The fantastic Hoary Fox of Brazil: bringing the nocturnal into the light

Hoary Fox is a small South American canid endemic to Brazil whose spatial organization and territoriality is still unknown.  The current study was an attempt to describe and document the spatial organization and patterns of home range overlap of two neighbouring Hoary Fox mated pairs in Mato Grosso, Brazil.  This is the first time that the response of neighbouring Hoary Foxes to social disruption of an adjacent pair has been documented.

The elusive and non-cooperative canid of Brazil

Image 1. Adult male Hoary Fox Lycalopex vetulus from Mato Grosso, Brazil.

The Hoary Fox Lycalopex vetulus is a small omnivore-insectivore canid with a distribution restricted to open areas of the Brazilian savannah.  This solitary species has a monogamous mating system consisting of a reproductive pair with extensively overlapping home ranges.  A recent assessment has classified the Hoary Fox as Vulnerable to extinction in Brazil.

Data on spatial organization, territoriality, and social behaviour of the Hoary Fox is restricted to a few studies.  The spatial relationship between neighbouring pairs of Hoary Fox as well as the factors related to changes in home range size, however, are still unknown due to the difficulty in observing these elusive nocturnal species.  The study by Dalponte et al. in eastern Mato Grosso, Brazil, was an attempt to determine the territoriality and spatial organization of two breeding pairs of Hoary Foxes with adjacent home ranges through radio tracking from October 2002 to April 2003.

Territoriality and spatial organization of Hoary Fox

Image 2. Pastures in the study area filled with termite mounds.

The largest Hoary Fox home ranges described in the study were relatively smaller than those reported in previous studies conducted in central Brazil.  One of the factors that influenced the smaller home range size of Hoary Fox in the study would have been movement restriction during reproductive stage — including the period dedicated to raising off-springs when mobility of breeding pairs and family groups is limited to their natal range.  Another factor would have been the abundant resource concentration in the area — leaf-feeding termites during the dry season and dung beetles during the rainy season — that could meet the food demands of Hoary Fox all-year-round.

Response to social disruption of a neighbouring pair

After the death of both individuals of one pair, the neighbouring pair progressively occupied the vacant space, expanding markedly its range into about half the area originally occupied by the previous pair.  Factors driving a pair of Hoary Foxes to expand their territory into a vacant area after the death of the neighbouring pair were not clearly determined.  The absence of territorial defence (e.g., urine-marking, scat deposition, body-rubbing, scraping, and roar barking), however, could have contributed to the changes in the spatial organization.  Although the number of monitored foxes was small, this is the first time that the responses of neighbouring foxes to social disruption of an adjacent pair have been documented for Hoary Foxes.

Reference

Dalponte, J.C., H.S. Lima, S. Klorfine & N.C. da Luz (2018). Home range and spatIal organizatIon by the Hoary Fox Lycalopex vetulus (Mammalia: Carnivora: Canidae): response to social disruption of two neighbouring pairs. Journal of Threatened Taxa 10(6): 11703–11709; https://doi.org/10.11609/jott.3082.10.6.11703-11709