Early spring - April
The first human visitors were not exactly swamped with migrant arrivals but there were about 4 days with around 10 new Willow Warblers and up to 5 Chiffchaffs. Close to 10 Blackbirds were ringed, as they head back to Scandinavia for the summer. Small numbers of Reed Buntings, Meadow Pipits and Goldcrests were also ringed. Some nice Goldfinches, Linnets and Redpolls visited the lab! 40-50 shearwaters, mostly old retraps, were handled on most nights. There were some other nice handlings: an amazing total of 3 Sparrowhawks were ringed, a Pied Wagtail and an excellent Wheatear. The first female Chiffchaff arrived on the 12th but otherwise all the warblers were males. The clear night skies probably allowed many migrants to pass over the island on their way to their breeding grounds. Other good sightings included a Short-eared Owl, 3 Greylags, and lots of crows of all sorts.
Two Mallard were retrapped 4 years after they were originally ringed together.
Work was done on a water transfer system that should be able to keep the tanks full for supplying the hot water and toilet systems.
Surprisingly, migration continued to be steady throughout April despite excellent weather. The 13th saw 16 Willow Warblers being ringed along with a Chiffchaff. The 14th produced 21 Willow Warblers, 2 Chiffchaffs and a Blackcap. There was a steady trickle of Swallows too, totalling around 20. Two great Northern Divers were seen close by. The Black Guillemot colony was gathering in strength with around 80 present. The Eiders were very noisy – lovely!
The 20th April was a really good day with 50 Willow Warblers arriving and of these 28 were ringed. Just one Chiffchaff was caught, but a nice arrival was 5 Greenland Wheatears of which one was caught. Though this sub-species is identifiable in the field, it is best to catch and measure them to be certain as they are around 10% longer in the wing and weight. Passing through the day were 80 Swallows, 15 House Martins, 10 Sand Martins and an early Swift.
The 21st was nearly as good with 24 Willow Warblers ringed out of 40 arrivals, 2 Chiffchaffs, a Blackcap and two very early Whitethroats. A total of 3 Blackcaps were ringed out of 4 seen over the weekend, bringing the year’s total to 6 ringed. Most of the Willow Warblers over both weekends were males so the bulk of the females have still to arrive. Our impression is that the main Willow Warbler migration has been a bit late this year by around a week. Over the two weekends last weekends of April, about 116 passerines were ringed.
The Eider ringing project which was put on hold last year due to the Bird Flu scare was restarted this year, this time on Big Copeland. There was a first full breeding bird survey of the whole island in early May and simultaneously a party searched for Eider Duck nests, ringing 28 ducks, a further 22 nests were located and 7 broods already hatched were seen offshore. As only the 100m coastal strip was searched, we came to a whole island estimate of 100 pairs. Eventually we will survey and ring the females on Mew Island. Those involved in the catching of the Eiders end up quite splattered by one of the most obnoxious, smelly droppings that is unimaginable. Worse than finding it on your clothes is finding it in your hair!
Breeding Birds
Big Copeland is the second most important breeding seabird site in Northern Ireland, after Rathlin. Therefore we have focussed our attention in recent years on monitoring the breeding seabird success rates.
By the second half of May, terns were settling in to their various colonies, and the first Black-headed Gull chicks were hatching. Large numbers of Shelduck were still around the island displaying as were still a surprising number of Eiders. A 4 foot Tope, found dead at the northwest side of the Big Island was interesting to see, as was a nest of the giant eggs of Great Black-backed Gull. A pair of Mediterranean Gulls looked very handsome in their full adult plumage. Perhaps the best sighting on one of the survey visits was a swirling group of 8 Buzzards in a thermal.
There were some day trips in late May. The island was looking its best because of the flowering bluebells, Red Campion and white Sea Campion. Broods of Eiders were in the sea and the very tame Black Guillemots entertained the visitors. A nice Spotted Flycatcher was caught on one such day, for all to admire and photograph.
