Key Traits
The most familiar kingfisher species in North America and Europe are indeed specialists that eat mostly fish. And they do so in spectacular fashion. So they get a lot of attention and admiration for their fishing skills.
But what about the many other kingfisher species? It turns out that more than half of them are not fish-eating specialists. Fish-eaters are actually in the minority. Depending on which kingfisher species you’re talking about, it’s diet might be mostly insects, lizards, earthworms, or another type of creepy crawly.
These are mostly small-ish birds. They’re generally quite a bit smaller than a crow, but larger than a House Sparrow. However, the smallest species is the African Dwarf Kingfisher, which is only 10 cm long. That’s 4 inches. The length of a bird is measured from the tip of the bill to the tip of the tail. So at 10 cm long, the African Dwarf Kingfisher is a teeny tiny bird.
The largest species is the aptly named Giant Kingfisher, also found on the African continent. It has a great scientific name, Megaceryle maxima. This bird is about the size of a crow, approximately 44 cm or 17 inches long. The Giant Kingfisher looks like a gigantic version of its cousin, the Belted Kingfisher, which is our familiar species in the US.
The Kookaburras of Australia and New Guinea are actually kingfishers, in case you didn’t know. The famous Laughing Kookaburra is the world’s heaviest kingfisher species, with females weighing an average of 352 grams, or 12.4 ounces.
To accentuate their giant bobble-heads and oversized bills, kingfishers have stubby feet and short, squared off tails.
They’re among the few types of bird that have syndactyl toes. This means that of the three toes that face forward on the foot, the outer and middle toes are fused together for most of their length. Syndactyl translates as “together fingers.” Humans are sometimes born with syndactyly, where some fingers or toes are fused. In kingfishers, the syndactyl toe arrangement increases the surface area of the sole of the foot. So it probably improves the bird’s grip while perching.
I said that kingfishers have short tails, and that’s true for the vast majority of species. But there are 9 species in the genus Tanysiptera that just can’t play by the rules. These are the paradise-kingfishers. The central pair of tail feathers on these birds are long, elegant, and colorful… some combination of blue and white.
Unlike what we see in birds like peacocks and wild turkeys, the fancy tail feathers of paradise-kingfishers aren’t found on only the male. Both sexes have them. Why do they have such glorious tail streamers? Good question. The evolutionary process of sexual selection is probably at work here. But I haven’t turned up any research that confirms this specifically for these long-tailed kingfishers.
Similarity between males and females is the general rule in kingfishers. You usually can’t tell them apart by just looking at them. Some exceptions include the Giant Kingfisher and the handful of species in the western hemisphere. These birds show some sexual dimorphism, where males and females look different. But get this: these kingfishers flip the script so that it’s the female who shows more color than the male. The female Belted Kingfisher, for example, has a rust-colored band across her lower breast. The male doesn’t have this; he has to make do with his simple blue and white plumage.
And speaking of plumage colors, Kingfishers are, as a group, a brightly colored lot. I just looked at illustrations of all the world’s kingfisher species and, wow, my retinas are still burning with the afterimages. It was all a bunch of brilliant blue, orange, turquoise, hot pink, white, and green. Many species have orange bills that I would describe as neon or day-glow. They’re unreal.
Interestingly, the gorgeous blue, turquoise, cyan, and green shades of kingfisher feathers don’t come from any pigments. Most vertebrates aren’t able to produce pigments in this color range. At the microscopic level, the seemingly colored parts of blue feathers on kingfishers are actually just gray or translucent.
The blues we see come from the way white light interacts with the microscopic structures of the keratin proteins in feathers. Blue wavelengths get scattered by the feathers, while other wavelengths pass through or get absorbed.
This is a form of what’s called ‘structural color.’ Specifically, this is an example of the Tyndall Effect. That’s what causes smoke from a motorcycle tailpipe to look blue-ish. And it’s where blue eye color comes from in humans. Blue-eyed people don’t have any blue pigment in their eyes. It’s just a natural magic trick—a trick of the light scattering off of microscopic structures in the iris.
These birds aren’t known for singing pretty songs. But that’s okay. They do make some fun sounds. The Belted Kingfisher, common across North America, makes what is described as a harsh, uneven ‘rattle.’ Across the pond, in Europe and Asia, the Common Kingfisher is a similarly well-known bird. It has a softer, whistle-like call.
Diversity and Distribution
The family Alcedinidae is made up of all the world’s Kingfishers and Kookaburras. At last count, there are between 114 and 120 species. 118 is the official number on Clements Checklist, which is what eBird uses.
