A hot knot of toads: Aggregation provides thermal benefits to metamorphic Andean toads

Abstract

We tested the thermal benefits of aggregation ("knotting") for a high-elevation (>4300 m) population of metamorphic Rhinella spinulosa. Fewer knots were recorded when the sun was low on the horizon and aggregating toads dispersed under cloudy skies or when experimentally shaded. Body temperatures of sun-exposed toads averaged 2.3 °C higher when in knots than when solitary. Proximity to water and similarity in body size between aggregating and solitary toads suggest that grouping is not imposed by a need for reducing evaporative water loss. Aggregation apparently provides thermal benefits, which should translate into faster growth.