REPTILES & AMPHIBIANS • 28(1):26–29 • APR 2021 26 HTTPS://JOURNALS.KU.EDU/REPTILESANDAMPHIBIANS Reptiles & Amphibians ISSN 2332-4961 REPTILES & AMPHIBIANS ONSERVATION AND NATURAL HISTORY Copyright is held by the authors. Articles in R&A are made available under a Creative Commons Attribution-NonCommercial 4.0 International license. B ody temperatures of ectothermic reptiles in general and crocodilians in particular can be lowered by the loss of heat through radiation, convection, or evaporation of body fluids, can be either raised or lowered by conduction of heat to or from the substratum (thigmothermy) or air, or can be raised by the absorption of radiant heat (heliothermy) from the sun (Bogert 1949; Huey 1982; Pough 1983). Crocodilians have a “preferred” body temperature of around 30–33 °C, which they achieve by shuttling back and forth between warm and cool parts of their environment (Lang 1987; Grigg and Kirshner 2015; IUCN Crocodile Specialist Group 2019). Such behavior can be affected by climatic conditions, social interactions, circadian rhythms, and reproductive state (Lang 1987; Venugopal and Prasad 2003). Crocodilians gape by opening their mouth for long periods to help circulate air and permit cooling while basking (Spotila et al. 1977), although mouth gaping probably has other functions as well because it also occurs during rain and at night (Loveridge 1984). Gujarat is home to one of the largest populations of Mugger Crocodiles (Crocodylus palustris) in India, with par- ticularly large populations around Saurashtra and Kutch in central Gujarat and a smaller population in southern Gujarat (Vijaykumar 1999; Vyas 2010; Vasava et al. 2015). Most of the Mugger populations and habitat in Gujarat are con- sidered secure and safe, although human-crocodile conflicts appear to be increasing along the Vishwamitri and Narmada Rivers, likely the result of human encroachment into Mugger habitat (Vyas 2010). The Vishwamitri River provides habi- tat for breeding and basking Muggers; along one 25-km stretch of river, Vyas (2012) counted 155 Muggers. Earlier studies showed only a small number of Muggers inhabiting the wetlands of Anand and Kheda Districts (Vijaykumar et al. 1999), but more recent surveys have revealed substantial Mugger populations in these districts (collectively known as Charotar), where crocodiles share various ecosystem services (water, fish, and space) with humans (Upadhyay et al. 2013; Vyas 2013). Herein we provide information on the effects of water and ambient temperatures and anthropogenic activities on the basking behavior of crocodiles in the winter and post- winter seasons in Anand District, Gujarat. We conducted this study from December 2018 to March 2019 at Pond Deva in central Gujarat, India (22°37'12.86"N, 72°44'6.14"E; Fig. 1). The climate is tropical semi-arid mon- soon; monsoons last from June to September, peaking in July and August; and temperatures start rising from mid-April and peak in May (Vasava et al. 2015). Using binoculars, we searched for basking crocodiles during five daily sessions (0800–1000 h, 1000–1300 h, 1300–1400 h, 1400–1600 h, 1600–1800 h) and recorded air and water temperatures and anthropogenic activities (wash- ing clothes near the shore, cattle grazing, throwing stones at crocodiles, and fishing) during each session. We encountered 40 crocodiles that we assigned to either large (≥1.5 m) or small (<1.5 m) size classes, observed each for five minutes, and recorded the basking behavior and type of basking site. Basking behavior was classified as: (1) Entire body on land (Fig. 2A); (2) entire body on land and gaping (Fig. 2B); (3) partially on land (Fig. 2C); (4) partially on land and gap- ing (Fig. 2D); (5) floating and not moving; (6) floating, not moving, and gaping; (7) floating and moving (Fig. 2E). Types Basking Behavior of Marsh Crocodiles ( Crocodylus palustris) in Pond Deva, Anand District, Gujarat, India Urvi Dave and Nikunj Bhatt Biology Department, Vitthalbhai Patel & Rajratna P.T. Patel Science College, Sardar Patel University, Vallabh Vidyanagar 388 120, Gujarat, India (drnikunjbhatt@vpscience.org) Fig. 1. Map showing the location of study area at Deva, Anand District, Gujarat, India (red dot).