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Feathered Facts

Can Birds Smell?

For many years, scientific literature claimed that birds couldn’t smell or didn’t rely on their sense of smell for any purpose. However, research over the past few decades has proven that this claim is entirely false. Multiple studies show the fascinating and varied ways birds rely on smell for survival. Some bird species can even smell better than humans! 

A Scrub-Jay close up shot.
Image by Jerry Ting via Flickr.

Before explaining the studies that changed the answer to the question, “Can birds smell?” let’s discuss why it was previously believed that birds couldn’t smell. From there, we’ll uncover how species such as turkey vultures, dark-eyed juncos, seabirds, and others use their olfactory sense to survive. 

Why Science Believed Birds Couldn’t Smell

In John James Audubon’s notes on turkey vultures, he states, “The experiments instituted upon Vultures show that not only are they not led to their prey by the sense of smell, but also that they are not made sensible by it of the presence of food when in their immediate proximity.”

The experiments Audubon mentioned took place in the 1820s. He hypothesized that turkey vultures relied on their eyesight, rather than their sense of smell, to find carrion. He conducted two experiments to test this hypothesis. 

A Turkey Vulture, a bird who we now know can smell despite previous contradictory evidence.
Image by Gavin Edmondstone via Flickr.

In one of the experiments, he stuffed a deer skin with grass and left it out in the open with its legs up. Turkey vultures came to the deer and ripped it open, only to fly away once they realized there was only useless grass. 

In another experiment, Audubon placed a rotting pig carcass in a ravine and covered it with foliage and brush. No turkey vultures came down to the carcass. 

From these results, Audubon concluded that turkey vultures did not use smell to find food. This finding significantly influenced scientific literature, so much so that it became a popular belief that birds couldn’t smell or didn’t rely on smell. 

The Evidence That Finally Said Yes to Can Birds Smell

There have been many pioneers who dedicated years of research and field study to finding an answer to the question, “Can birds smell?” They weren’t content with the original findings. Although Audubon thought them to be fully conclusive, many scientists didn’t agree—and with good reason. Now, we have genetic evidence and field study reports that undoubtedly support the fact that birds can smell. 

Birds Have Olfactory Receptors 

To be clear, most early biologists and ornithologists didn’t believe birds couldnot smell at all. Rather, they believed birds only had a rudimentary sense of smell and relied on their other senses for survival. After all, birds still have an olfactory system, which consists of the nose and nasal cavities. They also have an olfactory bulb, which is the brain’s smell center. 

Research shows that within a bird’s olfactory system are olfactory receptors: proteins in the nasal passages that attach to odor molecules and translate the smell to the brain. Early scientists believed that these receptors were few and possibly mutated or nonfunctional. 

Some Birds Have More Olfactory Receptors Than Even Humans

However, further research on several bird species showed that they contain several (at least a hundred or more) active olfactory receptors. For comparison, humans have about 100-200 functional receptors. A recent study compared the genomes of a hummingbird, emu, chicken,  manakin, and zebra finch. The study found that these birds contained the following numbers of functional olfactory receptors: 

  • Hummingbird: 109
  • Emu: 296
  • Chicken: 355
  • Manakin: 117
  • Zebra Finch: 69
A Blue-throated Hummingbird
Image by Matthew Studebaker via Flickr and website.

This means that these birds, especially the emu and chicken, have diverse scent receptors that allow them to pick up on a variety of smells. These birds were chosen for the study because they have “multiple publicly available genome assemblies on GenBank.” 

According to the study, “These five species are representative across the three major groupings of extant birds [bird species that are alive and not extinct], including the Paleognathae and two groups within the Neognathae, Galloanseres, and Neoaves, represent diverse ecology, and include two important avian models, chicken and zebra finch.” As such, they represent other related bird species, giving biologists an idea of how many receptors each bird species might have based on these findings.  

Field studies on various bird species have confirmed the genetic findings above and have added compelling evidence that says “yes” to the question: Can birds smell? In fact, they do it quite well. 

New Evidence Challenged the Original Turkey Vulture Smell Experiment

Let’s go back to the turkey vulture experiments that started the whole controversial question: can birds smell? In 1960, ornithologist Kenneth Stager proved that Audubon’s original findings were inconclusive. Stager discovered that turkey vultures only feed from a carcass within a specific timeframe. They prefer it to be fresh and won’t go to a carcass after about four days. 

Given that Audubon’s experiment used a rotting carcass, it’s likely the carcass was too far gone even for the turkey vultures. Furthermore, Stager proved that turkey vultures can smell and identified the specific scent they are attracted to: ethyl mercaptan. 

Freshly decaying carcasses emit ethyl mercaptan. This compound also happens to be added to natural gas so that we can smell it when there’s a leak. Because of this, natural gas engineers have even followed vultures to areas where there are leaks in gas pipelines. 

Further Experiments Addressed Whether Other Birds Can Smell

Turkey vultures aren’t the only birds that rely on smell to sniff out their next meal. Researcher Gabrielle Nevitt proved that Antarctic seabirds, such as shearwaters, albatrosses, and petrels, rely on smell to find food. 

A close-up shot of a Fulmar, a tube-nosed bird who can smell very well.
Many seabirds, like this tube-nosed Fulmar, rely on their sense of smell to find food. Image by Anne Canright via Flickr.

In her experiments, she dipped tampons (of all things) in pungent compounds found in marine fish and krill and hung them on kites to see if any of the above birds would come swooping in. They did. 

So many came that she brought the kites down in fear that the birds would get tangled in them. She also dropped vegetable oil mixed with the fishy compound into the water and found that the birds flocked to the oil. 

