Butterflies respond to habitat disturbance in tropical forests through activity shifts

Habitat disturbance can alter the dynamics of the forest microclimate by disrupting the canopy structure, particularly in structurally complex tropical forests. These changes may impact ectotherms, of which performance and fitness are highly sensitive to climatic conditions. Behavioural responses, such as changes in activities, may help buffer forest ectotherms like butterflies from microclimate changes in disturbed tropical forests. Using field surveys from four tropical forest sites in Asia, we compared flight activity peaks, durations and intensity for populations of 21 forest-associated butterfly species between open-canopy and closed-canopy forests. We then compared the temperature and illumination that each species experienced during its activity period between the two forest types. Although butterfly populations began their activity earlier and reached peak levels sooner in open-canopy forests compared to closed-canopy forests, the duration and intensity of activity remained similar across populations. Despite these shifts in activity timing between forest types, butterflies experienced comparable temperature conditions in both forest types, but were exposed to higher illumination levels in open-canopy forests. Overall, we demonstrate that tropical butterflies can compensate for microclimate changes in tropical forests by shifting their activity patterns. This may help butterflies buffer against temperature increases but not against higher illumination levels following forest canopy opening due to habitat disturbance. Our results emphasize the importance of understanding how animal activity responds to habitat disturbance.