North America is home to many blue birds, but few are as similar as the Blue grosbeak and Indigo bunting. These small birds share a similar distribution and are most prevalent in the eastern half of the USA, and are part of the same family, Cardinalidae.
Also, both migrate south in fall in winter and share wintering grounds in Central America. So, what are the differences between Blue grosbeaks and Indigo buntings?
Blue grosbeaks are much larger, measuring 14 to 19cm (5.5 to 7.5in) with a wingspan of 26 to 29cm (10 to 11in). They weigh around 26 to 31.5g. Indigo buntings are around 13cm long and weigh approximately 15g - so almost half the size. While both male birds are blue, Blue grosbeaks have rusty orange wing bars, whereas the Indigo bunting has all-blue wings with black tips.
Things get a little more complicated when comparing juveniles, females, and molting males.
Read on to find out more tips and techniques for identifying these beautiful birds!
These birds are similar in size, but you can still often tell them part by comparing their size.
Blue grosbeaks measure 14 to 19cm (5.5 to 7.5in) with a wingspan of 26 to 29cm (10 to 11in). They weigh around 26 to 31.5g (0.9 to 1.1oz)
Indigo buntings measure 11.5 to 15cm (4.5 to 5.9in) long, with a wingspan of 18 to 23cm (7.1 to 9.1 in). They weigh around 12 to 14.5g (0.51oz).
Blue grosbeaks are larger and heavier. Some are likely to be twice as big and heavy as Indigo buntings, and this is obvious when the birds are side by side. Blue grosbeaks also look stronger and have thicker, larger bodies and heads.
This is the case for both males and females - female Blue grosbeaks are bigger and stockier than female Indigo buntings.
Perched Blue Grosbeak
There are many other differences between Blue grosbeaks and Indigo buntings besides their size.
Male Indigo buntings and Blue grosbeaks are primarily blue, but Indigo buntings are lighter overall and are more uniform in color.
Blue grosbeaks are a darker blue and have rusty orange-brown wing bars and tips that Indigo buntings lack. Indigo bunting wings are blue with black tips. Blue grosbeaks also have striped black tails, which Indigo buntings lack.
Another important consideration is that male Indigo buntings molt in the fall and start to resemble females, whereas male Blue grosbeaks remain blue all year round.
Females are a little tougher to tell apart. Female Indigo buntings are virtually all brown and are highly uniform in color, with no patterning other than the slighter lighter chest and slightly darker wings.
Blue grosbeak females have much darker brown wings with bolder patterning. In addition, they have a tiny blue patch in the corner of their wings and traces of blue across their face and breast.
Female Blue Grosbeak
Female Indigo Bunting
Indigo buntings have relatively small bills, whereas Grosbeaks have large, triangular bills that are quite distinctive. Both males and females possess this large distinctive bill which makes it easy to tell them apart from Indigo buntings when they’re in the same vicinity.
Both species share a relatively similar North American distribution and are most abundant in the eastern half of the country.
However, the Indigo bunting extends further north to southeast Canada, as far west as Manitoba and as far north as central Quebec.
Conversely, the Blue grosbeak doesn’t extend as far up the Atlantic coast and is largely absent from Canada. The northernmost populations are found in the Dakotas.
Both birds extend toward the southwest, but the Indigo bunting is a rarer visitor to this part of the US.
Both species live in weedy, shrubby fields and generally avoid denser woodlands. Their habitats are actually very similar, but the Blue grosbeak prefers more open and flat land than the Indigo bunting, which lives in hilly or semi-mountainous terrain.
Close up of an Indigo Bunting perched on a branch
Both birds share similar diets consisting of both insects, invertebrates, and plant foods like berries and seeds.
Both birds are migratory, heading from North America into much of Central America and the Greater Antilles. However, the Indigo bunting’s migration can be considerably longer, stretching from Canada all the way to Panama.
Both species are capable of melodic songs. Indigo bunting males have a bright, lively song consisting of sharp, clear, high-pitched notes. The song is short, lasting for 2 seconds or so.
Blue grosbeak males also have a high-pitched song, but it lasts longer (3 seconds or more) and is more melodic. The males of both species sing from branches, telephone poles, buildings, and other elevated positions.
Blue grosbeaks are more active from July onwards, whereas Indigo buntings are active earlier, from around mid to late May.
Molting male Blue Grosbeak bathing
Both species become territorial in the breeding season. However, blue grosbeaks are perhaps more sociable than Indigo buntings and often gather in flocks to forage - you’re more likely to see them in large groups.
Indigo buntings are also sociable outside of the breeding season, but to a lesser extent. Both species migrate in flocks.
Indigo Bunting male molting into winter plumage
The juveniles of both species are predominantly brown, looking more like females. Males molt into their adult plumage and slowly turn blue in the case of both the Indigo bunting and Blue grosbeak.
But when male Blue grosbeaks obtain their adult plumage, they retain it for life. In contrast, Indigo bunting males molt their blue plumage in fall and winter, making them tricky to tell apart from the females.
Juvenile Blue Grosbeak
Indigo Bunting Fledgling
Only the males of each species are blue. The females are a browner, more cinnamon color.
The Indigo bunting female is almost totally brown, with a lighter-brown chest and slightly darker wings. The Blue grosbeak female features much bolder patterning on her darker wings and has a stockier form.
She also has traces of blue on her upper wing, chest, and head, whereas female Indigo buntings lack any blue.
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