The individual identification of animals is essential for long-term population ecology studies. Injuries and tag loss can negatively impact animal welfare and parameter estimates. We used time-to-failure curves and multistate mark-recapture models to estimate injury rates, body condition decline, tag loss and survival probabilities associated with two tags commonly used in bats: metallic arm bands and steel ball chain collars. We monitored two colonies of Carollia perspicillata at União Biological Reserve, southeastern Brazil, from 2013 to 2019. Every other month, we marked individuals with arm bands, collars or both. Collars did not cause noticeable injuries, but were lost at a higher rate than arm bands (1.5–2.5 times). The arm band-related injury probability between captures was ~ 0.2, and after 17 months half the marked animals developed injuries. Animals marked as juveniles were less likely to get injured than adults. Injuries were associated with a lower body condition in females. Body condition was positively associated with apparent survival; however, a direct effect of arm band injuries on survival estimates was not observed. The tag loss rates caused a negative bias in survival estimates. Mark-recapture studies should evaluate the efficacy of the marking technique, accounting for potential animal injury, tag loss, and bias in parameter estimation. Marking individuals should be limited to studies that monitor species with high recapture probability, using the least harmful tags possible, and balancing the burden to the animals with the potential to generate knowledge.
We describe the first known case of disproportionate dwarfism in bats. The specimen is an adult male Seba's short-tailed bat, Carollia perspicillata (Linnaeus, 1758), captured in a ground-level mist-net during a survey in a lowland Atlantic Forest area in southeastern Brazil. Examination of the specimen skull showed craniofacial anomalies, including microdontia in the upper incisors, oligodontia in the third upper molars, fusion of the nasal septum and the left ventral nasal concha, and a narrower foramen magnum. Post cranial changes were mainly related to shortened radius, tibia and metacarpals, compared to the reference sample in multivariate space. Given its unusual morphology with short wings and average body mass, the dwarf would have higher wing loading, fly faster, require more power to fly, and have a shorter flight range compared to the species pattern. Because it presented good body condition and reached adulthood, possible mechanisms of functional compensation are discussed.
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