Thermal Biology and Thermoregulatory Behaviour of Agama agama in Contrasting Urban and Rural Thermal Environments in Abuja, North Central Nigeria

This study investigates the thermal biology and behavioural thermoregulation of Agama agama across contrasting urban and rural thermal environments in Abuja, Federal Capital Territory, North Central Nigeria. Urban heat island effects modify the operative thermal environments available to ectotherms, and understanding whether lizards can effectively thermoregulate in thermally modified urban landscapes is important for predicting the ecological consequences of urbanisation. Active body temperatures, operative environmental temperatures (measured using copper lizard models), substrate and air temperatures, and thermal performance curves were determined at six urban and six rural sites during both seasons. Thermoregulatory accuracy (db), thermoregulatory effectiveness (E), and exploitation efficiency were calculated. Active body temperatures were significantly higher in urban sites (38.1 degrees C) than in rural sites (36.2 degrees C), but did not exceed critical thermal maxima. Thermoregulatory effectiveness was higher in urban sites (E = 0.72) than rural sites (E = 0.58), indicating more precise thermoregulation in more thermally heterogeneous urban environments. Time spent basking was reduced in urban lizards, suggesting reduced thermoregulatory costs where suitable hot substrates are abundant. Sprint performance trials showed significantly better performance at urban operative temperatures, suggesting a potential fitness advantage. The study addresses a gap in the thermal ecology of African lizards in urbanised environments and provides a framework for assessing the winners and losers of urban expansion among Nigerian ectotherm communities. Keywords: thermal biology, Agama agama, urban heat island, thermoregulation, Abuja.