Fair Isle’s Seabirds in 2004

Overview: The 2004 breeding season will go down as the worst in living memory for Fair Isle’s seabirds (Table 2). Numbers of birds attempting to breed were at their lowest levels for many species (Table 1) and very few chicks were seen. Common Guillemot, Razorbill, Black-legged Kittiwake, Arctic Skua, Arctic Tern and Common Tern all failed to fledge any young whilst just a single Great Skua fledged from a pitiful 96 AOT (Apparently Occupied Territories). As in most years of poor productivity, it is a lack of Lesser Sandeel (the staple diet of nearly all seabirds in Shetland) that is at the root of the problem.

Northern Fulmar: The number of breeding birds at monitoring plots decreased by a massive 52.5% compared to 2003 to the lowest number since monitoring began in 1986. Fledging success was however better than last year. A productivity figure of 0.43 chicks fledged per Apparently Occupied Site (AOS) is slightly above the previous ten-year mean of 0.40.

Northern Gannet: Gannets first successfully nested on Fair Isle in 1974 (five pairs raised three young) and the population has grown exponentially since. This is the only species to be doing well on Fair Isle in recent years and although the population growth has slowed (an island total of 1868 Apparently Occupied Nests is almost the same as in 2003) breeding success is expected to be typically high. 

European Shag: Numbers of AON (Apparently Occupied Nest) varied at the five monitoring plots compared to 2003 but the overall figure was similar – an encouraging halt in the long-term decline. Numbers at the monitoring plots have declined by 43.8% since 1986. Numbers of AON at the breeding productivity plot in 2004 were however equal to the lowest ever (53 in 2002). Breeding success was extremely disappointing. A productivity of 0.69 chicks fledged per AON is the worst since monitoring began in 1986. Unlike many other species, Shags suffered losses fairly late on when chicks were close to fledging. A large number of chicks (322) were ringed in June/July but weeks later many colonies were littered with dead or dying chicks and many ringed and unringed birds were found washed up on the island’s beaches. A productivity figure of 0.69 is therefore perhaps an over-estimate!

Arctic Skua: The island population continued its long-term decline in 2004. A total of just 33 AOT (Apparently Occupied Territory) - a massive 40% decrease from 2003 - is the lowest figure since the colony was being established in the 1950s. Only a small number even laid eggs and all were depredated (presumably by Great Skuas). Despite evidence of recruitment from other Shetland colonies, several poor breeding seasons since 1990, as a result of food shortages combined with inter-specific competition from Great Skuas are undoubtedly the reasons behind the slide.

Great Skua: Numbers of AOT decreased by 33.8% compared to 2003 to 96 – the lowest number since the1950s. Although many pairs laid eggs, intra-specific depredation was rife and of the small number of young that hatched most were taken shortly after. Miraculously however, one chick did fledge from Sukka Mire. This is the third season of extremely poor breeding success in a row and must have implications for the future viability of the colony.

Mew Gull: In stark contrast to all the other seabird species, the number of nesting Mew Gulls reached an all-time high in 2004. A total of 13 nests were found (including six on Buness) and although just two chicks successfully fledged, they were only the 2^nd & 3^rd to do so in the past four years.

Black-legged Kittiwake: Another disastrous year for this most-troubled species. Numbers of AON at the monitoring plots fell by a massive 40.8%, from 463 in 2003 to just 275 this year. In 2003 50% of pairs managed to lay eggs and 36.5% went on to hatch young - all of which later starved or were depredated. In 2004, although 61.8% of AONs apparently produced eggs, only three (1.09%) hatched chicks – none of which survived beyond a week and all colonies were deserted by mid-July.

Common Tern: Common terns first nested on Fair Isle in 1970 and annually since 1972, but since a peak of 59 pairs in 1989 there has been a steep decline with just a handful of pairs throughout the 1990s and it has been barely hanging on as a breeding bird since. One pair frequented the Havens for part of the season in 2003, but no nesting attempt was suspected amidst the nearby Arctic tern colony on Bunesss. This was the first time in over 30 years that Common tern had not bred.  In 2004, although at least one pair of Common terns was seen regularly in the Havens, they did not, for the second year running, attempt to breed. However, one pair did nest near South Lighthouse and successfully fledged one chick in August!

