Reproduction of Richardson's ground squirrel (Spermophilus richardsonii) in southern Saskatchewan

1972 ◽  
Vol 50 (12) ◽  
pp. 1577-1581 ◽  
Author(s):  
D. H. Sheppard
Keyword(s):  
Sex Ratio ◽  
Litter Size ◽  
Ground Squirrel ◽  
Ground Squirrels ◽  
Spermophilus Richardsonii ◽  
Live Trapping ◽  
Native Grassland ◽  
Adult Sex Ratio ◽  
The Mean ◽  
Sexually Mature

Adult Richardson's ground squirrels (n = 238) were collected near Regina, Saskatchewan in April and May of 1969 and 1970. The adult sex ratio (males: females) of collected animals was 1:3.3 compared with a juvenile sex ratio of 1:1 obtained by live trapping in 1967and 1968. The breeding season extended from 3 to 28 April but 77.8% of all conceptions occurred between 7 and 16 April. All yearlings seemed to be sexually mature and the mean litter size for all females baaed on living embryos was 6.93 ± 0.18. Mortality of embryos was 6.83%. Yearlings were smaller than adults but mean litter sizes of yearlings and adults did not differ. Ground squirrels collected from cropland had a significantly larger mean litter size, were somewhat heavier, and had significantly longer humeri than those from native grassland.

Population parameters of ringed seals (Phoca hispida Schreber, 1775) in the Svalbard area

1987 ◽  
Vol 65 (4) ◽  
pp. 1021-1027 ◽  
Author(s):  
Christian Lydersen ◽  
Ian Gjertz
Keyword(s):  
Sex Ratio ◽  
Ringed Seal ◽  
Adult Males ◽  
Population Parameters ◽  
Phoca Hispida ◽  
Age Class ◽  
Ringed Seals ◽  
Males And Females ◽  
The Mean ◽  
Sexually Mature

Samples were taken from 284 ringed seals (Phoca hispida) in the Svalbard area during April–July 1981 and March–April 1982. The age of 283 seals was determined by reading annuli in the cementum of the canine teeth. The mean age of the males was 11.3 years, and of the females, 14.9 years. Females were found to be significantly older than males. The mean length of sexually mature ringed seals was 128.9 cm for both sexes. The mean weight of adult males and females was 53.5 and 61.4 kg, respectively. Females were found to be significantly heavier than males. The sex ratio was 47.8% males and 52.2% females. Studies of microscopic sections of testis and epididymis from ringed seal males showed that 63, 75, and 80% of 5-, 6-, and 7-year-old animals, respectively, were sexually mature. The weights of testis and epididymis, diameters of tubuli, and the size of testis all showed a marked increase in the 5-year age-class. Macroscopic sections of ovaries from ringed seal females showed that 20, 60, and 80% of 3-, 4-, and 5-year-old animals, respectively, were sexually mature. The size of the ovaries showed a marked increase in the 5-year age-class. The ovulation rate of ringed seals from Svalbard was calculated to be 0.91.

Description of Sarcocystis campestris sp. n. (Protozoa: Sarcocystidae): a parasite of the badger Taxidea taxus with experimental transmission to the Richardson's ground squirrel, Spermophilus richardsonii

1983 ◽  
Vol 61 (2) ◽  
pp. 370-377 ◽  
Author(s):  
Richard J. Cawthorn ◽  
Gary A. Wobeser ◽  
Alvin A. Gajadhar
Keyword(s):  
Ground Squirrel ◽  
Prepatent Period ◽  
Ground Squirrels ◽  
Intermediate Hosts ◽  
Patent Period ◽  
Sporocyst Residuum ◽  
Experimental Transmission ◽  
Taxidea Taxus ◽  
Spermophilus Richardsonii ◽  
Large Round

