The Use of Mirrors to Deter Nest Box Predators
By John Clarke, December 2002
On a local estate we run a nest box scheme
and many of the 150 boxes attract small, hole-nesting birds such as Tits.
Damage and/or predation by Great Spotted Woodpecker is fairly common but
in some plantations became so bad that boxes were damaged within days of being
put up. In two sites the problem
forced us to abandon attempts to provide artificial nest sites.
| Some years ago I was waiting for a farmer
outside his house in Herefordshire when I noticed a colony of House Martins.
There were about thirty nests under the eaves of the house but most strikingly,
just below each one there was a small piece of mirror. The farmer
explained that he had once reared an orphaned Great Spotted Woodpecker in a
budgerigar cage.
As the bird grew he provided a perch, then a ladder and
then a bell – all of which the young bird accepted. However, when he
hung a mirror in there the woodpecker went berserk apparently terrified by its
own reflection. The farmer had problems with GSW predating his House
Martins nests and so stuck pieces of mirror below each one. The effect was
instant, and from then on he had no further instances of nest damage.
|
Great Spotted
Woodpecker
|
I fixed small mirrors to 14 nest boxes,
siting 12 in 3 plantations where the worse damage (usually 100%) had occurred.
The other two were sited in gardens. After six months one plantation box
and one garden box had been damaged. After eighteen months a further two
boxes had been damaged in a second plantation. At least 10 of the nest
boxes had been occupied by tit spp.
To summarise, Mirror Boxes in one plantation
were 100% effective, in the second plantation 75% survived for 18 months; and in
the third 50% survived for 18 months. Two of the four damaged boxes were
accessed via the side and not by enlarging the entrance hole.
So, mirrors clearly deter GSW from attacking
nest boxes. I doubt if the idea will catch on but it does provide an
interesting insight into bird behaviour.
This Page Revised:
January 16, 2009
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