Before and After...

I bumped into a woman at the Point of Ayr last Sunday afternoon when out walking near the lagoons. She was sifting through various shells on the seawall and when I got chatting to her, she said that she had been doing some research into the diet of the local Oystercatchers on behalf of the EU Fisheries Directorate.

She is a visiting Professor of Zoology at the University of Liverpool and kindly e-mailed me a draft copy of some of the work she had carried out recently. It’s very interesting reading, so I have plucked out a few paragraphs from Prof’ Loila’s summary:

“It appears that the Oystercatchers’ diet is more catholic in its taste of food that we had anticipated. Alongside more traditional morsels such as Cockles and Mussels, we found that a significant number of the waders consumed small amounts of coal. There is no obvious explanation for this behaviour, but I would speculate that it may be due to a number of reasons.

Firstly, it is not uncommon for pregnant woman to crave coal - in additional to other strange foodstuffs. The fact that over sixty-five percent of the Oystercatchers eating coal were female seems to support this theory.


Why male Oystercatchers would consume coal is more of a mystery. Perhaps, prior to the breeding season the birds are looking to “Black-up” in an effort to make themselves more appealing to a potential mate. This, however, is pure speculation.


Curiously, four other species of Oystercatcher: Blackish (Haem’ ater), American Black (Haem’ baxchmani) , African Black (Haem’ moquini) and Sooty (Haem Fuliginosus) are essentially uniform black in plumage – perhaps some of the ‘Pied’ birds – some of whom mix with their darker relatives on overwintering and breeding grounds - are attempting to imitate their appearance.

If this is true, then we really could be witnessing evolution, first-hand, before our very own eyes.


The consumption of coal as not limited to the shorebirds that spent the majority of time near the Point of Ayr – where the coal deposits are found – either.


During the winter of 2009/10 we ringed a number of individuals and found that birds were travelling from all over the estuary, but more astonishing was the discovery that a handful of birds came from as far as Morecambe Bay and Lavan Sands.”


Interestingly, another piece of research carried out over twenty years ago by Professor Di Oxine of Bangor University found that the high morbidity rate of Oystercatchers on Anglesey one winter was due to the build up of lethal doses of chemicals built up in the birds’ livers, after they developed a habit of nibbling on driftwood.”

I must admit to being a little sceptical of the benefits of much scientific research (including the amount of unnecessary ringing), but this piece of work is very compelling indeed.

Source: A Study into the Diet of Oystercatchers on the Dee Estuary (2009-11) by Prof Loila (Universad y Granada)

Until later.