Body temperatures and movements of hibernating snakes (Crotalus and Thamnophis) and thermal gradients of natural hibernacula

Abstract

1989. Body temperatures and movements of hibernating snakes (Crotalus and Thamnophis) and thermal gradients of natural hibernacula. Can. J. Zool. 67: [108][109][110][111][112][113][114]. Although temperate zone snakes spend a large part of each year in hibernation, we know relatively little about their behavior during this part of the annual cycle. We used radiotelemetry to monitor temperatures and movements of hibernating rattlesnakes (Crotalus viridis) in southern British Columbia and garter snakes (Thamnophis sirtalis) in northern Alberta, and measured thermal profiles inside their hibernacula. A reference site near the garter snake hibernaculum, superficially resembling a winter den but not used by snakes, also was monitored. A thermal gradient (temperature increasing with depth) formed during the winter in the rattlesnake den, but only minimally so in the garter snake den. Differences in thermal profiles were attributed to differences in subsurface geomorphology. The reference site exhibited much greater temperature fluctuation than the den itself, with lethal temperatures prevailing throughout the winter. Therefore, suitable hibernation sites may be limited in some areas despite a superficial appearance of abundance. As ambient temperatures declined during early winter, snakes made lateral movements inside their hibernacula, and exhibited changes in body temperature which we interpreted as movements to warmer (deeper) microsites. Body temperatures recorded during winter ranged between 2 and 7°C. In early spring the thermal gradient collapsed and the rattlesnake den gradually underwent a uniform increase in temperature. A similar increase in subterranean temperatures occurred in the garter snake den. Temperature change was perhaps a stimulus for emergence in rattlesnakes, but possibly not in garter snakes. The hypothesis that hibernating snakes orient along a seasonally reversing thermal gradient is not unambiguously supported.MACARTNEY, J. M., LARSEN, K. W., et GREGORY, P. T. 1989. Body temperatures and movements of hibernating snakes (Crotalus and Thamnophis) and thermal gradients of natural hibernacula. Can. J. Zool. 67 : 108-114. Bien que les serpents de la zone tempkrke passent une grande partie de l'annke en hibernation, il exite peu d'informations sur leur comportement durant cette partie de leur cycle annuel. Nous avons utilisk des techniques de tklkmktrie pour mesurer la tempkrature et les dkplacements chez des serpents a sonnette (Crotalus viridis) du sud de la Colombie-Britannique et chez des Couleuvres raykes (Thamnophis sirtalis) du nord de 1'Alberta et nous avons ktabli leurs profils thermiques dans leur hibernaculum. Un site tkmoin non utilisk, voisin de l'hibernaculum des couleuvres et vaguement semblable, a kgalement etk soumis aux mesures. IJn gradient thermique (augmentation de la tempkrature en fonction de la profondeur) a kt6 observk durant l'hiver dans le terrier des serpents a sonnette, mais ce gradient ktait minimal dans le terrier des couleuvres. Les diffkrences entre les profils the...

Endocrine mechanisms mediating temperature-induced reproductive behavior in red-sided garter snakes (Thamnophis sirtalis parietalis)

“…Hawley and Aleksiuk, 1975;Hawley and Aleksiuk, 1976;Jacob and Painter, 1980;Crews and Garstka, 1982;Licht, 1984;Whittier et al, 1987a;Macartney et al, 1989;Grobman, 1990;Crawford, 1991). For example, Etheridge et al (Etheridge et al, 1983) demonstrated experimentally that increasing ambient temperatures stimulate emergence of the six-lined racerunner (Cnemidophorus sexlineatus) from winter dormancy.…”

“…However, some species (especially those inhabiting extreme northern latitudes) can occupy underground dens at depths where ground temperatures do not change significantly before spring emergence. Red-sided garter snakes (Thamnophis sirtalis parietalis) in Manitoba, Canada emerge at body temperatures as low as 0.5°C (Lutterschmidt et al, 2006), suggesting that increases in ground temperatures may not be the only thermal cue utilized by ectotherms (Macartney et al, 1989;Lutterschmidt et al, 2006). Indeed, emergence of red-sided garter snakes from hibernation may be regulated, at least in part, by an endogenous circannual cycle (Lutterschmidt et al, 2006).…”

Freezing survival of the garter snake Thamnophis sirtalis parietalis

“…Individuals from northern populations frequently migrate considerable distances between summer grounds and communal dens, where they hibernate in large numbers (Gregory 1982). Indeed, the availability of suitable den sites may be one factor that limits the distribution of garter snakes in northern regions (Gregory 1982;Macartney et al 1989). Presumably temperature, moisture content, and ventilation are criteria important in the choice of hibernation sites.…”

The natural history, ecology, and epidemiology of Ophidiomyces ophiodiicola and its potential impact on free-ranging snake populations

“…Our data suggest that snake populations that hibernate in the lower part of the thermal range of 0 Ce10 C (Macartney et al, 1989) should have less infection during the spring than snake populations that hibernate in the upper part of the thermal range of 0 Ce10 C. In addition, our data also suggest that with increasing global temperatures, snake populations will be more vulnerable to O. ophiodiicola infection in regions experiencing frequent mild winter conditions.…”