Sarcocystis campestris sp. n. (Protozoa: Sarcocystidae) is an heteroxenous coccidium with badgers (Taxidea taxus) as natural and experimental definitive hosts and Richardson's ground squirrels (Spermophilus richardsonii) as experimental intermediate hosts. Free sporocysts (10.2 × 8.0 μm with a large, round sporocyst residuum consisting of a single refractile granule), obtained from intestinal scrapings of badgers (carcasses frozen 2 years at −20 °C), were orally administered to juvenile Richardson's ground squirrels. Acute fatal sarcocystosis developed in some squirrels at 11–13 days postinoculation (p.i.). Meronts (second generation) were present 9–12 days p.i. in the vascular endothelium of many tissues (especially the lungs). Cysts developed in skeletal muscle, contained metrocytes (7 × 5 μm) 30 days p.i., and beginning 46 days p.i., bradyzoites (12.0 × 3.5 μm) were present. Cysts were macroscopic as early as 258 days p.i. Squirrel carcasses containing cysts (76 days p.i.) of S. campestris sp. n. were fed to Sarcocystis-free badgers. The prepatent period was 9 days and the patent period at least 13 days. Both badgers were ill early in the patent period and passed unformed feces during the patent period. Free sporocysts were 10.2 × 8.0 μm and each had an elongate sporocyst residuum containing numerous small refractile granules.

Growth and its relationship to the initial annual cycle of the golden-mantled ground squirrel, Spermophilus lateralis

1981 ◽  
Vol 59 (6) ◽  
pp. 865-871 ◽  
Author(s):  
John A. Phillips
Keyword(s):  
Litter Size ◽  
Annual Cycle ◽  
Ground Squirrel ◽  
Growth And Development ◽  
Reproductive Effort ◽  
Ground Squirrels ◽  
Active Season ◽  
Spermophilus Lateralis ◽  
Significant Difference ◽  
Two Populations

Thirty-eight litters of golden-mantled ground squirrels (Spermophilus lateralis), from two populations that experienced different lengths of active season, were born and raised in the laboratory. Growth and development in young were inversely related to litter size. Offspring from smaller litters were both able to attain their prehibernation peak of body mass sooner and hibernate after fewer days of homeothermy than squirrels from larger litters. Young that remained homeothermic throughout the initial overwintering period were always from large litters and among the slowest growing littermates. Fecundity was lower in females from the temporally compressed environment. There was no significant difference between populations in the nutrition provided by mothers to their litters. The results suggest that reproductive effort is more conservative in populations of ground squirrels that experience short seasons of activity, yet this conservatism allows the offspring of those populations to reach independence and attain the prehibernation state of preparedness at an earlier age than their counterparts from populations of more moderate climates.

scholarly journals The adaptive utility of Richardson’s ground squirrel (Spermophilus richardsonii) short-range ultrasonic alarm signals

2006 ◽  
Vol 84 (9) ◽  
pp. 1322-1330 ◽  
Author(s):  
David R. Wilson ◽  
James F. Hare
Keyword(s):  
Ground Squirrel ◽  
Ground Squirrels ◽  
Alarm Calls ◽  
Older Individuals ◽  
Alarm Signals ◽  
Active Space ◽  
Spermophilus Richardsonii ◽  
Ultrasonic Calls ◽  
Audible Alarm ◽  
Signal Type

Richardson’s ground squirrels ( Spermophilus richardsonii (Sabine, 1822)) produce audible (ca. 8 kHz) and (or) ultrasonic (ca. 48 kHz) alarm vocalizations that warn conspecifics of impending danger. Audible calls have a larger active space than ultrasonic calls because they travel farther, are louder, and contain frequencies to which conspecific and allospecific recipients are more sensitive. In our first experiment, we presented an alarming stimulus to 103 squirrels to examine the effect of threat proximity on signal type. The ratio of ultrasonic to audible alarm calls increased with increasing distance from the stimulus. We conclude that the size of the active space influences signalling strategy and that squirrels emitting ultrasonic calls can signal conspecifics to the exclusion of distant predators. As recipients of ultrasonic calls must be close to the signaler, one context in which ultrasonic calling may be most adaptive is during natal emergence when juveniles are particularly abundant, highly vulnerable to predation, and clustered in space. In our second experiment, we broadcast ultrasonic alarm signals to emerging juveniles and found that they, like older individuals, responded to calls by increasing vigilance. We discuss the adaptive utility of multiple signalling strategies in light of our findings.

