Reproduction, Growth and Development, and Behavior in the Mexican Prairie Dog, Cynomys mexicanus (Merriam)

Abstract

Reproduction in C. mexicanus is unique among prairie dogs in that the reproductive season is extremely protracted, and may last for 6 months. The growth rate is equal to or greater than in other members of the genus. Molting in C. mexicanus is complex, involving four or more overlapping phases. Behavior patterns and vocalizations in C. mexicanus are most similar to those of C. ludovicianus. Alarm barks, chatter barks, growls, screams and elation calls of C. mexicanus show varying degrees of similarity to those of C. ludlovicianus. Considering the rapid development, it is estimated that C. mexicanus pups are capable of reproduction during their lst year. INTRODUCTION Although growth and development have been studied in numerous North American sciurid rodents (Clark, 1970), little information is available on the early postnatal growth and development in prairie dogs (Cynomys) prior to emergence of pups from their burrows at approximately 6 weeks of age. Johnson (1927) presented the first account of black-tailed (C. ludovicianus) pups born in captivity, and Anthony and Foreman (1951) provided additional data on growth and development during studies of reproductive physiology of the same species. Tileston and Lechleitner (1966) compared the biology of white-tailed (C. leucurus) and black-tailed (C. ludovicianus) prairie dogs from colonies in Colorado and presented data on seasonal weight changes in adults and pups after emergence. Bakko and Brown (1967) investigated reproductive physiology of white-tailed prairie dogs from Wyoming and also reported on seasonal weight changes of adults and postemergent young. King (1955) studied demography and behavior of black-tailed prairie dogs from colonies in South Dakota and Smith (1958) reported on the natural history of black-tails fror colonies in Kansas. Information on reproduction in white-tailed and Gunnison's prairie dogs also was presented by Stockard (1929), Aldous (1935), Longhurst (1944) and Scheffer (1947). We found no information on the biology of Cynomys mexicanus except for brief mention in systematic accounts (e.g., Hollister, 1916). The first laboratory breeding and subsequent birth of a litter of six C. mexicanus pups is reported herein. Information is provided on growth and development, behavior and vocalizations of adults in the laboratory and the field. Because C. mexicanus may represent a relict population derived from C. ludovicianus (Hoffmann and Jones, 1970), we have compared our data with similar published data for other Cynomys.