Wednesday, 25 January 2012

Overlooking Long-eared Owls - (Asio otus), Búho Chico


A Long-eared Owl leaves the roost at dusk

Finding Long-eared Owls has always been difficult for me in Cadiz province. Not just because they are nocturnal but they are quite scarce breeding birds here.
It now seems clear that they may have been overlooked by myself and others during our winters when Short-eared Owls roost together here in the south. The other day I spotted some owls which I though were all the same species, namely Short-eared, but there amongst them were three Long-eared Owls in the same tree. I've seen Long-eared Owls in winter in Northern Europe roosting together and always thought that different species of owl wouldn't mix in a roost. How wrong I was...

Here's a photo of a Long-eared Owl above and a Short-eared below

Perched owls (when you can see something of them) are fairly straightforward to identify especially with those ear-tufts of the Long-eared Owl compared to the very slight tufts and chubbier faced Short-eared Owls. Confusion often arises with owls of the same size and structure in flight which is clearly the case with Short and Long-eared Owls. Thier flight, profile and general structure in the air are almost identical.
Outside of the breeding season there are no calls to listen to to separate them and fleeting views of owls in flight, once you get over that 'Wow!' factor, move so silently and quickly that you barely have time to check on identification differences.


Comparison of Long-eared (L) and Short-eared Owl (R) in similar flight pattern. (click to expand)


Here are a few pointers that can help in separating these two beautiful species in flight.

Tail: The Long-eared has much finer barring on the tail compared to the broader bands on the Short-eared. This may be a good one to check first as birds flying away from you are more likely than ones coming straight to you - alas!

Wing - Primaries: Long-eared has finely barred primaries compared to the darker broader band and dark tips of the Short-eared


Wing: This finer barring shows up well on the upperside, although it's more apparent on the underside. *The underside will have better background contrast, especially at dusk, against a wooded area with lots of shadows.
(The light was starting to fade and using my set up of Canon 7D with 400 f/5.6, auto ISO, 2,000sec with central point focusing, hand held - was indeed stretching the equipment to it's max...)


Wing - upperside: There is also less lighter spotting on the wing coverts than in the Short-eared.
The Long-eared Owl doesn't show a white trailing edge to the wing as with Short-eared Owls


Eye Colour: You can't always see the eye colour but here the iris is a deep orange whereas in the Short-eared Owl the iris is bright yellow.


Body Markings: Here the neck, breast and flanks of the Long-eared Owl are much more boldly marked with 'fish-bone' streaking. The Short-eared Owl has less streaking to the lower body with much plainer streaks


This rear view shows the flank and tail - something to concentrate on for ID purposes if you only manage a fleeting glimpse


Both species have very similar structures and of course in flight, those ear tufts of the Long-eared Owl are invisible


From now on I'll be looking more closely at roosts and trying to get an idea of numbers of wintering Long-eared Owls.
If you'd like to watch a good little film about this topic then click here. It's worth it...

5 comments:

Christian said...

Very nice explanation and photographs.

Andalucian Guides - Strait Nature News said...

Thanks Christian - most appreciated! Stephen

waine said...

thankyou for information,again!and finding video, top stuff.
most usefull.

Alf King said...

Great shots Stephen and very informative commentary.

Andalucian Guides - Strait Nature News said...

Thanks Alf,
Good to see that your are still enjoying the blog!
Kind regards, Stephen

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