Gluttonous predators: how to estimate prey size when there are too many prey

Area of Science:

• Ecology
• Zoology
• Herpetology

Background:

• Prey size significantly influences food consumption and feeding ecology studies.
• Accurate measurement of individual prey items is standard but challenging for predators consuming numerous small prey (e.g., ants, termites).
• Amphibians and reptiles often feed on a high volume of small invertebrates, complicating prey size estimation.

Purpose of the Study:

• To develop and validate a reliable procedure for subsampling stomach contents to estimate prey size in predators consuming large numbers of small prey.
• To create a protocol that minimizes sampling effort while ensuring precise prey size estimations.
• To facilitate future research on the feeding habits of amphibians and reptiles.

Main Methods:

• Developed a novel protocol utilizing a bootstrap procedure for subsampling stomach contents.
• The method aims to achieve a maximum precision error of 5% with a minimum 95% confidence level.
• Evaluated the procedure's efficacy for estimating prey size in relevant predator groups.

Main Results:

• The bootstrap subsampling procedure provides a statistically sound method for estimating prey size.
• The protocol achieves high precision (≤5% error) and confidence (≥95%) in prey size estimation.
• Demonstrated the practical applicability of the method for analyzing stomach contents.

Conclusions:

• The developed subsampling guideline effectively addresses the challenge of estimating prey size in predators with high-volume, small-prey diets.
• This method reduces sampling effort and enhances the accuracy of feeding habit studies in amphibians and reptiles.
• The protocol offers a valuable tool for precise prey size estimation in ecological research.