Suppose that you discover that a farmer’s barn has an owl living in it. The owl is full grown, and weighs about 2 kg. It lives entirely on small animals which in turn feed on grain stored in the barn. How much acreage of grain is required to keep this barn owl fed? As stated above, Barn Owl weighs 2kg. I searched on google and I was able to find that Barn owls eat about 2/3 of their weight per day. They eats voles. It will be about 474,500 g a year. For the calculation, I set voles' weight as a 30 g and it will be 15,817 voles per year. Voles eat grain about their body weight per day, so they eat 10,950 g of grain a year. An acre of wheat equals 3,000 kg of grain approximately. 1 vole eats about 11kg per year, so 15,817 vole eat 173,987 kg of grains. To raise 173,987 kg of grains, we need 58 acre of grain.
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