So there’s a fair amount of species diversity within the family Alcedinidae. These 118 species are divided into three major genetic lineages. Each lineage represents a unique subfamily. The unofficial names of these subfamilies are the pygmy kingfishers, the forest kingfishers, and the water kingfishers.
The forest kingfisher subfamily, technically named Halcyoninae, has the most species, about 70. The kookaburras and paradise-kingfishers are in this subfamily.
The water kingfisher subfamily is called Cerylinae. It has the lowest diversity of the three subfamilies, with only 9 species. The Belted Kingfisher and Giant Kingfisher are in this group. So are the other 5 western hemisphere species and the Pied Kingfisher, which is widely distributed across sub-saharan Africa and southern Asia.
And then you got your pygmy kingfishers. Let’s not forget about those little buggers. Not only are these birds cute, they’re among the most brightly colored kingfishers.
The scientific name of the pygmy kingfisher subfamily is Alcedininae. They’re also called river kingfishers. There are about 35 species in this subfamily. The Common Kingfisher, Alcedo atthis, is one of them. Of course, in Europe they just call this bird the kingfisher.
So we’ve got three subfamilies, these three major lineages within the family Alcedinidae. Even though birds in these subfamilies all look roughly similar to us silly humans, the three lineages have been genetically distinct for millions of years. The closer you look, the more differences you would probably find among the forest kingfishers, the water kingfishers, and those adorable pygmy kingfishers.
Kingfishers are all over the planet, for the most part, so that makes this a cosmopolitan family. A cosmopolitan species or family or whatever is found across all or most of the Earth.
Kingfisher species are not, however, evenly distributed around the planet. Most of their diversity is in the Old World. Only 6 species live in the New World, in the Americas. And we find more kingfisher species concentrated in the tropical latitudes than in temperate areas. North of Mexico, we have pretty much just one species, the Belted Kingfisher. Northern Europe and Asia have the Common Kingfisher and a few more species in the Far East.
Given their cosmopolitan distribution, it’s perhaps not surprising that kingfishers live in lots of different habitats around the world. Yes, many species do hang out near water. Some kingfishers hang out at the edges of lakes and ponds, others prefer rivers and streams. Some live exclusively in mangrove forests along the coast; some live on tiny coral atolls in the middle of the ocean.
But there are also a bunch of species that aren’t particularly interested in large bodies of water. The many species in the forest kingfisher subfamily, for example, live mostly in tropical forests or open woodlands. Other kingfishers live up in the mountains or in the desert. The best known desert-lover is probably the Red-backed Kingfisher of Australia, Todiramphus pyrrhopygius. This little bird lives all across the Australian continent, but it seems to prefer the super dry habitats of the interior.
Most kingfishers live in more or less the same place all year. Our familiar Belted and Common Kingfishers, however, are among those that migrate. Populations of these northern species retreat southward from regions that freeze up in the winter.
Evolution
Let’s take a brief look at the evolutionary history of Kingfishers. Two recent research papers on the evolution of kingfishers and their close relatives shed a lot of light on this question. Ornithologists based at the University of New Mexico conducted both studies. The researchers used genetic data to build phylogenies, also called evolutionary trees. They built a tree for the kingfisher family in the first paper and another tree for kingfishers plus their close relatives in the more recent paper.
Using a bit of fossil data and some complicated statistics, the researchers were able to calibrate their evolutionary trees in time. This allowed them to estimate when—and also where—kingfishers first came on the scene, way back in the day. It looks like these birds originated in southern Asia, in India or Malaysia, sometime between 20 and 34 million years ago. At that time they would have split away from their closest relatives, the Motmots. Motmots are also colorful, sit-and-wait predators. They live exclusively in the New World tropics.
From southern Asia, kingfishers diversified and spread around the world in multiple waves of colonization. Along the way, the three subfamilies formed and diverged.
A lot of the species diversity we see today among kingfishers is the result of relatively recent evolution. This brings us to birds in the genus Ceyx and birds in the genus Todiramphus. These genera contain 25 and 30 species, respectively. ‘Genera’ is the plural form of genus. These two diverse genera contain nearly 50% of all kingfisher species. Birds in the genus Ceyx birds in this genus are in the pygmy kingfisher subfamily. Kingfishers in the genus Todiramphus are in the forest kingfisher subfamily.
