Société nationale de protection de la nature et d'acclimatation de France, Paris (FRA)
Abstract
An Index of abundance (Indice Ponctuel de Présence) has been used to estimate the seasonal changes of bird populations in three different pine woods of central Britany, planted respectively 5, 10-15, and 40 years ago. Data are given on the species recorded monthly in each of these three woodlands. The 10-15 years old pine plantation is the richest in birds, both in the number of species and in the number of individuals. In each habitat, the maximum number of birds has been recorded in spring and in autumn, but seasonal changes in the abundance of birds become smaller as the trees become older. In winter time, the number of granivorous and polypha- gous birds decreases as the pines get older, whereas the number of insectivorous birds increases considerably
