Tuesday, 23 March 2010

Dried Out Barn Owl

As a ringer you always look forward to that 'white window envelope' with a BTO stamp on it lying on your door mat when you come home from work. It usually means details of a recovery, or if you are lucky several recoveries! Yesterday was one of those days and I eagerly opened the envelope wondering what it would be.

I could see that it was a Barn Owl chick that had been ringed from a brood of two by Will on 19th August 2009 at a farm close to Nateby near Garstang. I looked to see where it had been found and it had been found on 5th February 2010 at a property near Bilsborrow, Preston. It wasn't freshly dead when found and the finding details said that it was found behind some straw bales with a possible broken leg and it was very dried out. It had moved a distance of 7 km in 170 days.

Not very exciting I hear you say and I would agree. Then I started to think about the finding circumstances, "...behind straw bales...", and the fact that the farm it was ringed on was a mixed farm and produced straw. The nest site of this particular pair was in a building and not in a box and I know for a fact that in previous years they have nested on top of the straw bales. My theory is that this Barn Owl chick fell down behind the straw bales close to the nest site and died. Some bales were bought by the people at Bilsborrow and low and behold when moving some of the bales they found the Barn Owl "very dried out".

It is often an issue with relatively sedentary species like Barn Owl as to whether some of the movements have been assisted in some way. The 'Migration Atlas' states "...some individuals killed on roads may be transported for some distance before falling from the vehicle with which they had collided. This often leads to an overestimation of the dispersal distances for such birds".

Of course I am only guessing as to what might have happened to this bird as the movement of 7 km is well within the median distance of natal dispersal of 12 km. We'll never know, but it's interesting to speculate. Below is a picture of a Barn Owl that Ian took in the Fleetwood area recently; thanks Ian.


8787 said...

IT IS A VERY NICE SUGGESTION, THANK YOU LOTS! ........................................

sebi_2569 said...

very interesant your photo; bravoo