14 Oct 2014


As I was feeling slightly better Sunday I spent the day in the beautiful autumnal sunshine canon netting Oystercatchers in North Wales with SCAN.

A leisurely start saw us meeting up at 08.45 and setting three nets along a shingle ridge well before the high tide. The next three hours were spent lying down in a sandy hollow listening to the radio chatter but not being able to see where the birds were. We had couple of false alarms when we thought we had a reasonable number of birds in the catching area but they got spooked. Finally Steve gave the order to be ready and he remotely fired the canons.

Racing from our position after lying dormant for three hours wasn't the best warm up ever designed and there were a few cramped falls and tweaked muscles!

After covering with sheets of  hessian to keep them calm experienced people extracted birds from the net and passed them to runners to put into holding cages where they were kept warm and calm before ringing and processing. Photo below shows the ringing team and the holding cages with team hound, Noko, showing a complete disregard for whats going on around her.

Quite a few retraps from previous years were caught including some of our previous colour ringed birds. Star bird though was one I extracted with a combination of black and white colour rings - not one of our combinations. When processed it was found to be wearing a ring from the Icelandic ringing scheme!!!

All birds were weighed and had their total head / bill depth measured as this gives an indication of the sex ratio between males and females. Most of the birds were adults and in various states of moult - see photo below:

Oystercatcher having total head / bill and bill depth measurements taken by Ros. Females have sharper bills whilst males have blunter deeper bills. This enables them to utilise slightly different food sources avoiding competition in severe weather.

Eye colour changes with age in Oystercatchers with adults having a deep red eye whilst juveniles are muddy brown. Quite a few of the birds had 'blown' irises as can be seen from the photo's below. The reason for this is not really well known but a study of Black Oystercatchers in New Zealand suggests it may be related to the sex of the bird being more common in females.

A great day with around 350 Oystercatchers being caught and processed. Once again there were quite a few undergraduates from the Bangor University Bird Club present and hopefully a few will be keen enough to come again and start training as the next generation of ringers.

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