For the conservation breeding programme, for obvious reasons, we need both female and male birds. So, as the birds grow up, we’re anxious to find out who’s what. We can make a reasonable guess based on their size, because the females are on average larger than the males. But to be sure, we have them “feather sexed”.
To do this we gently pluck two flank feathers from each bird when we handle it to check and replace leg bands. We send these feather samples to a lab to identify the sex chromosomes. We now have the results for the birds that hatched this summer.
The 2012 birds are eight males, eight females and one individual whose sex is still unclear (this is because there wasn’t enough genetic material in the sample for a positive test). We also had the 2011 birds feather sexed, to confirm results from tests made late last year using a different method.
We discovered that we may have fewer females than we thought. The previous results suggested we had seven males and four females from 2011, but the new results suggest we may have only two females. We will take further feather samples next time we handle the three birds whose gender we don’t know.
The overall total of 28 birds represents maybe 10% of the world population and with at least 10 females, the signs are good that that we may be able to reach our target of 10 breeding pairs. If we do, from 2015 we should be able to return as many as 40 eggs a year to Russia, where they’d be hatched and the chicks reared and released on the breeding grounds.
Sadly, we recently lost one of the 2011 birds. Despite intensive treatment by our veterinary team, the bird ‘Green left’ died in late September. Its post mortem results were inconclusive but we suspect the bird died because it had a congenital (malformed) heart condition.
The loss of any bird is tough on the team. We feel a huge responsibility, both for these individual birds and for their species. We have to remind ourselves that it is fantastic to have 28 Spoon-billed Sandpipers at Slimbridge, with the potential for some of them to breed next summer. In the wild, in recent years, for every 40 eggs laid, just one or two birds have been surviving long enough to return to Chukotka and attempt to breed themselves.