Brown-headed Cowbird

The world of birds seems to be full of endless surprises. Even the smallest and the most inconspicuous birds always seem to have surprising traits that catch avid birdwatchers by surprise. The Brown-headed Cowbird is a stout Blackbird that has fascinated ornithologists for a variety of reasons. For centuries they follow large bison herds on grasslands as they eat insects that are purged from the grass after it is grazed by the herds. Today, they continue to be seen as they follow cattle from coast to coast across North America.

About Brown-headed Cowbirds

Their methodology for raising their young is also unique as they display parasitic behaviors. These birds typically nest other bird’s nests and are typically indiscriminate in their selections of such nests. For a few decades in the 20th century, the massive growth of cattle-based industries led to a huge population surge of these birds. This led to further negative impacts on other bird species as Brown-headed Cowbirds became increasingly abundant. However, there has been a minute decline in their total numbers over the last few decades.

You can find these curious birds in fields, meadows, and lawns across central North America. With males flaunting their glossy black plumages and their gurgling songs during the migration and winter seasons. The more you learn about them, the more interesting they can get.

● Brown-headed Cowbird Photos, Color Pattern, Song
● Brown-headed Cowbird Size, Eating behavior, Habitat
● Brown-headed Cowbird Range and Migration, Nesting

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Brown-headed Cowbird Color Pattern

Brown-headed Cowbirds are highly sexually dimorphic in appearance. The two sexes can be easily distinguished from each other through the color of their plumages. Adult males have a plain brown head, neck, and upper chest while the rest of their bodies are glossy black. While most of the body seems to emit a greenish tint in the black plumes. Their backs can give out a distinct violet sheen that makes them stand out and seem almost iridescent. In poor lighting, their heads also seem like they are black if observed from a distance. Their bills, legs, and feet are also black while their irises are brown.

Adult females are brownish-grey overall with a faint green gloss that is less prominent than the sheen seen in males. Their wings have darker centres and blackish shaft-streaks, especially on the back. Brown-headed Cowbird’s wings and tail usually either have dusky brownish-grey hues or are entirely brown while being narrowly streaked with darker shades of brown. Their chins and throats are typically far paler than the rest of their bodies and sometimes seem to be whitish, features that stand out with their unstreaked dusky chests and brownish mandibles. Their legs and feet are also dusky while their irises are brown.

Juveniles resemble females but have underparts that are streaked with dull brown or whitish shades. Their upper parts vary from dark brown to sooty greyish brown while their feathers are a narrow pale greyish-brown with whitish margins. Brown-headed Cowbird’s wing covets and tertials are far more broadly and conspicuously margined with buffy undertones, while the lateral edges of their feathers are a darker brown. Their legs and feet are brownish and their mandibles are paler in color.

Description and Identification

There are multiple ways to identify these extravagant birds. Firstly, they can be found feeding on the ground with other groups of Blackbirds and Starlings on grassy plains, parks, lawns, or pastures. Males can be seen gathering on lawns to strut and display for mates as they call out for females with their noisy calls that resemble clicks, whistles, and sometimes even flowing gurgles. In order to differentiate them from other Blackbirds, look out for the green and violet sheens present in the coats of the males. They are also smaller in size when compared to other Blackbirds, donning shorter bills as well.

Secondly, these birds often follow herds of cattle in order to secure prey. This is also an important identifier as the locations of the two can be closely related in many cases. While yards with livestock have the highest chances of encountering these Cowbirds, open grounds and lawns with grain also attract these birds. Females of this species are a little harder to detect due to their plainer appearances but can often be found in close proximity to other flocks foraging on the ground. These birds are also frequent visitors to bird feeders and do not seem to mind human inhabitation too much. Attentive birdwatchers will not have much trouble in finding and identifying these Cowbirds.

