Reproduction and Food Habits of Merriam's Kangaroo Rat, Dipodomys merriami

Abstract

Collections of Merriam's kangaroo rat (Dipodomys merriami) were made from a creosote bush community near Las Vegas, Nevada, during the period 30 May 1962 to 31 January 1965. All months of the year were represented and 985 specimens were examined. The reproductive condition of all specimens was determined. Some males were in reproductive condition, as evidenced by scrotal testes or abdominal testes 5 millimeters long or longer, during all months of the year. Approximately 50 per cent or more males were in reproductive condition during the period February through September. Some females were reproductively active in the period January through August. Visible embryos, recent placental scars, lactation, and swollen vulva were the criteria for determining reproductively active females. Two or more litters may not be uncommon. The stomachs of 740 kangaroo rats were examined and food items were separated into categories of seeds, greens, and insects. The diet is primarily made up of seeds. Greens were an important source of food in the period February through May and again in August. Greens made up more than 30 percent by volume of the stomach contents during these months. We suggest that greens are utilized primarily as a source of water during the period of reproduction.