On the importance of alpha behavior integrity in male Capybara Hydrochoerus hydrochaeris (Mammalia: Rodentia: Caviidae) following immuno-contraceptive treatment

Abstract

As the human population continues to grow, habitat for wildlife shrinks, driving fauna either into extinction or into new habitats, which can create new problems.  In Brazil, the Capybara Hydrochoerus hydrochaeris has become a pest by invading urban and agricultural areas.  These mammals quickly multiply owing to abundant food supply and a lack of natural predators, and they can serve as amplifying hosts for Rickettsia rickettsii, the pathogen of potentially life-threatening Brazilian spotted fever.  Species-specific population management strategies that respect public opinion and consider animal welfare are required for the effective mitigation of this tick-borne zoonotic disease.  In order to control Capybara populations it is necessary to take into account their social dynamics, which are centered on polygynous dominant males with hormone-driven secondary sexual characteristics.  To be a viable management tool, a contraceptive strategy targeting these males must preserve their social status to prevent other males from replacing them.  As part of a larger research project on the efficiency of anti-Gonadotropin-releasing hormone (GnRH) vaccine treatment in free-ranging Capybaras, the aim of this study was to observe the impact of this treatment on alpha male and overall social group behavior.  At the end of the 18-month-study, there were no recorded births involving the immunized animals, and alpha male sexual characteristics and group integrity were preserved.  These results encourage the use of this anti-GnRH vaccine as an alternative population control tool in male Capybara.