. The Canadian field-naturalist. 1991 Wrigley, Dubois, and Copland: Prairie Rodents in Manitoba Table 1. Reproductive data on the Plains Pocket Gopher in southcentral Manitoba. Number and Length Number of Estrous of Embryos Placental Date Females (mm) Scars 14 April 11 22 3 3- 8 4- 8 4-25 27 2 4- 8 28 5 5-15 25 May 1 6- 1 June 1 5- 5 5- 9 4- 3 3- 7 4 9 4 12 3 17 4-11 3,3 19 3-13 4-38 4 22 3 24 4-24 4-13 5,2,4 25 3-24 4,4,3 26 3-34 3-11 4-23 3,3 25 July 2 3- 6 26 7,5 9 October 8,3, -old scars Average (n = 20) (n= 19) Range 3- 6 2-8 of the range (Vaughan 1962). An alternate possibility i
. The Canadian field-naturalist. 1991 Wrigley, Dubois, and Copland: Prairie Rodents in Manitoba Table 1. Reproductive data on the Plains Pocket Gopher in southcentral Manitoba. Number and Length Number of Estrous of Embryos Placental Date Females (mm) Scars 14 April 11 22 3 3- 8 4- 8 4-25 27 2 4- 8 28 5 5-15 25 May 1 6- 1 June 1 5- 5 5- 9 4- 3 3- 7 4 9 4 12 3 17 4-11 3,3 19 3-13 4-38 4 22 3 24 4-24 4-13 5,2,4 25 3-24 4,4,3 26 3-34 3-11 4-23 3,3 25 July 2 3- 6 26 7,5 9 October 8,3, -old scars Average (n = 20) (n= 19) Range 3- 6 2-8 of the range (Vaughan 1962). An alternate possibility is that the animal was born late the previous summer and experienced retarded growth over the winter. Numerous young, weighing from 78 to 116 g, were captured from 17 June to 26 July in our sample. The uteri of two adult females taken on 25 July were slightly swollen, as if in the early stages of estrus, and there was no indication of earlier breeding. Other studies (Vaughan 1962) have found that a small percentage of individuals become pregnant in July and August. With our limited data, it appears that litters may be born from late January to August, but most are restricted to the period from late April to early July. Such an extended breeding season has adaptive value considering that pocket gophers have low opportunity to meet the opposite sex because of their subterranean existence and often isolated home ranges. During the first part of the breeding season in Manitoba, the frozen ground and snow cover would restrict accessibility of mates to those that live in adjacent burrow systems, for long-range surface movements are unfeasible. (Some limited activity does occur on the ground surface under the snow in early winter, as is evident by cores of excess earth stored in snow tunnels.) As Vaughan (1962) pointed out, there is considerable evidence that movements of pocket gophers from one burrow to another during the height of the breeding season are accomplished primarily under
Size: 1581px × 1581px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorottawafi, bookcentury1900, bookdecade1910, bookyear1919