FLEAS (SIPHONAPTERA) ASSOCIATED WITH GROUND SQUIRRELS (SPERMOPHILUS SPP.) IN MANITOBA, CANADA

1990 ◽  
Vol 122 (3) ◽  
pp. 449-458 ◽  
Author(s):  
Terry D. Galloway ◽  
John E. Christie
Keyword(s):  
Ground Squirrel ◽  
Ground Squirrels ◽  
Spermophilus Richardsonii ◽  
Eastern Chipmunk ◽  
First Time

AbstractTwenty-one species of fleas, seven of which are considered true ground squirrel fleas, were collected by various means from Spermophilus richardsonii (Sabine), S. tridecemlineatus (Mitchell), and S. franklinii (Sabine) in Manitoba. Opisocrostis tuberculatus tuberculatus (Baker), O. labis (Jordan and Rothschild), Neopsylla inopina Rothschild, and Rhadinopsylla fraterna (Baker) are ground squirrel fleas reported from Manitoba for the first time. These, in addition to Oropsylla rupestris (Jordan) and Thrassis bacchi bacchi (Rothschild), were restricted to the southwestern region of the province, but Opisocrostis bruneri (Baker) was collected throughout the range of the ground squirrels, irrespective of location. Fourteen species collected were considered accidental on ground squirrels, one of which, Tamiophila grandis (Rothschild) (an eastern chipmunk parasite), was recorded for the first time in the province.

Biology of The Southern Brown Bandicoot (Isoodon Obesulus) In South-Eastern Tasmania. II. Demography.

1998 ◽  
Vol 20 (3) ◽  
pp. 339
Author(s):  
S.A. Mallick ◽  
M.M. Driessen ◽  
G.J. Hocking
Keyword(s):  
Sex Ratio ◽  
Significant Decline ◽  
Home Ranges ◽  
Sexually Dimorphic ◽  
South Eastern ◽  
Live Trapping ◽  
Dry Conditions ◽  
Males And Females ◽  
The Mean ◽  
Two Populations

We used live-trapping to study the demography of two populations of the southern brown bandicoot, Isoodon obesulus, in south-eastern Tasmania from March 1992 to March 1995. The bulk of I. obesulus captures were in woodland/forest or within 3 m of its verge, with <10% of captures in 'open' pasture. Densities ranged from 0-0.35 animals/hectare. Both populations underwent a significant decline over the study period. This decline is thought to be the result of the exceptionally dry conditions over the three years of the study. Adult sex ratios (male/female) ranged from 0.6- 1.17. The sex ratio of pouch young was female-biased on both grids (range of 0.53-0.73). Isoodon obesulus were sexually dimorphic, with males being both heavier and larger than females. Only two juveniles were recruited to the populations over the entire three years of the study. Breeding among female I. obesulus was greatest in the December, low in the March, moderate in the September, and absent in the June trapping sessions. Mean litter size was 3.05 ± 0.26, with a range of 1-5 pouch young. For males and females, mean longevity for resident animals was 10.0 ± 3.7 and 13.5 ± 3.3 months, respectively. The mean home range area for the two resident males and the five resident females with ≥8 captures was 6.95 ± 1.95 and 3.28 ± 1.02 hectares, respectively. There was minimal overlap between the home ranges of individual I. obesulus.

Sexual differences in interyear survival and life-span of Richardson's ground squirrels

1989 ◽  
Vol 67 (7) ◽  
pp. 1827-1831 ◽  
Author(s):  
Gail R. Michener
Keyword(s):  
Sex Ratio ◽  
Life Span ◽  
Older Adult ◽  
Litter Size ◽  
Ground Squirrels ◽  
Sexual Differences ◽  
Maximum Life Span ◽  
Southern Alberta ◽  
Males And Females ◽  
Size At Birth

Although equal numbers of males and females were weaned in a population of Richardson's ground squirrels studied in southern Alberta, interyear survival was lower for males than for females in each year of life. Consequently, the sex ratio was biased toward females in both the yearling and older adult cohorts (overall ≤ 23 males per 100 females), and maximum life-span of males was 4 years, whereas that of females was 6 years. Compared with several other species of Spermophilus, Richardson's ground squirrels have a larger litter size at birth and a shorter life-span.

