The Indigo Bunting and Lazuli Bunting are two very similar species of small songbirds in the genus Passerina. They are closely related and can be difficult to distinguish visually, especially for beginning birders. However, there are some key differences in their plumage, range, habitat, diet, and vocalizations that can help identify them. In this article, we will go over the ways to tell these two buntings apart and highlight the main similarities and differences between them.
Plumage Differences
The plumage of the Indigo Bunting and Lazuli Bunting is quite similar during the breeding season. The males of both species have brilliant, shimmering blue feathers on their heads, wings, backs, rumps and tails. However, there are some subtle but noticeable differences:
- The Indigo Bunting’s blue plumage has a more purplish-blue hue compared to the Lazuli Bunting’s bright sky blue tones.
- The Indigo Bunting has darker blue feathers around its eyes that connect across the forehead, forming a distinctive “mask.” The Lazuli Bunting lacks this eye mask.
- The wing bars on Lazuli Buntings tend to be faint and thin, while the Indigo’s wing bars are usually bold and thick.
- Indigo Buntings have dark bluish-black tails, while Lazuli’s tails are black with white outer tail feathers.
During the winter months, both species molt into more dull brown plumages. The males are harder to differentiate but the Indigo often retains some blue on the wings and tail. Females have brown streaky plumages year-round. Indigo females tend to be warmer brown overall with faint wing bars while Lazulis are paler and grayer brown with bright white wing bars.
Range and Habitat
The ranges and breeding habitats of these two buntings also differ:
- Indigo Buntings breed in eastern North America from southern Canada down to northern Florida and eastern Texas. They migrate south to Mexico and the Caribbean for winter.
- Lazuli Buntings are found in western North America, breeding from southern Canada through the western half of the United States down into northern Mexico. They winter primarily in Mexico.
During the breeding season, Indigo Buntings prefer open deciduous woodlands, forest edges, thickets, and shrubby areas. Lazuli Buntings are found in more open habitats like riparian woodlands, shrub-steppe, mountain meadows, and ponderosa pine forests of the west. In winter, the buntings often mix together in similar brushy open areas and agricultural fields. But Indigos are rare vagrants west of their normal range while Lazulis are scarce east of the Great Plains.
Diet
Both lazuli and indigo buntings are primarily seed-eating birds that supplement their diet with insects when breeding. This includes:
- Seeds from grasses and weeds
- Grains like millet, oats, and rice
- Buds, berries, and fruits
- Caterpillars, grasshoppers, beetles, ants, wasps, and other insects
They forage for food on the ground or in low vegetation. Indigo buntings may sometimes take advantage of bird feeders for sources of millet and sunflower seeds.
Vocalizations
The songs and call notes of these two buntings also differ:
- The song of the Indigo Bunting is a series of paired notes that speed up into a buzzing, ringing warble often described as “sweet-sweet-sweet-sweet-see-see-see-see.”
- The Lazuli Bunting’s song is more varied, complex and melodic. It consists of a warbling sequence of shorter notes, chips, and trills.
- The call note of Indigo Buntings is a sharp, metallic “tsip.” Lazulis make softer, huskier “hreep” calls.
So the Indigo has a sweeter, buzzier song and sharper call compared to the more musical, intricate song and soft husky calls of the Lazuli Bunting.
Nesting and Reproduction
In terms of breeding biology, Indigo Buntings and Lazuli Buntings share many similarities:
- They both nest low in shrubs or small trees, building open cup nests out of grasses, stems, and leaves.
- Clutch sizes range from 3-5 eggs for both species. The eggs are pale blue or white with brown spots.
- Only the females incubate the eggs, for periods of 11-14 days.
- The young fledge from the nest at 9-12 days old.
- They may raise 2-3 broods per breeding season.
A few differences are that Lazuli Buntings occasionally nest on the ground in dense clumps of grass. Lazulis also tend to reuse nests for subsequent broods while Indigos build a new nest for each attempt.
Taxonomy
Indigo Buntings and Lazuli Buntings were formerly considered to be a single species – the Indigo Bunting. But based on differences in vocalizations, genetics, and other factors they were recognized as separate species in 1973. Their closest relative is the spectacular Painted Bunting of the southern U.S.
Some key facts about their taxonomy:
- Scientific name of Indigo Bunting: Passerina cyanea
- Scientific name of Lazuli Bunting: Passerina amoena
- Both species belong to the family Cardinalidae (cardinals and allies)
- Their genus Passerina also includes several other North American songbirds like Varied Bunting, Painted Bunting, Rose-bellied Bunting.
There are no recognized subspecies of either the Indigo or Lazuli Bunting. Where their breeding ranges overlap in the Great Plains they may hybridize, producing birds with intermediate plumage traits.
Conservation Status
Both the Indigo Bunting and Lazuli Bunting have large breeding ranges and abundant total populations. According to the IUCN Red List they are both classified as species of Least Concern.
Some major points about their conservation status:
- Global population of Indigo Bunting estimated at 19 million birds.
- Lazuli Bunting population estimated at 11 million.
- Populations are generally stable or increasing for both species based on Breeding Bird Survey data.
- They readily adapt to human landscapes like farms, rural areas, parks and suburban yards.
- Major threats include habitat loss, pesticide use, collisions with vehicles and buildings during migration.
More research is needed into the effects of hybridization in the Great Plains on genetics and fitness. Climate change may also shift and reduce the extent of suitable breeding habitat for these birds in the future. But currently their large populations confer resilience. Providing shrubby vegetation and native plants that supply seeds and insects can help support both species. Limiting pesticide use is also beneficial. Careful monitoring of trends will ensure conservation actions can be taken if needed.
Key ID Tips
To quickly recap the main ways to distinguish Indigo and Lazuli Buntings:
- Indigos have darker purplish-blue plumage; Lazulis are brighter sky blue.
- Indigos have a bold eye mask; Lazulis lack an eye mask.
- Indigos have thick dark wing bars; Lazulis have thin faint wing bars.
- Indigos have dark tails; Lazuli tails have white outer feathers.
- Indigo songs are sweet, buzzy warbles; Lazuli songs are more complex and melodic.
- Indigos make sharp “tsip” calls; Lazulis make softer “hreep” calls.
- Indigos breed in eastern North America; Lazulis in western North America.
Focus on subtle plumage differences like the eye mask and underpart colors. Listen for variations in songs and calls. Also consider the geographic location and habitat. With practice, birders can recognize these stunning blue songsters by sight and sound.
Conclusion
In summary, the Indigo Bunting and Lazuli Bunting exhibit a number of similarities as close relatives, including brilliant blue breeding plumage, musical songs, and preferences for open brushy habitats. But they differ in the details of their vocalizations, subtle aspects of male plumage, geographic breeding ranges, and habitat associations. Being aware of these distinguishing traits allows observers to confidently identify which species they are observing. Both lazuli and indigo buntings are thriving songbirds that provide aesthetic and ecological value across North America. Appreciating the nuances that set them apart deepens our understanding of avian diversity.