Here Come The Girls!

Having watched the Dee Estuary for a number of years now, it has started to become apparent that there appears to be an imbalance between the numbers of female and male raptors, with the fairer sex apparently in the ascendancy.

This is most marked with the populations of over-wintering Hen Harriers that, in general, tend to be adult females. This seems odd when I consider that all the birds I found on the Welsh Uplands in the spring (8/8) were male and even if you take into account that the females will generally be guarding the nest and the males are more visible, it seems strange that ‘grey’ birds are uncommon on the Dee. This is further supported Hen Harrier sightings from Ynys-Hir, that tend to be almost exclusively adult male birds.

Similarly, in the case of another wintering visitor, the Merlin, it is very seldom that I see an adult male bird; again, the Marsh Harriers that pass through and occasionally winter on the marshes are mostly adult females or immature birds.

The situation with Peregrines is less clear. I would speculate that female birds do outnumber male birds, but the ratio is less acute than is the case with the Harriers and the Merlin.

For obvious reasons, Buzzard, Osprey, Hobby, Red Kite are difficult to sex, with the added difficulty that all but the former are rare or uncommon. Kestrels and Sparrowhawks may demonstrate a bias one way or another but I am guilty of not paying the falcon or the hawk enough attention, so I cannot comment!

Obviously it is hard – but possible - to determine the gender of young raptors such as Harriers and Merlin, but even taking into account a certain degree of error I believe that for some reason the Dee Estuary holds an unusually high number of female birds

It would be interesting to know if anybody else has had similar observations, or perhaps this is a ‘natural’ imbalance – this would be understandable in the case of Marsh Harriers where I believe males often service more than one nest.

Any Comments?

Until later.