Peregrines (18 May 2004)

Few of us have the opportunity to be as close as this to a wild Peregrine Falco peregrinus. This is the adult female of the pair that nests on a lighting gantry on an industrial building, and it is possible to view the nest ledge, and the adults' favourite perches, through a slit in the surrounding framework, which is how I got this photograph. The birds obviously know when they are being watched, but this did not deter her from returning to the perch within seconds after we had replaced the access door after ringing her chicks.

This adult is an unusually brown bird that has bred here for several years, and was depicted on her nesting ledge a year ago on this website. I can find no published reference to an adult Peregrine with upperparts looking as brown as this, and would appreciate any comments from readers. Unfortunately she is unringed and of unknown origin. Those looking carefully at this bird will notice that she has blood on her head, breast and legs (see photo at end of page) from her latest kill. The chicks had bulging crops - as seen in the next photo - and the parents have no difficulty finding food in the surrounding area.

The three chicks were, as we knew from the careful observations of the staff on the site, at the perfect age for ringing, 16 or 17 days old, and with their wing feathers just emerging from the quills. There was only a small amount of difference between the largest and smallest chick, whose wings are depicted here:

Peregrines cover their eggs as soon as they are laid, but usually only start their incubation proper with the third egg of the clutch, or sometimes the fourth, so the chicks hatch within a few hours of each other. Unlike with some birds of prey, there is little difference in size between chicks through asynchronous hatching. Females are larger than males although the sexes can be difficult to distinguish. The fourth chick of this brood disappeared, for unknown reasons, when very small. This is a good pair: whatever she looks like, they have raised 16 chicks (3, 4, 4, 2, 3) in the last five years.

Postscript (added 20 June 2004):

Of course, strictly speaking, the previous statement about raising chicks was somewhat premature, but the advantage of an industrial site is that there are always people keeping an eye on the birds' progress. In this case the site maintenance planner occasionally visits the building and sends photos of the chicks' development. By 9 June, at about five weeks of age, his photo shows that the chicks were looking almost fully grown:

Peregrine chick nearly fledged

and they took their first flight from the nest ledge two days later. Five days after leaving the nest they were flying strongly enough to join one of their parents on a nearby electricity pylon.

It will be another few weeks before the fledglings are able to catch their own prey, but they have made a good start.


David Norman.