Hi Beth and John,
While it may be that all animals will give off eye-shine when spotlit at
night, in the case of the Australian Owlet-nightjar it often appears that it
gives off no eyeshine at all. It must be giving off some but when I have had
one in the spotlight, the two large eyes seemed to act like black holes that
were absorbing the light rather than reflecting it. This apparent opaqueness
(I am sure it must exude at least a little eye-shine) may explain why you
hardly ever seem to see this bird at night, despite hearing them quite
often.
I have probably only actually seen an owlet-nightjar about twenty times or
so and I would think 75% of these sighting would have been in the daylight.
Most of my nocturnal sightings were of birds flying through the beam of the
car headlights where eye-shine was not a factor. When in the spotlight, just
those wide, black orbs- an amazing contrast with birds such as
White-throated Nightjar which reflect back like the brake-lights of a truck.
Sean Dooley
Melbourne
-----Original Message-----
From:
On Behalf Of Beth Symonds
Sent: Monday, 17 September 2007 9:38 AM
To: John Tongue
Cc: Birding-aus Aus
Subject: Owls and eye-shine
Hi John and all,
All animals will give eye-shine when spotlit at night. The shine is created
by the retina "reflecting" the light source back at you. Eye-shine is
routinely used to find animals at night time, in particular mammals, frogs
and birds, but even tiny little spiders will give fantastic eye-shine!
Animals with excellent night vision give better eye-shine than diurnal
animals (due to the comparatively larger pupil, which allows more light to
Beth Symonds
Brisbane
On 9/16/07, John Tongue <> wrote:
>
> Hi all,
> We just spot-lighted (spot-lit?) a pair of Boobook Owls in a tree in
> our Caravan Park in St. Helen's, Tas. They were getting very
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