The Science of Birds - Sandpipers

Episode Date: April 11, 2021

Birds in the family Scolopacidae include all the world’s sandpipers and birds such as godwits, curlews, snipes, dowitchers, willets, stints, and more.We know these as familiar ‘shorebirds.’ They haunt coastal habitats from autumn through spring (Oct to Apr, or so). But in summer most of them migrate long distances to breed in the highest temperate latitudes or in the Arctic.Learn about sandpiper diversity, evolution, feeding, and more in this episode.~~ Leave me a review using Podchaser ~~Link to this episode on the Science of Birds websiteSupport the show

Take a stroll on a sandy beach just about anywhere in the world, between December and March, and there's a chance you'll meet a plump little shorebird called the Sanderling. Scurrying back and forth across the beach in small flocks, sanderlings forage for tiny crustaceans and mollusks in the wet sand. These are those endearing little birds you've seen running up the beach just ahead of an incoming wave. They look like they're trying frantically to keep their sneakers dry. But when the wave recedes, the sanderlings turn around and chase after it. They peck and probe, snatching up invertebrates they find stranded in the sand.

After a hearty meal and some digestion, a sanderling will often hack up a pellet made of sand and bristling with bits of exoskeleton and shells. Sandalings are a species of sandpiper, one of the most familiar sandpipers, actually, because of their vast distribution across the world's coast. lines. In the non-breeding season, which is usually when we see them on beaches, sandalings wear a plumage of pale gray and white. They have black bills and black legs. They use those little legs to run at impressive speeds across the beach. One Spanish name for this species is Correlimus tridactilo, which means three-toed runner. Most of them hang out in flocks at this time of year, but here and there a sanderling will get all territorial and decide that it owns a particular patch of wave-washed beach.

It will vigorously chase off any other sanderlings that wander into its territory. The territory owner hunches its shoulders, throws its head forward, and runs full force at the intruder. A chase ensues with a blur of tiny black legs. The intruder might stop and turn around and act tough for a moment or two, but in the end they always back down. Like most other sandpipers, sandalings migrate far to the north in summer. They breed on the high Arctic tundra, mostly in Canada, Greenland, and Siberia. So we'd say this species has a circumpolar breeding range. It forms a sort

of ring around the North Pole. Ornithologists know much more about the lives of sanderlings in the non-breeding season than the breeding season. You can imagine it takes a lot more effort to study these birds way up in Siberia or Greenland, compared to on the beaches of, say, Southern California or Texas. The scientific name of the sanderling is Calidris Alba. Not to be confused with Idris Elba, the award-winning British actor.

The bird is Calidris Alba. The man is Idris Elba. People mix these two up all the time. Like when someone sees a sandalling skittering across a beach, they might say, wait, is that award-winning British actor Idris Elba? Why is he running around chasing waves

and eating worms. Hello and welcome. This is the Science of Birds. I am your host, Ivan Philipson. The Science of Birds podcast is a lighthearted, guided exploration of bird biology for lifelong learners. This episode is not just about the San Francisco. underling, in case you were wondering. No, today we're doing a deep dive into the entire family

of sandpipers and their allies, the family Scolopaceti. This is a diverse and fascinating group of birds. That means we have much to discuss naturally, so let's get on with the program. I'll begin by a new new. in mind-numbing detail the barely perceptible plumage differences between the many species of small sandpipers. I'm just kidding, of course. Let's not do that. But hey, if you got excited by that topic, kudos to you for being such a keener, such a zealous student of ornithology. No, instead, let's start as we usually do by talking about the key traits of sandpipers, all these bird species in the family skull opacity. Starting with shape and size, the basic silhouette or outline is pretty consistent

among birds in this group. Their bodies are ovoid, in other words egg or football shaped. Their heads are relatively small and rounded. Most of them have legs on the longish side and fairly short tails. Many sandpipers are what we might call stocky with plump bodies and short necks. However, a handful of species are more lithe and graceful. In terms of size, the largest member of this family is the far-eastern Curlew, which gets up to 66 centimeters or 26 inches long, from bill to tail. But about one-third of that length is the Curlew's super-long bill. This oversized beast of a sandpiper has the scientific name,

Numenius Madagascariences. Madagascariences. You may know that when a species name has the suffix, ensis, that usually is a reference to where the animal was first discovered or where it originates, something to that effect. So among other places, the Far Eastern Curlew must surely hang out in Madagascar, right? Not so much, actually. This bird has never been recorded in Madagascar. It lives, well, in the Far East, Russia, East Asia, and down to Australia and New Zealand.

