In the nonbreeding season, they form huge communal roosts of a hundred birds or so. But in the rainy season, when it’s time to raise their young, they coalesce into tight-knit groups of two to four unrelated, socially monogamous pairs, plus a couple of nonbreeding helpers. Together each group builds a shared nest in which all of the females collectively lay their eggs more or less synchronously. They all share parenting care, raising the mixed clutch of young until they fledge. The groups are extraordinarily stable, says Riehl, often staying together a decade or more.
