Wildlife Damage Management, Internet Center for


Date of this Version

March 1981


Published in Proceedings of the Fifth Eastern Pine and Meadow Vole Symposium, Gettysburg, PA, March 4–5, 1981, Ross E. Byers, editor. Copyright © 1981 Derting and Cranford.


Photo-period and nutrition are important variables affecting reproductive activity and growth in many rodents. Field and laboratory studies indicate that long photo-period (spring-summer) cause Increased growth while short photo-periods (fall-winter) inhibit these processes. In the montane vole (Microtus montanus) recently weaned animals gain weight at a much lower rate under short photo-periods or in total darkness than under long photo-periods (Vaughan et al., 1973; Peterborg, 1978). Adult M. montanus had more offspring and larger mean litter sizes under LD 18:6 than LD 6:18 (Pinter & Negus, 1965). Similarly, long (LD 16:8) or increasing photo-periods stimulated the onset of puberty in M. arvalis, while short (LD7:17) or decreasing photo-periods inhibited the onset of puberty (Lecyk, 1962). Short photo-periods caused reduced spennato-genesis and seminal vesicle weights in male M. arvalis, while long photo-periods induced increased ovulation in females. In contrast, photo-period had no effect on the reproductive rates of M. orchadensis (Marshall & Wilkinson, 1956). Dicrostonyx groenlandicus reared on LD 6:18 grew faster than those on LD 20:4, but the latter group had larger testes (Hasler, 1975). In M. agrestis, long photo-periods stimulated male reproduction and caused greater body weight gain than did short photo-period. Females produced fewer young, had lower ovarian and uterine weights, and fewer, smaller Graafian follicles under short photo-periods as compared to long. However, there was no effect on female body size (dark & Kennedy, 1967; Breed & Clarke, 1970; Baker and Ranson, 1932). Microtus pennsylvanicus juveniles and adults had higher body weights under LD 18:6 than LD 6:18 (Pistole, 1980). M. oregoni reproductive activity is stimulated by long photo-period, but due to fossorial habits this species appears to be less sensitive to light than more terrestrial forms (Cowan & Arsenault, 1958). There have been no reports of winter breeding in Clethrionomys gapperi possibly because of their behavioral avoidance of light during the winter (Evemden & Fuller, 1972).