Moth abundance and breeding success in a Great Tit population where moths are the main nestling food

The relationships between the timing of breeding and the reproductive success of Great Tits Parus major, and the phenology and abundance of the most abundant prey type in the nestling diet (Peridroma saucia moths, Lepidoptera, Noctuidae), were studied in orange groves in eastern Spain during three years. There were significant differences in moth abundance between the three years. A seasonal peak in P. saucia abundance was detected only one year, and this was very late in relation to the Great Tit breeding period (89% of the chicks had fledged by this date). This suggests that the timing of the Great Tits is not related to the phenology of moths. Breeding success seems to be favoured by high moth abundance. However, in a very early year, breeding success was comparatively high in spite of the low moth abundance. We suggest that caterpillars are available during a short period, and most years are nearly over when nestlings are present, the breeding success being related to the abundance of moths. Nestlings could be fed more caterpillars in exceptionally early years, and breeding success is therefore not related to moth abundance.

Barba E., Garcia D.M., Gil-Delgado J.A. & Lopez G.M., ARDEA 82 (2): 329-334