Barn Owls at six-and-a-half weeks
On last month’s expedition to ring a brood of Barn Owls we found another barn containing a nest-box that no-one had been aware of. Closer inspection revealed three newly-hatched chicks. As they were reckoned to be about one, three and five days old, they were too young to be ringed that day.
We came back nearly six weeks later and found an adult (which immediately slipped away) and two well-grown chicks. Don’t ask what had happened to the third…
A. ringing the elder one
D. retrieving the chicks in cotton bags
These chicks were slightly less advanced than the other brood when we ringed them – see how much down they still have compared to these.
M. who was supervising (Barn Owl ringing needs a Schedule 1 endorsement to the ringing permit) looked up the wing measurements in the tables, and pronounced the birds to be between 44 and 46 days old. This agrees very well the estimate of one to five days old when we first found the brood. It also suggests, unsurprisingly, that it was the youngest sibling that did not survive.
Young Barn Owls Tom Beasley Suffolk
After 2014’s massive year for Barn Owl breeding, 2015 has been miserable. M reckons he has inspected 40 boxes in the whole county this year and ringed one single chick!
A retrieving the chicks
Better news, though. A box near Sherborne contained a very young chick and three eggs at the beginning of July.
Several weeks later there were three well-grown young, just past the ‘ugly’ stage and shedding their juvenile down whenever they moved.
Measuring to estimate the age
All three were ringed and measured. Incredibly (to me at least) you can age the chicks pretty accurately by measuring the seventh primary feather’s length and looking it up in guru Colin Shawyer‘s tables.
M weighing a chick in the bag
Weighing was also a surprise – the older the chick, the lighter they are.
They reach their maximum weight in the nest and slim down to flying
weight as they develop.