Wildlife Diary 21st April and Osprey Q and A

Rain, rain and more rain- our poor ospreys have spent most of today looking very bedraggled but never slacking in their duty incubating their three precious eggs. The female had a good fish around lunchtime and the male again did some incubating, but he has just caught another fish around 8pm and again isn’t sharing!

His liking for very large fish nearly got him into serious trouble earlier today- Lindsey tells me he was fishing right in front of the hide, and seemed to struggle lifting the fish out of the water “he was up to his oxters, flapping furiously, struggling to get out of the water- he finally managed it but was obviously very wet and flew very low over the water and couldn’t gain height”.

 He was clearly seriously waterlogged and lucky he was able to get clear, otherwise he’d have been at risk of drowning. Unfortunately after all that drama, he got the fish to his usual perch, but dropped it before he could share it with his mate- she was not impressed and she flicked him away from the nest with her wing to send him off again!

Q: When will the eggs hatch?

A: We hope all will go smoothly with our osprey’s incubation this year but we can’t take for granted these eggs will hatch- for example last year they failed, to our disappointment. If all goes well however, the earliest we could expect a hatching egg would be the 21st May, but most likely the eggs will hatch in succession between to 23rd and the 29th May. This is based on the average osprey incubation being between 37 and 39 days (though it can be a couple of days longer or shorter).

Q: Has our female ever laid four eggs, and is this possible?

A: Yes ospreys can on occasion lay four eggs, but this is very unusual and it is even rarer for all four chicks to hatch and survive. We don’t believe this female has ever laid four eggs before – her reliable average is three. Oops I stand corrected: in 2005 ( as one of our longstanding vounteers has pointed out)  our female did indeed lay 4 eggs – though only two chicks out of this clutch survived.

Q: Why are the eggs spotted- they don’t seem very camouflaged?

A: Most birds of prey have similarly spotted or specked eggs- in fact many British birds do. Though to us they seem to stand out, from a height or distance the outline of these eggs blurs easily and blends them into their background very effectively.

Q: How long can the eggs stay uncovered safely?

A: This depends on two things:  firstly the weather- if it is cold and wet even a short time might be risky, and secondly predators: if a parent bird is close by and able to defend the eggs they will be ok. We have known eggs on this nest to be uncovered on a warm day for up to 30 minutes or more and still be ok- but we were all beside ourselves with worry until the female returned.

Q: Can Ospreys Drown?

A: Yes, this has been known- mostly in young or inexperienced birds (or just very unlucky ones) that attempt to catch fish too large for them to lift out of the water, but can’t let go in time. Sometimes is appears Ospreys can get their talons stuck in the ribs of a fish and are unable to release it and escape if they have miscalculated. If the bird gets dragged under or is in the water too long it can get waterlogged and drown quite quickly.  This is because Ospreys are not truly waterproof- their feathers have no slick oil like ducks -and they have to shake water out of their feathers quickly after diving to prevent becoming waterlogged.  

Q: When did they stop mating and how do we know the last egg has been fetilised?

A: Our ospreys last mated successfully on the 17th of April, though there were a couple of further attempts  on the 18th and 19th– the female looked like she had lost interest. This is entirely normal and ties in with the theory that the female looses interest in mating as soon as the final egg is fetilised internally, which then takes a couple of days to develop before being laid.

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Rain, rain and more rain- our poor ospreys have spent most of today looking very bedraggled but never slacking in their duty incubating their three precious eggs. The female had …

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