Dynamic changes in body form during swimming in the water snake Nerodia sipedon

Zoology ◽  
2008 ◽  
Vol 111 (1) ◽  
pp. 48-61 ◽  
Author(s):  
Abigail Pattishall ◽  
David Cundall
Keyword(s):  
Nerodia Sipedon ◽  
Dynamic Changes ◽  
Body Form ◽  
Water Snake

The role of temperature in microhabitat selection by northern water snakes (Nerodia sipedon)

1992 ◽  
Vol 70 (3) ◽  
pp. 417-422 ◽  
Author(s):  
Ian C. Robertson ◽  
Patrick J. Weatherhead
Keyword(s):  
Experimental Manipulation ◽  
Time Of Day ◽  
Microhabitat Selection ◽  
Nerodia Sipedon ◽  
Leopard Frogs ◽  
Water Snake ◽  
Northern Water Snakes ◽  
Water Snakes ◽  
Circadian Patterns

Using field observations and laboratory experiments we examined the role of temperature in microhabitat selection by an eastern Ontario population of northern water snakes (Nerodia sipedon). From 1349 random transects through a marsh we found that basking activity peaked at 09:00 and then declined steadily until 14:00 before increasing again. Our ability to detect snakes depended upon the microhabitat they occupied, and to the time of day when the snakes were encountered in water. In the field, temperatures of basking snakes averaged (±SE) 26.3 ± 0.7 °C (n = 36), while captive snakes in a thermal gradient showed a narrower selectivity, averaging 27.7 ± 0.4 °C (n = 21). The temperatures of basking snakes never exceeded 33 °C, even though a model snake placed in the sun reached 48 °C, suggesting that the snakes were thermoregulating to prevent overheating. In both the field and enclosures, water snakes basked more frequently as the temperature of the air increased relative to the water. Experimental manipulation of water temperature relative to air temperature revealed that temperature influenced microhabitat selection independently of circadian patterns. Finally, when in water, snakes tended to frequent habitats where leopard frogs (Rana pipiens), a common prey species, were most abundant, suggesting that prey distribution may also be an important component of water snake habitat selection.

Variation in offspring sex ratios in the northern water snake (Nerodia sipedon)

1998 ◽  
Vol 76 (12) ◽  
pp. 2200-2206 ◽  
Author(s):  
Patrick J Weatherhead ◽  
Gregory P Brown ◽  
Melanie R Prosser ◽  
Kelley J Kissner
Keyword(s):  
Sex Ratio ◽  
Sex Ratios ◽  
Birth Date ◽  
Nerodia Sipedon ◽  
Water Snake ◽  
In Captivity ◽  
Northern Water Snake ◽  
Northern Water Snakes ◽  
Gravid Females ◽  
Water Snakes

We used data from 88 litters of northern water snakes (Nerodia sipedon) to test predictions about how mothers would adaptively vary the sex ratios of their offspring. Larger mothers produced significantly more daughters (r2 = 0.04, P = 0.05), and mothers producing larger offspring produced significantly more daughters (r2 = 0.06, P = 0.02). Because neonate size did not vary with maternal size, these sex-ratio patterns were independent of each other. These patterns were more pronounced for wild females than for females maintained in captivity while gravid, but rearing conditions did not have a significant effect on sex ratio. Also, because sex ratios were similar between captive and free-living females despite captive females giving birth 16 days earlier, on average, and because sex ratios did not vary with birth date within the two groups of females, gestation appeared not to affect sex ratio. If females vary sex ratios adaptively, only the relationship between sex ratio and neonate size was consistent with our predictions. Limited evidence from other snake species also indicates variation in neonatal sex ratios that is nonrandom but not necessarily adaptive. A better understanding of these patterns will require information on the factors that affect the fitness of male and female neonates differently. An unexpected sex-ratio pattern that we found was that 14 of 19 stillborn young were male. We speculate that this pattern could be a result of male embryonic sensitivity to temperature. Thus, the need for gravid females to maintain a high body temperature so that their young are born with enough time to find hibernation sites may conflict with the need for embryos to develop at a safe temperature.

