Ever wondered what barn owls feed on? Well here it is. Barn owls typically eat small prey items such as mice and voles. They swallow them whole and their digestive system extracts the nutrition as juices and forms a pellet with the remains, namely bones and fur which cannot be digested. The pellet, which is black is regurgitated and dropped from the beak, approximately 6 hours afterwards. A pellet can contain the remains of 2-5 prey items depending on the prey. By collecting and studying these pellets the diet of the barn owl can be monitored which in turn tells us what small mammals are present in our countryside. One such study is being conducted by Derek Capes of Great Ayton to establish the extent of harvest mice within the National Park. Sample pellets from various locations are collected twice a year for analysis. Such is Derek’s knowledge of small mammals he only needs to see the jaw bone in order to identify the species. Two barn owl roost locations in Rosedale provide good numbers of pellets and the results, below are fascinating.
The field vole is the dominant prey for the barn owl with common shrew being an important secondary prey species. Field voles are more nutritious therefore less are required. Shrews are less so and the barn owl needs to expend more energy hunting a higher number. Results have revealed the presence of harvest mice here in the dale. Normally associated with arable crops the harvest mouse is also found to nest in long rough grass and rushes. A local resident at Rosedale East has actually seen harvest mice whilst cutting his grass. He has also provided this fabulous photo of one of our resident barn owls. Very much appreciated.
51 barn owl pellets collected in February 2017 in Rosedale East revealed 8 mammal species present, a total of 254 prey items with mean prey items per pellet of 4.98:
90 Field vole
1 Bank vole
16 Wood mouse
1 Harvest mouse
11 Brown rat
85 Common shrew
43 Pygmy shrew
1 Water shrew
6 birds
80 barn owl pellets collected in February 2017 in Rosedale West revealed 8 mammal species present, a total of 397 prey items with mean prey items per pellet of 4.96:
132 Field vole
12 Bank vole
7 Wood mouse
1 Harvest mouse
5 Brown rat
162 Common shrew
72 Pygmy shrew
4 Water shrew
1 bird
1 frog
The next pellet sample collections are in progress and the results will reveal mammal species over the Spring and Summer seasons. Updale Natural History Recorder
