The duration of the breeding season for the plains pocket gophers, Geomys bursarius, varies across the species' known geographic distribution (Connior 2011). In Texas, the period of reproduction for G. bursarius was reported to begin no earlier than late January and extends through October (Schmidly 2004). Previous research over a ten-year period in Texas supports this; however, Pitts et al. (2005) documented female G. bursarius carrying fetuses from as early as late January through November. The gestation period averages approximately four weeks (Bee et al. 1981), though a captive individual exhibited a gestation period of over seven weeks (Sudman et al. 1986). Typically, only 1 litter is produced in a season (Connior 2011), with 2.5 pups constituting an average litter size (Pitts el al. 2005). This paper documents evidence for copulation during the month of December, thereby confirming a year-round breeding within G. bursarius in Texas.
On 2 January 2009, eight female and one male G. bursarius were captured 2.3 mi SE of Alvarado (32 27′ 616″ N, 97 12′ 249″ W) in Johnson County, Texas. One female had four fetuses (2 in each of the left and right uterine horns) measuring 10 mm crown-rump, six had obvious swollen uterine horns, and one showed no evidence of reproduction. The one male G. bursarius was scrotal and had testes measuring 18 mm in length, with respect to Geomys, testes size rather than testes position is a more reliable measure of reproductive potential, males with testes measuring > 12.5 mm containing spermatozoa (Connier 2011). All nine specimens are currently housed in the mammal collection at the Fort Hays Sternberg Museum (FHSM), Fort Hays University, Hays, Kansas (Table 1).
On 31 January 2009, three additional G. bursarius, one male and two females, were collected at the Joshua High School, Joshua, Johnson County, Texas (32 27′ 035″ N, 97 23′ 025″ W). The one male was scrotal and had testes length of 20 mm, and the females were pregnant with 5 and 4 fetuses, respectively. The fetuses measured 20 to 22 mm crown-rump indicating that copulation occurred in December. These specimens are currently housed in the Mammal collections at FHSM and Tarleton State University (TSU), Stephenville, Texas (Table 2). These records provide definitive evidence that G. bursarius breed in December and possibly throughout the year in Texas (Pitts 2005).
We would like to thank C. Schmidt for assistance in collating accession numbers for vouchers and NSERC for supporting HMH in his research on mammalian systematics and evolution.
