BTO: Listen out for the autumn tawny owl

Tawny owl -- Picture: BTO/Jill Pakenham
Tawny owl -- Picture: BTO/Jill Pakenham
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Double-glazing may help to keep us warm but it’s a shame that it also cuts out the noise of tawny owls, proclaiming their territories at this time of year, writes the BTO’s Graham Appleton.

These are very early breeders so it is important to find a mate and carve out a good territory before winter starts to bite, in order to increase the chance of raising lots of chicks in 2014. The number of eggs laid depends upon the female being well fed in January and February; then the number of chicks that successfully fledge will be dependent upon both parents being able to supply owlets with a plentiful supply of food in the spring. If the flow of food slows down, older owls may well eat their younger siblings, as has been documented by the BBC’s Springwatch team.

Winter is a good and bad time for nocturnal owls. Like our other resident species, surviving snowy and icy weather will be a challenge, in some years, but for tawny owls there is actually more hunting time in the winter than in the summer. When not sitting in a favourite tree and hooting – or making the kee-vik call if it’s a female – a tawny owl silently hunts for mammals and birds. Soft wings, slow flight, big eyes and acute hearing all help this stealthy hunter to secure the food that it needs, either by pouncing on small animals, as they gather food amongst the leaf-litter or grass, or by plucking roosting birds from branches while they sleep.

Back in the days when I was an active bird ringer, trapping a tawny owl was an occasional bonus when catching blackbirds, redwings and other thrushes, as they came in to roost in an evening. Tawny owls used strong talons to grab their prey from the shelter of rhododendron bushes – but the same weapons were ready to injure an unwary bird ringer. I have very little feeling in my right thumb, thanks to an encounter with a tawny owl, caught in a mist net in Staffordshire over 35 years ago. Pulling apart the toes of the bird in order to extract the claws from my hand is an experience I remember quite clearly! I needed the help of a friend.

Some years ago, we asked the BTO’s Garden BirdWatchers and other volunteers to listen out for tawny owls in the autumn and winter, so that we could try to get a feel for what was happening to their numbers. They discovered that birds are most likely to be heard on a warm moon-lit evening in October so you may well have noticed quite a lot of activity over the last fortnight, especially in the first hour of darkness.