Escalated begging does not compromise nestling health

Area of Science:

• Behavioral Ecology
• Animal Communication
• Physiological Ecology

Background:

• Offspring begging signals are thought to be reliable due to viability costs.
• Existing evidence for these trade-offs is inconclusive, often due to methodological limitations.

Purpose of the Study:

• To investigate condition-independent trade-offs between begging effort and physiological condition in spotless starlings.
• To address limitations of previous studies by using uniform stimulation and multiple physiological markers.

Main Methods:

• Experimentally manipulated begging effort in spotless starling nestlings.
• Maintained constant food intake across all experimental groups.
• Assessed 14 physiological markers, including immune function and oxidative stress.

Main Results:

• No significant effects of increased begging effort were found on any of the 14 physiological markers.
• Confidence intervals for effect sizes consistently included zero or one (for lysis capacity), indicating no biologically relevant impacts.
• Findings suggest no direct physiological trade-offs linked to intense begging behavior.

Conclusions:

• The widely accepted differential benefit model for begging signal reliability may not be supported by direct physiological costs.
• This study challenges the assumption of intrinsic, condition-independent trade-offs between begging and physiological condition.
• Future research should explore alternative mechanisms maintaining the honesty of offspring begging signals.