Falco tinnunculus – CUDYLL COCH – Breeding resident
Kestrel numbers within the county have declined and are now considered to be at their lowest level since 1894. The reasons for the decline are discussed in detail. Much of the decline is attributable to loss of suitable breeding habitat due to changes in farming practices, but there are also other contributing factors. Productivity seems sufficient to maintain a viable breeding population, but many successful breeding sites become unoccupied in subsequent years. This indicates that either adult survival between breeding seasons is too low, or insufficient recruitment is taking place due to low survival of first winter birds following independence, or perhaps both.
A likely cause of the low survival of first winters is again change in farming practices reducing the foraging quality of the arable landscape but this assumes that Pembrokeshire kestrels disperse to lowland arable areas to over winter in line with the national trend (Shrubb 1993), an assumption for which there are no data to help validate. Predation cannot be ruled out as a cause of poor over-winter or post-fledging survival, but during the breeding season it appears to be insignificant. Competition for nest sites may occur inland and the provision of artificial sites in some areas may help, but it is concluded that nest site competition in not a significant factor that is driving the population decline, and until other factors are understood and mitigated for, then the kestrel population will not increase significantly in response to provision of artificial nest sites.
Paddy Jenks & Tansy Knight