Mimivk on flickr.com

Photo by Michelle van Kampen on flickr.com

This is something I spotted while responding to someone on Flickr.com. I noticed that Michelle van Kampen had posted a photo of a dead seabird. When I enquired, she posted a news story about it.

Interestingly, all of the media reports say that pollution probably isn't to blame. However, Niall Hatch from BirdWatch Ireland reckons that these birds were the result of a later breeding season than normal - when the fledglings left their nests, and went looking for food, they met with rough sea conditions, and were unable to feed. I've emailed Niall for more information, haven't heard back yet.

Just last night I was talking to a friend of mine from the north of England, himself a keen birdwatcher. We were talking about the birds - like the little egret - that were, until recently rare summer visitors in Britain in Ireland, but now they're quite common. A few weeks ago, my mother reported seeing nine egrets hanging out with two herons, near our house on the river Slaney. Unheard of when I was a nipper.

Could last week's birdkill be related to hotter summers, confusing the breeding patterns of guillemots and razorbills?

Here's the media mentions:

During the past week over 100 guillemots have been found washed up on the shores off County Down. The RSPB say tests were carried out and they revealed that the birds were starving to death. Dead guillemots and razorbills have also been found in Scotland and in the Republic of Ireland as far south as Wexford so the death toll could be in the thousands.

UTV: Seabirds perish on Co Down coast »

Hundreds of seabirds washed ashore along the east coast are believed to have died from starvation, according to bird experts, writes Breda Heffernan.

Rangers from the National Parks and Wildlife Service are carrying out tests on the remains found at beaches from Dundalk to Arklow. The birds are mainly guillemots, although razorbills and cormorants have also been found.

Niall Hatch from BirdWatch Ireland said it appeared many of the dead birds were extremely emaciated and may have starved to death. So far, there is no indication pollution was a factor.

Irish Independent: Washed-up birds may have starved »

Some reports from the UK and Irish governments on Climate change and migratory species:

Britain's changing wildlife »

DEFRA: Climate Change and Migratory Species (UK) » (pdf)

Climate Change: Implications for Ireland’s Marine Environment and Resources (Ireland) »

Update 27 September 2006:

Here's an email that came in from Niall Hatch at Birdwatch Ireland:

The recent spate of dead birds reported along the Irish east coast was a cause of much concern both to ourselves in BirdWatch Ireland and to the public in general. Obviously the initial worry was that toxic pollution or a contagious disease might have been the cause, but the National Parks and Wildlife Service were able very quickly to rule these out. The cause of death was confirmed as starvation, and all of the dead birds recovered were found to have been in an emaciated condition. Interestingly, many were also heavily infested with nematode parasites, which would likely have placed an additional burden on the birds' nutritional reserves. Such parasites are extremely common in many wild birds and tend not to cause them too many problems, but in cases where a bird is already weak and lacking in food they could perhaps be the final straw.

Despite the fact that various different species (Cormorants, Manx Shearwaters, Shags, Razorbills, etc.) were reported both to us and to the media as being found dead, all of the birds in fact turned out to be juvenile Guillemots. We would normally expect to receive reports of some dead young Guillemots and other auks at this time of year, as mortality of youngsters immediately after the breeding season can be quite high, though numbers reported this year do seem higher than normal. I suspect that the reason that the newspapers and other media initially chose to focus on the story may have been because they were mindful of a possible avian 'flu connection and so paid more attention to reports of dead birds than would normally have been the case.

Though no-one can be fully certain, I suspect that the deaths were likely due to a combination of factors that affected the birds. It is certainly true that most Guillemots at Irish colonies did begin to nest somewhat later than average this year, though it is not possible to say whether or not global warming played a role in this. I don't think it would be correct to say that the birds are confused as to the time of year or that the temperature is affecting their thinking in this regard: in very (perhaps overly) simple terms, if the climate were warmer we might expect the birds to attempt to breed earlier rather than later. Breeding can be delayed due to a number of factors, such as storms and other rough weather in areas between the wintering grounds and breeding colonies, meaning that the bulk of the birds are reluctant to travel. Also, poor feeding for the adults during the winter may mean that they need to spend longer building up their energy reserves in late spring/early summer before they are ready to go through the rigours of raising chicks. Of course, some of these factors themselves could conceivably have been caused or contributed to by global warming, but it is too early to be certain.

