The abiotic conditions and the effort of parental care. A choice between the pros and cons

Environmental pressures shaping the evolution and expression of parental care in anurans remain incompletely understood, particularly in semi-arid environments characterized by hydrological instability. Here, we investigated the parental care system of Leptodactylus macrosternum in a semi-arid region of Piauí State, northeastern Brazil. We monitored complete parental care events over ten consecutive days at a temporary pool, focusing on predator-repelling behavior, caregiver proximity to the tadpole shoal, and offspring attendance duration. Abiotic conditions were recorded daily, including water volume, evaporation rate, and water-surface retraction. Egg and tadpole abundance were quantified using DotDotGoose software. Relationships between parental behavior (offspring attendance duration) and abiotic conditions, as well as tadpole abundance, were evaluated using Pearson’s correlation coefficient. Parental care was provided exclusively by a single female. During the first 80 h, the female remained continuously present and actively repelled predators. Attendance became intermittent after 112 h and ceased entirely after 128 h. We found a strong negative correlation (r = − 0.98) between offspring attendance duration and pool desiccation, indicating that increasing evaporation and surface retraction were associated with reduced parental care. Following female abandonment, cannibalism by juvenile L. macrosternum emerged and intensified as water volume declined. After 192 h, rapid pool desiccation led to complete tadpole mortality; consequently, cannibalistic juveniles abandoned the site due to the loss of available prey. Our results demonstrate that parental care in L. macrosternum is highly sensitive to abiotic constraints, with offspring attendance duration tightly coupled to hydrological conditions. This study provides new insights into how environmental unpredictability mediates parental investment, larval survival, and cannibalism dynamics in semi-arid amphibian populations.