Date of Award
Doctor of Philosophy
Between April, 1981 and July, 1983, I collected 563 (211 male, 352 female) house sparrows (Passer domesticus) around London, Ontario, weighed their nutrient reserves (protein, fat, calcium) and determined their food habits, to see if nutrient reserves proximately control clutch size in this species. Daily energy demands during egg production were evaluated by analyzing changes in nutrient reserves. Captive house sparrows were studied to determine if stored fat was deposited in eggs.;The proportion of males and females that consumed high-protein foods varied with the seasonal availability of insects. Insect use was low until egg laying but then increased and remained high thereafter. Insect consumption by males and females was similar throughout breeding. The porportion of males and females that ate calciferous material was constant (low) until egg production began. Then most females, but few males, consumed claciferous materials. After laying, female consumption of calciferous materials declined and again equaled males.;Before egg production began, males used protein and fat but not calcium reserves; protein and fat reserves of females were constant but calcium was accumulated. Because the proportion of females that consumed calciferous materials did not change during prereproduction, females must have accumulated calcium through increased retention of calcium from their normal diet. After egg production began, male nutrient reserves remained constant through postreproduction. Female protein and calcium reserves declined linearly during egg production; fat reserves, however, increased while 50% of the fat in a clutch was being allocated, and declined rapidly thereafter. The use of protein and fat reserves was independent of clutch size as all postlaying females had at least enough protein and fat to build an additional egg. Protein and calcium reserves of postlaying females remained constant but fat increased.;Maximum daily energy required for egg production was, at most, 50% of basal metabolic rate. Fat ingested by captive house sparrows was deposited daily in the developing follicles and fat not put into follicles went to fat depots, which were used rapidly. I conclude that, although female house sparrows do use nutrient reserves during egg laying, their clutch size is not controlled thereby.
Krementz, David George, "Bioenergetics Of Breeding House Sparrows" (1984). Digitized Theses. 1373.