Although persistent infection with hepatitis B virus and woodchuck hepatitis virus has been associated with development of hepatocellular carcinoma in the host, little has been known of such an association with ground squirrel hepatitis virus (GSHV), which is closely related to the woodchuck virus. Colonies of GSHV-infected and -uninfected Beechey ground squirrels were observed for tumors for a...

Tree squirrels (Sciurus spp.) have exhibited high seroprevalence rates, suggesting that they are commonly exposed to West Nile virus (WNV). Many characteristics of WNV infections in tree squirrels, such as the durations and levels of viremia, remain unknown. To better understand WNV infections in fox squirrels (S. niger), we subcutaneously inoculated fourteen fox squirrels with WNV. Peak viremi...

Sequence variations in the melanocortin-1 receptor (MC1R) gene are associated with melanism in many different species of mammals, birds and reptiles. The grey squirrel (Sciurus carolinensis), found in the British Isles, was introduced from North America in the late nineteenth century. Melanism in the British grey squirrel is associated with a 24 base pair deletion in the MC1R. To investigate th...

Under natural conditions, wild animals encounter situations where previously rewarded actions do not lead to reinforcement. In the laboratory, a surprising omission of reinforcement induces behavioral and emotional responses described as frustration. Frustration can lead to aggressive behaviors and to the persistence of noneffective responses, but it may also lead to new behavioral responses to...

In two species of hibernators, hamsters and ground squirrels, erythrocytes were collected by heart puncture and the K content of the cells of hibernating individuals was compared with that of awake individuals. The K concentration of hamsters did not decline significantly during each bout of hibernation (maximum period of 5 days) but in long-term bouts in ground squirrels (i.e. more than 5 days...

The jaw, suprahyoid, and extrinsic tongue muscles were studied in 11 genera, belonging to five tribes, of Old World squirrels. Significant variation in most of the adductor muscles is evident. The most primitive state of sciuromorphy is seen in the African tree squirrels Paraxerus and Funisciurus, especially as reflected in the anterior deep masseter. A derived state of sciuromorphy is found in...

In golden-mantled ground squirrels, phase angles of entrainment of circadian locomotor activity to a fixed light-dark cycle differ markedly between subjective summer and winter. A change in ambient temperature affects entrainment only during subjective winter when it also produces pronounced effects on body temperature (Tb). It was previously proposed that variations in Tb are causally related ...

An increase in the use of plastic tubing systems to collect sap from sugar maples (Acer saccharum) has allowed syrup producers to boost production in recent years, but not without cost. Rodents gnawing on tubing, spouts, and fittings may cause damage in excess of $300,000 annually in Vermont, the largest maple producing state. Red squirrels (Tamiasciurus hudsonicu3), gray squirrels (Sciurus car...

Infectious disease introduced by non-native species is increasingly cited as a facilitator of native population declines, but direct evidence may be lacking due to inadequate population and disease prevalence data surrounding an outbreak. Previous indirect evidence and theoretical models support squirrelpox virus (SQPV) as being potentially involved in the decline of red squirrels (Sciurus vulg...