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.

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.

Effects of reproduction on survival and growth of female northern water snakes, Nerodia sipedon

1997 ◽  
Vol 75 (3) ◽  
pp. 424-432 ◽  
Author(s):  
Gregory P. Brown ◽  
Patrick J. Weatherhead
Keyword(s):  
Life History Theory ◽  
Mass Gain ◽  
Nerodia Sipedon ◽  
In The Wild ◽  
Future Reproduction ◽  
Northern Water Snakes ◽  
Survival And Growth ◽  
Reproductive Females ◽  
The Cost ◽  
Water Snakes

The cornerstone of life-history theory is the expectation that current reproduction will have a detrimental effect on survival and (or) future reproduction. When fecundity increases with body size, the cost to future reproduction arises through decreased growth of reproductive individuals. We investigated the effects of reproduction on aspects of survival and growth in female northern water snakes (Nerodia sipedon). We did not find a decrease in survival associated with mating despite the conspicuousness of mating aggregations, and pregnancy did not impair locomotor ability. We found evidence of a decrease in over-winter survival of reproductive females related to their emaciated state following parturition. Reproductive females grew less in length than nonreproductive females, but increased similarly in mass. Following parturition, reproductive females weighed less than in the spring, indicating that mass gain prior to parturition was invested in the litter and that most foraging occurred prior to ovulation. Captive reproductive females given food ad libitum grew in length at a rate similar to free-living reproductive females, but increased more in mass. Captive females weighed more after giving birth than in the spring, indicating that unlike that of females in the wild, some of their mass increase was due to energy storage, and also that they continued to feed after ovulation. Consistent with the prediction that smaller females would benefit more than larger females from reproducing less and growing more to increase future fecundity, we found that smaller females participated less in mating aggregations and reproduced less often.

scholarly journals Relations between morphology, buoyancy and energetics of requiem sharks

2016 ◽  
Vol 3 (10) ◽  
pp. 160406 ◽  
Author(s):  
Gil Iosilevskii ◽  
Yannis P. Papastamatiou
Keyword(s):  
Body Temperature ◽  
Negative Selection ◽  
Swimming Performance ◽  
Ontogenetic Changes ◽  
Cost Of Transport ◽  
Pectoral Fins ◽  
Confined Spaces ◽  
Reef Sharks ◽  
The Cost ◽  
Derivatives Of

Sharks have a distinctive shape that remained practically unchanged through hundreds of millions of years of evolution. Nonetheless, there are variations of this shape that vary between and within species. We attempt to explain these variations by examining the partial derivatives of the cost of transport of a generic shark with respect to buoyancy, span and chord of its pectoral fins, length, girth and body temperature. Our analysis predicts an intricate relation between these parameters, suggesting that ectothermic species residing in cooler temperatures must either have longer pectoral fins and/or be more buoyant in order to maintain swimming performance. It also suggests that, in general, the buoyancy must increase with size, and therefore, there must be ontogenetic changes within a species, with individuals getting more buoyant as they grow. Pelagic species seem to have near optimally sized fins (which minimize the cost of transport), but the majority of reef sharks could have reduced the cost of transport by increasing the size of their fins. The fact that they do not implies negative selection, probably owing to decreased manoeuvrability in confined spaces (e.g. foraging on a reef).

Demography and sexual size dimorphism in northern water snakes, Nerodia sipedon

1999 ◽  
Vol 77 (9) ◽  
pp. 1358-1366 ◽  
Author(s):  
Gregory P Brown ◽  
Patrick J Weatherhead
Keyword(s):  
Sexual Maturity ◽  
Sexual Size Dimorphism ◽  
Survival Rates ◽  
Seasonal Patterns ◽  
Nerodia Sipedon ◽  
Size Dimorphism ◽  
Mortality Cost ◽  
Northern Water Snakes ◽  
Water Snakes ◽  
Better Than

We used data from a 9-year mark-recapture study to determine whether demographic factors could explain female-biased sexual size dimorphism in northern water snakes (Nerodia sipedon). Most males reached sexual maturity at 3 years of age, while most females delayed maturity for an additional year. Female survivorship was not significantly lower than that of males, despite the fact that females grow as much as four times faster than males. Among females, survivorship increased until maturity and decreased thereafter, suggesting a survival cost to reproduction. Life-table calculations indicated that the increase in both survival rates and fecundity with body size made 3 years the optimal age for females to reach sexual maturity. However, if females were not large enough at 3 years of age, their best strategy was to mature the following year. Seasonal patterns of mortality suggest that mating imposes a high mortality cost on males. Intermediate-sized males survived slightly but not significantly better than small and large males. This slight survival advantage of intermediate-sized males was not sufficient to explain why males are so much smaller than females. Therefore other selective factors must be responsible for males retaining a small size. A reproductive advantage associated with small size seems the most likely possibility.

scholarly journals The rising cost of warming waters: effects of temperature on the cost of swimming in fishes