Why are these two genera so rich in species? The deal has to do with tropical islands. In the last few million years, these little buggers have been colonizing one island after another, forming new species all along the way. Islands are, in general, hotbeds of evolution, where new species form more often than on the mainland. This is mostly because of the geographic isolation of islands. You know, like the Galapagos Islands, Darwin’s Finches, all that good stuff?
Kingfishers in the genus Ceyx have been forming new species across the Philippines and the islands of Indonesia. Similarly, Todiramphus kingfishers have been island hopping across the Pacific, across Oceania. They’ve been forming new species all over the place, from Fiji to New Zealand to French Polynesia. Many of these species exist on only one small island.
Conservation
Let’s talk about conservation issues with Kingfishers. I wish I could say that there are no such issues. We could just skip ahead to talking about how kingfishers hunt and make babies and all that. But, unfortunately, at least 43 of the 118 kingfisher species are in definite trouble. So that’s over one third of all the species.
According to the IUCN Red List of threatened species, there are 4 critically endangered kingfishers as well as 2 that are endangered. This is at the global level. And then we have 10 species that are in the vulnerable category and another 26 that are considered near-threatened.
Now, we’ve talked about how much of the world’s kingfisher species diversity is strewn across a bunch of islands—in the Philippines, Indonesia, and the western Pacific Ocean. And you know that birds and other critters on islands tend to get hammered by human shenanigans. Animals on islands are extra vulnerable to habitat destruction, hunting, and the ravages of invasive species. So putting all this together, you can predict where most of our endangered kingfishers are. That’s right, on islands.
In our list of how many kingfishers are in trouble, I didn’t mention the one species that’s in the most dire situation. The Guam Kingfisher, Todiramphus cinnamominus, once lived on only it’s namesake island. Guam is a small, isolated island north of New Guinea and east of the Philippines. Brown Tree Snakes were accidentally introduced to Guam not long after World War II. In the following decades, this invasive snake was responsible for wiping out many of Guam’s native bird species.
By the mid-1980s, the Guam Kingfisher was almost extinct. The last 29 kingfishers were caught and taken into a captive breeding program, to save the species. So the Guam Kingfisher is one of only a handful of bird species in the world with the sad distinction of being ‘extinct in the wild.’ There are only around 200 Guam Kingfishers at a couple breeding facilities in Guam and in the mainland US. Conservationists plan to reintroduce them at some point, but the Brown Tree Snake and feral cats are still a major threat. We can all hope that, somehow, someday this bird will thrive in the wild again.
Diet and Foraging
Most of the cool stuff about kingfishers has to do with how they eat. So it’s time to get more into all of that.
Kingfishers are mostly what we call ‘sit-and-wait’ predators. They sit on a branch and wait until they spot something moving below, either in the water or on the ground. Maybe a juicy fish, an insect, or a small reptile. It varies from species to species, but kingfishers eat all kinds of other stuff, too, like crabs, amphibians, mollusks, and even baby birds and small mammals. To maintain their high metabolisms, kingfishers scarf down a lot of these other critters—50%-60% or more of their body weight every day.
Having zeroed in on its prey, a kingfisher darts down to nab its meal using its massive bill. Again, not like a spear, but like a pair of tongs.
Most species have small bodies, short tails, and rounded wings. These features allow a kingfisher to accelerate quickly from its perch to reach its target in a flash.
Some kingfishers can hover in the air while hunting, rather than sitting on a perch. The most famous hoverer is the Pied Kingfisher, Ceryle rudis. I mentioned that this bird lives in Africa and southern Asia. The Pied Kingfisher is the largest bird in the world that is capable of sustained hovering. It’s about 27 cm or 10.5 inches long.
The Pied Kingfisher hunts over large bodies of water like lakes and lagoons, far from any branches to perch on. While hovering, it peers down into the water, looking for fish. It keeps its head amazingly stable while the rest of its body moves around with each wingbeat.
What plumage pattern do you expect a Pied Kingfisher to have, based on its name? Pied usually refers to a black-and-white all over sort of coloration in birds and other animals. We’ve got the Pied Heron, the Pied Thrush, Pied Cormorant, and so on. The Pied Kingfisher is indeed black and white.
One of the take home fun facts of this blog, I think, is that only a minority of kingfisher species actually specialize in eating fish. Two large eyes fill most of the space in the large skull of a kingfisher. The vision of these birds is pretty spectacular. It would have to be given their ability to catch skittish, fast moving prey like small fish.
Most other types of birds have eyes that only face outward to the sides, such that they have only monocular vision. But some birds like hawks, hummingbirds, terns, and kingfishers have binocular vision as well. This is where both eyes see at least part of the same image, providing more accurate depth-perception than monocular vision. Kingfishers have a narrow band of binocular vision straight ahead, aligned with their bill.
