New survey of Clare Island. Volume 9: Birds ed. by T.K. Kelly

Abstract

Reviewed by: New survey of Clare Island. Volume 9: Birds ed. by T.K. Kelly Joe Furphy New Survey of Clare Island. Volume 9: Birds T.K. Kelly (ed.) (Royal Irish Academy; 166 pp; €35) ISBN: 978–1–911479–41–3 Any published work must be seen as a picture of a particular time and place, but one of the strengths of New Survey of Clare Island. Volume 9: Birds is the way in which comparisons are made with other locations and species. While it is particularly interesting to see the tables in the Appendices giving comparative statistics for several Irish islands, for many readers their fascination will be with the unanswered questions on bird population make-up and the differences between Clare Island and other islands, especially where habitats, food resources and land use etc., appear superficially similar. An early chapter lists the avian species so far recorded on Clare Island. Some are given longer descriptions, contributing towards an understanding of relationships not only inter-specifically, but also spatially in relation to the situation on the nearby mainland, although few direct comparisons to topography or land use are made. The Clare Island avifauna benefits from a lack of general human interference; only two species are listed as deliberate introductions: Canada goose Branta canadensis and Pheasant Phasianus colchius; ironically, throughout Europe both species are often unwelcome; questions therefore need to be asked about their effects on the native populations on Clare Island. Separate chapters are devoted to seabirds, land birds and water birds. The seabirds chapter raises several interesting and relevant questions regarding the population dynamics of several species. Contrasts with population changes in other seabird colonies not only make interesting reading but also pose questions as to why there is so much variation in numbers in colonies that externally appear similar in terms of habitat and available food supplies. By way of example, Gannets did not nest on Clare Island until 1978 but the numbers have dramatically increased, while the number of Fulmars, similarly open-sea feeders and cliff-nesters, has decreased. Fortunately, there have been several national and European censuses of seabirds, so there are sufficient data available to allow basic comparisons to be made and research projects instituted to ascertain reasons for such discrepancies. However, a full analysis of the causes for fluctuations in bird population requires evidence from a large range of parameters, several of which are not readily available. In considering the distribution and population changes in land birds, proximity to the mainland is a factor, and it is postulated that the changes on Clare Island may be related to fluctuations on the adjacent Mayo shores. Much of the land area of Ireland has been subject to changes in land use and land management, factors with profound effects on the distribution and population dynamics of land birds. Clare Island is fortunate in that it has been spared most of the recent changes, with the result that bird numbers and their distribution can be related much more to naturally induced fluctuations than in most of mainland Ireland. The major 21st-century survey involved a series of transects, after which estimates were made of the populations of the various species throughout the island. Most groups are open-habitat and generalist species, and it is noted that hole-nesting birds are absent, despite the presence of woodland. The absence of rooks is similarly remarked upon, and a chapter devoted to examining possible reasons for this concludes that the island is simply not large enough to sustain a colony of this species. The limitations of conducting detailed survey work on farmland are mentioned, especially the necessity to avoid walking on cropped land or through flocks of animals. A chapter is devoted to the land birds (excepting raptors) of other Irish islands. As well as producing a series of fascinating graphs, diagrams and lists, we learn about the difficulties in making accurate deductions on many aspects of the inter-island contrasts, due to the lack of statistics on which any conclusions can be based. The chapter on waterbirds highlights the difficulties in surveying breeding populations in certain locations, partly due to the secretive behaviour of several species during the...