Populations of ferruginous and Swainson's hawks increase in synchrony with ground squirrels

1989 ◽  
Vol 67 (10) ◽  
pp. 2596-2601 ◽  
Author(s):  
Josef K. Schmutz ◽  
Daniel J. Hungle
Keyword(s):  
Ground Squirrel ◽  
Prey Density ◽  
Prey Species ◽  
Ground Squirrels ◽  
Crop Damage ◽  
Agricultural Fields ◽  
Fledging Success ◽  
Spermophilus Richardsonii ◽  
Buteo Regalis ◽  
Buteo Swainsoni

We compared changes in the densities of breeding ferruginous (Buteo regalis) and Swainson's hawks (Buteo swainsoni) over a period of 9 years with the abundance of a major prey species, Richardson's ground squirrel (Spermophilus richardsonii). We used the amount of poison distributed by landowners annually in their attempts to reduce crop damage by ground squirrels as an index of ground squirrel abundance. Though ground squirrel abundance was positively correlated with hawk density overall, the hawks differed in their responses to changing prey density. Breeding density and fledging success of the ferruginous hawk, a food specialist, were consistently correlated with squirrel abundance. The density of Swainson's hawks increased only where grassland was interspersed with agricultural fields. Fledging success of Swainson's hawks was not correlated with ground squirrel abundance. We suggest that the availability of small prey in spring affected breeding dispersion and reproductive success of Swainson's hawks.

scholarly journals Determination of an optimal dose of medetomidine-ketamine-buprenorphine for anaesthesia in the Cape ground squirrel (Xerus inauris)

2011 ◽  
Vol 82 (2) ◽  
Author(s):  
K. E. Joubert ◽  
T. Serfontein ◽  
M. Scantlebury ◽  
M B Manjerovic ◽  
P. W. Bateman ◽  
...  
Keyword(s):  
Ground Squirrel ◽  
Abdominal Cavity ◽  
Optimal Dose ◽  
Ground Squirrels ◽  
Temperature Logger ◽  
Xerus Inauris ◽  
Cape Ground Squirrel ◽  
The Mean ◽  
Surgical Implantation

The optimal dose of medetomidine-ketamine-buprenorphine was determined in 25 Cape ground squirrels (Xerus inauris) undergoing surgical implantation of a temperature logger into the abdominal cavity. At the end of anaesthesia, the squirrels were given atipamezole intramuscularly to reverse the effects of medetomidine. The mean dose of medetomidine was 67.6±9.2 μg/kg, ketamine 13.6±1.9 mg/kg and buprenorphine 0.5±0.06 μg/kg. Induction time was 3.1 ± 1.4 min. This produced surgical anaesthesia for 21± 4.2 min. Atipamezole 232±92 μg/kg produced a rapid recovery. Squirrels were sternally recumbent in 3.5 ± 2.2 min.

scholarly journals High Spring Mortality of Adult Richardson’s Ground Squirrels, Urocitellus richardsonii, Associated with a Severe Rainstorm in Southwestern Saskatchewan

2012 ◽  
Vol 126 (2) ◽  
pp. 148
Author(s):  
Gilbert Proulx
Keyword(s):  
Mortality Rate ◽  
Ground Squirrel ◽  
Mortality Rates ◽  
Ground Squirrels ◽  
Natural Mortality ◽  
The Mean ◽  
Strong Winds ◽  
Heavy Rains ◽  
Urocitellus Richardsonii

Heavy rains with strong winds in southwestern Saskatchewan from 20 to 29 May 2010 flooded fields where adult Richardson’s Ground Squirrels (Urocitellus richardsonii) had recently been live–trapped. Natural mortality rates in six marked populations (n = 11 to 29 animals) ranged from 9.1 to 42.9%. The mean mortality rate of populations (28.9%) was significantly greater than that estimated for four populations (8.5%) studied in April and May 2007 and 2008 during drought periods. This finding is in agreement with past studies on other ground squirrel species which showed that spring snowstorms and heavy rains caused an increase in natural mortality rates.

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