Other seabirds breeding in the Irish Sea, such as various tern species, Cormorants, etc., bred at the normal or average time this summer, and did not seem to be affected by food shortages at all. Many of these species, particularly the terns, rely on the same general prey (sand eels) as the Guillemots, and they seemed to cope just fine. In fact, Guillemots can catch prey at a far greater depth than then terns can, which means that when food is scarce the Guillemots and other auks usually tend to fare better than the terns. Also, there is no evidence that the breeding itself went badly at the Irish auk colonies once it had commenced, and the adult birds certainly seemed to raise their chicks as normal, which would lead us to believe that there was still plenty of food available for them throughout the summer.

I think that the key factor here is that all of the dead Guillemots were juveniles. These leave their nests and fend for themselves before they are able to fly (though they are able to swim and dive extremely well), which means that they need their prey to be relatively close by. Normally this is not a problem in mid-summer, and by the time September comes the youngsters are more mobile and better able to follow the fish shoals. However, if the young birds were a few weeks behind in terms of their development, they would still not have been able to fly properly and, if the fish moved significantly, may not have been able to fly with the older birds to follow them. Young terns, which don't leave their colonies until they can fly, did not suffer any problems, and seem to have been able to feed just fine on the sand eels. The increased incidence of nematode parasitism amongst many of the young Guillemots may have made an otherwise survivable situation more deadly; the reasons for this increase in parasites is not yet known, but natural fluctuations are very common and do not themselves necessarily give cause for concern. There is a degree of speculation involved in this analysis, of course, and the precise reasons for the deaths may never be known, but hopefully it is just a one-off incident that was the result of several specific and unfortunate circumstances combining and hitting the birds simultaneously. If the pattern is repeated in future years, however, it may be evidence of a more fundamental problem - it is too early to say yet.

It is also important to point out that, though the precise number of casualties is uncertain, as for every bird that washes up on shore there will on average be several more that die at sea and are never found, we are still taking about a small proportion of the total Irish Guillemot population. The vast majority of the juveniles seem to have survived, and, unless this pattern is repeated for several more years, there is no immediate cause for worry. We need to be vigilant when it comes to seabird deaths, certainly, and it is encouraging that this incident has shown that the Irish media seems to appreciate and respect this more than they have in the past. Ireland's seabirds are monitored very closely each year, so if further problems do arise we would expect them to be noted very quickly. Certainly the tragic situation that has occurred in the North Sea over the past couple of years, where seabird breeding success has been disastrous, thankfully has not been mirrored at Irish colonies.

I notice on your blog that you also make reference to the recent colonisation of Little Egrets in Ireland and Britain. This has been one of the most interesting ornithological events of recent times, and the reasons for it are not fully understood. We do not know whether global warming has been a factor; it may indeed have been part of the reason, as traditionally the egrets were more or less confined to warmer areas of continental Europe. The spread of this species towards Ireland has been happening gradually for several decades, and it is now quite a frequent sight, particularly on the south and east coasts. There could also be other factors at play, however, and to single out global warming alone could be jumping the gun. The Little Egrets have managed to find a niche that other species were not exploiting as adeptly, and Ireland possesses an abundance of ideal habitat and food for them. Given enough food, they are quite capable of surviving very cold weather, such as they frequently encounter in winter on the continent, and their spread here could perhaps be a response to a reduction in water pollution in Ireland; we simply don't know.

There is actually a long history of new bird species colonising Ireland under their own steam: the Collared Dove, which first appeared here in 1959, and the Fulmar, which appeared in 1911, are two prime examples - both are now common breeders in Ireland. The 19th Century also saw several new colonists that we take for granted nowadays, including the Stock Dove and the Tufted Duck, so this is certainly not a new phenomenon.