Nevitt went on to further prove that tube-nosed seabirds use smell to find food. She honed in on the specific scent they track: dimethyl sulfide (DMS). This gas is emitted by phytoplankton when krill feed on the microscopic plants. Krill are a major food source for these birds. Through various experiments, she found that tube-nosed seabirds could detect the smell of DMS and track it over miles of open water. 

Poor-sighted Birds Rely on Their Sense of Smell

ides seabirds, other birds rely on their sense of smell, rather than their eyesight, to find food. One of the earliest leading researchers on birds’ olfactory senses, Bernice Wenzel, discovered that the New Zealand kiwi relied on smell to find earthworms and other invertebrates. 

Kiwis are flightless, nocturnal birds with poor eyesight. They are the only bird species to have their nostrils at the end of their long beak, which sways back and forth above the ground to pick up scents. Based on genetic findings, kiwis have one of the largest olfactory bulb sizes in birds and about 600 olfactory genes. 

A Kiwi, a bird who can use smell to navigate in the dark.
Since kiwis are nocturnal and have poor eyesight, they rely heavily on their keen sense of smell. Image by Shaun Lee via Flickr & Facebook.

Another example is the European white stork, which is attracted to the smell of freshly mowed grass. This species has learned that when grass is cut, they are more likely to find exposed insect and rodent prey. Researcher Martin Wikelski and his colleagues proved this by spraying the smell of cut grass over an unmowed field. Sure enough, the storks came to forage, even though the field hadn’t been mowed. 

These are just a few examples (of many) that show how diverse bird species rely on smell to find food. However, sniffing out food isn’t the only way birds rely on their sense of smell to survive. 

Other Ways Birds Rely on Scent

Research shows that a bird’s sense of smell correlates to the size of the olfactory bulb in their brain. Based on this, it’s easy to assume that small birds, such as dark-eyed juncos, who have tiny bulbs, don’t rely on smell as much. However, professor and researcher Danielle Whittaker discovered that juncos relied on smell, rather than visual cues, for reproduction. 

Mating, Escaping Predators & Dodging Parasites

Juncos have a gland at the base of their tail that secretes what is known as “preen oil.” They use this oil to protect their feathers, but it also has a scent. Whittaker found that juncos had individual scents, which allowed them to be distinguishable in their flock. She found that females were attracted to a male’s scent more than to visual factors. She also discovered that juncos with strong “male-like” or “female-like” scents had more success raising their young to fledging.

A pair of Dark-eyed Juncos, birds who can smell to tell a female from male.
Juncos use their sense of smell to distinguish male and female birds in their flocks. Image by Mike Nolen via Flickr.

Even though juncos have a small olfactory bulb and subsequently fewer scent receptors, these small sparrows significantly rely on smell for their social and reproductive life. Similarly, the Eurasian blue tit and European starling can detect aromatic plants, such as mint or milfoil. These birds weave these plants into their nests for two reasons: one, the scent seems to play a part in attracting the female: and second, these aromatic plants repel parasites. 

Furthermore, the blue tit won’t enter its nest if it smells weasels. It can also find prey by smelling the volatile chemicals emitted by pine trees when they are attacked by insects. 

The crested auklet, a seabird found on St. Lawrence Island in the Bering Sea, smells like tangerines. Scientist Julie Hagelin found that these birds start producing this scent in early spring, and it wears off over the summer. Females are attracted to strong-scented males, and she says, “the scent could function as a kind of ‘olfactory ornament,”. This is similar to how male birds adorn bright feather colors in spring to attract a mate. 

Some Birds Use Smell To Find Their Way Home

Apart from reproduction and foraging, birds rely on scent to find their favorite roosting spots or burrows. Burrowing birds, such as the diving petrel, can distinguish their burrow among many others based on the scent. The rock dove, or pigeon, can find its way back to its roosting site using smell alone and can even find its way back over 1,000 miles. 

Can Birds Smell? 

A close-up of a grackle nose.
Image by JPatR via Flickr.

Nowadays, there’s no doubt about whether birds can smell or not—they most certainly can. So the next time someone asks you, “Can birds smell?” I hope you answer with an enthusiastic, “Yes!”  

Perhaps you’ll tell them about the unassuming dark-eyed juncos who choose their mate by scent. Or the mighty albatross, who flies over the open sea, tracking their prey by the smell of DMS. Maybe you’ll tell them about the turkey vulture, and how the famous John James Audubon got it all wrong. No matter what part of the research you tell them, just make sure they know birds definitely can smell.   

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Black & White Birds in North America

When people seek out beautiful birds, they’re often drawn to the most colorful ones. Yet, beauty is about so much more than just colors. There are a lot of stunning birds around the world with black and white feather patterns. Even just in North America, some of the most mesmerizing birds are black and white. So, what are some common black & white birds in North America to keep an eye out for?

There are lots of birds that have black and white feathers. Some are only black and white while others have hints of vibrant colors mixed in. Below are some of the most common and most memorable black & white birds living across North America.

1. Black-and-White Warbler (Striped Black & White Birds)

A Black-and-white Warbler
Image by Edward Post via Flickr.

The black-and-white warbler only has black and white feathers, but those two colors appear in a unique display of stripes that are sure to catch your eye. You’ll commonly see them probing moss and bark with their tiny, sharp beaks as they search for insects to eat. When breeding, they live across Canada and parts of the United States, but they eventually migrate down to Mexico and Northern South America when they’re not breeding.

2. Common Loon (Black & White Water Birds)

A Common Loon swimming through the water.
Image by Rick Cleland via Flickr.

You can almost always find common loons near bodies of water, where they can dive under the water without causing a splash to stealthily catch fish. They breed near quiet, secluded freshwater lakes across Canada and the United States, and when they’re migrating and not breeding, you’ll likely see them along coastlines and near estuaries, rivers, and lakes. Breeding adults have bold black feathers with white spots along their wings and bodies.

