BTO migration blog

Spring and autumn are exciting times for anyone who watches birds. Here on this blog we will make predictions about when to expect migrant arrivals and departures, so that you know when and where to see these well-travelled birds.

Friday 14 October 2011

Here come the nomads

Over the last few days we have seen an arrival of Short-eared Owls at many East Coast sites, suggesting these are birds arriving from elsewhere in Europe. We receive a substantial influx of Short-eared Owls most autumns, with numbers increasing from August through to November. Information gleaned from ringed individuals suggests that many of these birds will be from Finland, Norway, Sweden and the Low Countries. Interestingly, the BTO ringing database also holds records of one from Iceland and one to the Faeroes, highlighting the wider origins of some birds.

Wintering Short-eared Owl, by Amy Lewis

Short-eared Owls have a reputation for being wanderers, avian nomads that seek out the opportunities offered by prey populations whose numbers can change dramatically from one year to the next. This nomadic behaviour is not restricted to the autumn and winter but can also be seen in breeding birds. The numbers breeding on favoured moorland sites across northern Britain may vary considerably between years as the birds respond to the availability of small mammal prey, particularly Field (or Short-tailed) Voles.

Birds that breed on our moorland will move to lower ground come autumn, favouring downland, rough grazing land and coastal marshes, where they may mix with individuals that have arrived from further afield. Some of our breeding Short-eared Owls will themselves make a sea-crossing, choosing to winter in France and Spain, again highlighting the fluid nature of this wandering owl.

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