Zoological Studies

Vol. 53, 2014

Influence of microclimate on the activity of Royle's pika in the western Himalaya, India

Sabuj Bhattacharyya1,2*, Bhupendra Singh Adhikari1 and Gopal Singh Rawat1

1Department of Habitat Ecology, Wildlife Institute of India, P.O. Box # 18, Chandrabani, Dehradun, India
2Current address: Centre for Ecological Science, Indian Institute of Science, Bangalore 560012, India

Background: A central aim in ecological research is to improve understanding of the interactions between species and their environments; these improvements will prove crucial in predicting the ecological consequences of climate change for isolated montane species, such as Royle's pika. We studied the influence of habitat microclimatic conditions on the activity patterns of Royle's pika in the period May to August (2008 to 2011) within six permanently marked plots deployed along an attitudinal gradient (2,900 to 3,680 m) within the Kedarnath Wildlife Sanctuary, India. Pika activity was recorded through direct observation during the period from 0600 to 1900 on each observation day and normalised as the percentage of individuals observed in an hourly interval relative to the maximum number of individuals sighted in a particular plot during the observation day. Microclimatic data in pika habitat were recorded across the altitudinal zones using automatic data loggers, a soil thermometer and a hygrometer deployed within the site during each observation interval.
Using linear mixed effect models, we simulated pika activity as the number of active versus inactive individuals with logical alternate combinations of habitat microclimatic parameters, altitudinal zone and daily time interval. The pika had a bimodal activity pattern with high activity in the morning and evening hours and low activity during midday hours. The best fit candidate model demonstrated that pika activity increased with ambient humidity and decreased with increasing temperature.
Conclusions: The reduction of activity due to an increase in temperature was significantly higher in the subalpine zone (2,900 to 3,200 m) than in the alpine zone (3,400 to 3,680 m). Thus, Royle's pika avoids heat stress by reducing activity during warm midday hours and taking shelter in microclimatically favourable cooler talus habitat. We showed that changes in habitat microclimatic conditions (specifically, increases in temperature) might significantly restrict Royle's pika daytime activity.

Key words: Activity; Kedarnath Wildlife Sanctuary; Microclimate; Pika; Thermal stress.

*Correspondence: E-mail: bhattacharyyasabuj@gmail.com