A Review of accounts of luminosity in Barn Owls Tyto alba
|Paper by Fred Silcock Updated 2006-06-07 Created 2004-06-04|
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Published in "Australian Raptor Studies II - Birds Australia Monograph 3", 1997.
Reproduced with Author's permission
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Summary. The historical
anecdotal accounts of luminosity in the Barn Owl Tyto alba, in
England and Australia, are reviewed and found to be convincing. There are
many eyewitness accounts of unexplained lights behaving like hunting Barn
Owls, and some of those lights were seen ultimately to be luminescing Barn
Owls. This phenomenon may be a plausible explanation for the Will o' the
Wisp and similar myths in England, and the Min Min Light in Australia.
The cause of the luminescence is more contentious. Contamination of the
owl's feathers by luminescent fungi, from decaying wood within tree hollows,
is here considered to be an unlikely cause. Instead, it is proposed that the
Barn Owl may be intrinsically bioluminescent. However, this hypothesis
requires scientific investigation.
There is some
evidence that phenomena such as the Will o' the Wisp in England and Min Min
Light in Australia are luminescing Barn Owls Tyto alba (e.g. Purdy
1908; Gurney 1908; McAtee 1947; Bunn et at 1982; Macnamara 1989). However,
the source of the luminescence is yet to be resolved. The most common
explanation for such luminescence is that the owls have become contaminated
with luminous fungi that grow inside hollow trees (e.g. Bunn et al. 1982)
although, for reasons discussed herein, that explanation is unsatisfactory.
Bioluminescence, the emission of light from living organisms, is found
mostly in sea fauna, in some bacteria and fungi and in a few insect and
earthworm species. Bioluminescence is odd in its distribution in that there
may be forms or strains of the possessor, or closely related species, in
which the luminosity is not found (Harvey 1920).
Therefore, if a bird species possessed luminescence, it would not be unusual
if no other bird species possessed this characteristic or, if there happened
to be two species possessing luminescence, they could be as unrelated as the
emu and the albatross.
Is there any reason why birds could not bioluminesce? In a private letter Peter J.
Herring, editor of Bioluminescence in Action (Academic Press, London 1978)
said, 'There is no fundamental reason why there should not he a
self-luminous bird (or mammal or reptile) but none has been reported'.
Phosphorescence has been reported in skunks (Corliss 1981); old reports of
luminescent organs in a lizard have have discounted (Roth & Gans 1960).
Bioluminescence in birds, as opposed to iridescence, has never been proven
to exist. Nevertheless, the existence of luminosity of some kind in barn
owls Tyto Alba is supported by many historical accounts, and
periodically there is renewed interest in this phenomenon (e.g. Toms 1996).
This paper considers four premises:
There is sufficient evidence to
suggest that one or more of the following are true.
Barn Owls are indeed luminous, as
has been often reported.
Luminescence is intrinsic to the
owls and does not arise from contamination with luminous fungi.
Luminous natural phenomena, such
as the Will o' the Wisp and Min Min Light, represent sightings of luminous
Only the Barn Owl is considered
in this paper, because all the evidence gathered points to that species, and
luminescence has been confused with iridescence in the few reports (in
Corliss 1981) concerning other birds.
[At this point a misconception regarding the former scientific name for the
Barn Owl, Strix flammea, must be corrected. Much has been made of flammea supposedly indicating that the Barn Owl's luminescence has long
been recognised scientifically. In Latin 'flammea' means fiery or flaming.
However, Strix flammea Linnaeus 1766 was not only preoccupied by Strix flammea Pontoppidan 1763 for the Short-eared Owl (now Asio
flammeus), it was wrongly applied. Although describing the Barn Owl
accurately, Linnaeus erroneously based his name for it on an illustration,
in "Olof Rudbeck's Book of Birds", of the Short-eared Owl which has fiery
eyes (M.P Walters in litt.). Therefore, Strix flammea in the present
context is irrelevant.]
McAtee (1947) discussed luminosity in birds, and in his annotated references the
Barn Owl is mentioned ten times. Purdy (1908) described in detail his
experiences with luminescing Barn Owls, and named thirty or so persons in
his neighbourhood who had seen luminous owls.
