CHANGES IN TOTAL-BODY CALCIUM AND DIET OF BREEDING HOUSE SPARROWS

We collected House Sparrows Passer domesticus around London, Ontario, estimated their total body calcium masses,food habits and egg producti on to test for the effects of endogenous calcium levels on control of clutch size. Before egg production began, calcium levels increased sig nificantly and remained high through the end of egg laying, and then d eclined significantly after egg laying, We found no evidence that clut ch size was related to endogenous calcium levels. Upon first ovulation , Mouse Sparrows greatly increased consumption of calciferous material s such as snail shells, bird eggshells and calciferous grit. Their die t returned to normal after the final egg was ovulated. Daily calcium i ntake was sufficient to meet eggshell calcium needs.