Golden-mantled ground squirrels (Citellus lateralis Say) typically inhabit coniferous forest regions, but they occasionally occur in desert shrub habitats. The principal purpose of this study was to observe activities of mantled squirrels in a sagebrush community, and to ascertain factors which contribute to their success in an unusually arid habitat. Squirrels of this community belong to the subspecies C. l. lateralis; however, intergradation between typical C. l. lateralis and C. l. castanurus is evident. This community is in the Wasatch Mountains at an elevation of 5,750 feet, and in the Upper Sonoran Zone. These three conditions were not previously recorded for members of this subspecies.

The thesis deals with vocalizations produced by Eurasian ground squirrels of the genus Spermophilus. It is mainly focused on inter-species and intra-species variability in acoustic structure of alarm calls which are emitted in presence of predators.The major part of the thesis deals with intra-species variability in acoustic structure of the alarm calls in five Eurasian ground squirrels, Spermophilus citellus, S. taurensis, S. xanthoprymnus, S. suslicus and S. fulvus. It has been confirmed that the alarm calls of these ground squirrels show a high level of species specificity. The thesis further describes another vocalizations produced by three Eurasian ground squirrel species, Spermophilus suslicus, S. citellus and S. fulvus, and shows that with the exception of the alarm calls, vocal repertoires of these three ground squirrels are remarkably similar. The last part of the thesis deals with individual distinctiveness of the alarm calls of three Eurasian ground squirrels, Spermophilus citellus, S. taurensis and S. xanthoprymnus. It has been shown that the alarm calls of these species have a significant potential to encode information about caller identity.

This research describes and analyzes the behavior of free-living Uinta ground squirrels (Spermophilus armatus) temporally, spatially and with reference to differences in sex, age, population density and habitat. In addition, the relationships between local meteorological parameters and time spent above ground are described and analyzed. The frequency of eight behaviors, feeding, moving, encounters, upright, motionless, grooming, nest gathering and calling, among ground squirrels was found to be labile, varying in frequency with time of day, period of the season, sex, age, population density and habitat, and varying in spatial distribution within the home range. The dominant behavior, feeding, was most frequent during the first and last two hours of the day and tended to occur within the home range core during these hours. During the midday periods home range use became more general and the frequency of the other behaviors increased as feeding frequency decreased. During periods of sexual activity (the beginning and end of the homeothermic season), male ground squirrels displayed high frequencies of encounters, moving and calling behaviors.

No description available.

Various methods were employed to detect changes in the peripheral degradation of thyroxine (T4) in adult Uinta ground squirrels (Citellus armatus) collected at two different altitudes (5400 and 9000 feet.) Plasma half-life of injected T4-125I (tl/2) was significantly decreased with altitude, as was T4-125I distribution space (TDS) and T4 degradation and secretion rate (TSR). In vitro deiodination of T4-125I by heart homogenates was not affected, while urinary excretion of thyroxine derived iodide was increased at high altitude 44-70 hours post-injection. Both total and free serum T4 concentrations were reduced at high altitude, although not significantly. The cause of the reduced tl/2 at high altitude was not evident, while the decreased TDS was probably due to a reduced plasma volume. Increased urinary and fecal clearance could account for the decreased total and free serum T4. TSR was reduced due to the low TDS and T4 concentration observed in high altitude squirrels.

Thyroid uptake and distribution of 125I, concentrations of T4 and T3 in serum and thyroids and concentrations of TSH in serum and pituitaries were measured to determine thyroid function of Uinta Ground Squirrels (Citellus armatus) native to 5,400 and 9,000 feet elevations to evaluate alterations in the state of the thyroid due to increased altitude. Uptake of 125I was 60 percent lower by squirrels from 9,000 feet. Incorporation of 125I into T3 was greater at the higher elevation, but absolute thyroid T3 concentrations were similar at both elevations. No significant differences were found in serum T3 concentrations, but squirrels living at 9,000 feet had higher serum T4 levels than those living at a lower elevation. Urinary excretion of T3 by squirrels from the 9,000 feet elevation was lower compared to excretion by squirrels native to 5,400 feet. Elevated pituitary TSH levels were also found in squirrels native to the higher altitude. These findings indicate a chronic hypothyroid state of squirrels living at 9,000 feet compared to those living at 5,400 feet.

No description available.