The Speaker Method: A Novel Release Method for Offspring Mammals and 5-Year Study on Three Costa Rican Mammals

Abstract

Nowadays, wild animals are threatened by humans, with the number of species and individuals decreasing during recent years. Wildlife rescue centers play a vital role in the conservation of wildlife populations. This study aims to describe a new release technique, the Speaker Method, to rescue and facilitate the reunion of different baby mammals that arrived at a wildlife rescue center with their mothers within their natural habitat, avoiding the need for captivity. This method is based on a recorded baby’s cry played on a speaker to make a “call effect” in the mother. The efficacy of the Speaker Method for babies’ reunion with their mothers was 45.8% in Hoffmann’s two-toed sloths (Choloepus hoffmanni) and 91.9% in brown-throated sloths (Bradypus variegatus). Among the mantled howler monkeys (Alouatta palliata), 50% of the babies could be released using this new technique. The findings suggest that the method could be helpful in the early release of young individuals, highlighting higher release outcomes in these three species compared to traditional nursery care provided by human caretakers, who face inherent difficulties in raising young animals without their mothers.

Simple Summary: This study presents the Speaker Method as a novel approach for wildlife offspring release to facilitate their reunion with their mothers in their natural habitats, thereby avoiding the need for captive rearing. This method uses call records of the offspring to attract their mothers effectively. In this context, we aimed to prove the Speaker Method’s efficacy in releasing the offspring of three mammal species that arrived at a wildlife rescue center. The study showed promising results, successfully releasing 45.8% of Hoffmann’s two-toed sloths, 91.9% of brown-throated sloths, and 50% of mantled howler monkeys. These results provide empirical effectiveness for the Speaker Method as a release technique for offspring, underscoring its superiority over conventional nursery care by humans facing inherent challenges in rearing young animals separated from their maternal sources.