So what gives with this scientific name? I don't really know. Some dude way back in the 1700s apparently came up with this name for some reason. Moving on. The smallest of our sandpipers is a toss-up between the little stint and the least sandpiper. These tiny buggers come in at a length of 12 to 15 centimeters or about 5 inches long. The little stint is probably a bit smaller than the least sandpiper. so we might say the little stint in terms of body length is last but not least.

And while we're naming birds based on their size, we should rename the far-eastern curlew. I say we should call it the most sandpiper. It's when we look at the bills of sandpipers that we find the greatest diversity of shapes. Their thin bills show a wide range of lengths and degrees of curvature. Some are short, others are absurdly long. Some are arrow straight, some curve or droop down. A few even curve upwards, which is also kind of wacky. We'll talk more about Sandpiper Bills shortly. Species in the family Scolopaceti are not what we would call colorful birds. They tend to be brownish on top with

lighter undersides. Other colors mixed in to varying degrees are gray, black, white, and rusty red. The patterns made by these earthy colors among the feathers can be intricate and beautiful when seen up close. Some species also have bold, black, and white markings in their wings that are only visible in flight or when the birds flash them deliberately during displays. If, like me, you're a sucker for brightly colored birds, sandpipers can seem a little dull in the plumage department. But we need to appreciate that this coloration is a consequence of natural selection, an adaptation that helps these birds survive. They live and feed in open habitats with little cover, so they're vulnerable to both aerial and terrestrial predators. Two aspects of

sandpiper plumage provide these birds with great camouflage against predators. Number one, being dark on top and light on bottom makes you harder to see. This is called counter-shading. When a bird is lit from above by the sun, counter-shading can even out the tones between the bird's upper and lower sides, making it appear less three-dimensional. With counter-shading, a sandpiper kind of washes out and blends in with the background. Number two, the complex checkered and streaky patterns of browns, white, cream, gray, and black on a shorebird's upper side break up the bird's outline, helping the bird disappear into the vegetation of its surroundings. This is especially important in the breeding territory.

since many of these birds nest on the ground, out in the open. Plumage differences between males and females are highly variable among species. Sexual dimorphism is strong in some species like the ruff. Male ruffs sport large, boldly patterned head tufts that look sort of like a lion's mane. Female ruffs are plain by comparison. They look like your everyday vanilla sandpiper. Many other species, on the other hand, show, little if any noticeable differences between the sexes.

Now, how about sounds? What sort of sounds do sandpipers make? They aren't technically songbirds in the taxonomic sense. Most sandpipers make relatively simple vocal sounds. They make alarm or flight calls, and they make breeding vocalizations that we call songs. Let's have a listen to a few, shall we? Here's the breeding song of the Dunlin, Calidris Alpina. This bird is in Canada.

Males of the American Woodcock, Scolo Pax Minor, make this buzzy sound at dawn or dusk as part of their display to attract the ladies. The upland sandpiper, Bartramia Langecouda, is an oddball in this bird family because it's completely terrestrial. It's a grassland species that couldn't give a hoot about the coast or wetlands. Here's the ethereal cry of the upland sandpiper, heard on the American prairie. Over in Europe, we have the common sandpiper, actitis hypolycus. This species breeds all across Eurasia and spends the winter in Africa, southern Asia, and Australia. When flushed, the common sandpiper makes a sound like this. Here's another call from a bird that just got flushed.

