THE EFFECT OF ENVIRONMENTAL-FACTORS ON SURVIVAL OF GRAY PARTRIDGE (PERDIX-PERDIX) CHICKS IN POLAND DURING 1987-89

1. The survival of grey partridge chicks was estimated from the brood sizes in several areas of Poland, and related to weather conditions, abundance of insect food, occurrence of weeds, and the use of herbicides. 2. Geometric mean brood size in different areas and years ranged from 7.5 to 11.2, with a mean of 9.3, and the estimated chick survival rate ranged from 42 to 71%, with a mean of 56%. 3. Chick survival rates increased with mean temperatures and decreased with increasing numbers of rainy days in June. 4. Chick survival rates increased with numbers of plant bugs, but they had no significant effect after removal of the effect of weather. Numbers of plant bugs increased with temperature. 5. Density and species diversity of dicotyledonous weeds in cereals were relatively high, and differences in weeds between areas were not in accordance with differences in the abundance of insects selected by partridges. The application of herbicides in Poland so far has not had a marked indirect negative effect on the survival of partridge chicks. Presumably the occurrence of permanent cover in crop fields has a positive effect on chick survival.