Social Behavior of Microtus pennsylvanicus in Relation to Seasonal Changes in Demography

1981 ◽  
Vol 62 (4) ◽  
pp. 738 ◽  
Author(s):  
A. Bruce Webster ◽  
Ronald J. Brooks
1987 ◽  
Vol 65 (12) ◽  
pp. 2931-2937 ◽  
Author(s):  
Michael H. Ferkin ◽  
Joshua O. Seamon

Olfactory cues play a major role in inter- and intra-sexual agonistic behavior for Microtus pennsylvanicus. We show that seasonal changes in odor preference and behavioral interactions coincide with varying patterns of social organization. Odor preference trials were conducted in a Y maze and social behavior was measured in dyadic encounters in a neutral arena. During the breeding season, paired encounters between females contained more agonistic acts than did encounters between males, or those between males and females. Breeding males preferred the odor of females to the odor of conspecific males. In contrast, breeding females preferred their own odor and the odor of males to the odor of other females. The data support female exclusiveness during the breeding season. During the nonbreeding season, paired encounters between females contained fewer agonistic acts than did encounters between males or those between males and females. Nonbreeding females preferred the odor of female conspecifics to their own odor or the odor of male conspecifics. These results are consistent with group nesting and a relaxation of female territoriality during the nonbreeding season. Nonbreeding males did not exhibit a preference for their own odor, the odor of other males, or the odor of female conspecifics. Our results indicate that nonbreeding males are solitary, and overwintering groups are female-biased. Odor preferences may underlie seasonal changes in social organization.


Copeia ◽  
1976 ◽  
Vol 1976 (3) ◽  
pp. 467 ◽  
Author(s):  
Judy A. Stamps ◽  
David P. Crews

1969 ◽  
Vol 47 (4) ◽  
pp. 547-555 ◽  
Author(s):  
L. A. Didow ◽  
J. S. Hayward

Wild meadow voles were collected each month of the year and analyzed for the mass and composition of their brown adipose tissue. The relative mass of brown adipose tissue decreased with increasing body weight in both summer and winter.Seasonal changes in the relative mass of brown adipose tissue were inversely related to seasonal changes in ambient temperature. In mature voles, the relative mass of brown adipose tissue was lowest during summer (0.5%) and increased rapidly to a level of 1.7% in early winter. Similarly, immature voles had their lowest relative mass in summer (1.0%) and increased this to 2.3% in winter. Both groups showed some decrease in the winter amount of the tissue when the subnivean environment became established. The percentage composition of brown adipose tissue with respect to water, lipid, and protein did not change significantly through the year.The results provide corroboration for laboratory studies which show that the mass and composition of brown adipose tissue are related to the requirement for cold thermogenesis. In voles, this requirement was present throughout the year and varied only in degree.


2021 ◽  
Vol 8 (4) ◽  
pp. 538-557
Author(s):  
Laura M. Bernstein-Kurtycz ◽  
Diana C. Koester ◽  
Rebecca J. Snyder ◽  
Jennifer Vonk ◽  
Mark A. Willis ◽  
...  

In natural environments, bear behavior follows seasonal patterns but the zoo environment differs from the natural environment in several ways, including the presence of zoo visitors. Although typically difficult to disentangle, we were able to tease apart the effects of seasonal changes and visitor density on the visibility and behavior of 10 bears representing five species housed at Cleveland Metroparks Zoo due to the disruption caused by COVID-19. We conducted a longitudinal bear behavior monitoring project from June, 2017-November, 2020. Bears were more visible in the spring and in the presence of visitors, locomoted more and were less inactive when large crowds were present, foraged and locomoted more when it was earlier in the day, and locomoted more at higher temperatures. There were limited differences in bear visibility to observers between 2020 (when the zoo was temporarily closed to visitors) and the previous three years. There were no differences in rates of stereotypy or social behavior across seasons, crowds, or daily attendance categories. Based on these limited differences, neither season nor visitor density seemed to have an apparent effect on bear behavior or welfare.


1995 ◽  
Vol 73 (2) ◽  
pp. 243-252 ◽  
Author(s):  
Terry L. Derting ◽  
Edward B. Noakes III

Changes in gut capacity may be important for a species adapting to increased energy requirements or decreased food quality in a seasonal environment. We conducted a comparative study of seasonal changes in gut capacity in two rodent species with diets of different types. Although the lengths and masses of gut organs differed between species within a season, the species did not differ in the types of gut changes that occurred from summer to winter. All organs except the colon had significantly heavier wet and dry masses in winter than in summer. No significant differences in organ lengths, volumes, or surface areas occurred with season. Increased mass of the small intestine was due to large increases in the mass of the mucosa and smaller increases in the mass of the serosa. In winter, Microtus pennsylvanicus had significantly lower body mass than in summer. Peromyscus leucopus had no change in body mass in winter but may have used torpor as an energy-conservation mechanism. Energy-conservation adaptations in each species may have minimized the need for large changes in the gut organs.


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