Arabian babblers (a bird) concealed 100% of copulations; did not prefer to copulate under shelters; concealed mating solicitations from adult conspecifics; and subordinates did not attack dominants who courted the female

Why conceal? Evidence for concealed sex by dominant Arabian babblers (Turdoides squamiceps). Yitzchak Ben Mocha, Roger Mundry, Simone Pika. Evolution and Human Behavior, https://doi.org/10.1016/j.evolhumbehav.2018.05.009

Abstract: Striking uniformity exists in humans' preference to conceal sexual activity from conspecifics' view. Yet, little is known about the selective pressures acting upon its evolution. To investigate this question, we studied the cooperatively breeding Arabian babbler (Turdoides squamiceps), which has been suggested being the only other species where dominant individuals conceal sex regularly. We examined whether birds indeed conceal sex and tested different hypotheses, postulating that sex concealment functions to avoid predators, signal dominance status, or to avoid social interference. The results showed that birds concealed 100% of copulations; did not prefer to copulate under shelters; concealed mating solicitations from adult conspecifics; and that subordinates did not attack dominants who courted the female. We argue that none of the hypotheses tested explains our findings satisfactorily and postulate that dominants conceal sex to maintain cooperation with those helpers they prevent from mating. Empirical desiderata for testing this ‘Cooperation-Maintenance’ hypothesis are discussed.

Keywords: Arabian babbler; Concealed sex; Cooperatively breeding species; Human sexual behaviour; Tactical deception; Cooperation maintenance hypothesis