The Lark Bunting: Colorado’s Sweet Songbird of the Plains
The lark bunting ( Calamospiza melanocorys) is a captivating bird species native to the grasslands of North America. Designated as the state bird of Colorado in 1931, this medium-sized sparrow exhibits striking plumage, unique behaviors, and a fascinating life history. This article delves into the world of the lark bunting, exploring its physical characteristics, behavior, habitat, conservation status, and more.
Physical Characteristics
The lark bunting is a robust sparrow with a distinctive appearance. Perhaps its most notable feature is its large, conical bill, which is pale blue-gray in color . This stout bill is well-suited for cracking seeds, a primary food source for the lark bunting .
Adult lark buntings range in size from 5.5 to 7.1 inches in length, with a wingspan of 9.8 to 11.0 inches . They have similar dimensions to a house sparrow, measuring approximately 6.5 inches from beak to tail . Their weight varies between 1.3 and 1.5 ounces .
The plumage of the lark bunting varies dramatically between sexes and seasons. Breeding males are unmistakable, with a velvety black body and contrasting white wing patches . These white patches are formed by the wing coverts and the edges of the innermost flight feathers, known as tertials . Nonbreeding males, females, and immature birds have a more subdued appearance. They are brownish-gray above and pale with brown streaking below, with a noticeable white patch on the upper wing . Females also have a pale stripe over the eye and a dark “mustache” stripe that contrasts with a white throat patch .
Behavior and Habitat
With their strong legs and bills, lark buntings are primarily ground foragers, spending much of their time hopping or walking on the ground as they search for food . They use these tools to uncover seeds and insects in the soil. Interestingly, they have a unique galloping gait that they employ when pursuing fast-moving insect prey .
These birds are highly social, often forming large flocks during migration and in their wintering grounds . During the breeding season, however, they become territorial and aggressively defend their nesting sites . Lark buntings are easily disturbed and will typically fly to a low branch or fence when alarmed .
Lark buntings are diurnal, meaning they are most active during the day, with peak activity periods typically in the early morning and late afternoon .
Habitat
Lark buntings are found primarily in the Great Plains of North America . Their breeding range extends from southern Canada through the central United States . They prefer open, grassy habitats such as prairies, pastures, and cultivated fields, where they can easily find food and nesting sites . They avoid bare ground when nesting and favor areas with a mix of short and tall grasses, as well as shrubs for shade and protection from the sun . They often nest at the base of a small shrub or cactus .
During migration, lark buntings can be found in a variety of habitats, including grasslands, shrublands, and agricultural fields . In their wintering grounds, which extend from the southern United States into central Mexico, they inhabit desert scrub, grasslands, and agricultural areas .
Diet
Lark buntings have a varied diet that consists of both seeds and insects . The proportion of each in their diet varies depending on the season and the availability of food sources. During the breeding season, insects make up a significant portion of their diet, particularly grasshoppers . They also consume beetles, true bugs, bees, ants, and other invertebrates . In winter, their diet shifts towards seeds, mainly those of weeds and grasses, as well as some waste grain .
Mating and Nesting
Lark buntings are known for their unique mating displays. Males perform a courtship song while flying upwards and then descending with a series of zigzagging movements . This display, often called “skylarking,” is accompanied by a melodious song that consists of varied whistles and trills . In spring and summer, males sing two different types of songs. They are sung either slowly and distinctly or more rapidly, as trills .
Lark buntings typically nest in dispersed colonies . The nest is an open cup built on the ground in a grassy area, usually sheltered by overhanging grass or weeds . The female chooses the nest site and constructs the nest using grass, weeds, rootlets, and fine grass, often lining it with plant down or animal hair . When threatened, lark buntings may sound alarm calls and perform displays to defend the nest and chicks. They will also perform distraction displays such as the “mouse-like run” or “broken-wing act” .
Females lay 4–5 eggs, sometimes as few as 3 or as many as 7 . The eggs are pale blue to greenish-blue, usually unmarked but sometimes dotted with reddish-brown . Incubation is primarily carried out by the female, although the male may help at times . The incubation period lasts 11–12 days . Interestingly, female mate choice varies significantly from year to year, with females showing preferences for different male traits such as black coloring, wing patch size, and beak size .
