RACING PIGEONS – IMPACT OF RAPTOR PREDATION

The loft-based trials assessed whether or not deployment of these deterrents resulted
in complete cessation of attacks at lofts but did not evaluate whether deterrents
reduced the frequency of raptor attacks.
The trials of loft-based deterrents involved three treatment groups: replica owls (n=17
lofts), replica owls plus balloons (n=3 lofts) and control (no visual deterrents) (n=16
lofts). The deterrents were evaluated over a single season only.
Of the 20 lofts with deterrents, 14 reported a total of 39 attacks by sparrowhawks.
These attacks resulted in the loss of 24 birds (59% of attacks resulted in a kill)
representing approximately 11% of all birds lost during exercise. The use of these
deterrents, therefore, did not result in complete cessation of attacks by sparrowhawks
at the loft.
The Lancaster University study then compared the loss rate of pigeons at lofts with
visual deterrents (3.5 pigeons per loft per year) with loss rates recorded in two
previous studies in different geographic areas. In Wales and western England,
fanciers reported an average loss of 2.7 pigeons per loft per annum (Shawyer et al.
2000), whilst a Royal Pigeon Racing Association (RPRA) survey, covering 14 UK
regions, reported a loss of 2.3 pigeons per loft per annum (range 0.2-5.2). As the
estimate for loss rate at lofts with deterrents fell within the ranges reported for the
other two studies it was suggested that the frequency of attacks at lofts with visual
deterrents were not significantly reduced. Such a comparison, however, clearly does
not constitute a valid full evaluation of deterrent efficacy.
Dixon (2002) states that the attack rate was highly variable between lofts and that
lofts located close to (1ha) suffered significantly higher
rates of sparrowhawk attack compared with lofts located well away from woodland.
This highlights the loft-specific risk of attack. With the rate of attack strongly
influenced by local conditions a comparison between attack rates at lofts with
deterrents in Dixon (2002) and attack rates in previous studies located in different
geographic areas (and in other years) does not provide a valid evaluation of deterrent
effectiveness. The appropriate experimental design and analysis would involve
comparison of attack rates at lofts with and without deterrents within the same study
area. Deterrent and control lofts should be matched for the risk of exposure to attack,
for example with respect to distance from mature woodland, or randomly assigned in
a larger study. In Dixon (2002) attack rates at control lofts were not reported. It is
unknown, therefore, whether attack rates would have been higher in the absence of
deterrents.
As the report of the Lancaster University study acknowledges, there is little firm
evidence to suggest that either of these devices (model owl and eyespot balloons) act
as a deterrent to raptors. In addition, subsequent deployment of these devices also
failed to apply basic principles designed to optimise deterrent effectiveness. The
trials used inanimate rather than mobile model owls and the schedule of repositioning
models at weekly intervals was too infrequent. Frequent re-siting of deterrent devices
is an essential requisite of avian control. For example, in protecting crops it is
recommended that gas cannons are re-positioned at least every two or three days (e.g.
Harris & Davis 1998, Transport Canada undated).
A robust evaluation of pigeon-based deterrents was constrained by small sample sizes.
Wing transfers were applied to a total of 174 young-birds from 15 different lofts.
During exercise flights around the loft one marked pigeon was lost (subsequently
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