See if you can hear the tone of sour indignation in the voice of this, greater yellow legs. Some sandpipers make sounds with body parts other than their syrinxes. Recall from the Science of Birds Episode 5 that the syrinx is the voice-producing organ of birds. If you haven't listened to Episode 5, you better add that to your to-do list for tonight. Wilson's Snipe, Gallinago Delaceta, uses a variety of vocal sounds, but it also makes a so-called winnowing sound with its tail. During a swooping aerial display,

this snipe spreads its special tail feathers and beats its wings to force air across the tail. The effect is, well, this. I love that sound. It takes me back to summer evenings in Alaska. Wilson's snipe are zipping through the sky all over the place up there, threatening their rivals and trying to attract,

mates by making their winnowing sounds. Most other snipe species in the genus Gallenago make these kinds of non-vocal sounds. What say we move on now to discussing the diversity, distribution, and habitats of sandpipers. This episode is about sandpipers, right? So why have I been talking about birds like yellow legs, stints, and curlews. Those guys don't have sandpiper in their names. It's because I'm using the word sandpiper here in a broader context. It's the general name we can use for all birds in the family scolopacity. Sandpiper rolls off the tongue a little more smoothly than scolopacid. This family includes a little over 90 species in 15 genera. But only 23 of these species have common names that include the word sandpiper. Other birds in the family

skullopacety include wimbrils, godwits, turnstones, knots, dowwitchers, phall ropes, shanks, and a few others. We commonly lump this rowdy bunch of birds into the broader category of shorebirds. This isn't a technical word that applies to any specific taxonomic lineage. It's just a somewhat helpful colloquial word, sort of like the word raptor. Instead of saying shorebirds, birders in Europe tend to call these birds waiters. At least, that's my understanding. But here in the U.S., birders use the term waiter

to mean a large, long-legged bird like a heron, egret, flamingo, crane, or something like that. See, this is why common names are so dang confusing. There are other bird families we include in the shorebird category. For example, the plover family and the Avicet family. Birds in those families bear some superficial resemblance to sandpipers, but they aren't closely related. So, all sandpipers, all members of the family scolopacety, are shorebirds. But not all shorebirds are in the family scolopacity.

Make sense? Capish. Now, within scolopacety, there are several genuses, genera, that is, that are more diverse than the others. First is Calidris, not to be confused with Idris. This genus includes 24 species, including some familiar friends like the Western Sandpiper, Dunlin, and Red Knot. Also in the genus Calidris is the least sandpiper and the last but not least sandpiper, otherwise known as the Little Stint.

Here's another bird lingo difference between North America and Europe. In Europe and Asia, Stint is the term. term used for the nine or so species of taincy-weensy sandpipers in the genus Caledrus. In the U.S., our collective name for these same little birds is Peeps. Peeps, like those revolting, chick-shaped marshmallow blobs that take up space in my Easter basket every year. Space which, I should point out, might otherwise be filled with something I really want to eat, you know, like a brittle, hollowed-out chocolate bunny rabbit. Thanks for the peeps, Grandma. Next up, we have 17 species in the genus Gallenago. These are all Snipes.

I love Snipes, but man, they look weird, with their eyes placed so high and far back on their heads. They look like some kind of unholy grasshopper bird hybrid from the 13th dimension. But if you listen to Episode 7, which was all about the eyesight of birds, you'll remember that the eye placement of snipes and Woodcocks gives them incredible 360-degree. Grie vision, which is pretty cool. The third species-rich genus in this family is Tringa. It contains 13 species, including the Wandering Tattler, Willett, the two yellow-legs species, and the several shank species. Scolopaceti is another example of a cosmopolitan family.

Its members can be found all around the world, including many of the most far-flung islands. But if you're hoping to find them in the depths of the depths of the Sahara or other large deserts, you're going to be disappointed. And guess where else you won't find any sandpipers? Let me just cue up my broken record here. That's right. Antarctica. Antarctica. Antarctica. Nope. No sandpipers in Antarctica, except for a few lost souls that show up very rarely at the far northern tip of the Antarctic Peninsula. Anyway, regardless of where we see them in the non-breeding season, most species in this

family breed in the high latitudes of the northern temperate zone or in the Arctic. Only a handful breed in the tropics. We'll talk more about breeding in Skolopacids in a few minutes. And in case you're wondering, the species observed most frequently in North America are the Willet, the spotted sandpiper, and the greater yellow legs. In Europe, the most commonly reported species are the aptly named common sandpiper and common red shank, along with the ruddy turnstone. You know, if you're not careful when you try to say ruddy turnstone,

you might accidentally call it the turdy rune stone. Be careful with that one. As for habitats, we often see sandpipers on the coasts, obviously, which is where many of them hang out in the northern winter. This is their non-breeding season. At that time, sandpipers forage in intertidal ecosystems and prefer habitats like mudflats, especially near the mouths of rivers. Environments like estuaries are teeming with tasty, nutritious invertebrates that the birds scarf down.

