As regular CFZ-watchers will know, for some time Corinna has been doing a column for Animals & Men and a regular segment on On The Track... particularly about out-of-place birds and rare vagrants. There seem to be more and more bird stories from all over the world hitting the news these days so, to make room for them all - and to give them all equal and worthy coverage - she has set up this new blog to cover all things feathery and Fortean.

Friday, 3 February 2017

Gull decline on Scottish island linked to decline in fishing discards

Date: February 1, 2017
Source: Taylor & Francis Group

The research, published in the British Trust for Ornithology (BTO) journal Bird Study, looked at the breeding populations of three species of large gull; Herring Gull, Great Black-backed Gull and Lesser Black-backed Gull on the Hebridean island of Canna, and the relationship between these gull populations and the fall in the quantity of fish landed in the nearby harbour of Mallaig.

Between 1985 and 2000 an annual average of 13,726 tonnes of fish was landed in Mallaig. However, between 2007 and 2014 this had fallen to 4,456 tonnes. This has apparently had a profound effect on the Canna gull population. The number of breeding pairs of Herring Gulls peaked at 1,525 in 1988, Great Black-backed Gulls reached 90 pairs around the same time and the highest number of Lesser Black-backed Gulls was recorded at 63 pairs.

At the latest count around 130 pairs of gulls bred on Canna in total, comprising of up to 95 pairs of Herring Gulls, 18 pairs of Great Black-backed Gulls and 13 pairs of Lesser Black-backed Gulls. This population decline has also been associated with low breeding success, with only a small number of chicks successfully fledging in more recent years.

Simon Foster, lead author on the paper, said "The Canna seabird study is one of the longest running annual studies in the world. It is an enormous privilege to be part of the team of highly skilled, dedicated volunteers who have been collecting the data for over 48 years. This has allowed us to track the changing fortunes of seabirds. The gull data are interesting -- if you look over a short time period you can see large changes, however over a longer period and using anecdotal information from the 1930s it becomes apparent that Canna gulls may be returning to more normal, albeit lower levels."

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