Monitoring wild species is a fundamental aspect of conservation efforts and provides biologists with valuable information. However, animal handling and marking are often required, which can result in injuries, pathogen transmission, and stress. These factors can, in turn, impact individual behavior and survival. Over the past few decades, several non-invasive monitoring techniques have been developed, including the use of digital datasets of distinctive patterns for individual identification.

A recent study, accepted for publication in Acta Herpetologica, introduces a novel non-invasive methodology to predict body condition from digital pictures in 8 different species of Speleomantes cave salamanders. These salamanders accumulate fat in their tails, so it was hypothesized that tail thickness could provide valuable information about individual energy storage.

To test this hypothesis, 915 dorsal pictures of Speleomantes cave salamanders, with known sex, weight, and length, were selected from digital archives. Tail length and area were calculated for each individual using the software ImageJ, and the Fat Tail Index (FTI) was determined as an indicator of fat tissue. FTI was then compared to the Scaled Mass Index (SMI), a well-established indicator of individual condition in amphibians.

The results showed a significant positive correlation between FTI and individual body condition in Speleomantes, even in the absence of weight data. This finding highlights the importance of digital imaging in conservation studies. The correlation was strongest in female salamanders and in a group of four Speleomantes species from Sardinia, known for their larger size. Further physiological and morphological studies are needed to explain the observed differences in the predictive capabilities of FTI across different cave salamander species.

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