Brown-headed Cowbird Song

Brown-headed Cowbirds have several vocalisations that can be seen manifesting themselves through their perched songs and flight whistles. Males give out a gurgling song when they perch, a sound that roughly sounds like “glug glug glee”, “bublowcomsee”, or “bub ko lum tseeee”. These songs are typically divided into two phrases, with the first
maintaining a fluid quality in low frequencies, and the second ending in pure tones of higher frequencies that can hold a buzzing quality to it. These calls are almost always heard when there are other Cowbirds nearby and are generally more intense if the other Cowbird is male.

Their flight whistles tend to be 2–5 syllables of pure tones with an extreme range of frequencies. It can be best described as an inhaled, squeaky “whssss” followed by an exhaled “pseeee”. Occasionally, subtle buzzes or trills are added to these calls. These calls are also primarily done by the males. Females give out a chatter-call that can be rendered as a “ch’ch’ch’ch’ch”, a vocalisation that sounds significantly different from the male chatter-call. Males tend to have little to no variation in the frequency of their chatter calls. Females may give out many chatter calls in rapid succession while males do not give more than one or two. Juveniles also give out a rudimentary chatter-call.

Both sexes give out a clicking sound that resembles a “kek” and “kuk”. Both sexes make these sounds during courtship rituals as the two sexes chase each other. It can often be interpreted as the signs given by a male when he shows interest in a potential mate.

Brown-headed Cowbird Size

Brown-headed Cowbirds are Blackbirds that fall in the small to medium range of their species. Compared to other blackbirds, they have shorter tails and thicker heads. Their bills are distinctive with their thicker base and shorter length, giving them a finch-like appearance at a glance. They are also sexually dimorphic in size, with males being roughly 10% larger than females. Males are 7.5–8.7 inches in length with a wingspan of 14.2 inches approximately. While females are 6.3–7.9 inches with a wingspan of 12.6–14 inches. Males roughly weigh between 1.5–1.8 ounces while females weigh 1.3–1.6 ounces. Their measurements make them fall between Sparrows and Robins in terms of their size.

Brown-headed Cowbird Behavior

The feeding behaviour of these birds is mostly foraging on the ground as they walk across grassy terrains with mixed flocks of Blackbirds, Grackles, and Starlings. They derive their names from their close association to grazing livestock and can thus also be seen following herds of cattle as they graze. They rarely forage on branches and can often be found running after insects.

Their behaviour in-flight displays constant wingbeats as they fight in straight, direct lines. When males sing, they raise their back and chest feathers and ruffle them slightly as they lift their wings and spread their tail feathers before bowing forward. Sometimes, large groups of males may do this together. Females also do this towards courting males. Both sexes have preening movements that are similar to other passerine birds and can be observed scratching their heads over the wings. The way they stretch is lateral, with their legs extended backwards and their side wings extended fully while their tails are spread.

The females of this species exhibit parasitic behaviors. They do not build their own nests but instead quietly look for signs of other birds building nests. They typically flutter through the foliage to chase birds away from their nests. Young Cowbird nestlings may also roll out the eggs of other bird species when they hatch.

Brown-headed Cowbird Diet

These birds mostly eat seeds from grasses and weeds and some waste crop grains. These plant-based food items make up for around half of their diet during the breeding seasons and more than 90% during the winter seasons. The rest of their diet is composed of insects like grasshoppers, beetles, caterpillars, centipedes, and millipedes. Since the
females of these species lay large numbers of eggs at once, females also tend to consume snail shells and sometimes the eggs of the nests they visit in order to meet the large calcium requirement.

Brown-headed Cowbird Habitat

Brown-headed Cowbirds live in temperate to subtropical grasslands with low and scattered trees. They can also be seen inhabiting woodland edges, brushy thickets, prairies, fields, pastures, orchards, and urban areas like suburban residential lands and agricultural farms. They avoid dense forests due to the lack of areas that they can forage in.

Deforestation has ironically helped their populations as they have begun to expand their range eastwards in the United States. They favor open or semi-open countries at all seasons and can sometimes even be found in deserts.

Range and Migration

These birds have a vast range that spans from south-eastern Canada, through all of the United States and Mexico, to northern Central America. Many flocks present in the United States are permanent residents of their habitats but may travel short distances in search of food supplies. Populations at northern parts of their range are short-distant migrants and can travel as far as 530 miles during the migration season towards their wintering grounds.

