Tuesday, 21 April 2009

Overdue Eggs or Mistaken Identity?

We have been suffering a torturous wait here at the Osprey Watch centres for the appearance of our first eggs of the season. We have been getting lots of questions about why it is that the eggs are 'late', as they are usually laid 7-14days after first mating. However, the eggs have in the past been laid as late as the end of April, so we are not yet out of the realms of 'normal'- we are not panicking yet, just being impatient!

Firstly our nest has not been a quiet place this spring with an unusually high amount of intruder disturbance with others ospreys at the site. In particular last Saturday's violence may just have put off our female laying. This is unlikely but possible, especially since both our resident birds have been mating frequently and showing all the usual nesting behaviour such as nest 'renovation'.

The other even less likely possibility is that we have had a case of mistaken identity with the females and a changeover last Saturday.

Since 'our' female is unringed, we rely on recognising her distinctive head markings each year. Could it be that the female who arrived on the 1st April was coincidentally another unringed female with a similar marking? Could our male " white SS" have been courting another lady that first week, and when his 'real' lady turned up on the Saturday, she chased the interloper off? This would mean of course she has only been on 'her' nest for a week, accounting for the lack of eggs as yet.

The reason we are unsure is that the extreme violence of that encounter made identifying the females very difficult- in such a flurry of feathers , quite who was chasing who was unclear.

Could it be that there was a changeover amongst all that excitement? If the 'intruder' was in fact a resident bird coming home to find an interloper in her place, it would certainly account for the amazing violence and persistence she showed!

We will be reviewing the recorded footage over the next couple of days to see if we can unravel this mystery!

No comments:

Post a Comment

Please feel free to leave your comments on the blog. We've got a few house rules:
1. We (Forestry Commission Scotland) will review all comments and reserve the right to not publish them at our discretion.
2. There will be a time delay between submission and posting. Comments posted on a Saturday or Sunday won't be moderated until the following Monday.
3. Please make comments appropriate and relevant.
4. If you've a comment or question about Tweed Valley Ospreys , you can e-mail tweedvalleyospreys@gmail.com as we might not be able to respond here.
5. We won't publish comments that are abusive, indecent, unlawful or defamatory; published comments may be removed at any time; and individuals are personally liable for the comments they submit.