Indigo Bunting - Passerina cyanea

Indigo Bunting has an unusually complex molt strategy, with a preauxiliary molt occurring prior to migration in the first cycle, followed by an incomplete preformative molt after fall migration. Older individuals begin their prebasic molts on the summer grounds, but complete it during or after fall migration. There are also partial to incomplete prealternate molts which occur primarily on the winter grounds but may not complete until after spring migration. As a result, there can be considerable variation in the appearance of individuals of the same age and sex.  In general, molt limits on the wings provide the best clues for ageing. Individuals that are FCF or older can generally be sexed by the presence (male) or absence (female) of blue body feathers.

Quick tips

• Examine the wing for molt limits and feather quality - FCJ (juvenile) birds have uniformly brown feathers, with distinct buffy tips to the greater coverts; FCX (HY) birds typically have somewhat darker and fresher lesser and median coverts (tinged blue on males) and have sometimes replaced the innermost greater coverts; FCF (HY/SY) birds have generally replaced all greater coverts, their innermost secondaries and outermost primaries, and sometimes also one or two outer primary coverts, resulting in multiple contrasts with the retained paler juvenile feathers (more subtle in females); FCA (SY) individuals typically show a similar pattern to FCF but with some contrastingly fresh dark brown (female) or blue-edged (male) inner greater coverts and tertials; DCB (AHY/ASY) individuals have primaries, secondaries, and primary coverts that are largely uniform in darkness and wear, mostly deep brown (females) or blackish with blue edging (males) but with some variation in colour possible among feathers; DCA (ASY) individuals show uniformity in the appearance of primaries and secondaries, though these may appear substantially paler and more worn than the fresh alternate greater coverts.
• Look at the rectrices - they are uniformly brown, narrow, and tapered on FCJ/FCX (HY) individuals, uniformly more broad and rounded on FCF/FCA (HY/SY) and DCB (AHY/ASY) individuals, and occasionally with contrastingly fresh central rectrices in DCA (ASY) individuals.

Species account prepared by McGill Bird Observatory (2016). Last updated by Marcel Gahbauer (Mar 2022)