Observation resolution critically influences movement-based foraging indices

Area of Science:

• Ethology
• Behavioral Ecology
• Zoology

Background:

• Movement-based indices, including moves per minute (MPM) and proportion time moving (PTM), are widely used to quantify animal foraging behavior.
• Previous studies often lack clear reporting of data temporal resolution, leading to potential inconsistencies in MPM and PTM estimates.
• The impact of varying observation temporal resolution on these crucial behavioral metrics remains largely unquantified.

Purpose of the Study:

• To empirically assess the sensitivity of foraging indices (MPM and PTM) to alterations in data temporal resolution.
• To compare foraging index estimates across a range of temporal resolutions relevant to both high-resolution recording and unassisted field observation.

Main Methods:

• High-speed video recording of movement sequences in 20 Acanthodactylus boskianus lizards.
• Progressive reduction of data temporal resolution from high-speed recordings.
• Calculation and comparison of MPM and PTM at each distinct temporal resolution.

Main Results:

• Significant discrepancies in MPM (68% difference) and PTM (48% difference) were observed when data resolution was reduced to levels relevant for unassisted field vision.
• MPM estimates at the highest temporal resolution were an order of magnitude greater than previously reported values for lizards.
• These findings highlight substantial variability in foraging index quantification based on observation resolution.

Conclusions:

• The temporal resolution of data collection critically influences the accuracy and comparability of MPM and PTM foraging indices.
• Existing published foraging data, particularly for lizards, may be subject to significant over or underestimation due to unstated or varied temporal resolutions.
• Recommendations are provided for standardized data collection protocols to ensure the reliability and reproducibility of future movement-based foraging studies.