Arctic Terns arrived early on Mew Island and quickly developed into a bustling and noisy colony of 350 pairs. The sound of the terns on Mew was a nice new background to the range of sounds to be heard by weekenders on the observatory itself. However, by the second week of June, the weather had broken and heavy rains and thunderstorms soon reduced the colony to a remnant of the early promise. As the rains eased, only 150 young (instead of the hoped for 600+) were half grown or more, but the Lesser Black-backed Gulls arrived at the edge of the tern colony and by early July they had eaten all the remaining tern chicks. Ten pairs of Mew (Common) Gulls and 24 pairs of Black-headed Gulls nested with the terns but a mixture of weather and predation reduced success to very low levels.
The breeding birds on the observatory itself all apparently did well with 11 pairs of Meadow Pipits, over 6 pairs of Reed Buntings, and 6 pairs of Sedge Warblers. Large post-breeding flocks of Meadow Pipits have been a constant feature of the late summer. Common (Mew Gulls continue to decline at the often flooded shore colony at the south but were spreading elsewhere on the island and especially to Mew.
Big Copeland in mid-June
The trip to ring the young Black-headed Gulls found only one young bird of ringable age (or any age). So it was obvious that there had been a major egg disappearance. The only explanation was that there had been an illegal collection of all the eggs that were in easily accessible colonies. All species of gulls were involved though the Herrings and Lessers on the north side of the island were missed probably due to remoteness and the thin spread making a search not worth the effort. Everyone consulted agrees with our opinion that such a complete clean sweep could only be explained by human activity. Sheep could be regarded as possibly involved but the detailed evidence rules them out. There was no trace of any shell remains, for example. The possibility of a human cause is apparently plausible to the police and other parties in England and Scotland, judging from information they have about similar events there, apparently. Such stolen eggs are eventually destined for human consumption.
The new PSNI Liaison Officer and the Sergeant in Donaghadee are working hard on the case and preparing a strategy to prevent it from happening again next year.
Fewer terns attempted to breed on Big Copeland this year. It seemed likely that the Mew colony consisted of birds that transferred from the Big Island. The total of breeding pairs of Arctic Terns on both islands at the start of June was just over 1000 pairs, similar to last year. However by late June the tern colonies on the Big Isle had all failed due to the exceptionally wet weather. There were unofficial reports from Bangor of 8 inches of rain in June instead of the usual 2 inches.
It was not all bad news however. Lapwings, Eiders and Shelduck all seem to have had quite a good year.
The Shearwater Study
During June, five projects were done on shearwaters. An estimation of colony size using the play-back method was carried out both on the observatory island on Big Copeland. Indications are that there has been no significant change in numbers since the last surveys of 6-7 years ago, though on the observatory, the trend is probably still slightly upwards.
We have also carried out a study of the procedure of the play-back method, to determine how accurate it is. Copeland is one of several other sites in the UK that has been evaluating the method.
The principle is simple. If a recording of a male shearwater is played down a breeding burrow and a male is incubating the egg, it will respond by calling back. A female will ignore the call of the taped male. A sample of burrows across the island was tested and the number of responses in the sample areas counted, the total number of breeding pairs will be twice the responses counted, as it can be assumed that half the sitting birds are males and half females, as it is known that they share incubation equally. There is quite a lot of counting involved, and much other information is collected and analysed such as burrow density and occupancy. Eventually statistic methods are applied to determine the reliability of the calculations. It seems the observatory’s colony is around or just over 3000 pairs, while somewhat less than 2000 pairs nest rather thinly over Big Copeland.
A fourth check on two constant sites on the observatory which are surveyed every year has been done. This study is to try to detect annually any fluctuations in breeding numbers, rather than having to wait 6-8 years between major surveys.
Finally, a project was carried out by the Department of Zoology, Oxford University, to try to follow the travels of a sample of a dozen or so shearwaters during their off duty spell away from the nest while their partner incubates the egg. The position of the bird can be detected by a small electronic device temporarily attached to the birds back. When it returns to the nest (always in one of our special study burrows, of which there are now 120), a few days later, the device is removed and the information in the sensor is downloaded into a computer and the journey reconstructed. The results indicate that Copeland Shearwaters travel to the area south of the Mull of Galloway and even to the Cumbrian coast on their summer feeding trips.
