A while ago, a visitor caught me out with a question about ospreys.”When do ospreys find the time to moult?”
I was caught off guard; I new that most birds moult in the late summer/early autumn after the nesting period is over, but with ospreys they have to migrate then. I tried leafing through Roy Denis’ book “a Life of ospreys”, whilst continuing the conversation, but as there is no index I couldn’t find the right section. The visitors left, and I promised to investigate further.
I passed the query onto Jan Richards, one of my fantastic Wigtown Bay Visitor Centre volunteers, who promptly found the correct section in Roy Dennis’ book. I thought I would share the answer with everyone, to extend your knowledge and understanding of these amazing birds if you are as ignorant as me, and haven’t read Roy’s book from cover to cover!
“Moulting
When you look carefully at adult ospreys through a telescope, you can see that the mantle (the back) and wings are not a uniform dark brown, but made up of fresh, dark brown feathers among pale washed-out ones. This mixture is due to the moult, a process that takes two years to complete. Incubation is a good time for female ospreys to renew their worn feathers but the males, of course, have to be in peak flying condition during this time and so their moult occurs in winter. The large, strong feathers of the wing and tail last for two years before being replaced, unlike in most smaller birds which moult once or even twice a year. Some of the feathers are moulted in Africa and their replacements look fresh and new. Others, which have suffered that year’s wear and tear in the searing sun of Africa, appear ragged and very worn. The moult of the big flight feathers of the wings is quite unusual in ospreys, in that it starts with the inner-most feathers and occurs in successive waves across the wing. This variation in moulting times can be seen very clearly when you examine the range of light and dark feathers in an osprey’s wing or tail.” p71 Roy Denis’ book “a Life of ospreys”.
Another question that has kept occurring during the year, is “why aren’t there any ospreys in Ireland?”
This is a question that I have found only partial answers to. Roy Dennis says in his book “a Life of ospreys” that ospreys were historically recorded in Ireland up until 1779, but they were probably made extinct slightly earlier than in other parts of the UK. A combination of this prolonged absence and the information available about the “usual” migration paths of British and Scandinavian ospreys going through mainland UK, will contribute to their maintained absence. However, hopefully it will only be a matter of time, as the population increases, before a wayward couple decide that Ireland is a good place to start a family.
Does anyone know if ospreys are ever recorded migrating over Ireland, and if any projects have ever tried building platforms to encourage them to breed there?
Are there any other burning questions that people would like answered, or discussed? If so please post them up here, and I will try to circulate them as widely as possible to try and find some answers.
I'm fortunate fo have Roy's book - I bought it earlier this Osprey season and so not completely read it yet. I've immediately gone to page 71, thank you very much Ian.