Purdy described his own experiences of seeing lights behaving like hunting
Barn Owls, emitting noises like Barn Owl vocalisations, and ultimately being
seen to be a pair of Barn Owls, one seen emerging from its roost. In one
instance, the light was described as 'slightly reddish in the centre, and
resembled a carriage lamp'. Purdy related what he described as the 'best
display' yet observed by him and two other witnesses on 19 December 1907:
Its luminosity seemed to have
increased and it literally lighted up the branches of the trees as it flew
past them. After watching it for about half an hour, it was joined by a
companion bird hardly so bright. This kept about a hundred yards behind it,
but not constantly.
'A Country Teacher' (Anon. 1907, also cited by Gurney 1908) told of luminescing birds. After first seeing
them the teacher mentioned the fact to his pupils, and found that several of
the children knew of them as a 'gum allurt'. On making enquires he learnt
from teachers in other parts of Shropshire that their pupils 'knew both the
term and the thing'. He found the roosting place of the birds, which were
Barn Owls, in a barn about a hundred metres from the school and kept them
In another account in England, Gurney (1908) reported:
That luminous Barn Owls have
been seen before in the same part of Norfolk is certain... We have it on the
best authority - namely, from the man himself - that some years ago
Frederick Rolfe, gamekeeper now retired, saw what could have been nothing
else when stopping up fox-earths at West Bilney. A few nights afterwards he
saw the same shining bird again, subsequently shot it, and found that it was
a Barn Owl. He said that the bird 'was emitting a very bright light when
near him and that it continued to give out a slight glow for some hours
after it was dead'.
Gurney (1908) also reported:
The light at its brightest was
about as brilliant as the light of a bicycle lamp from three to four hundred
yards away and that was what Mr Purdy at first took it for. Anyhow, the
light does not seem to have had the effect of giving warning to rats and
mice, for Mr Hammond's bailiff saw it drop on one and heard the little
animal shriek. On one occasion the shining bird was quietly seated on a
gate, and another time on the ground, having probably just dropped in
pursuit of a mouse.
Dobbs (1911) gave an account of
moving lights assumed to be owls. She described the lights as a reddish
yellow, like the oil lamp on a bicycle or carriage and as strong, though a
shade redder; they were not the white phosphorescent light expected, and
sometimes reflected strongly in the river. She thought that the lights were
visible only when moving partly or fully toward the observer, and noted that
they seemed to flicker as though crossed by the beats of a bird's wings. One
or commonly two lights, exceptionally up to four, were seen.
There is much in the description of their movement and behaviour that
suggests foraging Barn Owls, and indeed the local ferryman recognised them
as owls. Dobbs saw them most often on damp nights with heavy overcast, but
also on clear nights with a half moon; on one occasion she observed them
more than two hours after sunset on a dark night.
Moffatt (1911) also quoted the ferryman as seeing them best on moonless
nights in damp weather. These conditions would seem to rule out reflection
of ambient light.
Although luminous birds, thought to be Barn Owls, have been reported in Spain and
South America (McAtee 1947) their existence in rural England, and perhaps
Europe, may have been observed much more than realised. I refer to the
well-known phenomenon of English folklore, Will o' the Wisp. This mysterious
light, about the size of a lantern light, has been known for centuries. It
was to be seen bobbing along country lanes, hovering one moment and the next
streaking off across fields, rising when necessary to glide over fences and
hedgerows, observed following roads that led to cemeteries and sitting on
tombstones, striking fear into the hearts of many who saw it, believing it
to be an omen of death or evil and given to luring lost wayfarers to their
doom in bogs.
The name of the phenomenon might vary from place to place: in one locality
it might be Will o' the Wisp, in another Jack 0' Lantern, or Joan of the
Wad, Jenny Burn-tail, Kitty wi' the Whisp, Spunkie or Corpse candle (Clarke
Anybody seeing this sprite might merely have been seeing, without knowing, a
luminescing Barn Owl, at least in some instances.
Jack o' Lanterns were said to fly at and 'baffle' people carrying lights.
Anon. (1908) reported that he had an owl flying at and knocking against a
lantern he was carrying at night through a churchyard. Perhaps territorial
owls mistook lanterns for intruding (luminescing) owls.
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