Arctic Tern: The Arctic tern population fluctuates in response to the previous year’s breeding season and following three disastrous breeding seasons, Arctic terns again decreased in 2004. Although numbers peaked at around 300 birds in one day in late May, all other counts during the spring fluctuated daily and were all below 150 birds. A mere 11 AIA (Apparently Incubating Adult), the lowest since 1985 (when the colony was in it’s infancy) were reported, and only one nest was actually found, a massive decline from the peak count of 2,836 AIA, recorded as recently as 2001. As expected, no chicks fledged and one wonders if any birds will even attempt to settle next year!

Common Guillemot: As in 2003 birds were very late to return to ledges and attendance was very sporadic right up until early May. The first eggs were not laid until 13^th May. Overall numbers at monitoring plots declined for the 4^th year in a row to the lowest ever recorded – a 26% drop from 2003 and less than half the number seen in 1987. The low attendance at colonies meant that birds could not effectively guard against attacks from Herring Gulls and Great Skuas. Eggs were either abandoned or stolen and of the small number that hatched, all starved or were depredated. Ringing trips into colonies were met with depressing scenes. Colonies were almost desolate and the small numbers of chicks that were present were obviously very weak and dying. No chicks were ringed - normally 1500 – 2000 would be ringed each year! A 100% breeding failure is unprecedented amongst this species, which is normally fairly resilient when all around are failing and is a clear indication of how serious the (lack of) food situation was in 2004.

Razorbill: Numbers at the Lericum monitoring plot were only slightly below average and although hatching success at the Easter Lother productivity site was better than it was for Guillemot, the chicks suffered a similar fate and none fledged. Productivity in 2003 was the lowest on record at 0.43 chicks fledged per egg laid and the 1990 – 2003 average was 0.61. A complete failure to fledge any chicks in 2004 is (as with Guillemot) unprecedented.

Atlantic Puffin: Puffins had a comparatively successful breeding season. An estimated productivity figure of 0.63 is similar to last year (0.65) and only marginally below the previous ten-year mean (0.67). Perhaps the slower growth rate and later fledging, compared to other auks, is beneficial to this species.

Conclusion: Another depressing year for Fair Isle’s seabirds (and for Shetland as a whole) and with news that other colonies around the coast of Britain are now experiencing similar problems the future does not look bright.

It would appear that there is a complete absence of Lesser Sandeels of the correct age class. Only a handful of food samples were collected on Fair Isle in 2004 and, combined with feeding watches and casual observations in the colonies, it was apparent that the sandeels that were available were very small. Sprats and other Gadoids were common food items brought into the colonies by all three of the auk species but Puffins were also seen to be bringing in an unusual number of Snake Pipefish. These are almost unpalatable to young puffins and were regularly found discarded near the entrance to burrows.

If, as suspected, this is as a result of “Global Warming”- a change in sea temperature and shifts in ocean currents, resulting in a redistribution (retreating north) of plankton and therefore Sandeels, then the depressing fact is that it may be already too late for Fair Isle’s/Shetland’s/Britain’s seabirds, even if the powers that be brought a complete halt to the production of the contributing pollutants tomorrow. Sadly all we, as Ornithologists in the field, can do is keep monitoring the situation and provide the raw facts to convince the men in suits that this is a serious issue and something must be done!!

Table 1: Population trends at annual monitoring plots 

Numbers refer to: Apparently Occupied Nest (AON) for Gannet, Shag, Kittiwake and Puffin; Apparently Occupied Site (AOS) for Fulmar; Apparently Occupied Territory (AOT) for Great and Arctic Skua; Apparently Incubating Adult (AIA) for Arctic Tern; Attendant Adults for Guillemot and Razorbill

*1986 was first year of intensive monitoring programme under contract to JNCC (Joint Nature Conservation Committee)

**Guillemot and Kittiwake counts since 1987

***Razorbill counts since 1990

Table2: Breeding success at annual monitoring plots 

Numbers refer to productivity ie number of chicks fledged per apparent nesting attempt