This year has been a very good year for small mammals providing a good food source for owls and raptors. Field voles, bank voles, harvest mice and wood mice are just some of the items on the menu on this reserve. The small mammals like long, tussocky grass to run around in and we have plenty of that around the wetlands and the bund.
There are various barn and tawny owl boxes around the reserve some of which have been used this year. The box in the Jubilee Wetlands was used successfully for breeding by the barn owl with five chicks being reared.
I was given the pleasure of cleaning out the barn owl boxes a couple of weeks ago. Apart from the maggots, it was really interesting.
A couple of the boxes had been used by stock doves, with eggs left as evidence, some hatched and some not.
The box where 5 barn owl chicks had been reared was an eye opener; for the life of me, I don’t know how they all fitted in there, it was about 30 – 35 cm deep in poo!!
There was another box with evidence of current roosting with plenty of fresh pellets which have been fascinating to take apart.
Pellets are composed of fur/feathers and bones i.e. the indigestible parts, which are compressed in the gizzard before being regurgitated.
The pellets were soaked in water for about half an hour before pulling them apart. I avoided one of the pellets which the soaking revealed as containing a lot of maggots (yuck!!!).
The pellets were now easy to pull apart, separating the bones from the fur. A lot of patience and dexterity is needed as the pellets have been well compacted by the owl and the fur has to be pulled off many of the bones.
The part skeleton below shows a field vole which came from one pellet. In the same pellet there looked as though there may have been another complete skeleton, also a field vole. Field voles can be identified from the teeth some of which were still in the jaw bones. There are a few teeth shown in the photo below, just above the top jaw bone.
In another pellet there were 4 sets of jaw bones, all from field voles.
From the evidence it looks as though most of their diet comprised field voles.
All in all, it was a good year for the barn owls with many sightings by our visitors and it's good to know they are still using the boxes for roosting. With such a high percentage of field vole skeletons in the pellets it must also have been a good year for them in terms of numbers.
Hopefully the barn owls will survive the winter and, maybe, next year we will see an increase in the number of boxes used for breeding.