Reproduction and nutrient reserves of bushy-tailed wood rats (Neotoma cinerea)

Abstract

Body composition and energy content of female bushy-tailed wood rats (Neotoma cinerea) were examined in relation to reproductive status. We assessed the extent to which nutrients for offspring were obtained from endogenous reserves, and whether use of these reserves might influence the timing of spring breeding. Among breeding females, fat levels were highest during pregnancy, and were depleted during lactation. The mean reduction in energy content from pregnancy through lactation (266 kJ) accounted for 21% of the estimated 1260 kJ contributed by a female to her offspring in this period. Females potentially gained 3.0 days of nutritional support from their endogenous reserves during winter, but this fell to 2.0 days during summer and was only 0.8 days during lactation. Thus, females support the nutritional demands of lactation primarily by increasing their ingestion of food. Nevertheless, large endogenous reserves may enable some females to begin breeding early in the spring, when the abundance of food is unpredictable.