Male-only care and cuckoldry in black coucals: does parenting hamper sex life?

Abstract

Providing parental care often reduces additional mating opportunities. Paternal care becomes easier to understand if trade-offs between mating and caring remain mild. The black coucal Centropus grillii combines male-only parental care with 50% of all broods containing young sired by another male. To understand how much caring for offspring reduces a male's chance to sire additional young in other males' nests, we matched the production of extra-pair young in each nest with the periods during which potential extra-pair sires were either caring for offspring themselves or when they had no own offspring to care for. We found that males which cared for a clutch were not fully excluded from the pool of competitors for siring young in other males' nests. Instead, the relative siring success showed a temporary dip. Males were approximately 17% less likely to sire young in other males' nests while they were incubating, about 48% less likely to do so while feeding nestlings, followed by 26% when feeding fledglings, compared to the success of males that currently did not care for offspring. These results suggest that real-life care situations by males may involve trade-off structures that differ from, and are less strict than those frequently employed in theoretical considerations of operational sex ratios, sex roles and parenting decisions.

The evolution of reversed sex roles and classical polyandry: Insights from coucals and other animals

“…When feeding nestlings, a male's success in siring extra-pair young was lowest with a reduction of 41% compared with a "free" male. Once the young left the nest, extra-pair siring success of their fathers increased again, being only 21% lower than that of "free" males (Safari et al, 2019). In summary, caring males had a reduced extra-pair siring success, but it was not zero.…”

“…Motivated by this lack of information and the unexpected high rates of extra-pair paternity in black coucals (Safari & Goymann, 2018), we tested whether there is a trade-off between caring and mating in black coucals by quantifying a male's success in siring extra-pair young when he is incubating or caring for nestlings or fledglings relative to when he has no young to care for (Safari et al, 2019). In fact, male black coucals succeeded in siring extra-pair young even while providing care at their own nests.…”

The evolutionary genetics of paternal care: How good genes and extrapair copulation affect the trade‐off between paternal care and mating success

“…If the indirect effect of paternal care is sufficient, it can even overcome a trade‐off with both reduced male mating success and reduced viability in both sexes. Additional support for this theoretical finding comes from studies that find evidence for paternal care even in species where it almost certainly represents opportunity costs for males (e.g., (Buchan et al., 2003; Safari et al., 2019). However, the extent to which such a trade‐off is found across species remains an open question (Stiver & Alonzo, 2009), and in some cases, male parental behaviors may evolve that avoid or mitigate associated costs.…”

Partial paternity does not always select for female‐biased care

“…We looked for empirical studies on the relationship between extra-pair fitness and paternal care. We found evidence for tradeoff between these quantities in a number of species: house wren (Whittingham and Dunn 2005 show a negative covariance between extra-pair and within-pair fitness), penduline tits (Szentirmai et al (2007) use path analysis to show that males benefit from deserting the brood and gaining extra-pair mating opportunities), zebra finches (Hill et al 2011 show that males who receive extrapair mating opportunities incubate less), great tits (Patrick et al 2012 show that explorative behavior in males correlates with paternity gained outside the nest but negatively with within-pair paternity), African cichlids (Bose et al 2018 show that socially monogamous brood tending males do not gain much extra-pair fertilizations), black coucal (Safari et al 2019 quantify the cost of each component of care for additional mating opportunities using an information theoretic approach), hair-crested drongos (Lv et al 2020 show that males with longer tarsi are heavier and more likely to sire extra-pair offspring but they incubate less) and house sparrows (Schwagmeyer et al 2016 show that males are less likely to obtain extrapair matings while in feeding stages of care). Differences between alternative male reproductive tactics in some species also suggest a trade-off between paternal effort and extra-pair fitness: white-throated sparrows (white males are less parental and attempt more EPCs, whereas tan males are more parental and gain fewer EPCs; Tuttle 2003) and superb fairy-wren (monogamous males are more parental and spend less time seeking EPCs, whereas dominant males in the cooperatively breeding groups show low parental care and spend more time seeking EPCs; Dunn and Cockburn 1996).…”