obvious cause of death).

One Lesser Black-backed Gull nest contained three eggs, although one was a very small unviable egg. A Herring Gull nest with two eggs was also located.

While on the islet Chris, Phil and Catherine caught three adult guillemots, and remarkably (given the low numbers ringed in the islands), two of the birds were local re-traps (H1317 - originally ringed as an adult on the Humps in 2003 and H1387). 24 eggs were counted under the main breeding boulder in the centre of the islet.

Our final landing for the day was on Godin, the innermost of the four Humps. With no Great Cormorants nesting on Longue Pierre this year, the entire colony was back on Godin. It was excellent to have a large team for this landing, as the cormorants were at all stages of nesting from incubating eggs to feeding almost fully grown youngsters. With five people we were able to encircle the islet and then coral the birds successfully, enabling 23 chicks to be colour ringed. Six chicks were too large and were left unringed as they wandered in places too dangerous to try to catch. Some chicks were too small to ring, and there were a number of nests still containing eggs.

A rough nest count produced 35 Great Cormorant nests. This season therefore appears pretty regular for Great Cormorant – a species which (unlike European Shag) can feed equally successfully in fresh and sea water. It is interesting that The Humps colony now appears to be stable at c 30 -35 pairs. It does not appear to be expanding any further.

It is the cormorant colony that now dominates Godin. Most of the European Shag have moved to other sites. Only a small handful of Shag appear to be nesting on Godin now. The small Common Guillemot colony (c 15 pairs) appeared to be OK, with many of these birds incubating their single eggs under the boulders at the north-east end of the islet. 32 Great Black-backed Gulls were counted overhead, but only a handful of nests (all with three eggs) were located (not that we spent time looking for them). Once the cormorant colour ringing had been completed we left the rock.

No Common Terns were observed on this visit. There had been colony of 20+ pairs on Godin last season, but they arrived late in 2013, and hopefully may do so again this season.

This had been a really valuable visit showing that, against expectations the Common Guillemot colonies on The Humps appeared largely intact with the birds nesting as normal. The tiny populations of Atlantic Puffins (three – four pairs) and Razorbills (three-six pairs) also appear to have survived the winter storms and are breeding as usual. Great Black-backed Gulls, an important top predator in the Island’s marine eco-system, were also on par with recent years. Cormorants continue to produce a good number of young, but the colony appears to have stopped growing. Not surprisingly this would appear to be a poor year for European Shag – almost certainly a combination of the prolonged winter storms (meaning that many adult birds may not have reached breeding condition) and the continued murky state of the sea (making hunting fish prey more difficult than usual).

And we thought that was the end of a good day’s monitoring…until Sea Fisheries offered more…and so we went to Sark…but that’s another account!

 

 

PKV

16 May 2014