Abstract:

Aims: Niche differentiation is an important mechanism for carnivores to coexist when they have similar functional or morphological characteristics. Of the most common methods of niche differentiation (e.g., spatial, nutritional, and temporal niches), temporal niche differentiation (i.e., activity-rest cycles within circadian rhythms) is often considered the easiest for animals to adjust. The manner in which these sympatric small- and medium-carnivores maintain their temporal niche has attracted increasing attention from researchers, but is not well-studied.

Methods: We conducted a systemic camera-trapping survey in Chishui Alsophila National Nature Reserve, Guizhou Province, China (GCANNR) to investigate patterns of coexistence between sympatric small- and medium-sized carnivores (i.e., Prionailurus bengalensis, Paguma larvata, Viverricula indica, Arctonyx collaris, Melogale moschata, Mustela kathiah, M. nivalis and M. sibirica). We detected 2,299 independent photographs of carnivores and used kernel-density estimation and coefficient of overlap index (Δ) to examine how circadian activity rhythms for each species differed in the presence or absence of human disturbance (i.e., outside or within GCANNR, respectively). We also quantified the temporal differentiation of these carnivores.

Results: The circadian activity rhythms of small- and medium-sized carnivores revealed that the dominant species P. larvata, V. indica, and M. moschata and the common species P. bengalensis exhibited nocturnal activity patterns. Meanwhile, the common species A. collaris and M. kathiah, and the rare species M. nivalis and M. sibirica, showed cathemeral activity patterns. There was high overlap in the circadian activity rhythms of nocturnal dominant species (Δ > 0.90, 95% CI, 0.79-0.97) within and outside of GCANNR. Despite this, dominant carnivores outside GCANNR had a peak in early-morning activity 1-2 h earlier than those inside GCANNR. Common species had a low overlap coefficient for their circadian activity rhythms within and outside of GCANNR, as well as those of rare species (Δ < 0.80). Further analysis was conducted on the overlapping activity rhythms among the sympatric dominant and common species using the same trapping sites. P. bengalensis and A. collaris showed the lowest coefficient of overlapping (Δ = 0.49, 95% CI, 0.28-0.69). Meanwhile, there was no significant temporal differentiation in the activity rhythms among the three dominant species (P. larvata, V. indicaand M. moschata; Δ > 0.90), and the Δ was 0.6-0.8 between the other species pairs.

Conclusion: Circadian activity rhythms of the sympatric small- and medium-sized carnivores in GCANNR were affected by the human activities. These carnivores were able to coexist largely due to temporal differentiation. Most of the common species avoided the dominant species in temporal activity. In contrast, the coexistence among dominant species in the same distribution was not promoted by temporal niche differentiation, so the role of nutrient niche differentiation may have been more important. Thus, our results indicated there were patterns of temporal differentiation for several sympatric small- and medium-sized carnivores, but nutritional or spatial niche differentiation also aided in integrating these carnivores, helping them coexist. These results indicate that it is important to pay attention to the ecological niche differentiation pattern of species while managing wildlife protection areas; doing so would help formulate more effective conservation policies.

Key words: sympatric coexistence, infrared camera, circadian activity rhythm, temporal niche, human disturbance