At home in the short grass prairie of North America, the range of Richardson's ground squirrels includes portions of Alberta, Saskatchewan, Manitoba, Montana, North Dakota, South Dakota, and Minnesota.
At home in the short grass prairie
of North America, the range of Richardson's ground squirrels includes portions
of Alberta, Saskatchewan, Manitoba, Montana, North Dakota, South Dakota,
and Minnesota.
Richardson's ground squirrels prefer open terrain
with high visibility to detect approaching predators. They fare well
in human-modified habitats such as city parks, over-grazed pastures, the
edges of cultivated fields, and perennial crop fields. In areas of
intense agricultural cultivation with small patches of suitable habitat,
it is not uncommon to see an 'island' of ground squirrels surrounded by
an 'ocean' of crops.
Territory
Each adult Richardson's ground squirrel maintains its own home range into which it will allow only its closest kin to intrude. A female's home range during the summer months averages around 240m2, and its borders will often overlap those of its neighbours, especially if those neighbours are kin such as sisters and adult daughters.
The core area is defined as the area within a ground squirrel's home range where it spends 50% of its time. The core area, which includes the main burrow system as well as favourite feeding sites, usually covers 20-40m2 during the summer. data
The range of an individual ground
squirrel is not static, but changes throughout the year in response to
various factors. Below are some of the main trends.
Home-range use during the mating season
At the beginning of the mating season,
male Richardson's ground squirrels do not defend a well-defined territory.
Instead, they adjust the location of their range on an almost daily basis
in order to increase their proximity to estrous females. On average,
the range of one male will overlap the ranges of at least one neighbouring
male and ten estrous females. data
The range of a female prior to insemination is overlapped by an average
of two males. (see Reproductive
Behaviour)
Home-range use throughout the rest of the season
The range of females increases from early spring to summer, and maximum territory size occurs in mid-June to July when juveniles are independent. As home-range size increases, so does the extent of overlap with neighbouring females. In mid-summer, a female’s home range may overlap that of six or seven other females. Territory size then decreases as hibernation approaches. Even when home ranges are largest, the core areas usually do not overlap. data
After the mating season, the territories
of adult males decrease. Territory size and location of males are
set in part by pregnant and lactating females who, through aggressive behaviour,
restrict males to areas where there are no natal burrows. (see social
organization) Prior to hibernation, ranges of adult males again
decrease further.
Juvenile Ranges
Throughout the summer, juveniles maintain a core area that overlaps extensively with that of their mother, and will also tend to overlap the core areas of their siblings. This newly formed core area rarely overlaps with the core areas of unrelated adult females. data
As the season progresses, the amount
of overlap declines as juveniles acquire their own distinct areas.
The spatial patterns set up as juveniles are maintained into adulthood,
so that most yearlings spend their lives surrounded by kin. (see Dispersal
and Kinship)