Title

Ontogenetic Variation in the Thermal Biology of Northern Pacific Rattlesnakes

Presenter Information

Caleb Loughran

Document Type

Oral Presentation

Location

SURC 137B

Start Date

16-5-2013

End Date

16-5-2013

Abstract

The strong size discrepancy between adults and neonates within many species of ectotherms results in drastically different rates of heating and cooling. For squamate reptiles, this may have important consequences for how individuals regulate their body temperature in nature. We hypothesized that since neonate snakes can heat and cool faster than adult snakes they would have more variation in body temperatures and may therefore show different thermal preferences than adult snakes. To test this hypothesis, we investigated thermal preferences of neonate and adult Northern Pacific Rattlesnakes in a laboratory thermal gradient at temperatures ranging from 10°C to 35°C. Hide boxes were placed (at intervals of 5°C) throughout the gradient to offer snakes refugia at a range of temperatures. Snake body temperatures were recorded throughout the day using an infrared thermometer and behaviors associated with recorded body temperatures were also recorded. Neonate snakes had a broader range of body temperatures than did adults and were also active more often than adult snakes, using a wider range of locations throughout the gradient. These differences suggest that the thermal biology of neonate rattlesnakes differs from that of adults, which appears to translate into differences in behavior and microhabitat use. The ecological implications for these differences are important for each age class, as they may result in differences in activity patters, movements, and habitat use. Field studies to corroborate these findings are currently underway.

Faculty Mentor(s)

Dan Beck

Additional Mentoring Department

Biological Sciences

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Ontogenetic Variation in the Thermal Biology of Northern Pacific Rattlesnakes

SURC 137B

The strong size discrepancy between adults and neonates within many species of ectotherms results in drastically different rates of heating and cooling. For squamate reptiles, this may have important consequences for how individuals regulate their body temperature in nature. We hypothesized that since neonate snakes can heat and cool faster than adult snakes they would have more variation in body temperatures and may therefore show different thermal preferences than adult snakes. To test this hypothesis, we investigated thermal preferences of neonate and adult Northern Pacific Rattlesnakes in a laboratory thermal gradient at temperatures ranging from 10°C to 35°C. Hide boxes were placed (at intervals of 5°C) throughout the gradient to offer snakes refugia at a range of temperatures. Snake body temperatures were recorded throughout the day using an infrared thermometer and behaviors associated with recorded body temperatures were also recorded. Neonate snakes had a broader range of body temperatures than did adults and were also active more often than adult snakes, using a wider range of locations throughout the gradient. These differences suggest that the thermal biology of neonate rattlesnakes differs from that of adults, which appears to translate into differences in behavior and microhabitat use. The ecological implications for these differences are important for each age class, as they may result in differences in activity patters, movements, and habitat use. Field studies to corroborate these findings are currently underway.