3. Black-Capped Chickadee

Spot black-capped chickadees on the Osamequin Nature Trails and Bird Sanctuary, Rhode Island.
Image by Jerry Ting via Flickr.

While the black-capped chickadee isn’t a completely black & white bird, it has a bold black head with a white strip in the middle. Then, its wings are gray while its body is light brown and white. Many people find these birds adorable because of their oversized round heads, which accentuate their coloring. You can find these cute birds across Canada and the Northern United States year-round because they don’t migrate.

4. Carolina Chickadee

A Carolina Chickadee perched on a branch.
Image by David Alexander via Flickr.

The Carolina chickadee looks almost identical to the black-capped chickadee. It has a round black-and-white head with a gray and white body. Overall, black-capped chickadees have bolder colors, but Carolina chickadees still have notable black and white markings around their faces. Carolina chickadees have a much smaller range, only living in the Southeastern United States. Since they’re so similar, the black-capped chickadees and Carolina chickadees can breed to create a hybrid when in the same location.

5. Downy Woodpecker (Black & White Woodpecker)

Male and Female Downy Woodpeckers
Image by Mike Nolen via Flickr.

The Downy Woodpecker, one of North America’s most common woodpeckers, has a beautiful black and white feather pattern, including black wings with white spots. The only part of their bodies that doesn’t seem to match it is the tiny red patch on their heads. You can find these birds year-round across most of Canada and the United States. In the winter, these birds join flocks of other species, such as chickadees and nuthatches.

6. Hairy Woodpecker

A Hairy Woodpecker
Image by Rockytopk9 via Flickr.

Hairy woodpeckers look very similar to downy woodpeckers. They have black and white feathers, including black wings with white spots and a white belly. Like downy woodpeckers, males have a red spot on their head (although it’s a much lighter red than the one on the other species). They have a wide range that spreads from most of Canada to parts of Mexico. They don’t migrate, so you can find them across their range year-round.

7. White-Breasted Nuthatch

Perched Bird With Seed
Image by Rockytopk9 via Flickr.

This species has a white face and belly paired with black and gray coloring on their wings and back. They’re called nuthatches because they collect large nuts and seeds, jam them into tree bark, and hit them with their sharp bills so they “hatch.” These birds typically stay in the same range year-round, which stretches across most of the United States, parts of Southern Canada, and inland areas of Mexico.

8. Black-Billed Magpie (Black & White Birds with Blue Wings)

A Black-billed Magpie - Iconic Corvidae of the West
Image by nickinthegarden via Flickr.

At first glance, black-billed magpies look just black and white. They have a solid black head with a black and white body. Yet, when they spread their wings, you can see that some of their feathers have a beautiful tint of blue, adding to their stunning appearance. You can find these unique birds across the Northwestern United States and Southwestern Canada. They build massive nests that can take them up to 40 days to complete.

9. Rose-Breasted Grosbeak (Male Birds are Black & White)

A Rose-breasted Grosbeak perched on a thin branch.
Image by Jfranciskay via Flickr.

Most people know the male rose-breasted grosbeaks for their bright red patch on their chests, but otherwise, their bodies are completely black and white. The females have a very different appearance with brown feather patterns. These birds breed in Canada and the Northeastern United States, and then they migrate down to Southern Mexico and Northern South America. In rare cases, rose-breasted grosbeaks create hybrids with a similar species, the black-headed grosbeak.

10. Blackpoll Warbler (Male Birds are Black & White)

A Blackpoll Warbler

Male blackpoll warblers have beautiful white feathers with black speckles and a hint of brown on their wings. Females are mostly brown and white, so they don’t share the same beautiful black and white coloring. They have a large range that includes Northern Canada when breeding, Eastern United States when migrating, and Northern South America during the non-breeding season. They make the longest overwater journey of any songbird (about 1,800 miles!)

11. Black Skimmer (Black & White Seabird)

Two black skimmers on a mud flat.
Image by Brian Tillotson via Flickr.

Black skimmers have black backs and white bellies. Yet, their long, red bills with black tips are one of their most notable features. While flying, they skim the water with their unique bills, catching fish whenever they feel them. The shape of their bills allows them to quickly relax their neck and close their jaws to capture fish. In North America, these birds only appear along the east and west coastlines. Populations of them also appear in parts of South America.

12. American Oystercatcher

An Oystercatcher walking across sand.
Image by frank1556 via Flickr.

American Oystercatchers have dark black heads, white bellies, and brown/gray wings. Like black skimmers, their most notable feature is their bills. These birds have narrow red-orange bills that create a unique contrast from their black and white feathers. They use their beaks to probe sandy and stony areas for oysters and other mollusks. They’re found in salt marshes and barrier beaches of North American coastlines, along with some South American coastlines.

13. Ladder-Backed Woodpecker

A Ladder-backed Woodpecker climbing up a thin tree.
Image by Hawk Person via Flickr.

Ladder-backed woodpeckers are beautiful black & white birds because of their striped and spotted patterns. The males also have large red patches on their heads, but the females do not. Unlike most woodpeckers, they typically live in deserts and thorn forests rather than woodlands. They forage among thorns and spines across Mexico and the Southwestern United States.

More Black & White Birds in North America

There’s no shortage of black & white birds in North America. Here are some more species to keep an eye out for:

  • American Coot
  • Black Phoebe
  • Black-Billed Cuckoo
  • Black-Crowned Night Heron
  • Black-Necked Stilt
  • Bufflehead
  • Mute Swan
  • Razorbill
  • Royal Tern
  • Snow Goose
  • White Pelican
  • Wood Stork
  • Yellow-Bellied Sapsucker

Have You Spotted Black & White Birds in North America?

