Friday, 10 May 2013

Possible hatching dates for ospreys and herons....

The waiting game has begun in earnest as we watch the two live screens with the heron nest and the osprey nest on camera at Kailzie Gardens Osprey and Nature Watch Centre and the osprey nest at Glentress Peel Wildwatch room. The ospreys and herons at the nest are engaged in full time incubation duties and it is fascinating to watch the behaviour and different strategies adopted by the two different species towards their nesting activities and in the rearing of their young.

Glentress Peel Wildwatch
The osprey pair at the main nest behave as a very close partnership. The incubation duties appear to be equally shared and there seem to be genuinely affectionate moments between the two expectant parents. They sidle up close together, often the male will gently nudge the female until she is persuaded to rise up off the eggs and let him take a turn at incubating.

During this period a lot of nest scraping takes place and fiddling about with sticks to move from one side of the nest to the other, possibly a way to occupy the time. It is easy to tell the difference between the adults not just because the male has the leg ring white SS but he is about one third smaller than the female and has a pure white chest, whereas the larger female has a streaked chestnut band of feathering on her chest and the markings on the back of her head crest look like a chocolate coloured concorde. 

Heron adults appear to be identical to each other, the text books tell us that the parents share incubation duties but we have never witnessed a swapping over at the nest, so perhaps this only happens infrequently. We have not witnessed any interaction between parent birds and never know if it is the male or the female that is sitting on duty. Apparently the male heron is the larger of the two but only really noticeable in wing length and beak length which is not obvious at all when they are sitting incubating. Both birds are strikingly handsome with long black head plumes and sleek grey plumage with streaked black, speckled, neck feathering. They sit motionless when incubating for long periods and often we double check that the camera is still working, when suddenly, the bird will stand and reach down to turn the three blue/green eggs.
Osprey incubation takes between 37 and 42 days and the first egg was laid on 12th April, so we can expect that the earliest likely hatching date for the first egg could be 19th May.

Kailzie Osprey and nature watch
Kailzie Osprey and nature watch

The heron eggs were laid on 20th April, 24th and 27th April and they take 25 to 26 days to incubate, meaning that we will have live hatching on camera anytime from the 16th May. Because they have nested so late this year it will be the first time we have ever seen the heron chicks when they have just hatched. We are very excited about watching the heron chicks develop this year as we get to see the family raised right from the very start. Heron siblings behave with a great deal of rivalry and there can be many dramas, often with older siblings killing off younger ones and even eating them.

Ospreys have never displayed such behaviour in the nest in the ten years that we have watched this family. The parents are very attentive to their young whereas the heron parents have a very different approach, delivering food and leaving the chicks for long periods in the nest alone.

The camera nest box became occupied with a blue tit nest building very early in April and then all activity seemed to come to a halt. The warm sunny weather seems to have kick-started the nesting imperative and the blue tit has been seen actively nest building again, although we have not seen any eggs yet. It would appear that the cold snap has caused the blue tit to delay laying which is good because they need to wait until there is a plentiful supply of caterpillars to feed any young. Last year they were caught out by laying early and the wet weather meant there were no caterpillars. We watched as one chick after another starved and the sad image of the blue tit removing dead nestlings is hopefully not to be repeated this year. Populations do fluctuate due to seasonal variations but over time should even out.

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