Brown-headed Cowbird Lifecycle

The clutch sizes of these birds tend to be large, with females typically laying nearly one whitish brown egg per day for several weeks during the breeding seasons. While the average number of eggs each season can go up to 40. In exceptional cases, females lay more than 70 eggs in a single season. Since the females lay eggs in the nests of other species, their social behaviour is not well known and thus the incubation period can greatly vary depending on the nest selected. However, over 140 of the different bird species have been observed to raise young Cowbirds. They are often fed by the host parents as well. Hatched Cowbirds are entirely naked and blind, but the young grow much
faster compared to other bird species and generally leave their nests after 10–11 days.

Nesting

As discussed earlier, the females of this species lay eggs in the nests made by other species. They utilize nests of over 220 different bird species, including Red-winged Blackbirds, Ovenbirds, Yellow Warblers, Song Sparrows, Chipping Sparrows, Red-eyed Vireos, Eastern Towhees, and Spotted Towhees. The selected locations can be varied but tend to be above the ground, ranging from shrubs and treetops to nests in tree cavities. These birds select nests that contain eggs of smaller volume and sometimes size than their own.

Anatomy of a Brown-headed Cowbird

Brown-headed Cowbirds have stout builds that are comparable to other Blackbirds but are distinguished by their thick finch-like heads and smaller beaks. Their tails are much shorter than other Blackbirds, and they are only slightly smaller than Red-winged Blackbirds in their total size. Males tend to be slightly larger and more voluminous than females and seem to be plumper as well. On the other hand, females bear a more delicate and slender appearance in comparison. The legs of these birds are mid-size in relation to their size, and their wings are slender and pointed.

Final Thoughts

These Cowbirds are considered to be pests by many human settlements. Their surge in numbers during the 20th century drove many other bird species to the endangered status, resulting in active and periodic efforts to control their populations in order to maintain other bird species in the vicinity. They are very easily found and tend to increase their activities in a particular location after active efforts to remove them are made, a very unique detail that was unexpected to the scientific communities that studied them. Despite the slight drop in their populations over the recent decades, their conservation status categorises them under Least Concern.

Brown-headed Cowbirds are some of the most easily found birds in the United States. Individuals who may not be avid birdwatchers can find these birds, but distinguishing their unique behavioural patterns from other Blackbirds is a skill that only attentive bird-lovers have. So the next time you decide to stroll down to your backyard, scatter some grain on the ground and see if these parasitic but curious birds take the bait.

Ornithology

Bird Watching Academy & Camp Subscription Boxes

At the Bird Watching Academy & Camp we help kids, youth, and adults get excited and involved in bird watching. We have several monthly subscription boxes that you can subscribe to. Our monthly subscription boxes help kids, youth, and adults learn about birds, bird watching, and bird conservation.

Bird Watching Binoculars for IdentifyingBrown-headed Cowbirds

The most common types of bird watching binoculars for viewing Brown-headed Cowbirds are 8×21 binoculars and 10×42 binoculars. Bird Watching Academy & Camp sells really nice 8×21 binoculars and 10×42 binoculars. You can view and purchase them here.

Brown-headed Cowbird Stickers

Stickers are a great way for you to display your love for bird watching and the Brown-headed Cowbird. We sell a monthly subscription sticker pack. The sticker packs have 12 bird stickers. These sticker packs will help your kids learn new birds every month.

Bird Feeders For Brown-headed Cowbirds

There are many types of bird feeders. Bird feeders are a great addition to your backyard. Bird feeders will increase the chances of attracting birds drastically. Both kids and adults will have a great time watching birds eat at these bird feeders. There are a wide variety of bird feeders on the market and it is important to find the best fit for you and your backyard.

Bird Houses For Brown-headed Cowbirds

There are many types of bird houses. Building a bird house is always fun but can be frustrating. Getting a bird house for kids to watch birds grow is always fun. If you spend a little extra money on bird houses, it will be well worth every penny and they’ll look great.