Next time you see a black & white bird in North America, pay attention to the details. Look at its feather patterns and unique features, such as its bill, vocalizations, and habits. Black & white birds can be just as beautiful as other bird species, so make sure to admire them.

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The 11 Species of Wren in North America

Globally, over eighty species of wrens exist. 11 of these species reside in North America. Some species are more common than others. This is a complete guide to every species of wren in North America, including identification pictures, their range and which habitats you can spot them in.

What is a Wren?

Wrens are small brown birds in the Troglodytidae family. This is a family of birds that is diverse and span across the globe. They are small, often brown, with compact, rounded bodies. Their tails are short and upright and may appear cocked. They have slender, pointed bills and have dark markings on their backs and wings. Some even have a unique pale marking resembling eyebrows. 

Wrens are active and curious birds. They are known for ‘disappearing’ into tight spaces in search of their primary food source: insects. They are territorial and quite feisty during the breeding season. While wrens are social, they prefer to nest alone. These birds are also very vocal – a characteristic that makes them easier to spot.

The 11 Species of Wren in North America

Let’s get to know North America’s most common species of wren.

House Wren

A House Wren catching a small insect.
Image by Edward Post via Flickr.

Range: The House Wren’s range spans the United States., southern Canada, Mexico, and northern South America. This bird migrates south for winter. 

Habitat: We consider this bird one of the most adaptable species in North America as their range is enormous, as seen above. They live in urban, suburban, and rural areas. For unknown reasons, they are quite frequently found near human structures. 

Description: These birds have a pale underside with dark streaks on its back. 

Carolina Wren

A Carolina Wren perched on a branch.
Image by Peter Granka via Flickr.

Range: This bird’s range spans the southwestern United States and parts of Northern Mexico. This includes western Arizona, southern Nevada, parts of southern Utah, and some areas of the south coastal region of California. 

Habitat: Carolina Wrens inhabitat woodlands, gardens, and bushy areas. They prefer to be near water. This bird also frequents areas with chaparral on the coastline.

Description: These birds a reddish-brown body and white throat. This is one of the wren species with a distinctive pale eyebrow. 

Winter Wren

A Winter Wren perched on a large dead tree.
Image by Jim Moodie via Flickr.

Range: The Winter Wren lives in the northeastern region of the continent. Its breeding territory expands as far south as southern Canada, including the Ontario and Quebec regions. During migration, these birds move into the northeastern US, particularly in the northern Appalachians. 

Habitat: They prefers dense woodlands and thick brush. They also frequent areas near streams and other wetlands.

Description: These birds have a dark brown coloration. This bird is unique because it often holds its tail down instead of up. 

Bewick’s Wren

A Bewick's Wren perched on a shrub
Image by Jeff Maw via Flickr.

Range: The Bewick’s Wren’s range extends through the western and central United States and into parts of western Canada and Mexico. It is also found in the Great Basin and Rocky Mountains.

Habitat: This bird resides near the forest’s edge and prefers shrubby areas. 

Description: It is grayish-brown and has a white throat and eyebrow. 

Canyon Wren

A Canyon Wren perched on a rock.
Image by Jim Moodie via Flickr.

Range: We find this bird in the southwestern United States, including Arizona, New Mexico, Nevada, and Texas. It also resides in parts of Mexico, including Sonora, Chihuahua, and Durango.

Habitat: It prefers rocky areas and semi-arid habitats like desert regions. It infrequently is an inhabitant of riparian zones. 

Description: The Canyon Wren is a reddish-brown bird with a long, curved bill.

Rock Wren

A Rock Wren perched on a rock.
Image by Jim Moodie via Flickr.

Range: The Rock Wren lives in the southwestern United States and parts of northern Mexico, especially in areas like Sonora and Chihuahua.

Habitat: This bird enjoys dry, mountainous regions. As its name suggests, it prefers rocky terrain, allowing for building nests in tight crevices, to woodland or brush. 

Description: This brownish-gray bird has a light-colored belly and sometimes pale streaks on its back. 

Sedge Wren

A Sedge Wren perched in between two upright branches.
Image by Edward Post via Flickr.

Range: This bird lives primarily in North America’s central and eastern regions, including southern Canada and the eastern and midwestern United States. This bird flies as far south as Florida, Texas, and sometimes Mexico during migration.

Habitat: The Sedge Wren’s typical habitats are marshes, wetlands, and grasslands.

Description: This small, brown bird has dark streaks on its wings and a pale belly.

Marsh Wren

A Marsh Wren perched on a snowy branch.
Image by Jim Moodie via Flickr.

Range: The Marsh Wren’s range is primarily in the eastern United States. However, it has a small presence in the central and western United States. During migration, it goes toward the Gulf Coast in the United States and Mexico.

Habitat: It lives in wetlands, marshes, and reed beds. 

Description: This brown bird has a streaked back and white belly. 

Pacific Wren

Cute Pacific Wren
Image by Eric Zhou via Flickr.

Range: This bird’s range consists of the western coast of North America, particularly in Alaska and the Pacific Northwest. 

Habitat: The Pacific Wren’s main habitat is coastal forests.

Description: This is a dark brown bird with muted coloration. It is similar to the Winter Wren but with less distinct markings.

Cactus Wren

A Cactus Wren perched on a cactus.
Image by Edward Post via Flickr.

Range: The Cactus Wren resides in the southwestern United States and northern and central Mexico. 

Habitat: This bird prefers desert environments with plenty cacti, shrubs, and trees for nesting.

Description: It is relatively large for a wren and has a distinctive appearance due to its heavily streaked body and white throat and belly. Its back is marked with black and white spots and it has a white stripe spanning from its beak to the back of its head.

