The species leaves holes in fields creating a nuisance for farmers
Control of Richardson’s ground squirrels is ideally done in early spring before mating, but that opportunity might already be past.
Many of the rodents, commonly referred to as gophers by prairie farmers, have already emerged from their burrows and mated.
Gail Michener, a biology professor emeritus at the University of Lethbridge, described the species’ mating habits April 7 in a talk organized by the Alberta Wildlife Society in Lethbridge.
Juvenile female gophers will mate within three or four days of emerging from hibernation. Females are in estrus for only two hours of a single afternoon, so there is intense competition among males to find receptive females on any given day.
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Twenty-three days after breeding, the females give birth to their one litter of the year, with five to eight young.
Newborns weigh about seven grams at birth but increase to 70 grams by the time they emerge 30 days later. Only 12 percent of males survive to become adults. Fighting during mating and predation add up to high mortality.
In contrast, 30 percent of females survive to adulthood and then have a 50 percent chance of surviving for a second year.
Michener, who studied gophers for 30 years, said the oldest female she encountered lived to be seven.
Adult males go into hibernation by June and females by July. After that, it’s the juveniles that are seen on the prairie. They are the bane of farmers in large numbers because they dig holes and eat crops.
Control measures include shooting, trapping, strychnine and underground asphyxiation using gas.
The species has undergone several changes to its Latin name, and as of 2009 is known in scientific circles as Urocitellus richardsonii.
It was originally labeled Arctomys richardsonii, after British scientists identified specimens collected by surgeon naturalist John Richardson.
Richardson sailed with the first and second Franklin expeditions that were launched to find the Northwest Passage through the Arctic.
He encountered the ground squirrels when the expedition sailed into Hudson’s Bay in 1819 and then travelled through part of the Prairies to reach the Arctic.
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For more information, visit research.uleth.ca/rgs.
- A taxonomic revision in 2009 recognizes 26 species of North America ground squirrels. The six species found in Canada are:
- Arctic
- Columbian
- Franklin’s
- golden-mantled
- Richardson’s
- thirteen-lined ground squirrel
- The ground-dwelling species with the most similar appearance to Richardson’s ground squirrels are the Wyoming ground squirrel (Urocitellus elegans) and the black-tailed prairie dog (Cynomys ludovicianus).
- The similarity in appearance between Wyoming ground squirrels (Urocitellus elegans) and Richardson’s ground squirrels is so great that for years the Wyoming ground squirrel was considered to be a subspecies of the Richardson’s ground squirrel. However, genetic evidence, including a difference in numbers of chromosomes, justifies classification as a separate species. The Wyoming ground squirrel occurs in three distinct non-contiguous locations in the U.S., primarily in Montana/Idaho, Wyoming/Colorado, and Nevada.
- Black-tailed prairie dogs (Cynomys ludovicianus) are almost twice the size of Richardson’s ground squirrels, with a chunkier body, heavier limbs and broader face. They live in complex family units called coteries, which communally defend a common territory and burrow system. Black-tailed prairie dogs construct large volcano-like mounds, and they use the snout to pack the soil above the entrance, leaving conspicuous nose imprints. Richardson’s ground squirrels simply discard excavated soil into a loose mound.
- Columbian ground squirrel (Urocitellus columbianus) overlaps ranges with the geographic ranges of Richardson’s ground squirrels in the foothills of the Rocky Mountains, so both species are sometimes seen in proximity. Columbian ground squirrels are about 50 percent larger than Richardson’s ground squirrelsand they have more colourful pelage, with flecked fur and a rufous snout.
- Northern pocket gophers (Thomomys talpoides) are members of the rodent family Geomyidae, so are only distantly related to ground squirrels in the rodent family Sciuridae. Terminological confusion arises because many species of ground squirrels are colloquially called gophers, even though they are not true gophers. In regions where ground squirrels are called gophers, which includes much of the Canadian Prairies, the true pocket gophers are often colloquially called moles, adding to the confusion.
