When the Rutland osprey chicks are ringed, the trained staff seize the opportunity to take measurements of the birds and weigh them while they are in the hand. This furthers our understanding of osprey ecology and helps indicate the sex of the birds.
As well as being heavier than males, females are generally the chunkier of the sexes. Females tend to have thicker bills, legs and larger heads and this is usually noticeable as early as around five weeks old when the chicks are ringed. It is worth remembering, however, that the female chick 057 is by far the youngest of the brood (having hatched six days later than the first two chicks and four days after the third), therefore the sexual dimorphism usually seen in ospreys isn’t so marked and some of her biometrics are actually a little smaller than her male siblings.
Biometric measurements of Manton Bay chicks 21-06-2019
|BTO ring no.||Colour ring no.||Sex||Bill to cere (mm)||Bill depth (mm)||Head inc. bill (mm)||Tarsus length (mm)||Tarsus thickness (mm)||Wing length (mm)||Weight (g)|
The ringing of the osprey chicks is conducted as quietly and efficiently as possible by our trained ringer, in order to keep stress to the osprey chicks and the adult birds (as well as Wildlife Trust staff undertaking the work) to a minimum. The welfare of the birds comes first and is prioritised above all else.