DECLINING REPRODUCTION AMONG SWAINSONS-HAWKS IN PRAIRIE CANADA

Swainson's hawk (Buteo swainsoni) population densities were apparently healthy and reproduction was consistently high in Saskatchewan (2.09 young per successful nest), and in southern Alberta (2.03 young per su ccessful nest) through 1987. Our analysis of 2719 successful nestings revealed that near Kindersley, Saskatchewan, six consecutive years of declining production began in 1988, the worst 6 yr in 25 yr of study. Declines in production were evident at Hanna, Alberta by 1991. In 1993 , productivity was only 1.14 young/successful nest near Hanna and 1.27 young/successful nest near Kindersley. The decline in productivity wa s accompanied by a drastic decline in the number of the Swainson's haw k's main prey, Richardson's ground squirrel (Spermophilus richardsonii ).