How the many sizes and shapes of beaks came to be
Eldon Greij explains how beaks evolved to fit the functionality of each bird species.
Eldon Greij
Eldon Greij is professor emeritus at Hope College, located in Holland, Michigan, where he taught ornithology and ecology for many years. He is the founder of Birder’s World magazine and the author of our popular column “Amazing Birds.”
Eldon Greij on social media
How flamingos thrive in harsh environments
Founding Editor Eldon Greij explains how the unique feeding behaviors of flamingos help them thrive in highly alkaline lakes and lagoons.
Manakins’ wild courtship rituals explained
Eldon Greij explains Manakins dazzling visual and audio displays during their courtship rituals.
Male Satin Bowerbirds must master many skills
Eldon Greij describes the skills a male Satin Bowerbird must possess in courting females — from constructing an intricate bower to a frenzied song-and-dance routine.
Why many birds evolved to eat fruit
Want to learn more about birds? Sign up for our biweekly newsletter! After watching migrant Swainson’s Thrushes refuel on fruiting shrubs in Michigan one fall, an … Read More “Why many birds evolved to eat fruit”
How albatrosses fly, find food, and nest
Albatrosses are large, heavy birds with goose-like bodies and long, narrow wings. The smaller species have wingspans of 6 to 8 feet, while those of … Read More “How albatrosses fly, find food, and nest”
The value of flocks
While I was walking a wooded area near a Michigan pond one spring, the forest floor stopped me cold. It was carpeted with White-throated Sparrows … Read More “The value of flocks”
Eldon Greij: Birds are the original ultralights
Humans have been fascinated by flight since their earliest writings, and accounts of attempts to master the airways are scattered throughout history. Using kites and … Read More “Eldon Greij: Birds are the original ultralights”
Eldon Greij describes how birds’ streamlined teardrop shape enables them to fly
Sometimes we are so busy looking at the differences between birds that we forget the similarities. Birds resemble each other in many ways. Perhaps none … Read More “Eldon Greij describes how birds’ streamlined teardrop shape enables them to fly”
A cross-country celebration of birdsong
A review of Listening to a Continent Sing: Birdsong by Bicycle from the Atlantic to the Pacific, by Donald Kroodsma
How homing pigeons find their way home
Birds have internal compasses that can determine directions from the sun’s position during the day, star patterns at night, and Earth’s magnetic field. A compass … Read More “How homing pigeons find their way home”
How feather wear gives starlings and other birds their snazziest plumage
As a rule, birds undergo a complete molt after the breeding season. Prior to the next breeding season, many birds undergo a partial molt (typically, … Read More “How feather wear gives starlings and other birds their snazziest plumage”
How Africa’s hummingbird-like sunbirds find nectar
It was the final day of safari, and our Land Cruisers were slowly making their way to the bottom of Ngorongoro Crater, in northern Tanzania. … Read More “How Africa’s hummingbird-like sunbirds find nectar”
Eldon Greij explains why some birds practice siblicide
The primary goals for birds are to survive, successfully breed, and dominate the gene pool. There are almost as many strategies to meet those goals … Read More “Eldon Greij explains why some birds practice siblicide”
Behavior: How owls can hunt even in total darkness
Imagine being in a pitch-black room, your pupils maximally dilated, but you can’t see a thing. You feel helpless. Now picture a Barn Owl on a … Read More “Behavior: How owls can hunt even in total darkness”
Bird basics: Six different feather types explained
Feathers are the ultimate characteristic of birds. No other (living) animals have them. The qualifier is required because feathers have now been found in fossil … Read More “Bird basics: Six different feather types explained”
Curious birds that can’t take flight but sure can run
Ratites are a small group of mostly huge, flightless birds. Think ostrich, rhea, emu, and cassowary. Where did they come from? We used to think … Read More “Curious birds that can’t take flight but sure can run”
Eldon Greij tells what birds can smell
Conventional wisdom has maintained for years that birds have remarkable special senses, especially vision and hearing. Olfaction, on the other hand, was relegated to the … Read More “Eldon Greij tells what birds can smell”
How birds are able to dive and swim below the waves
As birds diverged from their early ancestors, many exploited aquatic habitats by wading or swimming. Others took to diving. Diving creates a problem for birds: … Read More “How birds are able to dive and swim below the waves”
Nest basics
Perhaps nothing speaks to the cleverness of birds more than the variety of their nests. Driven primarily by predation, birds construct and locate nests to … Read More “Nest basics”
Eldon Greij explains the clever way birds keep legs and feet warm
Whether a bird spends the winter in high latitudes or migrates to more southerly climes in fall has less to do with temperature than with … Read More “Eldon Greij explains the clever way birds keep legs and feet warm”
The amazing way birds land
It was March, just before evening, and Sandhill Cranes were rising high above the Platte River in Nebraska, soaring in tight circles, and then dropping … Read More “The amazing way birds land”
Why Mallards and other birds have no teeth and sometimes eat pebbles
It is generally well known that birds lack teeth. What is not as well known is that ancient birds had them. Several fossil bird species … Read More “Why Mallards and other birds have no teeth and sometimes eat pebbles”
Eldon Greij describes the most abundant bird in the world
On a recent game drive in northern Tanzania, in eastern Africa, our driver pulled to a stop next to a group of acacias decked out … Read More “Eldon Greij describes the most abundant bird in the world”
Eldon Greij explains what every birder should know about bird poop
While protein is essential in the diet of all animals, it can have side effects that make it a double-edged sword. Protein consists of many … Read More “Eldon Greij explains what every birder should know about bird poop”
Eldon Greij describes birds’ varied and surprising mating strategies
For birds and other organisms, winning at the game of life is defined as leaving behind more offspring than other members of your species. Biologists … Read More “Eldon Greij describes birds’ varied and surprising mating strategies”
Eldon Greij describes the amazing way that birds breathe
Birds are busy animals. Consider insect-hawking flycatchers, far-flying shorebirds, and hovering hummingbirds, and you get a picture of how active birds can be. That’s why … Read More “Eldon Greij describes the amazing way that birds breathe”
The amazing muscles and bones that make birds fly
Flight is essential for birds and captivating for birdwatchers. Consider the speed of a diving falcon, the burst of a flushed grouse, the erratic pattern … Read More “The amazing muscles and bones that make birds fly”
Why woodpeckers can hammer without getting headaches
The feeding strategy of woodpeckers requires two specialized adaptations: one understood by the whole world, the other known to but a few students of birds. … Read More “Why woodpeckers can hammer without getting headaches”