Reproductive skew in the polygynandrous acorn woodpecker

Reproductive skew in the polygynandrous acorn woodpecker.

Reproductive skew models, which focus on the degree to which reproduction is shared equally (low skew) or monopolized by a single individual (high skew) within groups, have been heralded as providing a general unifying framework for understanding the factors determining social evolution. Here, we test the ability of optimal skew, or "transactional," models, which predict the level of skew neces...

Patterns of reproductive skew in the polygynandrous acorn woodpecker.

We compared observed levels of reproductive skew in the cooperatively breeding acorn woodpecker (Melanerpes formicivorus) with those predicted by two alternative transactional models. "Concession" models predict the degree to which parentage is shared assuming that a single dominant is in complete control of reproduction. Alternatively, "restraint" models predict reproductive sharing assuming t...

Distress Calls in the Acorn Woodpecker

Acorn Woodpeckers live in extremely stable kin groups. Nonetheless, only 59.9% of birds caught in roosting aggregations gave distress calls or fear screams. Distress calling was highly repeatable among individuals and apparently heritable. However, the incidence of distress calling did not vary seasonally or according to age, sex, or status. Also, with two marginally significant exceptions, dis...

ACORN-STORING BY THE CALIFORNIA WOODPECKER By WILLIAM E. RITTER

Temporal variability and cooperative breeding: testing the bet-hedging hypothesis in the acorn woodpecker.

Cooperative breeding is generally considered an adaptation to ecological constraints on dispersal and independent breeding, usually due to limited breeding opportunities. Although benefits of cooperative breeding are typically thought of in terms of increased mean reproductive success, it has recently been proposed that this phenomenon may be a bet-hedging strategy that reduces variance in repr...