The thick billed longspur (Rhynchophanes mccownii) and chestnut-collared longspur (Calcarius ornatus) are two species of passerine birds in the family Calcariidae. They can be distinguished by several key differences in their plumage, breeding habitat, distribution, behavior, and vocalizations. Understanding how to identify these two similar species is an important skill for birders across the Great Plains and western North America. This article will provide a detailed overview of the differences between thick billed and chestnut-collared longspurs.
Plumage Differences
The most notable difference between thick billed and chestnut-collared longspurs is in their plumage.
Thick Billed Longspur
The thick billed longspur is a large, heavy-billed longspur with the following identifying features:
- Brown upperparts with heavy black streaking
- Pale buffy underparts with sparse dark streaking on flanks
- Bold black and white face pattern
- Thick conical bill
- Black tail with white outer feathers
Adult males in breeding plumage have a black throat, black chest patches, and a reddish-brown nape. Females are duller overall with a buffy throat and breast. In winter, they lack the black throat and chest markings. Juveniles resemble females but are more brownish overall.
Chestnut-Collared Longspur
The chestnut-collared longspur is smaller and slimmer than the thick billed, with the following features:
- Gray-brown upperparts with dark streaking
- Pale underparts
- Bold black and white face
- Thin pointed bill
- Black tail with white outer feathers
Breeding males have a black throat, chestnut “collar”, and a black belly. Females have a buffy throat and breast. In winter, they lack the black throat and chestnut collar. Juveniles resemble females but are more brownish above.
Breeding Habitat Differences
The breeding habitats of these two longspurs also differ:
- Thick billed longspurs breed primarily in shortgrass prairie and other open grasslands, especially those grazed by bison or cattle.
- Chestnut-collared longspurs breed in both shortgrass and mixed-grass prairies, preferring drier habitats with sparser vegetation.
Thick billeds tend to favor moister prairie habitats than chestnut-collareds. The two may nest alongside each other but thick billeds are more likely to be found in pure grasslands.
Range and Distribution
These species have overlapping but distinct breeding and wintering ranges:
- Thick billed longspurs breed from southcentral Canada through the Great Plains. They winter primarily in the southcentral United States into Mexico.
- Chestnut-collared longspurs breed from northern Canada through the northern Great Plains. They winter from the southern Great Plains through the southwestern U.S. and Mexico.
There is broad overlap across the Great Plains but thick billeds range farther east while chestnut-collareds extend farther north and west. In winter, thick billeds concentrate more east and south while chestnut-collareds go west.
Behavioral Differences
Some subtle behavioral differences exist between the species:
- Thick billed longspurs walk more than hop, and prefer running across open ground if flushed.
- Chestnut-collared longspurs tend to hop more than walk, and fly short distances if disturbed.
- Thick billeds form larger flocks outside the breeding season while chestnut-collareds gather in smaller groups.
- Thick billeds roost communally on the ground while chestnut-collareds may roost scattered on plants.
In general, thick billed longspurs tend to be more gregarious than the somewhat solitary chestnut-collareds. But both species form mixed-species flocks in migration and winter.
Vocalizations
The songs and call notes of these species also differ:
- Male thick billed longspurs have a high-pitched song of “wolf whistles” and chatter calls.
- Male chestnut-collared longspurs sing a melodious, bell-like song and have a rattling call.
- Thick billeds have a soft, musical flight call while chestnut-collareds have a harsh “chap” call in flight.
Learning the vocalizations is key to distinguishing between these otherwise similar-looking grassland birds.
Conclusion
While thick billed and chestnut-collared longspurs can appear similar at first glance, they exhibit key differences in plumage, habitat, distribution, behavior, and vocalizations. Thick billeds are chunkier with heavier bills, favor moister prairie, range farther east, and are more gregarious. Chestnut-collareds are slimmer with pointed bills, prefer drier prairie, range farther west, and are more solitary. Paying attention to subtle field marks and songs is needed to properly identify these species across the Great Plains and western North America.
