Friday 10 May 2013

Chicks of Logged Birds

Breeding season is well underway. Despite a few days of high winds experienced over most of Portugal, this season seems set to be a good year for breeding storks with no sign of the rain and low temperatures in the crucial first weeks after hatching that caused many nests to fail last year.

The birds do not all breed in synchrony together and so far I have seen chicks ranging from just hatched to 30 days old whilst some adults are still incubating eggs. 

Our logged birds feature along the full length of this spectrum: Ricardo's chicks being oldest and Carlos perhaps still on eggs (or his chicks too young for their heads to appear above the sides of the nest yet). Here are some photos of the logged birds with captions about their progress:
 



LEFT: Brutus regurgitating food for his chicks. The head of one can be seen next to his bill. Brutus appears to have 3 chicks, although his nest is deep so this is not confirmed because his chicks are still small.
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RIGHT: Aldina (left) had 3 eggs and all these have hatched. Her chicks are still young and small which is why they are not visible in this picture.  Her neighbours 4 chicks (right), just visible as white bundles, are about 3 weeks older than Aldinas chicks. Aldina's chicks are the youngest of all the chicks in this colony.


BELOW: A blurry shot of Aldinas 3 10 day old chicks huddled together.




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RIGHT: The biggest nests are usually occupied by the highest quality breeders. Ricardo has a big nest on a pylon. His chicks are the oldest of all the logged birds. The heads of 2 20-30day old chicks can just be seen above the top of the nest.





















LEFT: Carlos is the only logged bird nesting alone rather than in a colony. His nest is on a tall purpose-built post topped with a nest platform. No heads of chicks have been seen yet, so I think he is still on eggs. Compare the nest size with Ricardo's. Carlos has a much smaller nest.



















RIGHT: Phil has chosen to nest in a beautiful, old Cork Oak tree. His nest is low enough to see in to and has 4 very young chicks under 1 week old.












 






LEFT: Nathalie on a branch above her nest. If you click on the photo to enlarge it and look closely you can just see the logger on her back.
Sadly, Sara's breeding attempt seems to have failed in the last few days. I visited her nest on 5th May and saw no sign of her, her partner or any eggs/chicks. After a day or so without transmitting she suddenly abandoned her breeding site and is now in Spain. 

The reasons behind her breeding failure are unknown. The weather has been good and predation is unlikely because there is always an adult in attendance at the nest. It is possible that late returning migrants out-competed her for her nest however I saw no other adults at her nest. It is possible her partner died or she is a young, inexperienced mum and was not tending her chicks with sufficient care and therefore they did not survive. It is not uncommon for first-time breeders to fail. It is unlikely that she will attempt to breed again this year. Will Sara migrate to Africa now that her breeding season is over? Or will she stay in Iberia?

Keep checking up on the storks movements at the BTO's website to see where Sara goes (follow the link to the BTO stork tracking pages on the front page of my blog).



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