Thursday, 24 April 2014

Nesting Ravens Part Two

We're nearly finished up with the Raven ringing already this year. They are one of the earliest breeders amongst the Irish avifauna. Most chicks will probably be on the wing now within the next week or two. We've managed to ring a total of 29 chicks from eight different nests visited which gives an average of 3.6 chicks per nest. While this is an extremely small sample set, it is a very high ratio. One of the nests visited had failed. I've added captions to most of the shots below with further info. Again all of these shots of nests, eggs and young were taken under license from NPWS.

Newly hatched Raven chicks, the three remaining eggs shouldn't be far from hatching either.

Two week old chicks, more bill and legs than anything else.

Same chicks from above safely back in the nest.

Chicks begging for food.

Five chick nest.

Four chick nest

Note the pale iris of young. The pink mouths of young Raven gradually turns black after 2 -3 years as they reach maturity. They also retain the pink/pale gape line for a short while after leaving the nest. Adult Ravens are readily identified at this time of time as they begin primary moult and consequently have noticeable gaps in the wings.

Young in the nest usually cower in the nest if they perceive any danger to make themselves less obvious to potential predators. They are usually very docile in the hand when being ringed.

More relaxed chicks before they spotted me.

This nest contained four eggs on 5th March. When we re-visited it on 14th April to ring the chicks this is what we found - an empty nest!

Nest from above. One of the most accessible nest locations which may explain the failure.

Barbed wire interwoven into the nest. Ravens will use anything to hand in the nest construction. They have a bad habit of using bailing twine and fishing line in the inner cup. I've seen chicks ensnared in this material in the past unfortunately.

This nest contained several sheep bones including hip bones. I've also seen them using cetacean bones at coastal sites before.

The view below!

Irene O'Brien arriving at a nest. You can make out the remains of the previous years nest at Irene's feet. Many coastal nests are "blown-out" by severe gusts over the winter period.

There isn't usually much evidence of prey items at the nest. The closest thing are these regurgitated pellets. Some contain huge amounts of beetle cases at some times of the year.

I just happened to come across this poor guy while checking a nearby pair near Renvyle. I had assumed that logically it must be one of the local Connemara birds which we had ringed. However Irene informed me that it actually came from the very first clutch of Ravens she had ringed as part of her study near Westport, Co. Mayo in 2011. It's about 37km between the two sites as the Raven flies. The body was too far decomposed to determine how it died but I don't think it was human persecution as there's been a resident breeding pair at this location only 200 metres away every year.

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