When hunting, a kingfisher first uses its monocular vision to detect the movement of any small critters. Then it switches to binocular vision as it swoops down to dive bomb its prey.
There’s some more interesting stuff about the anatomy of kingfisher eyes. This has to do with the fovea. You may know about this because this structure is also in the human eye. The fovea is a tiny dimple, a depression, in the middle of the retina. It’s the spot where we get our sharpest vision. This is because the fovea is densely packed with color-sensitive cone cells.
Some birds, like our little kingfisher buddies, have not just one fovea in each eye, but two! Each eye has two foveae. One of them provides sharp eyesight for the bird as it looks out to its sides, with monocular vision. This is the standard situation for bird eyes in general. The second fovea in the kingfisher eye is positioned further back on the retina. It allows for acuity while the bird is in binocular mode, as it rockets down towards its targeted prey.
The lens in the eye of plunge-diving kingfishers has a special shape that allows these birds to focus its vision underwater. Most birds can’t do that. And kingfishers have built in swim goggles, too. All birds have a third eyelid, called a nictitating membrane. It slides across the eye horizontally. When a kingfisher plunges into water, its nictitating membranes cover its eyes. And since the membranes are transparent, the bird can still see. See if you can notice (watch video) the nictitating membranes on the birds’ eyes. And also watch how the beak opens up to nab the fish.
The beaks of kingfishers are pretty special. Not just because they’re enormous or because, at least in some species, they're a blinding shade of orange. Kingfisher bills are superbly-adapted tools for catching prey. The bill of the classic plunge-diving, fish-eating kingfisher has a special, streamlined shape. It’s great for efficiently piercing the water’s surface at high speed.
There’s a really fun research study on kingfisher bills, conducted not that long ago by a graduate student at Bangor University in Wales. His name is Rowan Howe. He used 3D imaging to scan the bills of eight kingfisher species. Half of these were diving, fish-specialists and the other half were terrestrial.
After being scanned into a computer, the bills were 3D printed to make plastic models of each. Howe, the grad student, set up an apparatus to plunge each plastic model into water to accurately measure the deceleration of each kingfisher bill.
Low and behold, he found significant evidence that the bills of fish-eating specialists cause much less deceleration on impact. This tells us that the bill shapes of these species are indeed well-adapted to their special mode of feeding. These bills pierce the water in such a way that they minimize the force of the impact. 3D-printed kingfisher beaks… What a cool research project!
Kingfisher bills have also inspired the shape of a train. But it’s true, though. Some models of Japanese Shinkansen bullet trains have a sci-fi-looking, pointy front end. You see, back in the day, when these trains had the more standard bullet-shaped nose up front, they would make a deafening boom sound as they exited tunnels. The train produced a shock wave by pushing air at high speed through the tunnel. This was a problem. It bothered people and wildlife.
An engineer, who also happened to be a birdwatcher, was inspired by the bill of the kingfisher to design a more elongated, streamlined front end on his trains. And… it worked (watch video). The bird-beaked trains didn’t make the loud booms. These trains are also faster and more fuel efficient.
This is a splendid example of what’s known as biomimicry. Engineers can borrow designs from nature to solve human problems. Over millions of years, evolution has honed the shapes of bird beaks for specific purposes. Sometimes we don’t need to reinvent the wheel. We can just copy the wheel’s blueprints from our friends, the birds.
And speaking of friends… Some research on the Common Kingfisher in Spain has shown that these little birds like to buddy up with Eurasian Otters, Lutra lutra, otters also eat fish. Kingfishers follow otters around so they can either snatch up the fishy scraps left behind by the playful mammals or nab any little fish disturbed by all the furry activity. The kingfishers benefit from the behavior of the otters and the otters aren’t bothered by the birds.
This arrangement between kingfishers and otters is thought to be an example of what ecologists call commensalism. Commensalism is an association between two species, where one of them benefits and the other is unaffected. Apparently, this commensalism between kingfishers and otters occurs in other parts of the world, too, with different species. Pretty cool and pretty cute, if you ask me.
After a kingfisher successfully grabs prey, it usually flies to a perch to eat. It’s common for the bird to take its fish or other unfortunate prey animal and smack it hard against the tree branch. Repeatedly. This is probably to stun the prey and to break off any spines, or maybe to break some bones. Kingfishers swallow their prey whole, so this tenderizing process makes everything go down a little smoother.
