Wildlife Diary 10th April and More Osprey Questions

No eggs yet at the Loch of the Lowes osprey nest, but there is never a dull moment with our Ospreys!

As is so often the case in spring, we had some exciting intruder drama on the nest today, with at one stage three birds sharing the same small nest area very unhappily.

It is very common for intruder ospreys to fly over, or even land on, established osprey nests even when the resident birds are at home. This is usually interpreted as young birds attracted to either their natal nest, or one where they think they might have a chance to muscle in and stake a claim to breeding. However, it is also possible that some birds passing through on migration might just be curious enough to ‘drop in’, which might help explain why most intruders are only seen once.

During this incident today, the female became alarmed by the intruder’s proximity to the nest and frantically mantled as it landed: this is the name for the characteristic dropped shoulder, wings flattened posture Ospreys adopt when protesting or protecting.  Her protests drew in our new male bird who mustn’t have been far off, who also joined in, but it did seem to be the female doing most of the chasing of  the intruder off the nest. When it took off though, our male gave spirited chase just to make sure it left the area in a hurry and in no doubt whose nest it is.

During this dramatic incident, you could easily hear the birds both giving their characteristic high pitched alarm whistle- totally different form their usual calls. Working with ospreys you soon get an ‘ear in’ for these differences and this sound is always one our staff and volunteers on Nest Protection Watch listen out for intently.

It would be a rare spring indeed if there wasn’t some intruder activity at our nest, and generally these do no harm, as long as they aren’t too persistent or no eggs get trodden on during the scraps. In fact fending off such intruders may help our pair bond more closely.

This intruder today was also unringed and definately wasn’t our previous breeding male Green 7Y. We also do not beleive it was any other  bird so far seen on this nest this season.

Now for some more of your Osprey questions:

Q: What do we know about our male?

A: Alas very little: as he is not ringed, we cannot be sure of his exact age, his birthplace or ancestry. We are assuming he is a young bird based on his appearance and behaviour but we can’t say for sure what age he is.

Q: Is his behaviour typical of a first time dad?

A: Perhaps: We know it can certainly take a while for a young bird to settle into his duties and even for their hormones to be strong enough to prompt the right behaviours. However, I clearly remember doubting Green 7Y when he was the ‘new male’ in 2010 and look what a fabulous father he turned out to be, so perhaps we should give this young chap a chance to prove his credentials

Q: We doesn’t this nest have high sides like ‘crib rails’ to keep the eggs/chicks safe?

A: No two osprey nests are the same, and even from year to year they vary. This nest is enormous- more than 6foot square, and it has stood the test of time. Adding to the nest each spring is primarily the role of the male, and this one seems to favour softer bedding material for the centre, over large sticks for the sides. He seems to be intent on digging down to make a deep cup, rather than building up the sides, but this will work equally well to keep the eggs safe and sounds- if we have them!

Q: Where last years eggs infertile?

A:  As you may know, we had the eggs removed under special license and checked the eggs after they failed to hatch: initial tests proved they were fertile ( i.e. there was a tiny chick inside) but that they failed during incubation.

This means the parents fertility was not in question, and by far the most likely explanation for their death was the terrible cold and very wet weather during the incubation period, which meant the eggs got either too cold, or too damp, or both.

Further analysis of the eggs for traces of pollution etc were planned, but we have not yet had the results from the lab- we have been hassling them for some time!

Q: Is the female ok: she seems to be sleeping very oddly tonight?

A: Yes I’d have to agree she did adopt a rather unusual sleeping position earlier tonight, and her slow regular breaths were easily visible, but we don’t think there is anything wrong. We are of course hoping it may be a sign of her getting ready to lay an egg: birds can often look uncomfortable and fidget prior to egg laying.

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No eggs yet at the Loch of the Lowes osprey nest, but there is never a dull moment with our Ospreys! As is so often the case in spring, we …

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