COLONIZATION OF THE LAND

Bird Life on Surtsey

Surtsey had just risen above the ocean surface when the first birds made their landfall. Since then, around 90 bird species have been recorded on or around the island. Some of them are seen on feeding trips from their breeding colonies on neighbouring islands. Others are transient migrants en route between breeding areas elsewhere in Iceland or the Arctic and wintering grounds in Europe or Africa.

Regular bird observations were maintained on Surtsey from 1966 to 1971; these were directed primarily at staging migrants in spring and autumn. One question was their importance in carrying pioneering plant seeds to the island. Some very rare stragglers have been recorded on Surtsey, including the only Squacco Heron Ardeola ralloides to be recorded in Iceland, a species which nests in southern Europe.

The first birds began breeding on Surtsey three years after volcanic activity ceased. Two Black Guillemot (Cepphus grylle) nests and a Fulmar (Fulmarus glacialis) nest were discovered in 1970. Since then, a number of other species has been confirmed breeding on the island; Great Black-backed Gull (Larus marinus) in 1974; Kittiwake (Rissa tridactyla) and Arctic Tern (Sterna paradisaea) in 1975; Herring Gull (Larus argentatus) in 1981; Lesser Black-backed Gull (Larus fuscus), found around 1985; Glaucous Gull (Larus hyperboreus) in 1993; Snow Bunting (Plectrophenax nivalis) in 1996; Greylag Goose (Anser anser) and White Wagtail (Motacilla alba) in 2001; Meadow Pipit (Anthus pratensis) in 2002; and Puffin (Fratercula arctica) in 2004. Full confirmation of the White Wagtail and the Meadow Pipit was not obtained until in 2003, while the Greylag Goose probably bred first in 1999. Puffins were first suspected to breed in 2001 when they appear to have produced scrapes. In 2003 their behaviour indicated nesting, although this was not confirmed, while in 2004 they were found breeding in two places. Thus 13 species of birds have been found nesting on the island till (and including) 2004. Twelve of them appear to breed annually now, but the Arctic Tern has not been found with a nest since 1978. In addition to those 13 species, Ravens (Corvus corax) have built nests or have attempted to do so, but without laying eggs.

In the summer of 1990, a complete census was carried out of the numbers and distribution of the breeding birds. At that time the breeding species were six: the Fulmar was the most common breeder with at least 120 pairs, followed closely by the Lesser Black-backed Gull with around 120 pairs. There were 35 pairs of Great Black-backed Gull, 25 pairs of Herring Gull, around 15 pairs of Black Guillemot, and 4 pairs of Kittiwake.

In 2003, an entire island census was repeated, by which year the breeding species totalled eleven. As in 1990, the Fulmar was the most common species, with 350-400 nests. The Lesser Black-backed Gull came next with 150-200 pairs, Kittiwake had around 130, and Great Black-backed Gull, Black Guillemot, and Herring Gull each had 35-40 pairs. The Snow Bunting had reached 10 pairs, Glaucous Gull 4-5 pairs, and there were two pairs of each of Greylag Goose and Meadow Pipit. Only a single pair of White Wagtails was recorded; hence it is the rarest of the Surtsey breeding birds. One mixed pair of Glaucous Gull and Herring Gull was present in 2003.

Which Bird Species are likely to colonize Surtsey next?

A Rock Pipit Anthus petrosus was seen during the height of summer of 2002, a candidate breeder in years to come. The Oystercatcher (Haematopus ostralegus) and the Ringed Plover (Charadrius hiaticula) are also likely colonizers, while the Arctic Tern may well begin breeding again. The two petrel species, which nest on the other Vestmannaeyjar (Westman Islands), the Storm Petrel (Hydrobates pelagicus) and Leach’s Petrel (Oceanodroma leucorrhoa), have been considered potentials for breeding, but so far they have evaded discovery.

Bird communities are usually made up of species with different life styles; the complexity is dependent on the environmental conditions available in each location. In the beginning, all the breeding species on Surtsey island, relied on the ocean for their food. Such was the situation in the summer of 1990, but a decade later the island had become much more vegetated with increased insect life, making it possible for terrestrial birds to breed. Currently Snow Buntings, which are seed and insect eaters; Greylag Geese, which are grazers; and the insect-feeding White Wagtails and Meadow Pipits have successfully colonised the island. Ravens, which subsist on eggs, birds or by scavenging, appear to be able to sustain themselves on the island, but the general feeding conditions still seem to be too poor for breeding and raising young. The large gull colony of over 200 pairs probably could supply enough energy for a breeding pair of Ravens. However, the gulls that breed on Surtsey are large, hardy birds, which by their sheer numbers have probably no trouble keeping a few Ravens away.

The breeding birds are obviously very important in the formation of soil on the island, as well as in the development of the plant and insect communities. This is especially true for the seabirds, which actively transport nutrients from the ocean onto land. This is particularly noticeable within the main gull colony on the lava fields in the southern part of the island, where full vegetation cover has developed over a certain area as a result of their breeding and nutrient-transfer activities. The first birds began forming this colony in 1984.

Unfortunately, regular bird observations could not be maintained after the earliest years. It is important that seabird colonies be carefully mapped in future and the numbers of all the breeding populations monitored at regular intervals, perhaps every other year. Such observations will also assist botanists in examining the importance of birds in the formation of vegetation and animal communities on Surtsey.

New or rare bird species can be expected to reach Surtsey virtually at any time. It is important that such records be compiled. The author would be grateful for any such information from those who visit the island, not the least on new breeding species.

See a slideshow of bird life on Surtsey

(author: Ævar Petersen - aevar@ni.is)

- last updated 06-May-2007