Blind toads in paradise: the cascading effect of vision loss on a tropical archipelago

Abstract

AbstractOn the archipelago of Fernando de Noronha, nearly half of the individuals in the invasive population of Cururu toads have mouthpart, limb or eye deformities. Among these, a subset of adult toads is completely blind or has just one functional eye. In this study, we examined the consequences of this vision loss in relation to feeding and reproductive biology. Blind toads were handicapped relative to normal toads, whereas the half‐blind individuals were intermediate. In contrast to the expected active hunting mode used by normal toads, blind toads searched for prey using a sit‐and‐wait foraging strategy. The small sample of blind toads (n = 4) had no stomach contents. However, eight half‐blinded and 86 sighted animals presented stomach contents, and differed in general diet profile. Body condition as well as reproductive effort increased according to the number of functional eyes. Therefore, we suggest that shifts in feeding and hunting, as a consequence of vision loss, influence diet, with subsequent impact on overall body condition and reproductive effort. A cascade effect of this kind has not been previously reported and provides insightful data related to behavioral plasticity and reproductive fitness.