Factors affecting body temperatures of toads

Area of Science:

• Herpetology
• Ecology
• Physiology

Background:

• Ectothermic animals rely on environmental heat sources for thermoregulation.
• Understanding thermal variation is key to amphibian physiology and energetics.
• Bufo boreas subspecies inhabit montane and lowland environments with differing thermal challenges.

Purpose of the Study:

• Investigate factors influencing body temperature (Tb) variation in Bufo boreas boreas and Bufo boreas halophilus.
• Determine the role of natural thermal variation in the physiology and energetics of these toads.
• Analyze thermal selection behavior and its relation to environmental conditions.

Main Methods:

• Field observations of body temperature fluctuations over 24-hour periods.
• Laboratory experiments using thermal gradients to assess preferred body temperatures.
• Analysis of skin color variation and its impact on thermal radiation absorption.
• Measurement of evaporative water loss in relation to temperature and humidity.

Main Results:

• Bufo boreas exhibit substantial daily Tb variation (25-30°C), influenced by activity patterns and environment.
• Despite field variations, toads select a narrow preferred Tb range (averaging 23.5-26.2°C).
• Skin color affects thermal radiation absorption, with darker skins absorbing more heat.
• Evaporative water loss increases with skin temperature and vapor pressure deficit.

Conclusions:

• Boreal toads actively regulate their body temperature by selecting specific thermal environments.
• Skin properties and body size influence thermal dynamics and overheating risk.
• Amphibian thermoregulation is a complex interplay of behavior, physiology, and environmental factors.