Aging Passerines using Molt

limits

American Robin

ASY Male-no molt limit-broad feathers with dark shafts

American RobinSY Male-molt limit-narrow, “weaker” primary coverts

SY Female-molt limit-narrow, “weaker” primary coverts

Broad primary coverts with dark

shafts.

ASY

Narrow, weak primary coverts

with brown shafts.

Broad greater coverts

With no molt limit.

Molt limit within greater coverts.

SY

Replaced coverts

Retained coverts

Yellow-rumped Warbler

ASY Male-1 molt limit Alt plumage (greater coverts)

Yellow-rumped Warbler

SY Male-2 molt limit Alt plumage (greater coverts and retained first year feathers)

Indigo BuntingThe Test

Age?

No molt limit

ASYHow do you know?

Age?

Clear molt limit

SYHow do you know?