Chemical Signals of Conspecifics and Their Role in Seasonal Relationships in the Mongolian Hamster (Allocricetulus curtatus) (Cricetinae, Rodentia)

The hormonal response of Mongolian hamster Allocricetulus curtatus males to the urine and midventral gland secretion (MVGS)) of conspecific females during several seasons was studied. The animals were kept under natural photoperiod and temperature. In autumn no significant changes in the testosterone level in the blood of males in response to any of the exposed signals were observed. In winter and summer, this parameter increased in response to the diestrous female odors of urine and MVGS . In the spring the urine of conspecific estrous females stimulated a significant increase in the levels of both testosterone and cortisol. Moreover, the cortisol level did not increase in response to exposure of the odors of diestrous females in any season of the year. The level of progesterone significantly increased only when MVGS was exposed in the spring and summer periods, and the absolute values of this parameter were significantly higher in spring than in summer. Differences in responses to chemical signals in two closely related species (Eversmann's and Mongolian hamsters) are discussed in connection with the peculiarities of the intraspecific social relationships.