More amazing insights from Barn Owl GPS tracking

This summer, a huge effort was made to track the movements of Barn Owls by fitting them with small GPS data loggers. The results have been spectacular, and the staggering amount of detailed information is delivering new insights into the behaviour of this nocturnal and secretive species.

Barn Owl fitted with GPS data logger to assess habitat use and home range (J.Lusby, M.O'Clery, BirdWatch Ireland under licence from NPWS).

Adult Barn Owls were fitted with the devices at seven sites in Ireland in summer 2017, recording speed and exact location of the birds every ten seconds. Combined with the information from six adult Barn Owls from summer 2016 we now have 98 nights worth of data and are able to discover exactly where they went and when, where they hunted, how they moved about a landscape at night, where they roosted during the day, how long they spent perched, how long in hunting flight, which areas they favoured and which they avoided.

Here’s an overview of some of the sites. Further posts will show some of the specific findings as we interpret the huge amount of information.

(You can click on any of the images for a closer view).

Here's the GPS data from a Barn Owl site in Co Kerry, the information gathered from ten nights. This bird spent a considerable time hunting along the coast, not far from the nest site, even spending quite a time hunting nearby sand dunes. The owl which was tracked was a male and he proved to be the best hunter of all our tracked birds, delivering at least 48 prey items during the ten nights.

Another of our owls has a home range in Co. Tipperary, in a predominantly mixed arable and cereal-growing region. The owl ranged up to 3.2km from the nest site, well within range of the M8 motorway just 1.8km distant. The owl visited this motorway regularly over the nine nights of data we recorded. More on that on the blog soon.

At a third nest site in Co. Kerry, the female Barn Owl was tracked for 12 nights, revealing a much larger range than the Tipperary sites. This bird travelled up to 8.25km from the nest in search of food. These long range trips themselves have revealed some interesting aspects about Barn Owl foraging behaviour, but more on that soon.

Call back soon for more.

Barn Owl tracking - Tralee Bypass

Readers of this blog will recall several posts involving instances of Barn Owls being struck by vehicles on major roads (see HERE and HERE, for example).

Continuing with our project to discover the effects of major roads on Barn Owl populations (in conjunction with T.I.I.), in July 2017 we tracked a female Barn Owl whose home range included the Tralee Bypass (see a history of this nest site HERE). While we long suspected that the adult Barn Owls from this site might well be hunting along the Bypass, the findings from the GPS data loggers were astonishing... Over 11 nights, she hunted along the verges of the Bypass nine times, and crossed the road 14 times. She also frequently perched along the verges, spending around two hours close to the road. The dangers to the bird are obvious and yet, she and her partner managed to raise two chicks this summer.

You can click on the 'four arrows' symbol on the bottom right to see a full-screen view.

Barn Owl tracking of a female Barn Owl near the Tralee Bypass, July 2017 (J.Lusby/M.O'Clery, under licence from NPWS and BTO).

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More on this project soon.