2011 ◽  
Vol 8 (2) ◽  
pp. 266-269 ◽  
Author(s):  
Andrew M. Hein ◽  
Katrina J. Keirsted
Keyword(s):  
Water Temperature ◽  
Fish Species ◽  
Global Climate ◽  
Swimming Performance ◽  
Metabolic Cost ◽  
Quantitative Model ◽  
The Body ◽  
Energetic Cost ◽  
Cost Of Transport ◽  
The Cost

Understanding the effects of water temperature on the swimming performance of fishes is central in understanding how fish species will respond to global climate change. Metabolic cost of transport (COT)—a measure of the energy required to swim a given distance—is a key performance parameter linked to many aspects of fish life history. We develop a quantitative model to predict the effect of water temperature on COT. The model facilitates comparisons among species that differ in body size by incorporating the body mass-dependence of COT. Data from 22 fish species support the temperature and mass dependencies of COT predicted by our model, and demonstrate that modest differences in water temperature can result in substantial differences in the energetic cost of swimming.

Body temperature fluctuations in free-ranging eastern foxsnakes (Elaphe gloydi) during cold-water swimming

2006 ◽  
Vol 84 (1) ◽  
pp. 9-19 ◽  
Author(s):  
Carrie A MacKinnon ◽  
Anna Lawson ◽  
E D Stevens ◽  
Ronald J Brooks
Keyword(s):  
Body Temperature ◽  
Water Temperature ◽  
Swimming Speed ◽  
Cold Water ◽  
Temperature Fluctuations ◽  
Temperature Sensitive ◽  
Clear Trend ◽  
Thermal Biology ◽  
Rapid Temperature ◽  
Free Ranging

We examined the thermal biology of free-ranging terrestrial eastern foxsnakes (Elaphe gloydi Conant, 1940) that were voluntarily swimming in cold water during spring, in Georgian Bay, Ontario, Canada. Using temperature-sensitive radiotelemetry, we recorded body temperatures of foxsnakes during 12 cold-water swims, and subsequent warming on shore. During these swims, water temperatures were from 11 to 22 °C and distances of 85–1330 m were travelled. Snakes that were in cold water long enough equilibrated with water temperature and did not maintain a body temperature above ambient. The largest observed drop in body temperature was 22.6 °C (over 11 min) and the largest increase was 23 °C (over 66 min). Such large, rapid temperature fluctuations have not previously been reported in detail from snakes in the field. Twice as many telemetry observations as expected occurred between 1200 and 1400, suggesting that snakes chose to swim midday. Additionally, our results suggest that foxsnakes bask to raise their body temperature prior to swimming in cold water. We compared swimming speed and the coefficient of temperature change among foxsnakes and other snake species. Swimming speed was positively correlated with water temperature, similar to other findings. We found no clear trend between mass and the coefficients of cooling and warming; however, snakes cooled in water 2.8–8.6 times faster than they warmed in air.

Locomotion and antipredator behaviour in three species of semi-aquatic snakes

1995 ◽  
Vol 73 (2) ◽  
pp. 321-329 ◽  
Author(s):  
Stephen J. Scribner ◽  
Patrick J. Weatherhead
Keyword(s):  
Cold Water ◽  
Swimming Performance ◽  
The Body ◽  
Effect Of Temperature ◽  
Antipredator Behaviour ◽  
Thamnophis Sirtalis ◽  
Potential Cost ◽  
Water Snake ◽  
Defensive Behaviours ◽  
Water Snakes

For temperate-zone ectotherms, a potential cost of an aquatic lifestyle may be impaired locomotor performance, due to rapid cooling of the body when in cold water. Contrary to the hypothesis that more-aquatic species should be better adapted for locomotion at low temperatures, the decline in swimming performance with temperature was similar for three species of snakes (the northern water snake (Nerodia sipedon), eastern ribbon snake (Thamnophis sauritus) and common garter snake (Thamnophis sirtalis)) that varied in their association with aquatic habitats. The effect of temperature on antipredator behaviour was also similar for the three species; at lower body temperatures, snakes relied more on alternative defensive behaviours. However, antipredator behaviour was used less by water snakes than by garter and ribbon snakes. Except for the smallest individuals, all snakes crawled more slowly than they swam, and the difference in performance was greatest for the largest snakes. When crawling, all three species relied more on alternative defensive behaviours than when swimming. In the field, water snakes fled at greater distances from human "predators" than did garter and ribbon snakes, which tended to rely on crypsis. The greater dependence on flight as the primary antipredator behaviour by water snakes, and on other tactics such as crypsis by garter and ribbon snakes, does not conform to the generalization that a species' antipredator behaviour is related to its characteristic dorsal pigmentation pattern. Species differences in antipredator behaviour appear to be more strongly related to habitat use.

Growth and Sexual Size Dimorphism in Northern Water Snakes (Nerodia sipedon)

Copeia ◽  
1999 ◽  
Vol 1999 (3) ◽  
pp. 723 ◽  
Author(s):  
Gregory P. Brown ◽  
Patrick J. Weatherhead
Keyword(s):  
Sexual Size Dimorphism ◽  
Nerodia Sipedon ◽  
Size Dimorphism ◽  
Northern Water Snakes ◽  
Water Snakes
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