The ecology of seabirds on Ailsa Craig, Firth of Clyde

The Focus of this thesis is the ecology of seabirds on Ailsa Craig, a remote, high, rocky island situated in the Firth of Clyde in south-west Scotland. The island is principally an internationally important Gannet colony but has locally significant numbers of other breeding seabirds. The status of seabirds on Ailsa Craig and in the Firth of Clyde in general, was examined. Possible reasons for the observed species fluctuations are examined. Selected aspects of the breeding ecology of seven seabird species on Ailsa Craig were studied. These are Fulmar, Gannet, Great Black-backed Gull, Herring Gull, Kittiwake, Guillemot and Razorbill. Diets of adult and young of most species are analysed and the growth rate of young is also examined in most cases from hatching to fledging. Growth rate is presented, in most instances, as both the absolute growth rate and the instantaneous growth rate, the latter being used for comparative purposes since it accounts for variation such as individual size, which may be a factor of sex or clinal variation. Dietary data and chick growth rates largely reflect food availability in the marine environment, and this is discussed with respect to the diet and foraging behaviour of the species involved. Remote seabird islands are usually free of any naturally occurring mammalian predators but when alien mammals are transported to islands through anthropogenic agents the consequences for breeding seabirds can be disastrous. Burrow nesting species in particular can be seriously affected by fast- reproducing predators such as rats. Ailsa Craig was colonised by brown rats through shipwrecks around 1889. Following that time certain seabird species, all burrow nesters, gradually and completely died out. This was generally attributed to the effects of rat predation. The final section of this thesis describes a method whereby rats were eliminated from Ailsa Craig and details the techniques and monitoring methods involved. Following the commencement of rat eradication in 1991, preliminary results indicated increased biodiversity and increases in productivity of some bird species. Other important fauna and flora of the island also increased in the absence of rats. After monitoring for six years, the eradication of rats on Ailsa Craig appears to have been completely successful

Molecular evidence for gender differences in the migratory behaviour of a small seabird

Molecular sexing revealed an unexpectedly strong female bias in the sex ratio of pre-breeding European Storm Petrels (Hydrobates pelagicus), attracted to playback of conspecific calls during their northwards migration past SW Europe. This bias was consistent across seven years, ranging from 80.8% to 89.7% female (mean annual sex ratio ± SD = 85.5% female ±4.1%). The sex ratio did not differ significantly from unity (i.e., 50% female) among (i) Storm Petrel chicks at a breeding colony in NW France, (ii) adults found dead on beaches in Southern Portugal, (iii) breeding birds attending nest burrows in the UK, captured by hand, and (iv) adults captured near a breeding colony in the UK using copies of the same sound recordings as used in Southern Europe, indicating that females are not inherently more strongly attracted to playback calls than males. A morphological discriminant function analysis failed to provide a good separation of the sexes, showing the importance of molecular sexing for this species. We found no sex difference in the seasonal or nocturnal timing of migration past Southern Europe, but there was a significant tendency for birds to be caught in sex-specific aggregations. The preponderance of females captured in Southern Europe suggests that the sexes may differ in migration route or in their colony-prospecting behaviour during migration, at sites far away from their natal colonies. Such differences in migration behaviour between males and females are poorly understood but have implications for the vulnerability of seabirds to pollution and environmental change at sea during the non-breeding season

Notes and comments on the taxonomy of Jouanin\u27s Petrel Bulweria fallax and Bulwer\u27s petrel Bulweria bulwerii

Volume: 108Start Page: 71End Page: 7

A further specimen of the extinct Jamaica Petrel Pterodroma caribbaea (Carte, 1866)

Volume: 136Start Page: 209End Page: 21

An erythristic Yellow-billed Parrot Amazona collaria

Volume: 120Start Page: 58End Page: 5

Abundance and patterns of occurence [occurrence] in butterflies from Ailsa Craig, Ayrshire

Volume: 24Start Page: 137End Page: 14

Rabbit calicivirus disease on Ailsa Craig, Ayrshire in 2003

Volume: 24Start Page: 102End Page: 10

Frequency distribution of the expected number of runs of consecutive same-sex captures.

<p><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0046330#s3" target="_blank">Results</a> based on 10,000 random samples drawn from a population of 116 males and 755 females. The dotted vertical lines show the 95% CI limits of the number of runs expected from a random sequence of males and females (189–215 runs), while the solid vertical line shows the observed number of runs (181). The smaller number of same-sex runs observed than expected indicates a greater degree of aggregation than would be expected if males and females are caught in a random sequence.</p

Field sites location.

<p>European Storm Petrels were sampled on migration (Portugal), at the breeding colonies (adults - Sanda Island and chicks - Brittany) and near a breeding colony (Ailsa Craig).</p

Sex ratio of <i>Hydrobates pelagicus</i> controlled in different countries or re-trapped in Portugal.

<p>Sex ratio of <i>Hydrobates pelagicus</i> controlled in different countries or re-trapped in Portugal.</p