Reproductive behavior of Spix’s Whiptails in the wild: understanding the costs and benefits of mate-guarding

Across animal taxa, females of non-territorial species have potential opportunities to mate with multiple partners; hence, the primary mechanism available for males to ensure paternity is to guard the receptive female after copulation and repel other males. Hypothetically, mate-guarding is costly for males in terms of energy acquisition and increased risk of injury, and beneficial for females in terms of decreased harassment by other males and an increase in available foraging time. Here, we provide a detailed description of mating behavior and test these hypotheses in the Spix’s Whiptail (Ameivula ocellifera). Mating behavior is characterized by the following events: (1) a male courts a female in the entrance of her burrow; (2) if courtship is accepted by the female, a consensual copulation occurs; (3) after copulation the male accompanies the female during her daily activity, being aggressive towards other males; (4) when the female returns to the burrow, the companion male remains vigilant at the entrance and repels rival males. Besides the mate-guarding strategy, alternative mating tactics are adopted by some males that do not guard females after courtship and consensual copulation, while others try to copulate opportunistically with a female without prior courtship. Companion males spent more time vigilant, less time actively foraging, and captured less prey when compared to solitary males. Accompanied females captured prey in a similar proportion to solitary females but spent more time vigilant and less time foraging. Companion males won 100% of their interactions with rival males, chasing them away from the females. Accompanied females hence did not suffer harassment from other males when companion males were close. Our results evidence energetic costs of mate-guarding for males but not increased risk of injuries. By accepting mate-guarding, females do not appear to have energetic gains and lose the advantage of cryptic mate choice but can benefit from access to high-quality males and protection from harassment.