During eight intermittent years for which records were available, Dipodomys ordi richardsoni seldom bred from April to July. Breeding usually began in August or September and ended in March. Rate of reproduction was associated with precipitation, food supply and population densities of kangaroo rats and other rodents.
Following the 1956 drought, few females became receptive, few young were born, and the population declined. After the favorable growing season of 1957, most females in the sparse population became pregnant within the first two months of the breeding season. Most bred at least twice during that season, and young females born early produced litters before the season ended. In 1958, another year of abundant rainfall and plant growth, the population was dense and few females appeared gravid prior to mid-November. Following a moderately productive 1955 growing season, the population was sparse and reproductive activity was intensive from August to at least the following February. Young born early reproduced later the same season, but there was little indication of second litters produced by old females.