Sex ratios, mating behavior and sexual size dimorphism of the northern water snake, Nerodia sipedon

1995 ◽  
Vol 36 (5) ◽  
pp. 301-311 ◽  
Author(s):  
Patrick J. Weatherhead ◽  
Frances E. Barry ◽  
Gregory P. Brown ◽  
Mark R. L. Forbes
Keyword(s):  
Mating Behavior ◽  
Sexual Size Dimorphism ◽  
Sex Ratios ◽  
Nerodia Sipedon ◽  
Size Dimorphism ◽  
Water Snake ◽  
Northern Water Snake

The role of the midland water snake, Nerodia sipedon (Serpentes: Colubridae), as a predator: foraging behavior, kin recognition, and the response of prey

2002 ◽  
Vol 23 (3) ◽  
pp. 333-342 ◽  
Author(s):  
John Himes
Keyword(s):  
Kin Recognition ◽  
Activity Patterns ◽  
Prey Type ◽  
Size Class ◽  
Prey Fish ◽  
Nerodia Sipedon ◽  
Foraging Mode ◽  
Water Snake ◽  
Predator Foraging

AbstractThe midland water snake, Nerodia sipedon, is very abundant in portions of the southeastern U.S.A., where it may play an important role as a predator in freshwater communities. I examined whether foraging mode in naïve neonatal snakes was phenotypically plastic or canalized and I compared handling times and capture efficiencies for different prey types (juvenile fishes and frogs) between neonatal and adult snakes. I also tested for kin recognition by mother snakes by comparing their consumption of unrelated (non-kin) and related (kin) neonates according to time and the availability of alternative prey (fish). In addition, the response of prey in the presence and in the absence of snakes was tested by comparing the amount of time that juvenile fishes utilized areas containing different microhabitat complexities and by comparing the amount of time that fishes were actively moving. Overall, foraging mode was phenotypically plastic, handling times and capture efficiencies differed by prey type and snake size class, kin recognition was confirmed, and fishes did not alter their habitat selection or activity patterns in the presence of snakes.

Sex ratios, mating behavior and sexual size dimorphism of the northern water snake, Nerodia sipedon

1995 ◽  
Vol 36 (5) ◽  
pp. 301-311 ◽  
Author(s):  
P. J. Weatherhead ◽  
Frances E. Barry ◽  
Gregory P. Brown ◽  
M. R. L. Forbes
Keyword(s):  
Mating Behavior ◽  
Sexual Size Dimorphism ◽  
Sex Ratios ◽  
Nerodia Sipedon ◽  
Size Dimorphism ◽  
Water Snake ◽  
Northern Water Snake

Thermal constraints on swimming performance and escape response of northern water snakes (Nerodia sipedon)

1992 ◽  
Vol 70 (1) ◽  
pp. 94-98 ◽  
Author(s):  
Patrick J. Weatherhead ◽  
Ian C. Robertson
Keyword(s):  
Body Temperature ◽  
Water Temperature ◽  
Swimming Speed ◽  
Escape Response ◽  
Swimming Performance ◽  
Nerodia Sipedon ◽  
Water Snake ◽  
Northern Water Snakes ◽  
The Cost ◽  
Water Snakes

We examined the influence of body temperature on swimming speed of northern water snakes (Nerodia sipedon) and determined how variation in water temperature influenced their escape response. In a laboratory experiment, swimming speed increased as a function of water temperature and body size. Swimming speed was less thermally dependent at temperatures approximating the snakes' normal range of activity, suggesting that selection has favoured increased performance breadth at this range. In the field, basking snakes retreated to water when approached. Despite a decrease in swimming speed at lower temperatures, and the cost associated with reduced metabolic rate due to loss of body temperature, however, flight distances were independent of water temperature. We found that basking snakes retreated to water sooner when perched at lower heights, possibly indicating that N. sipedon are more vulnerable to predators when on low perches. Predicting water snake escape behaviour may require not only knowledge of variation both among snakes and in their environment, but also a better understanding of the interaction between the snakes and their natural predators.

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