Shearwaters, being nocturnal, are very difficult to monitor. Populations could crash before a problem might be detected. They are under threat at sea, as they can become entangled in fishing nets. There is concern that the food sources of many species of seabirds is declining due to the problems of climate change. There is every reason to suppose that shearwaters might be affected by this problem. The work on Copeland, along with studies on Skomer, Bardsey and Rum, is necessary to keep track of the fortunes of this species and therefore is of great importance in its conservation. Detailed results of this work will be made available to CBO members in the Annual Report for 2007.
The heavy rain in June had two other effects. The ponds on the island both filled. This has never happened before in the 45 years of the south pond’s existence. The other effect was that the heavy rainfall flooded many shearwater burrows, especially near the top of the cliff. Now that we have the shearwater study burrows, we can determine how serious the flooding has been. It is a known problem for shearwaters on Bardsey at times, and sometimes on Copeland. In the past the flooding has been noticed only in late July and August when the young have a reasonable chance of surviving unlike eggs. The flooding this June was not only at the wrong time, but it was more serious than anything that has previously occurred on Copeland. Burrows known to have eggs were flooded to ground level. Only around 30-40% of the breeding pairs seemed to have live young by August.
The shearwater study has continued unabated. Many retraps were recorded during August. The study burrows have greatly improved our understanding of the dynamics of our colony. The situation will be clarified further during September when the usual annual effort will be made to ring as many chicks as possible.
The separate study of the accuracy of the play-back method of estimating colony size, using the study burrows, has yielded another set of most interesting results. There are all sorts of strange things going on underground. Some restless adults can leave the egg cold and then re-incubate a day or two later, fights can occur and eggs lost or moved, threesomes can be involved in incubation, the length of time a bird may incubate without relief can be 7 days, though others change over after only one day. However, the most amazing thing relevant to the whole basis of the playback method is that we now have some evidence that males spend longer on the eggs than the females. It has always been assumed that the two sexes share incubation equally after the first week of incubation, which is done only by males. The workers on Rum have also found that the males play a larger role in incubation. If this turns out to be true on all three sites including Skomer, the method will still work but the calculations will be a bit different, resulting in the current estimations being reduced a bit, though not by much.
The Shag colony on the Maidens was visited in mid July and found to have almost totally failed. A quick dash in a brief weather window to ring them produced a total of only 13 young, soon to fledge, and no sign of earlier fledged birds. So the success rate in 2007 was only between 5 and 10% of what it might be in a good year.
The big vegetation management week now traditional in early July was very successful. All the balsam plants that could be found were removed or cut down. This has been a very big effort because the area to be tackled was nearly a quarter of the original area that was swamped by balsam. The work isn’t over yet because past experience shows that there will be scattered resurgences of balsam next year and possibly for several more years. This has previously happened even in areas that we thought we had cleared. It is hoped that the future work will not be so hard to do as it has been over the last 10 years. The work of the very dedicated team that has worked so hard on this project over these past years is much appreciated by everyone. It is going to act as a model and inspiration for conservationists elsewhere faced with the problem of habitats being destroyed by this pretty but invasive species. Late news – Due to the wet year the regrowth has happened so quickly that regrowing plants are already seeding. Unfortunately too few people have been available for dealing with the stragglers. Efforts will continue to try to prevent further seeding during the rest of the autumn.
Another in the long series of ringing visits to Inishglora Island in Co Mayo took place in mid August. Despite quite windy conditions, about 2200 new birds were ringed and over 200 retrapped from previous expeditions plus about 20 controls from elsewhere. Seventeen people were involved. It will be some time before a full analysis of the retraps and controls will be done, but full details will be in the Annual Report for 2007.
A special workday took place on the 25th August. The old well was cleaned out, dorm 2 was freshly painted, beaches were cleared of flotsam, the balsam war was continued and a large consignment of timber was carried up to the buildings. This was done by a volunteer group from local industry as part of a team building programme and was much appreciated.
Autumn migrants have been rather scarce. Almost none of the expected passerines such as the expected Willow and Sedge Warblers have appeared in August. Seabirds have been more noticeable including 3 Balearic Shearwaters in one day, and several fine views of various skuas.
| © Copeland Bird Observatory, 2006 |