from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Occurring outside of a stable pairing
Sorry, no etymologies found.
From what I can glean from Google, there’s one more bit of evidence in favor of “good genes” and against “good parenting” in this particular case: Female ducks are also unusually uninterested in any kind of extrapair copulation; unlike, for instance, most female songbirds, who willingly mate with a large/bright/loud/otherwise sexy male when their own male’s out of sight.
So it seems unlikely to me that they could effectively “punish” the female for extrapair copulation by neglecting her offspring.
What is diplomatically referred to as 'non-paternity' or extrapair paternity occurs about 4% of the time average of wide-ranging estimates.