The effect of illumination and time of day on movements of bobcats (Lynx rufus).

Aimee P Rockhill,Christopher S Deperno,Roger A Powell,Michael Somers

doi:10.1371/journal.pone.0069213

Aimee P Rockhill, Christopher S Deperno + Show 2 more

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https://doi.org/10.1371/journal.pone.0069213

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Journal: PloS one	Publication Date: Jul 8, 2013
Citations: 61	License type: CC BY 4.0

Affiliation: North Carolina State University

Abstract

Understanding behavioral changes of prey and predators based on lunar illumination provides insight into important life history, behavioral ecology, and survival information. The objectives of this research were to determine if bobcat movement rates differed by period of day (dark, moon, crepuscular, day), lunar illumination (<10%, 10 - <50%, 50 - <90%, >90%), and moon phase (new, full). Bobcats had high movement rates during crepuscular and day periods and low movement rates during dark periods with highest nighttime rates at 10-<50% lunar illumination. Bobcats had highest movement rates during daytime when nighttime illumination was low (new moon) and higher movement rates during nighttime when lunar illumination was high (full moon). The behaviors we observed are consistent with prey availability being affected by light level and by limited vision by bobcats during darkness.

Highlights

Hunting is a delicate balance of energy expended for unit of reward, and many factors affect timing of hunting activities by predators and prey [1].To optimize catch per unit effort, predators concentrate hunting efforts to periods of the day when prey are most active and readily available [2,3,4,5]
Many mammalian prey studies focused on illumination effects on foraging strategies, and optimality models predicted that prey species would shift habitat use and alter movement rates to minimize predation risk [7,9,10,11,12,13]
Bobcats can be flexible in their circadian rhythms and can adjust foraging time to track their prey, as can other mammalian predators who can fast longer than several hours [14,15]. Bobcats adjusted their movement rates with changes in illumination associated with moon phase and time of day

Summary

Introduction

Hunting is a delicate balance of energy expended for unit of reward, and many factors affect timing of hunting activities by predators and prey [1].To optimize catch per unit effort, predators concentrate hunting efforts to periods of the day when prey are most active and readily available [2,3,4,5]. Many mammalian prey studies focused on illumination effects on foraging strategies, and optimality models predicted that prey species would shift habitat use and alter movement rates to minimize predation risk [7,9,10,11,12,13]. Prey reduce movement rates, shift activity periods, reduce food consumption, forage for short periods, spend more time in dense habitat compared to open habitat, and reduce sizes of their foraging areas compared to during new moon periods [7,9,10,12,13,16,17,18,19,21,22,23,24,25,26,27,28,29]. Extreme behavioral changes are documented in prey, few studies have investigated the effects of lunar illumination on predator behavior [2,3,5]

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