But during the breeding season, these sandpipers live in open, grassy habitats with abundant moisture and plentiful insect prey. These locations aren't necessarily on the coast. Lots of species breed on the Arctic tundra, but some make their nests in grasslands, on rocky shores, or even in forests. Let's take a few moments to consider the evolution of our featured creatures, the 90 or so species of scolopacids.

The fossil record for this group is pretty lousy, so unfortunately it doesn't do much to help us determine the origin of sand. pipers, either geographically or temporally. Luckily, the genomes of our birds store lots of information about their evolutionary relationships. Genetic data tells us a couple things here. First, it tells us which bird families are most closely related to scolopacody. These are the Jakana family, the Seed Snipe family, and the painted Snipe family. Another close relative is the lonely Plains Wanderer of Australia.

I say lonely because its family is monotypic. It includes only one species. Pedianomis Torkatus, the Plains Wanderer. And doesn't that name just sound lonely? Plains Wanderer? Genetic differences between families, genera, species, or whatever, can be calibrated in time using the molecular. clock approach. Using a molecular clock, researchers have estimated that scolopacody

diverged from its relatives and became a distinct lineage about 25 to 35 million years ago. The other big thing that genetic data tells us is that there was a sort of proto-shorebird slash waterbird ancestor flapping around in the days just before the mass extinction that killed off all the other dinosaurs. So that was about 66 minutes. million years ago. These birds, our sandpipers, have a long history. One of the amazing things about the evolution of the family scolopacidi is the diversity of bill lengths and shapes among species. For at least 25 million years, natural selection has been molding and honing these bills. They're adaptations that allow this group of birds to

exploit diverse diets and foraging strategies. A major driving force that led to these differences was probably competition among species. Let's say you're a sandpiper with a short bill, and you like to poke around in the mud to snatch up small mollusks from the surface. But there's a closely related sandpiper species that eats the same prey. It bops around on the mud flat too, and it routinely gets all up in your business. If your species can, through many generations of natural selection, end up with a longer bill, well, then your descendants should be able to dig up mollusks from deeper down in the mud.

In that case, they wouldn't even care if they're shoulder to shoulder with that other pesky species with its short little bill. If this sort of evolutionary process happens between a bunch of species, you end up with an assortment of bill lengths. Multiple species of sandpipers and other shorebirds can forage side by side in the same habitat without being in direct competition.

We call this phenomenon resource partitioning. Many of these birds are, more or less, all after the same resource, invertebrates in the mud. But the birds coexist in apparent harmony because they probe for prey at different

depths and they forage in different ways. I already did a podcast episode on competition within species, but now I need to do one on competition between slash among species. We'll look at resource partitioning in more detail in that future episode. Evolution never sleeps, of course, so the story isn't over for sandpipers.

For example, the high species diversity we see in the genera Caledrus and Tringa is a relatively recent phenomenon. These birds have been forming new species rapidly over the last few million years. And hey, if humans don't kill them all first, these lineages will probably keep on bifurcating into new and wonderful species. If we're lucky, we'll get some new peeps someday. Imagine you're exploring the Ganges River Delta in Bangladesh, at the edge of the Bay of Bengal. This is a landscape of swamps and labyrinthians.