Sort of like owls, kingfishers often hack up a pellet after digesting their meal. This pellet contains any hard bits like bone fragments, scales, or shells.
When we learn about a family of birds, as we are today with Alcedinidae, we sometimes come across members of the family that really stand out. These species are outliers that, for one reason or another, seem kinda weird.
Our weirdo bird today is the Shovel-billed Kookaburra, also called the Shovel-billed Kingfisher. Its scientific name is Clytoceyx rex. The Shovel-billed Kookaburra lives in the rainforests of New Guinea. It’s a medium-sized kingfisher, with plumage that’s orange and brown with a splash of blue on the rump. What set’s this species apart is its bill. This is relatively short, but thick and deeply arched. So not your typical, elongated kingfisher bill. The Shovel-billed Kookaburra also forages in a weird way, compared to other members of its family. It usually forages on the forest floor, rather than from a perch. And ornithologists think this bird might be more active at night than in the day. Also weird.
That chunky bill isn’t just for show: the Shovel-billed Kookaburra literally shovels its way through patches of soil as it hunts for earthworms. It routinely plows a patch about 20 cm by 30 cm, down to 8cm deep. It eats other small animals too, but worms seem to be its favorite thing. Shovel-billed Kingfishers usually have bits of mud caked on the insides and outsides of their beaks. Fantastic! What a weird and wonderful bird.
Breeding
To keep up with the world’s insatiable demand for kingfishers, male and female birds dutifully pair up to reproduce. Kingfishers are monogamous. Depending on the species, a pair may stay together for only one season or for their entire lives. The Belted Kingfisher is one example of a seasonally monogamous species.
The Laughing Kookaburra is a species that mates for life. These birds are also cooperative breeders. Often, 4 or 5 of a mated pair’s older offspring will hang around to help defend Mom and Dad’s territory. These younger birds also help incubate the eggs and feed the nestlings.
Territoriality is the norm for kingfishers. They fiercely defend their stretch of a river or their patch of forest. The food resources and nesting habitat in their territory need to be protected from other members of the same species.
All members of the family Alcedinidae are cavity nesters. Most of them dig tunnels to make their nests. They dig tunnels in river banks or similarly exposed areas of soil, like road cuts or ditches. Other kingfisher species nest in tree cavities.
Amazingly, there are also species that make their nests by digging holes into the nests of tree-dwelling termites. These arboreal termite nests are big masses made of cemented termite poop and bits of wood. The termites don’t really do much to defend their colony against this avian invasion. A study that investigated nests of the Micronesian Kingfisher found termites crawling around in freshly excavated kingfisher cavities. But then the termites were never seen in there again. Maybe the termites just seal themselves up in their own little tunnels, leaving the birds to their business.
I have a new word to add to your vocabulary: termitarium. That’s the technical name for a termite nest: Termitarium. Or termitaria, in the plural case. Aquarium, planetarium, herbarium, termitarium… you get the picture.
When kingfishers excavate a nest tunnel, both sexes put in a lot of work. They use their bills at first and, once they can scramble around inside, they also use their feet. On river banks and other such places, the male and female often take turns flying fast and furious at the slope, ramming it with their bills. They use their bills like a pickaxe during this aerial ramming phase. Sometimes, these little birds ram the surface so hard that they crack their bills or even get fatally injured.
After several days or even several weeks, the birds finish digging their tunnel. They make a small chamber at the end where the eggs are laid. The Belted Kingfisher and the Common Kingfisher dig tunnels somewhere around 3-6 feet or 1 to 2 meters deep. But the longest tunnel on record for a kingfisher was made by a Giant Kingfisher. Good ol’ Megaceryle maxima. The tunnel was about 28 feet deep, which is about 8.5 meters.
Baby kingfishers are cared for by both Mom and Dad. At least in the fish-eating kingfishers, the nest chambers can become littered with all sorts of gross fish bones, scales, and other flotsam. It probably doesn’t smell too nice up in there.
Once the young birds have emerged from the nest and have fledged, the parents teach them how to catch prey. Mom and Dad will toss a dead or stunned fish or other food item into the view of the youngsters. They do this training exercise at least a few times. In most species, the family splits up after 1-4 months together. The newly fledged kingfishers are off on their own.
Life is hard for these young, relatively naïve birds. Many don’t survive their first few weeks being on their own. And kingfishers in general, including adults, have at best about a 50% chance of surviving from one year to the next. So even though there’s a record of a Common Kingfisher that lived to be 21 years old, most don’t live more than maybe 4 years. So it goes.