Sunday, 5 July 2015

Colour-ringing at Kilcoole

With just over 275 chicks on the beach, the Kilcoole Little Tern colony is booming! The wardens are run off their feet monitoring the newly hatched fluffy chicks (the “tinys”), which weigh a mere 6 grams when they hatch, and keeping an eye on the older chicks (the “chunkys”), which rapidly increase their body weight to over 30 grams after only two weeks. 

The newly hatched chicks are fitted with a British Trust of Ornithology metal ring with an individual ID number when they are one day old - just before they leave the nest and set out to explore their exciting new world beyond the shell that is the shingle beach! In the coming days and weeks these chicks are caught again by observant wardens to take measurements of their wing length and their weight. This data is then added to an existing database collected over the years at Kilcoole that is used to calculate growth rates of Little Tern chicks. Such data is valuable to our ecological knowledge of the Little Tern as an Irish breeding bird.

Little Terns are fitted with a metal ring on the right leg
Chicks only weigh a couple of grams in their first days out of the egg

Once the chick reaches roughly 10 days old (definitely a chunky chick now!), its legs have lost their baby-fat and grown long enough for colour-ringing. These older chicks are fitted with a plastic green colour-ring with an individual 3-letter inscription. Unlike the smaller metal rings, these can be read at a distance with a telescope, therefore it is possible to receive reports on colour-ringed Terns from other parts of Ireland, the UK and on their migration to West Africa. The green colour and the letter “I” at the beginning of the inscription indicates this is a bird from Ireland, whilst the position of the colour-ring on the left leg indicates it is from Kilcoole. This colour ringing scheme was only initiated into the Little Tern project last year, and as terns do not breed until they are two years old, there are no adults with Irish colour rings returning to the colony this summer. Next year will be an exciting year, because those chicks colour-ringed in 2014 will hopefully will return here to breed!

A 10-day old chick gets his colour-ring "IPN"

So far we have ringed a total of 230 chicks with metal rings and 30 with colour rings. Many more chicks will come of age for colour-ringing in the next week. On top of this, there are still 26 pairs of Little Terns sitting on nests in the colony, which means we may potentially reach over 300 successfully hatched chicks for the 2015 season!

Susan and Paddy

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