stream channels, crawling with pythons, crocodiles, and the occasional tiger. You come to the edge of a dense mangrove forest where a broad mudflat extends into a coastal lagoon. Among the many bird species foraging on the mudflat, you see a small, pale sandpiper, a kind of peep or stint, if you will. It's like a sanderling, but smaller, and there's something very different about its bill. You use your binoculars to get a closer look. You see this bird has a black bill that widens dramatically at the tip. It forms a weird sort of spatula shape. You're looking at a spoon-billed sandpiper, callidrous pygmia. It's one of the world's rarest and most endangered shorebirds. That weird bill is indeed spatulate, which is the technical word for its

shape. We also see spatulate bills on some ducks like the northern shoveler and on the six species of spoonbills in the family Threskyornithity. This feature of the spoon-billed sandpiper is unique among shorebirds. While foraging in shallow water, the sandpiper sweeps its head back and forth quickly, sifting out small invertebrates using its bill. Spatulate bills are ideal for sifting. Side note, I just want to point out that in the Ukrainian language, the name for this bird is Lopatania.

But for the record, I don't speak Ukrainian. Google translates Lopatania as shovel. So is the Ukrainian name for this bird seriously just shovel? Oh, look over there. There is small bird. It is shovel. Very interesting bird. Very rare.

It is always good to see shovel. Nice bird. I think something got lost in translation there. Other translations for the name of this species in Russian and Ukrainian came up as blade or spatula. I guess I should take Google's translation. translations with a grain of salt. Getting back on track, the spoon-billed sandpiper spends the winter mostly in just a few places on the coasts of Bangladesh, Myanmar, and Thailand.

These birds migrate far to the north to breed in the extreme northeast of Russia. Here's the sound of a male Spoonie on his breeding territory in Siberia. Sadly, less than 500 spoon-billed sandpipers remain on the planet. This is a critically endangered species. What has brought it so close to the brink of extinction? Two big factors are involved, habitat loss and hunting. Spoon-billed sandpipers, like many migratory shorebirds, depend on several habitat types between their breeding range, non-breeding range,

and the places they stop to rest and feed during migration. Vast swaths of coastal habitat have been destroyed by industrial-scale reclamation projects in China and Korea. These are places where spoon-billed sandpipers traditionally made stopovers during their long migrations. Expansive estuaries and tidal flats have been replaced by chemical factories, power plants, prisons, and oil drilling complexes. The bird's winter habitats in South Asia have also been heavily degraded by pollution, among other things. And that's also where hunting is a major problem.

Subsistence hunters illegally trap these sandpipers in their non-breeding habitats. I've taken so much time to tell you about the spoon-billed sandpiper because, besides being adorable and fascinating, it's a good poster child for the conservation of sandpiper and other shorebirds. Shorebirds have seen a precipitous decline in the last 50 years. Some of the hardest hit species, like Spoonies, are Arctic breeders that use the East

Asian Australasian flyway during migration. These birds are losing the critical habitats they need during migration and winter. Global warming and rising sea levels are major threats as well. Sandpipers are generally coastal critters, as human communities on the coasts come under threat from the rising sea, people are responding by building concrete sea walls and other structures. These can severely alter or destroy intertidal habitats. The International Union for the Conservation of Nature lists 31 of the world's sandpiper species in some category of endangerment. So that's a full one-third of all the

species in the family skull opacity. The IUCN Red List puts three species, including the spoon-billed sandpiper, in the critically endangered category. Another five species are endangered, four are vulnerable, and 19 are listed as near-threatened. Five members of this family have been driven to extinction by humans in the last few hundred years. All of them lived on Pacific Islands, including New Zealand. Each of these species was wiped out, mostly by invasive rats and other non-native mammals. Here in North America, we have, or had, the Eskimo Curlew, Numenius Borealis. This large sandpiper is listed as critically endangered.

However, no one has made a confirmed sighting of an Eskimo Curlew since 1963. So there's a good chance this species, too, is extinct. Reckless overhunting in the late 1800s was a big factor in this bird's demise. Once upon a time, it may have been one of North America's most numerous shorebirds. There used to be millions and millions of Eskimo Curlews, and now it seems likely that there are none. Turning now to look at the ways Sandpiper's forage and to look at what they eat. Let's consider again all those bills of varying lengths.

The length and curvature of a sandpiper's bill reflect where and how the bird forages. Species with short, thick bills like the surf bird pull muscles and barnacles off of rocks. Bills like this are also good for opportunistic generalists like the ruddy turnstone. These turdy runestones, I mean reddy turnstones, really do flip stones over with their stout bills to expose small prey animals. Fallaropes have very fine, almost needle-like bills. These are used to pluck tiny invertebrates out of the water. So these bills work sort of like forceps or tweezers.

