Owl Pellet Day
Posted on 2nd February 2018 at 12:59
The 22nd of January was a very enjoyable and educational day, with thanks to the Wiltshire Mammal Group and Paul Wexler for running a Barn Owl pellet analysis workshop.
Hosted at Wiltshire College, Lackham, the day started with a cup of tea and some chatting, once everyone had arrived and was seated we did a round-the-room for names. 14 people attended the workshop; a mix of ecologists, forest school leaders, students and people just interested in mammals. Some had found owl boxes on their land and had brought pellets from that site with them to analyse.
Paul gave a quick presentation covering what we’re likely to find in pellets, the legalities around them and where we are likely to find them; which apparently includes his own luggage when going on trips with students from the college, he said he needs something to do in the evenings. Then we were shown the recording form and dichotomous key used for working out whose bones are who’s in the pellet. The aim of the pellet analysis is to pick carefully through the pellet to uncover the bones left in it; from these bones you take skulls and jaws as these can be used to identify to species.
When in the lab we all took up a desk, 1 microscope, a tray, tweezers, dissection needle and a magnifying glass. Everyone was given a bag of pellets with the location from where they were collected. It’s very important to not mix up owl pellets from different locations; the records from owl pellets are used to give a presence or absence result for small mammals in the vicinity of the owl nest.
So with survey sheets in hand and tweezers at the ready we got to work. Fiona and I had 12 pellets in our little bag; they were surprisingly tough to initially break open, very compact and tight. But once in we were scratching around pulling out bones, we kept all the bones to one side and in groups of similar. The skulls were easy to spot in the pellet, but a little less easy to remove; with so many cavities and loops and bits of bone sticking out it’s a real excavation job to free the skull and remove the other matter, hair and bits, from inside. In most cases the jaws were attached to the skull so in an effort to not detach them it made the excavation all the fiddlier.
But with my bush hat on and tools in hand I really did feel, for a brief moment, like my favourite archaeologist: Indiana Jones!
Once a skull or jaw was free from the pellet and relatively clean we would turn our hunting minds to detective. The guide for identification was very good! Showing the difference in teeth design between insectivores (shrews) and herbivores (mice and voles), then looking in detail at the teeth structure and pattern. From our 12 pellets we pulled a total of: 37 Field Voles (Microtus agrestis), 4 Common Shrews (Sorex araneus) and 1 wood mouse (Apodemus sylvaticus).
A thoroughly brilliant day. I haven’t had this much fun looking at poo since we did a badger latrine survey in Shropshire, and this didn’t smell half as much! Thanks to Paul and the Wiltshire Mammal Group.
Wood mouse – four cusp holes on under first tooth.
Common Shrew lower jaw – insectivore, now space between teeth.
Field Vole lower jaw with first incisor extended to show length.
Share this post: