Northern flicker

Ten subspecies are recognized, one of which is now extinct, though it may be invalid.[9] The extant subspecies were at one time considered subspecies of two separate species called the yellow-shafted flicker (C. auratus, with four subspecies) and the red-shafted flicker (C. cafer, with six subspecies, five living and one extinct), but they commonly interbreed where their ranges overlap and are now considered one species by the American Ornithologists Union. This is an example of what is referred to in science as the species problem.

• The southern yellow-shafted flicker (C. a. auratus) resides in the southeastern United States. It is yellow under the tail and underwings and has yellow shafts on its primaries. It has a gray cap, a beige face, and a red bar at the nape of the neck. Males have a black mustache. Colaptes comes from the Greek verb colapt, meaning "to peck"; auratus is from the Latin root aurat, meaning "gold" or "golden", and refers to the bird's underwings. As the state bird of Alabama,[10] this subspecies is known by the common name "yellowhammer", a term that originated during the American Civil War to describe Confederate soldiers from Alabama.[11]
• The northern yellow-shafted flicker (C. a. luteus; formerly C. a. borealis) resides from central Alaska throughout most of Canada to southern Labrador, Newfoundland, and the northeastern United States.
• The Cuban yellow-shafted flicker (C a. chrysocaulosus) is restricted to Cuba.
• The Grand Cayman yellow-shafted flicker (C. a. gundlachi) is restricted to Grand Cayman in the Cayman Islands. The subspecific epithet is named after Cuban naturalist Juan Gundlach.

• The western red-shafted flicker (C. a. cafer) resides in western North America. It is red under the tail and underwings and has red shafts on its primaries. It has a beige cap and a gray face. Males have a red mustache. The subspecific name cafer is the result of an error made in 1788 by the German systematist Johann Gmelin, who believed that its original habitat was in South Africa among the Xhosa people, then known as the "Kaffirs". As the origin of the subspecies designation is regarded as offensive by some, proposals to change the scientific name of this subspecies to C. a. lathami have been presented to the American Ornithological Society. The Society, in accordance with the rules governing scientific nomenclature, has as of September 2018 declined to support a change of the subspecific name, but may consult with the ICZN on the matter.[12][13]

• The coastal red-shafted flicker (C. a. collaris) has a range that closely overlaps that of C. a. cafer, extending along much of the West Coast of North America from British Columbia to northwestern Mexico.
• The dwarf red-shafted flicker (C. a. nanus) resides in western Texas south to northeastern Mexico.
• The Mexican red-shafted flicker (C. a. mexicanus) resides in central and southern Mexico from Durango to San Luis Potosí and Oaxaca.
• The Guatemalan red-shafted flicker (C. a. mexicanoides) resides in the highlands of southern Mexico and Central America. It is considered by some authorities to be a separate species, the Guatemalan flicker (C. mexicanoides).
• The Guadalupe red-shafted flicker (C. a. rufipileus)† is extinct and was formerly restricted to Guadalupe Island, off the northwestern coast of Baja California, Mexico. It was last recorded in 1906. It may be invalid.[14] Vagrants of an extant mainland red-shafted subspecies (which one is unknown) have recently begun recolonizing Guadalupe Island as the habitat improved after the extirpation of feral goats.

• 
  C. a. cafer: female (left), male (right)
• 
  C. a. chrysocaulosus
  female, Cuba
• 
  C. a. mexicanoides
  female, Guatemala

This bird's call is a sustained laugh, ki ki ki ki, quite different from that of the pileated woodpecker (Dryocopus pileatus). One may also hear a constant knocking as they often drum on trees or even metal objects to declare territory. Like most woodpeckers, northern flickers drum on objects as a form of communication and territory defense. In such cases, the purpose is to make as loud a noise as possible, so woodpeckers sometimes drum on metal objects.

Like many woodpeckers, its flight is undulating. The repeated cycle of a quick succession of flaps followed by a pause creates an effect comparable to a roller coaster.

A male northern flicker guarding its nest cavity

According to an article published in Ibis, the availability of food affects the coloration of feathers in northern flicker nestlings. The article focused on the correlation between melanin spots and carotenoid-based coloration on the wings of nestlings with food stress via indirect manipulation of brood size. The article found that there was a positive correlation between the quality of the nestlings' diet and T-cell-mediated immune response. T-cell-mediated immune response was found to be positively correlated with brightness of pigmentation in flight feathers, but not related to melanin spot intensity.[21]

The northern flicker's breeding habitat consists of forested areas across North America and as far south as Central America. They are cavity nesters which typically nest in trees, but they also use posts and birdhouses if sized and situated appropriately. They prefer to excavate their own home, although they reuse and repair damaged or abandoned nests. Abandoned northern flicker nests create habitat for other cavity nesters. Northern flickers are sometimes driven away from their nesting sites by another cavity nester, the common starling (Sturnus vulgaris).

About 1 to 2 weeks are needed for a mated pair to build the nest. The entrance hole is roughly 5 to 10 cm (2 to 4 in) wide. A typical clutch consists of six to eight eggs whose shells are pure white with a smooth surface and high gloss. The eggs are the second-largest of the North American woodpecker species, exceeded only by the pileated woodpecker's. Incubation is by both sexes for about 11 to 12 days. The young are fed by regurgitation and fledge about 25 to 28 days after hatching.

Northern flickers are partial migrants, in which some southern populations are completely non-migratory.[23] Those that do migrate tend to begin their spring migration towards the beginning of April and make their return between September and October.[24] Individuals that breed farther north travel greater distances than their migratory southern conspecifics, often resulting in the convergence of northern and southern populations at wintering sites.[23] This discrepancy likely arises from the Northern flickers’ ground foraging behavior, in which prey can only be found in snow-free locations.[23] Furthermore, females tend to winter farther north than males, suggesting that parental investment and division of reproductive labour are key factors in determining individual migratory behavior.[23] Rising temperatures resulting from anthropogenic climate change have been shown to trigger migration prematurely in Northern flickers, as well as many other migratory bird species as evidenced in Sherbrooke, Quebec.[25]

Connections between breeding and wintering location of flickers.

Northern flickers are divided into eastern and western populations by the Rocky Mountains, with each population having a unique migratory pathway.[23] Individuals breeding in the prairie provinces of Canada, the Dakotas, and surrounding U.S. states winter in Texas, Oklahoma, and Arkansas.[23] Those breeding in southern Ontario and Michigan to New England winter from east Texas to the Carolinas, whereas those breeding in British Columbia and the Pacific Northwest winter from central California to Baja Peninsula, Mexico.[23]

During migration, Northern flickers may form flocks.[26] Additionally, the species’ propensity for roosting in cavities is not mitigated during migration. On average, 75% of individuals spend their nights in a cavity during migration, even in completely unknown locations.[26] Northern flickers demonstrate a high rate of nest cavity re-use, as opposed to excavating new cavities each year.[27] Furthermore, breeding individuals exhibit intense site fidelity, with pairs consistently returning to the specific nest cavity they used in the previous year.[28]