Many sandpiper species have straight bills that are much longer than their heads. These bills, too, function like forceps. But they're also great for piping sand, if you will, or probing for prey in mud, soil, or matted vegetation. At the extreme end of this distribution, we have the ridiculously long and decurved bills of the curlews. These are especially well adapted for snatching crabs and shrimp that live in deep burrows. How do sandpipers find such prey when it's buried out of sight?

Do they just probe and probe and probe some more, feeling around until they finally hit pay dirt? For the most part, yes. But these birds have a trick up their sleeve that greatly improves their chances of finding buried treasure like clams, crabs, and worms. They have something called a bill-tip organ. This is a cluster of special nerve endings called herpsed corpuscles. That's a strange word. It's hard to say.

Herpst. It's got four consonants crammed together in there with no vowels. When a sandpiper probes into wet sand or mud, the bill-tip organ with those herpsed corpuscles allows the bird to sense subtle changes in pressure. So this is an enhanced sense of touch that works sort of like echolocation. It allows the birds to feel their prey a short distance away

before they actually come in direct contact with it. Isn't that cool? Most sandpipers switch between this tactile hunting and visual hunting as needed. It depends on what kind of prey they're after. Another cool thing about many sandpipers is that they have an unusual ability called rinkokinesis. Rinkokinesis. I'd spell it for you, but we'd be here for a while.

This is the ability of a bird to independently move part of its upper beak, its upper mandible. In most vertebrates, including humans and most birds, only the lower mandible can move relative to the rest of the skull. Rinkokinesis of the bill tip has been found in dowwitchers, godwits, long-finding. billed curlews, leased sandpipers, and other species. It may be an adaptation that improves the ability of these birds to catch their burrowing and aquatic prey. Besides all this variation in bill length, sandpipers show quite a range of leg lengths. At least for wading species, there is a correlation between bill length and leg length. In general, if you gots a short bill,

you also got short legs. Long bill, long legs. Species with longer legs are able to forage in deeper water. These leggy dudes also need long bills to probe down into the watery depths. It's a really wonderful experience, I think, to visit a tidal mudflat between autumn and spring to look at all the shorebirds foraging side by side. To the casual observer, who isn't all that curious about birds, it might just look like a big mess of brown and gray birds with pointy bills. But with patience and careful observation, the differences between the species start to become more clear.

Even if you don't know the names of the species you're looking at, you can see how they move and forage differently. Some are pecking around at the surface in dry areas. Some are flipping over bits of seaweed. A few are rapidly probing the mud like little jackhammers. Others are chasing small fish around in need-deep water. You'll see that some of these birds are methodical as they forage, and some seem more haphazard in their approach. Briefly, I should point out that we've mostly been talking about how and what these birds eat in the non-breeding season. That's when they congregate on coastlines and when we observe them most frequently.

The diets of sandpipers in their breeding habitats can be quite different. Up in the Arctic tundra or in grasslands, these birds feed heavily on adult and and larval insects like flies and beetles. They also gobble up spiders, other invertebrates, and maybe some plant material like berries and seeds. Weirdo alert. Weirdo alert. The spoon-billed sandpiper, our beloved little Ukrainian shovel, is a weirdo in its own way.

But with today's weirdo alert, I want to bring your attention to another species. The Tuamotu sandpiper Prosobonia parvirostris This small, dark brown bird lives only on a handful of tiny islands in the remote Tuamotu archipelago. This is part of French Polynesia in the Pacific.

No other Scolopacid has such a short bill relative to its head length. I mean, this bird barely looks like a sandpiper with its little bill. So that's one bit of weirdness. The Tuomotu sandpiper is also weird because it doesn't migrate. It's what we call a sedentary species. This means it's one of the few sandpipers that breeds in the tropics. But here's the strangest, coolest thing about this bird. It's a nectar

ivore. It sips the sugary nectar from flowers, like a hummingbird or sunbird. It eats insects, too, but nectar seems to be a very important part of its diet. Toomotu sandpipers visit flowers and shove their faces into the corollas to get at the nectar. These birds even have specially adapted tongues that help them sip nectar. Like hummingbirds, Tuomotu sandpipers have forked tongues, what we would call bifurcated. No other shorebird has a tongue like that, and no other sandpiper is nectarivorous.

