Body mass changes, reproductive success, and mortality were studied in Columbian ground squirrels (Spermophilus columbianus) in southern Alberta from 1994 to 1996. Spring weather conditions varied widely between years: 1994 was a dry, warm spring, 1995 was extremely rainy, and in 1996 a major snowstorm during the first 2 weeks of May stopped foraging by ground squirrels during the latter part of their mating season. We predicted that adverse weather conditions during the mating season in general, and this snowstorm specifically, would influence reproductive success and survival. Mass changes during the first 2 weeks of May varied from year to year and reflected major differences in spring weather. Female reproductive success was highest in 1994 and lowest in 1996. In 1996, we observed a higher mass loss during the first 2 weeks of May in females that subsequently did not wean a litter than in those that did. Weaning success was higher for females that mated after the snowstorm than for those that mated before or during the snowstorm. The mortality rate during mating in 1996 was higher in males than in females and was higher than in 1994 or 1995 for both sexes. Overall weaning success of females was highest in 1994 and lowest in 1996. We concluded that the energetic costs of mating can lead to a high mortality rate for males and low reproductive success for females.

In a trial to investigate an ill-thrift problem in lambs on an Exmoor farm frequent oral drenching with cobalt sulphate was compared with pasture spraying. There were two groups of twin lambs reared respectively on sprayed and unsprayed pasture. One partner from each twin set was drenched with cobalt sulphate every two weeks. There were no significant differences in live-weight gain up to weaning time. Thereafter there was little difference in the progress of the twins on sprayed pasture. On the unsprayed pasture, however, the drenched lambs had gained an average of 9 lb live weight more than their partners over a period of 15 weeks but were still about 7 lb lighter than the lambs on sprayed pasture. Blood vitamin B12 concentration, assayed with Lactobacillus leichmannii, was not well correlated with the treatment of the groups and all values were above commonly accepted critical levels.