Both parents feed the nestlings . The young leave the nest about 9 days after hatching . Lark buntings typically raise one brood per year, but sometimes they may raise two . Fall migration begins very early, with some birds appearing south of the breeding range by late July .
Conservation Status
Although still relatively common, lark bunting populations have declined dramatically in recent decades . According to Partners in Flight, their numbers have fallen by an estimated 86% since 1970 . The species is designated as a Common Bird in Steep Decline, with an estimated global breeding population of 10 million .
The primary threats to lark buntings are habitat loss and degradation . The conversion of native grasslands to cropland, urbanization, and energy development have all contributed to the decline of suitable habitat for this species . Insecticide use may also be a factor, as it reduces the availability of insect prey .
Conservation Efforts
Several conservation efforts are underway to help protect lark buntings and their habitat. The Conservation Reserve Program (CRP) has been shown to benefit lark buntings by providing suitable nesting habitat in lands planted back to native grasses . However, the nomadic behavior of this species makes it difficult to precisely evaluate the effectiveness of the program .
Other conservation measures include:
- Maintaining native grasslands through appropriate grazing management and prescribed fire : Moderate grazing can help maintain a mosaic of suitable habitat for lark buntings, while prescribed fire can prevent the encroachment of woody species and promote the growth of native grasses.
- Protecting large tracts of land from agricultural development to limit habitat fragmentation : Habitat fragmentation can isolate populations and increase their vulnerability to predators and brood parasites.
- Reducing the use of insecticides in areas where lark buntings breed : Insecticides can directly kill lark buntings or reduce their food supply by eliminating insects.
- Raising awareness about the importance of grassland conservation : Educating the public about the value of grasslands and the threats they face can help garner support for conservation efforts.
The lark bunting serves as an indicator species for the health of grassland ecosystems, with population trends providing valuable insights into the state of these habitats and the effectiveness of conservation efforts .
Where to See Lark Buntings
Lark buntings can be found in a variety of grassland habitats throughout their range. During the breeding season, they are most numerous in large expanses of native grasslands with sagebrush . Watch and listen for breeding males as they deliver their flight song, rising up and then gliding down to earth as they sing .
In migration and winter, similar habitats are home to roving flocks of lark buntings . Slowly driving through appropriate habitat, watching and listening, is a good way to find this species .
Interesting Facts
- Lark buntings have two different flight-song types. The main song, sometimes given in flight, is a series of notes delivered in distinct phrases that differ in both pitch and speed. The other flight song is heard mostly from rival males and contains harsh, low notes, pauses, and sharp whistles .
- Female mate choice in lark buntings is radically different from year to year. In different years, females show preference based on males’ black coloring, size of wing patch, size of beak, as well as other characteristics .
- An observer in Kansas during the Dust Bowl year of 1937 noted that while other wildlife all but vanished, lark buntings actually increased and nested successfully . These birds may be able to survive periods of drought without drinking water, taking moisture from grasshoppers and other insects, their chief food during summer .
Ecosystem Services
Lark buntings provide several valuable ecosystem services:
- Insect control: As ground foragers, they play an essential role in controlling insect populations within their habitats, particularly during the breeding season when insects make up a significant portion of their diet .
- Seed dispersal: By consuming seeds, they aid in the dispersal of various plant species, promoting plant diversity and contributing to the overall health of their ecosystems .
- Ecotourism: Their presence within an ecosystem attracts birdwatchers and nature enthusiasts, providing opportunities for ecotourism and fostering an appreciation for the natural environment .
Conclusion
The lark bunting is a remarkable bird species that plays an important role in the grassland ecosystems of North America. Its striking appearance, unique behaviors, and fascinating life history make it a captivating subject for birdwatchers and nature enthusiasts alike. The lark bunting has adapted to thrive in the challenging environment of the Great Plains, exhibiting unique behaviors such as its distinctive mating displays and its ability to survive droughts by obtaining moisture from insects. However, this species is facing significant challenges due to habitat loss and degradation. Conservation efforts are crucial to ensure the long-term survival of this iconic songbird of the plains, and its continued presence is essential for maintaining the health and biodiversity of grassland ecosystems.
