20 Dec 2021

Osystercatchers with SCAN

 I managed to get out canon netting on Saturday with SCAN with the aim of catching a sample of Oystercatchers and Redshank as part of the ongoing studies on Lavan Sands. An early start saw me up at 5.30 am having breakfast and filling flasks of tea before steering the Landrover west along the North Wales coast road to our designated meeting point.

Because of the early tide the nets had been set the previous night so it was just a case of driving along the farm track to the beach and waiting in the vehicles until the rising tide pushed the birds up the beach to roost. 

After a bit of a nail biting wait as the birds seemed unsettled we made a decent catch of 96 Oystercatchers and 6 Redshank. The Oystercatchers included an Icelandic control with a Reykjavic metal ring and colour rings! 

As usual it was interesting to see these birds close up and refresh knowledge on ageing based on eye colour, bill colour and leg colour. Juvenile birds (Euring 3) have muddy brown eyes and dull greyish legs whereas (depending on their exact age) adults have redder eyes and pinker legs. Juvenile bills are darker tipped than adults as well and generally duller.

Juvenile (3) Oystercatcher with brown eyes, dull dark tipped bill and 
grey / pink legs

Adult (Euring 8) Oystercatcher (furthest from camera) with ruby red eye and bright pink legs compared to juvenile (Euring 3) 

Of course theres a whole load of age groups in between and it enabled everyone to become familiar with these. Compared to small passerines waders are long lived birds and some species can be aged on plumage and soft part characteristics / colours way beyond what is normally possible for small passerines who generally attain full adult plumage after their first post breeding moult in their 2nd year. The adult Oystercatcher above (Euring 8), for example, is at least 3 years old and probably older. The bird below is a  second calendar year bird (Euring 5) hatched last yer. The eye isn't as bright as the Euring 8 bird above and the bill still retains a lot of dark pigmentation and the legs are dull.

Oystercatcher Euring 5 (second calendar year) with dull bill and legs but brighter eye than juvenile.

It was a beautiful and frosty December morning and it was nice to be out and see some familiar friendly faces. With all the birds processed the gear was packed up and I set off back home and a hot mug of tea to warm me up. 

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