Dryness increases predation risk in efts: support for an amphibian decline hypothesis

Area of Science:

• Ecology
• Climate Change Biology
• Behavioral Ecology

Background:

• Amphibian populations are declining globally.
• Climate change is increasing environmental dryness.
• The impact of dehydration on amphibian anti-predator behavior is poorly understood.

Purpose of the Study:

• To investigate the behavioral responses of eastern red-spotted newt efts to desiccation and predation risks, both separately and in combination.
• To determine if environmental moisture influences responses to conspecific chemical cues and alarm substances.

Main Methods:

• Field observations and laboratory experiments were conducted.
• The study focused on the terrestrial juvenile stage (efts) of the eastern red-spotted newt (Notophthalmus viridescens).
• Efts were exposed to conditions simulating desiccation risk, predation risk (using chemical cues), and combined risks.

Main Results:

• When facing desiccation alone, efts exhibited water-conserving behaviors like moving to shade, descending slopes, reducing activity, and huddling.
• Efts were attracted to chemical cues from other efts but not adults, and reduced water loss by huddling.
• Under combined risks, efts reduced activity more than with single risks and avoided adult cues but not eft cues, suggesting complex chemical signaling.

Conclusions:

• Eastern red-spotted newt efts possess behaviors to mitigate dehydration, crucial for survival in drying environments.
• Dehydration stress can alter anti-predator responses, potentially making efts more vulnerable.
• Environmental moisture levels are critical factors influencing how amphibians respond to chemical cues and predation threats, impacting population dynamics.