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For various reasons, reduction or cessation of feeding (anorexia) can occur in either sex during periods of reproduction among vertebrates, from cichlids to elephant seals. Anorexia is commonly associated with gestation in snakes. Using radiotelemetry, we investigated the feeding and spatial ecology of a live-bearing viperid snake, the western diamond-backed rattlesnakes ( Crotalus atrox). Specifically, from 2001 to 2010, we determined the feeding frequency and home range size of adult females ( n = 27) during the active season ( March- October) in a population from the Sonoran Desert of Arizona. We addressed a central hypothesis: Do hunting and feeding occur throughout pregnancy? Also, we tested a corollary hypothesis: Does pregnancy influence home range size? We documented hunting and feeding from March to October and during pregnancy ( June to mid- September). Feeding frequency was significantly greater in late pregnancy, a result that is in sharp contrast to most other large-bodied vipers. Furthermore, home range sizes in gestating subjects did not differ from those in nonreproductive years. Births occurred from mid- August to mid- September and mean litter size was 3.4. Frequent feeding in C. atrox during gestation unquestionably provides energy and nutrients to the mother, which is likely important for survival, but such food consumption does not imply that nutrients are used by the fetuses. There is, however, recent evidence in other snakes, including a pitviper, that amino acids are transferred to fetuses. Feeding during pregnancy in C. atrox may be important for both income and capital mode reproduction. Hunting and feeding throughout gestation might be accomplished by having relatively small litters not burdened by a body cavity filled with fetuses. Reduction in litter size may thus be a life-history (fecundity) trade-off that permits females to survive and maintain pregnancy in regions where drought and high temperatures are often extreme and chronic. [ABSTRACT FROM AUTHOR]

During the mating seasons (late summer and spring), male copperheads (Agkistrodon contortrix; Serpentes, Viperidae) engage in aggressive physical interactions for priority of access to females. These fights generally involve two individuals and are characterized by prominent vertical displays, a high degree of physical contact, and the absence of biting. Ritualized aggression does not occur in females. Although intrasexual aggression in conspecifics has obvious energetic costs (e.g., lactate accumulation) that can affect subsequent behavior, few studies have addressed these costs in reptiles, and no studies have examined snakes. Moreover, recent studies suggest psychoneuroendocrine (catecholamines, glucocorticoids) regulation of metabolism during and following aggressive episodes. There were three main questions addressed in this study. Do winners and losers of staged, pair-wise encounters show differences in post-fight (60-min) levels of plasma lactate and corticosterone (CORT)? Are levels of plasma lactate correlated with levels of plasma CORT? Is fight duration correlated with levels of plasma lactate and CORT? Two different control groups (cage and arena) were used. Body length, body mass, duration of fighting, and season of testing were not correlated with levels of plasma lactate and CORT. At 60-min post-fight, losers had significantly higher levels of mean plasma lactate and CORT when compared to levels in winners and controls, and there were no significant differences between winners and controls. From our results, we suggest the following conclusions. First, elevated levels of CORT in losers, but not winners, result from psychoneuroendocrine factors rather than simple exercise. Second, elevated levels of CORT in losers retard metabolic recovery resulting in higher lactate levels in losers, whereas winners return to pre-fight levels within 60-min post-fight. Last, the CORT response has a net negative effect on metabolic recovery and may be implicated in the protracted suppression of aggressive behavior in losers.

An unusual and attractive pigmentation pattern mutation termed "salmon" has been identified in the United States in several captive colonies of the common neotropical boine snake boa constrictor [Boa constrictor (Boidae)]. Boa constrictors expressing the Sa pigmentation pattern appear to be restricted to regions of Panama. Animals with the Sa phenotype exhibit a sharp decrease in melanophore pigments (e.g., melanin) and an increase of xanthophore pigments (e.g., pteridines and carotenoids) throughout the body, including ventral and caudal regions. Moreover, the dorsal saddles (blotches) and lateral diamond patterns are greatly reduced and/or absent. Our study was initiated using a female B. constrictor born in captivity and expressed the Sa pigmentation pattern. Results from breeding experiments indicated an inheritance mode of autosomal incomplete dominance for the Sa and Wt alleles.

Reproductive cycles of the majority of squamate reptiles remain undescribed. Few studies are available on seasonal patterns of circulating steroid hormones in snakes. The goal of this study was to document the annual cycle of plasma testosterone (T) in male copperheads Agkistrodon contortrix, a North American pitviper (Serpentes, Viperidae). Two experimental conditions were used in this laboratory study. One condition (repeat-test group) consisted of 10 adult males that were sampled once each month for 11 months. The other condition (single-test groups) consisted of 10 groups each with 5 males (N = 50), and each male was tested a single time. The single-test condition was used to evaluate whether or not repeated handling and sampling affected T levels. The study was conducted from February-December, 1992. A well-defined seasonal pattern of plasma T levels was detected; patterns were similar under both experimental conditions with the exception that the repeat-test group had slightly lower levels. Levels of T were lowest (baseline) in April-May, increased in early summer (June), and were highest in late summer (August). Thereafter, T levels declined up to the time of hibernation (early November) and changed little during hibernation (November-January). Upon emergence from hibernation in late winter (February), T levels increased sharply from February to March and then decreased from March to April. The results are discussed in the context of timing of spermatogenesis, mating, and male agonistic behavior.

Fighting behavior between male copperheads (Agkistrodon contortrix) occurs during the two mating periods (late summer/fall and spring) to gain priority of access to females. Fights are characterized by prominent vertical challenge displays, swaying, and a high degree of physical contact that does not involve biting. At the moment of subordination, losers retreat quickly from fights and winners respond by chasing. Subsequently, losers do not participate in further challenge displays or fighting for at least 7 days, and also they show behavioral signs of stress, which includes submissive acts and suppression of sexual behavior. The goal of this study was to determine whether or not losers show elevated levels of plasma corticosterone (B) and depressed levels of plasma testosterone (T) relative to winners and controls. Winners and losers were produced in 13 staged trials. Two different controls (N = 26) were run. Males with no recent agonistic experience were (1) tested in the fighting arena in the absence of a competitive male but paired with a single female (N = 13), and (2) tested alone in their cages (N = 13). All trials, including controls, were conducted in spring and late summer. Mean B in losers at 1-hr postfight was significantly greater than in winners and both control groups in both seasons. Mean T was significantly greater in late summer in all groups, as expected, but in each season was not significantly different between the groups. Levels of B and T were not correlated with SVL, mass, or duration of fighting. This study provides further support for the social insensitivity/challenge hypotheses and is the first to document postfight B and T levels in snakes.