Sinaloa Wren

A Sinaloa Wren perched on the leaf-littered ground.
Image by Greg Lavaty via Flickr.

Range: The Sinaloa Wren is primarily found in Mexico on the western coast and sometimes in the interior. It is also sometimes found in southern Arizona.

Habitat: This bird inhabits a range of environments including thorn forests, deciduous forests, riparian zones, and semi-arid areas.

Description: It has a rich brown coloration with white streaks on its back. Also note the distinctive eyebrow marking and pale belly.

Fun Facts About North American Wrens

If your curiosity is not satiated yet, here are a few fun facts about wrens!

  • The average lifespan of a wren is two years. However, during banding operations, one was discovered to be nine years old.
  • These birds are insectivorous, meaning they mainly eat insects. They also eat seeds, nuts, fruits, and berries.
  • The male is the nest builder! He builds several nest sites, and the female picks her favorite.
  • Wrens have loud, complex songs. They also sing year-round. 
  • They have a behavior called troglodytism. This means they nest in cavities, crevices, and secluded spots. 
  • Their wingbeats are so fast that viewing distinct wing flaps is impossible. 
  • The Giant Wren resides in Mexico and is the largest bird in the wren family at around 8-9 inches long.
  • Wrens are indicator species, meaning their health and population sizes mirror the overall ecosystem.

Why Conservation of Wrens Matters

Wrens control insect populations and are also an important food source for predators, providing a balance in the food chain. They are also culturally significant, often featured in folklore, songs, and art. While most of these birds are not currently at risk, some species, including the California and Carolina Wrens, face threats due to habitat loss, invasive species, and climate change. 

Want to learn more about other North American Birds? Check out our other guides here:

Types of Woodpeckers in North America: A Guide

Types of Hummingbirds in North America: A Guide

A Guide to the Corvidae of North America

A Guide to Flycatchers in North America

Finches in North America: A Completed Guide

The 8 Species of Buntings in North America

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The Brown-headed Cowbird

Despite its unassuming looks, the brown-headed cowbird is one unique bird. 

What it lacks in appearance, the brown-headed cowbird makes up for in ingenuity – they effectively take over the nests of other birds, getting them to do the labor-intensive work of raising offspring. 

In other words, they’re parasites. 

Whilst the parasitic lifestyle isn’t for everyone, the brown-headed cowbird has opted out of the status quo with traditional nest building.

A close-up image of a male Brown-headed Cowbird.
Image by Peter via Flickr.

This article will aim to explore what exactly the brown-headed cowbird is, and how it has become one of the most successful brood parasites across North America. 

What is a Brown-headed Cowbird?

Dare I say drab? Boring even?

The brown-headed cowbird hasnt gone down the opulent route of evolution. 

You’ll see no bright colors or funky patterns on their plumage. Their feathers are short and very average looking. 

The brown-headed cowbird has a thick and pointed, yet stubby, finch-like beak. This beak shape allows the cowbird to forage for a range of seeds and insects. 

Basic Description

Size & Shape

The brown-headed cowbird is a relatively small yet stocky passerine bird, slightly smaller than a robin. 

Typically, they rarely exceed 9 inches in length and have a shorter tail than other species in the same family – such as Brewer’s blackbird and the red-winged blackbird

Males tend to be slightly larger than females.

Color Pattern

Brown-headed cowbirds are sexually dimorphic. 

This means that the males and the females differ in appearances, and the two sexes can be easily distinguished from one another. 

Adult males have a plain brown head, neck and, occasionally, upper breast. The rest of their bodies have glossy black plumage, with streaks of almost purple/green iridescence.  

Unlike the males, females do not have contrasting plumage. They are a brownish-grey all over, with a very faint gloss – a lot less pronounced than males. 

Female cowbirds also have streaking on their underbelly and wings. 

Where to Find Brown-headed Cowbirds

A pair of male Brown-headed cowbirds perched on a large stick.
Image by Roy Priest via Flickr.

The brown-headed cowbird has an extensive range, spanning Southeastern Canada through all of the US, Mexico and into northern Central America. 

Their large range, in part, is a consequence of human alteration of the environment. 

Unlike many other bird species, the brown-headed cowbird has directly benefited from deforestation caused by humans. 

As more of North America was converted from forests to pasture and farmland, the range of the brown-headed cowbird expanded Eastwards. 

The brown-headed cowbird favors open or semi-open countries at all seasons.

They can be found in a variety of habitats including prairies, fields, pastures, orchards, and agricultural farms. They avoid dense forests due to the lack of areas that they can forage in.

Many populations found across the US are non-migrants, and remain in their habitats year-round. Occasionally, when conditions are sub-optimal, some flocks travel short distances in search of food. 

Some populations, most notably those in Northern regions, are short-distance migrants. This means they stay on the American continent. They have been recorded travelling over 500 miles to reach warmer wintering grounds. 

Behavior and Feeding Habits

Brown-headed cowbirds are predominantly ground-feeders, often foraging amongst groups of blackbirds and starlings. 

They can be seen in pastures where cattle or horses are present, catching insects flushed out the grass by the large grazers. 

This is not a new feeding behavior. Centuries ago, it was a common site to see brown-headed cowbirds following the mighty herds of bison across the Great Plains. 

As the bison were hunted to near extinction, the birds sought other feeding opportunities.

Today, their diet consists of seeds, grains and insects. 

In the summer months, which coincide with the breeding season, their diet is equal parts insect and plant protein. Insects include grasshoppers, beetles, caterpillars, centipedes, and millipedes.

Female cowbirds can lay as many as three dozen eggs per season. To meet this large calcium requirement, females often supplement their diet with snail and egg shells.

The Impact of Brown-headed Cowbirds on Other Birds

A small Yellow Warbler feeds a much larger Cowbird fledgling.
A Cowbird Fledgling being Fed by a Yellow Warbler. Image by Michael W Potter via Flickr& Website.

When we think of parasites, what comes to mind?

Fleas? Leeches? Microscopic worms perhaps?

To most, a bird probably wouldn’t come to mind as a parasite. 

But that’s exactly what the brown-headed cowbird is: a brood parasite. 

Brood parasitism is a breeding strategy in which the parasite, in this case the female brown-headed cowbird, evades all parental care by laying its eggs in the nests of other birds. 

This strategy relies on other birds investing their own energy and resources in rearing the chicks of the cowbird. 

Brown-headed cowbirds have been known to parasitize the nests of over 220 different bird species, including Red-winged Blackbirds, Ovenbirds, Yellow Warblers and Song Sparrows.

Laying their eggs in the nest of other birds, the brown-headed cowbird will often remove the host bird’s eggs. This has led to a significant population decrease of many North American passerine birds. 

As chicks of the cowbird develop quicker than other species, host parents will invest more energy feeding the imposter. Cowbird chicks outcompete other chicks –  they raise their heads higher and they beg more loudly. 

When they are large enough, cowbird chicks may kill their nestmates; either by kicking them out of the nest, or by smothering them.

Whilst doing research for this article, I noticed many scientific papers, a few as recent as early 2024, starting with the title “First observations of Brown-headed Cowbird parasitism of….” and then the host species will be named. 

It seems that the cowbird is an opportunistic nester and, if conditions are right, will take over any nest it can. 

Perhaps this is an evolutionary arms race in action?

Are historic hosts, such as red-winged blackbirds or yellow warblers, becoming aware of when their nests have become parasitized, and are they fighting against it?

Yes. Yellow warblers can recognize the eggs of cowbirds. But, due to their smaller size, they cannot remove the eggs. To compensate, yellow warblers build new nests on top of parasitized nests

FAQ About Brown-headed Cowbirds

Can a cowbird fit in a bluebird house?

Yes, female cowbirds can fit through holes of bird houses. However, due to their parasitic nesting behaviors, it is relatively uncommon for brown-headed cowbirds to parasitize a bluebird house. 

A Red-winged Blackbird nest with two of its own eggs and one parasitic Cowbird egg.
A Red-winged Blackbird Nest with a Parasitic Cowbird Egg (brown). Image by Larry Reis via Flickr.

Most bluebird houses have an entrance hole of 1.5 inches in diameter. This is small enough to prevent the invasive European starling from gaining entry, but does not keep other birds out. 

How can I get rid of cowbirds in my yard?

If you want to remove cowbirds from your yard, always opt for non-intrusive and humane methods. Oftentimes, simplicity is the best approach. 

You can change the type of birdseed you use. Choose smaller seeds, such as safflower or nyjer seeds, instead of sunflower seeds or cracked corn. 

As cowbirds are ground feeders, ensure you clean up any spilt seeds that fall to the ground. This also prevents pests, such as rats. 

You could also introduce specialized feeders, such as tube feeders. This attracts a certain type of bird, such as hummingbirds. 

What do cowbirds eat?

Brown-headed cowbirds eat seeds, grains and insects. 

In the summer, their diet consists of 50% insects and 50% seeds. However, in the winter, seeds make up nearly 90% of their diet.

Where do cowbirds live?

Brown-headed Cowbirds live in temperate to subtropical grasslands and pastures across North and Central America.

They can also be seen in woodland edges, brushy thickets, prairies, fields, pastures, orchards, and urban areas like suburban residential lands and agricultural farms. They avoid dense forests where feeding opportunities are limited. 

Conservation Status

A cowbird perched on top of a bird house.
Image by Ramona Pioneer Girl via Flickr.

According to the IUCN, the brown-headed cowbird is considered Least Concern. 

Although their numbers are thought to be decreasing, their estimated population size is 130 million individuals. 

How to Coexist with Brown-headed Cowbirds

Sure, brown-headed cowbirds aren’t the best backyard guest. 

But that doesn’t mean you can’t live alongside them. 

By taking appropriate actions, such as cleaning spilt seed or changing bird feeders, you can limit the interactions you have with them in your own yard. 

Whilst it’s easy to villainize the cowbird, we need to remember that this behavior is completely natural. 

Parasitism throughout the natural world is a common phenomenon and can be beneficial in controlling populations. 

So, before hating on the cowbirds, just take some simple steps to reduce their presence. 

By adding more shrubs and refugia into your yard, you can increase your biodiversity without attracting cowbirds.

Final Thoughts

Due to their extensive range, brown-headed cowbirds are some of the most easily found birds in the United States.

Males are easy to identify with their brown heads and glossy black bodies and conical beaks. 

Human behavior, most notably our affinity with deforestation, has contributed to the widespread distribution of the cowbird. 

Brown-headed cowbirds do not construct their own nests. Instead, females lay their eggs within the nests of other North American birds. Due to this parasitic lifestyle, many passerine species have suffered population declines. 

You can deter cowbirds from your backyard by planting more trees, changing bird food to smaller seeds or using bird feeders that are specific to the bird you want to attract, such as tubular feeders.

Categories
Feathered Facts

Are Birds Dinosaurs?

Birds are dinosaurs.

There, I said it. 

But, as I sit watching a flock of finches, it’s hard to see the resemblance. 

How could this bird, no larger than a tennis ball, be related to the mighty T-rex?

Recent discoveries in paleontology have reshaped our understanding of dinosaurs, revealing their surprising connection to the birds we see today. 

Far from being just “terrible lizards,” many dinosaurs could have been feathered, warm-blooded, and displayed behaviors remarkably similar to modern birds. 

A reconstruction of a Sinosauropteryx, the first non-avian dinosaur found with feather-like structures, providing further evidence for the link between dinosaurs and birds. Image by Tanja Martin via Flickr.

Sinosauropteryx was a small, bipedal dinosaur with short arms, a large thumb, and a long tail. It was the first feathered dinosaur discovered that wasn’t directly related to birds, and its discovery in 1996

This article will aim to explore the relationship between birds and dinosaurs and how evolution shaped the way birds now exploit nearly all environments on our planet. 

Evolutionary Tree of Dinosaurs and Birds

Biology can be confusing. No doubt about it. 

Especially when all life, both extinct and living, is categorized into groups. 

Knowing where each animal fits into specific groups can be a challenge. 

Phylogenetic trees, also known as evolutionary trees, can help scientists understand the relationship between a group of organisms. 

So, where do dinosaurs and birds fit into this evolutionary tree? Buckle up and pay attention, you’re in for a ride. 

Amniotes are tetrapod animals with a backbone. This group comprises the vast majority of living terrestrial and semiaquatic vertebrates.

Amniotes can then be further split into mammals and sauropsids

Sauropsids are reptiles, and include all living and extinct groups. 

Within sauropsids, the squamates (lizards and snakes) and the testudines (turtles) diverged first. This was followed by the divergence of the archosaurs, which included the dinosaurs. 

Still with me?

Although the dinosaurs are no longer with us, we still share our planet with living archosaurs: birds, crocodiles and their relatives. 

Okay. That’s the complicated classification bit out of the way. Now, let’s explore the archosaurs in more detail. What is a dinosaur and how are birds related to this ancient group? 

What Is A Dinosaur?

“Welcome to Jurassic Park”.

An iconic line from an iconic film that shaped the modern mind on our perceptions on what dinosaurs should look like. 

But let’s be real. No one really knows what a dinosaur looks like. 

An artist’s representation of one of the smallest dinosaurs ever to have existed, Compsognathus, which grew to about as large as a chicken. Illustration by Hoppenbrock via Flickr.

One of the smallest dinosaurs known, Compsognathus grew only about as large as a chicken

For all we know, they could have been little feathered things, no larger than a chicken…

Using fossil records and fancy technology, scientists have discovered some species were in fact little feathered things the size of chickens. Who’d have thought it? 

Of course, like any other animal group, dinosaurs were diverse. They evolved an array of shapes and sizes, from the aptly named Giganotosaurus, to the hummingbird-sized Oculudentavis

But what makes a dinosaur a dinosaur?

Well, there are two main factors to consider:

  1. Dinosaurs are reptiles
  2. Dinosaurs have an upright stance

Dinosaurs Are Reptiles

First and foremost, dinosaurs are reptiles. Their name quite literally translates to “terrible lizard”. 

They first appeared about 251 million years ago, near the start of the Triassic Period.

But isn’t this article about birds and their relationship to dinosaurs? How can birds be related to these ancient reptiles?

Well, that brings us onto the second defining characteristic.

They Have an Upright Stance

Some reptiles, such as crocodiles and lizards, have legs that sprawl out to the side. Their thigh bones are almost parallel to the ground creating a side-to-side motion when they move. 

Dinosaurs, on the other hand, stand with their legs positioned directly under their bodies. A hole in the hip socket permits this upright stance.

Two Ostriches, a bird species that closely resembles the extinct dinosaurs.
Image by Kissandrew via Flickr.

Birds also have their legs positioned under their bodies. Coincidence?

Most dinosaurs went extinct by the end of the Cretaceous Period, about 66 million years ago, but there’s evidence that one lineage evolved into birds about 155 million years ago.

Dinosaurs May Have Been Warm-Blooded

An age old question – were dinosaurs warm or cold blooded?

It’s easy to default to “dinosaurs were cold-blooded because they are reptiles”.

And sure, our modern-day reptiles are cold blooded, whilst birds are warm blooded. So where do dinosaurs fit into all this?

Well, that’s where science comes in. 

Using fancy sciencey techniques, such as infrared spectroscopy, a group of scientists identified an abundance of molecules produced as waste during oxygen inhalation. 

To do this, the scientists used fossilized thigh bones from a range of extinct dinosaur species, as well as their living relatives – birds. 

You may be thinking “And, so what?” 

A higher abundance of these molecules suggests high-powered metabolism – something we see in modern day warm blooded animals to regulate their body temperatures 

This isn’t an isolated study. 

Other scientists have taken bone fragments and, where possible, soft tissue records, and discovered that not only did certain species grow remarkably fast, many also had insulating feathers – an adaptation used by some warm blooded animals to maintain a constant temperature. 

Nifty tricks from the dinos. 

Yet, despite the data, our knowledge is still limited. We simply don’t have conclusive evidence  about dinosaur metabolism as we don’t know how their internal mechanisms worked. A classic “pinch of salt” scenario. 

Other Similarities Between Birds And Dinosaurs 

Warm-bloodedness and bipedalism are sure signs of the relatedness between the two groups. 

But are there other similarities between birds and dinosaurs?

Absolutely.  

Dinosaurs and Birds Both Laid/Lay Eggs

As far as scientists are aware, all dinosaurs, both living and extinct, hatch from eggs.

However, unlike most other reptiles, which lay soft and leathery eggs, theropod dinosaur eggs were believed to be hard-shelled – much like our modern day bird eggs. 

A chickadee nest with six eggs.
The eggs of a Black-capped Chickadee. Image by Laura Erickson via Flickr.

Many fossilized nests have been found across the globe, with egg fragments laying close to the nest sight. This suggests hatchlings crushed the egg shells whilst either emerging, or moving around the nest. 

But Dinosaurs Don’t Have Beaks

How did a set of dinosaurian jaws, complete with an array of different tooth types evolve into the toothless jaws of modern birds? 

Simple – the suppression of the teeth and growth of the beak.

Why dinosaurs started to lose teeth and develop beaks isn’t clear. However, scientists speculate that there are two main reasons: faster development and new feeding opportunities.

Tooth development can take up to 60% of incubation time. By hatching faster, survival rates are improved, as hatchling can avoid potential predators or natural disasters. 

Using our trusted fossil records, scientists discovered how beaks in some dinosaurs and bird relatives originally expanded backwards as the animals grew up and tooth sockets closed off. 

Eventually, this process happened earlier and earlier in the developmental cycle until hatchlings emerged with beaks and no teeth. 

Modern day birds still have the bone gene BMP4. So, in theory, they do still have the ability to grow teeth. 

Birds Share Similar Weaponry to Dinosaurs

We don’t tend to think of birds as overly aggressive animals. 

Yet, when threatened, some birds have a few tricks up their wings – quite literally. 

The spur-winged lapwing is one such bird. 

When threatened, they use spurs like tiny clubs to fend off predators, guard their nests and compete with mates.

This behavior can be seen in some dinosaur species, such as Ankylosaurus and Stegosaurus.

Some Dinosaurs Had Feathers

Feathered dinosaurs? Have I gone mad? 

As crazy as it sounds, many scientists believe that the most prominent feature of birds – feathers – evolved in non-avian dinosaurs long before the earliest birds.

These feathered dinosaurs, or Theropods, are characterised by having three forward-facing toes and walking on two legs. Sounding familiar? 

Velociraptors are part of this group. 

Unlike Spielberg’s famous portrayal of these ferocious dinos, there is evidence that they were feathered. But these feathers were used for insulation, rather than flight. A glorified turkey. 

The First Bird 

Using fossil records, the origins of birds can be traced back to the time of the dinosaurs – some 165 – 150 million years ago. 

This was a very different time, and these early birds are unrecognizable from today’s avians. 

The iconic Archaeopteryx, discovered in 1861, has long been considered as the first bird. It is thought to have lived in the Jurassic period, some 150 million years ago. 

Although it had many bird-like qualities, such as feathers and the presence of a wishbone, Archaeopteryx also had many reptile-like qualities that we don’t see in modern birds. This includes sharp, pointy teeth, a long, bony tail and long claws on its hands.

Scientists also speculate whether Archaeopteryx could fly. But if penguins and ostriches have taught us one thing, it’s that the ability to fly isn’t a defining characteristic of birds. 

Whether Archaeopteryx was the first bird is still debated today. 

A fossilized Archaeopteryx. Image by Stanford Synchrotron Radiation Lightsource via Flickr.

However, the earliest modern bird fossil, that majority of scientists agree on, is that of Asteriornis maastrichtensis – more popularly called the wonderchicken.

Fossils of the wonderchicken date to 66.7 million years ago, just 700,000 years before the mass extinction that killed off the non-avian dinosaurs.

The wonderchicken is thought to have been a small, ground-dwelling bird, much like a rail/duck/chicken hybrid. 

Their fast reproduction rates and ability to fly may have helped it survive the devastating extinction event, which wiped out 75% of all life on Earth.

The Evolution Of Flight – Why Do Birds Fly?

Flight is a unique adaptation which has allowed some taxonomic groups to evolve great diversity.

Birds have been largely influenced by flight – their anatomy, physiology and behaviour are adapted to this complex mode of locomotion. 

Using flight, birds are able to forage on extensive areas, they can migrate over long distances and they are able to colonize all terrestrial habitats on Earth including high elevations, polar regions and distant islands. 

But how did they get there from ground-dwelling reptiles?

Birds, like theropod dinosaurs, are bipedal. This means they walked upright on their hindlegs. 

With their hindlegs occupied, their forelimbs were free to evolve to help them exploit a particular niche. Unlike bats, which are mammals and have both their forelimbs and hindlegs attached to a wing membrane, birds evolved wings independently. 

Can Birds Survive Another Mass Extinction?

Here we go. Doom and gloom time.

The current biodiversity crisis, often referred to as the sixth mass extinction, is happening at an alarming rate – much like the one that killed off the dinosaurs. 

But this time, there’s no meteor hurtling towards Earth.

This extinction event is anthropological – we humans are accelerating the effects. 

We’re losing species at a rate like never before. 

Climate change, habitat loss, introduced species. The list goes on. 

But birds survived once before. Can they do it again?

Unfortunately, it’s looking unlikely. 

The California Condor, a Critically Endangered Species
The California Condor, one of North America’s most endangered birds. Image by Dorothy Sutherland via Flickr.

Since the 1500’s, an estimated 182 bird species are believed to have become extinct due to human actions. This figure could be grossly underestimated, with the actual statistic being closer to 1,500 species

However, some bird species are adapting to a human-modified world. Species have adjusted their feeding habits, nesting locations, as well as songs and calls in response to human expansion and urbanization.

Final Thoughts on Whether Birds Are Dinosaurs

Birds are living dinosaurs – think more “astonishing avians” rather than “terrible lizards”. 

Modern-day birds retain many dinosaurian traits – bipedalism, feathers, egg-laying, and perhaps even warm-bloodedness.

Over millennia, birds evolved strategies to help exploit specific niches. They became smaller and adapted to fly, both of which could explain how early birds survived the mass extinction. 

Yet today, birds face their biggest threat: humanity. 

By monitoring birds and their populations, scientists can understand the broader ecological challenges they face. While mass extinctions in the past allowed life to recover over millennia, today’s crisis demands immediate action to protect ecosystems and species.