RACING PIGEONS – IMPACT OF RAPTOR PREDATION

5.2.3 Discussion
It was always recognised that searches for rings would reveal only an absolute
minimum number of the total number of racing pigeons taken by peregrines because
an unknown proportion of rings are not deposited in the nesting area, and furthermore
an unknown proportion would remain unrecovered from the nesting area. In addition
to rings not found during searches (due to being missed or being in situations where
safety dictated could not be searched), it is known that some rings are removed from
eyries and surrounding areas by a range of people. However, although rings were
probably removed from some sites (and certainly removed from at least one site),
CSL has no reason to believe that rings were removed in an organised manner from
any eyries in the study prior to the visit by CSL staff.
It should also be noted that only the remains of racing pigeons killed close to the eyrie
(or those where pellets containing rings were regurgitated close to the eyrie) can be
recovered by this method. Thus any racing pigeons killed away from the eyrie cannot
be accounted for by the recovery of rings from the vicinity of the eyrie.
There are many reasons, therefore, for concluding that the results of eyrie searches
can only provide a minimum figure for the total losses of racing pigeons to
peregrines, above which the real figure must lie, as also recognised by Dixon (2002).
Estimates for the potential number of pigeons killed by peregrine could be derived, in
turn, for domestic pigeons (i.e. feral/racing/rock dove etc.), racing pigeons and
Scottish racing pigeons based on the daily food intake (DFI) of peregrines. This
approach would require data on: (i) peregrine numbers, (ii) peregrine daily food
requirements, (iii) the proportion of peregrine diet which is pigeon, (iv) the proportion
of the pigeon component of peregrine diet that is Scottish racing pigeon. The
methodology for this approach is outlined in Annex 1.
5.3 REGIONAL VARIATION IN RECOVERY OF RINGS AMONGST FEDERATIONS
5.3.1 Method
Analysis of ring recoveries was conducted to determine the relative abundance of
rings from individual Federations recovered from eyries in different regions. This
provides information on whether birds from specific Federations are more vulnerable
to predation from peregrines in particular regions. Data were collated separately for
old birds (95 rings) and young birds (58 rings) last released in either 2001 or 2002.
The rings of pigeons released in earlier years were not included in the analysis
because of the change in the location of the release points, with a switch to the east of
the country in recent years.
Because of the relatively low numbers of rings involved it was not possible to analyse
data at the level of the individual Federation. Therefore, both eyries and the
Federations which issued the recovered rings were allocated to one of three regional
categories (Table 5.4).
56