Changes in the composition of the autumn food of Perdix perdix in West Finland over 20 years.
Composition of the crop contents of 622 partridges killed in October in 1962-64, 1968-70 and 1979-81 was studied. There were no sex- or age-related differences in the food eaten. The composition of the food remained unchanged from the first period to the second, the main components being grain, seeds of Galeopsis spp., seeds of other plants, green matter and animal matter. The crop contents also included 0.4% grit. Considerable changes took place from 1968-70 to 1979-81, the proportion of grain increasing by about 20% and that of the seeds of Galeopsis decreasing by more than 20%. The proportion of green matter was 2.7% during the former period and 4.3% during the latter. For animal matter the proportions were 0.04% and 1.2%. It is concluded that the decrease in the proportion of seeds of Galeopsis spp. and the number of weed species in the diet of the partridge is due to the increased use of herbicides and intensification of other agricultural practices.