Dining in the City: Dietary Shifts in Indian Rock Agamas across an Urban-Rural Landscape

Rapid urbanization is a growing threat to biodiversity, causing wide-scale extirpation of species from their natural habitats. Some species such as rock agamas, Psammophilus dorsalis, seem to be sufficiently tolerant and continue to persist in urban environments. Given that urbanization alters species composition at multiple trophic levels, we expect a shift in the diet composition and hunting modes of populations across rural and urban areas. Based on identified contents from stomach flushes, we found that P. dorsalis are generally myrmecophagous, and their diet is mainly composed of ants (Hymenoptera: Formicidae). Diet of males and females in each area overlapped highly (80-91%), even though males were significantly larger than females. Dietary overlap between urban and rural populations also was high (80.3%). Surprisingly, rural lizards had lower body mass indices than did urban lizards, despite the greater diversity of prey types and the larger volume of food consumed. This species uses a sit-and-wait hunting strategy, but we found that the rate of movement of males was higher in rural areas compared to urban areas, which likely results in higher energy expenditure. Individuals of P. dorsalis do not seem to be negatively affected by urbanization but instead manage to hunt in and around the small patches of vegetation that remain, enabling them to maintain a higher body condition than that of lizards in undisturbed rural habitats.