2012 BOC Meetings

27 March 2012 — A long-term study of the Black Guillemot colony at Bangor, Co. Down — Julian Greenwoood

Julian Greenwood commenced by examining the history of his study colony in Bangor, Co. Down, where Black Guillemots Cepphus grylle have nested for >100 years. Despite crowds of holiday makers, reconstruction of the harbour, powerboat competitions, ferry movements, sailing events, predation by Hooded Crows Corvus corax corone and nest-site competition from feral pigeons, the birds have bred successfully (mean 1.0 young per pair). Success has come, in part, from the provision of nesting boxes – there are now c.60 nesting sites in the harbour, c.50% of which are used per annum. Julian has been working with Black Guillemots for 27 years, during which he has discovered that the Bangor birds behave somewhat differently from information provided in the literature.

For instance, the pre-breeding season starts in October of the previous autumn when prospecting birds make their first visits and continue to visit constantly throughout the early mornings. These visits become earlier (in relation to sunrise) as winter turns to spring. First-egg dates have averaged 21 May (though egg laying has become earlier in springs with warmer sea temperatures). Socially, Black Guillemots are monogamous, but biologically they are not, with several examples of birds changing mates between seasons (sometimes returning to previous mates) as well as moving between sites within the colony. Ringing of young has shown movement from the Irish Sea to north Donegal and Co. Cork as well as to Scotland and England. There is a gap in ringing recoveries along the western Irish coast – a project for seabird ringers in the future.

12 June 2012 — What colour is that bird? How to recognise and name colour aberrations in birds — Hein van Grouw

Hein van Grouw presented an overview of the six most common aberrations found, illustrated with many photographs of their appearance in an array of different species, and provided a simple identification key to help name the aberrations correctly. The talk, on a topic of considerable confusion to many, was enthusiastically received and generated much discussion. Those interested in pursuing the subject further can consult his following papers: Not every white bird is an albino: “Sense and nonsense about colour aberrations in birds.” Dutch Birding 28, 79–89 (2006); “How to recognize colour aberrations in birds (in museum collections).” Journal of Afrotropical Zoology Special Issue, 53-59 (2010); and “What colour is that bird? The causes and recognition of common colour aberrations in birds.” British Birds106: 17-29 (2013).