Seasonal changes of fecal testosterone and antler development in a tropical white-tailed deer (Odocoileus virginianus) subspecies of the Huasteca region, Mexico
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Objective: to analyze the relationship between the level of testosterone in feces and the antler cycle, as well as to determine the reproductive period of the white-tailed deer (O. v. Veraecrucis) based on the habitat of four Management Units for the Conservation of Vida Silvestre (UMA) from the Huasteca region of Veracruz and San Luis Potosi, Mexico. Method: The study was carried out in four cattle ranches registered as UMA, located in the states of Veracruz and San Luis Potosi, in the Huasteca region of Mexico. Twenty-seven fecal samples and one hundred and ninety-two photographic images of male white-tailed deer were evaluated to identify the annual reproductive pattern. The samples and images were collected between February 2015 and July 2016. Stool testosterone concentration was determined using ELISA tests. Statistical analyzes of linear regression and correlation were carried out to identify the relationship of the testosterone concentration with the average growth of the antlers, non-metric multidimensional scaling for the ordering of the observed testosterone concentration values, growth stage of the antlers and environmental variables. To group the months in which the animals present similar reproductive characteristics, a k-means analysis was applied. Results: It was possible to identify a positive relationship between the annual variation of testosterone levels and the stages of the antler cycle; the lowest hormonal concentrations occurred from March to June and coincided with the molting and growth of new antlers, allowing to identify this period as non-reproductive, while, between July and February, the level of testosterone remained high, coinciding with the presence of ossified antlers. and velvet free, an indicator of reproductive activity in males.