Tuomotu sandpipers live on coral atolls that barely qualify as islands. Food resources are scarce there. So natural selection seems to have, favored birds that can make use of flower nectar, which is high in caloric energy. When members of an ornithological expedition in the early 1900s were collecting specimens of this bird, they described its call as meh, M-E-H, as in meh, makes me think these birds have a casual attitude of indifference. Like if you ask a Tuamotu sandpiper how it feels about strawberry ice cream or Taylor Swift, all you might get in response is a shrug of the shoulders and a meh.

Here's the actual call of this species. What do you think? Does this sound like meh to you? In general, species in the family, scolopacidi, tend to be highly migratory. As we've been discussing, most of them fly north in the summer to breed. The far north has almost continual sunshine in summer and a plethora of insects to eat. Protein-rich insects are also a great resource for feeding chicks. The migratory feats of these birds can be astounding.

They fly thousands of miles every year. To accomplish this, they need enormous amounts of food, first to build up fat and then to sustain themselves on their long-haul journeys. Long-distance migrants gather in staging areas, usually for a few weeks, where they gorge themselves to pack on fat. Once underway, they land for brief periods in one or more places to refuel. These stopovers occur in coastal habitats, where there's some kind of abundant and rich food source.

For example, Delaware Bay is a key stopover site on the east coast of North America. Every spring, hordes of horseshoe crabs crawl out of the sea to spawn on the beaches fringing the bay. A female crab can lay 100,000 eggs in the sand over the season, and those eggs are loaded with fat. Long before humans ever walked the shores of Delaware Bay, migrating red knots, ruddy turnstones, and many other shorebirds were landing there to feast on the bounty of horseshoe crab eggs.

Some of those birds make a one-way journey of over 8,000 miles, from South America to northern Canada. They need all the fat they can get. Stopover sites like this are so important that if they're destroyed or altered, the results can be devastating for sandpipers. As we discussed, the destruction of stopover and staging sites is a big part of what's causing the decline of the spoon-billed sandpiper and other shorebirds that use the East Asian Australasian flyway. No discussion of migration in Scolopacids would be complete without giving a shout-out to the bar-tailed godwit, Lymosa, Leponica.

This species breeds in the high Arctic, then flies to southern latitudes in winter. One population moves between Alaska and New Zealand. Recently, a bar-tailed godwit, fitted with a satellite tracker, broke the world record for the longest non-stop flight of Annie Bird. This individual is known as 4BRW. That sounds like the name of a droid in Star Wars, but it actually refers to the ID color bands on the bird's legs. This bird flew 7,500 miles non-stop over 11 days from Alaska to New Zealand. A feat of endurance like that requires lots of energy, as you can imagine.

Bartailed Godwitz fatten up dramatically over a couple of months while hanging out in their Alaskan staging area. At the same time, their flight muscles and lungs grow larger. And just before the long journey begins, the livers, kidneys, and guts of these godwits shrivel up. They atrophy. This is an adaptation that reduces some of the dead weight in the bird's body. I mean, no one really needs a liver, right? Now let's move on to talk about breeding in sandpipers. Birds have a variety of mating or breeding systems, and we find pretty much all of them in the family skull opacity. To produce the next generation, most sandpipers form monogamous pairs.

Monogamy is one breeding system. But some sandpiper species are polygynous, and others are polyandrous. In the polygynous breeding system, one male mates with multiple females. The females then care for the young. The Great Snipe, Gallenegro Media, is a perfect example. Males of this species gather in established breeding territories in northern Europe during the summer. These sites are called lecks. That's L-E-K.

Each leck is visited by multiple males and females. You may know that sage grouse do this sort of thing in North America. After sunset, each male Great Snipe stands on a small mound and performs an elaborate display. He flashes his white outer tail feathers and makes a sound like this. Males try to outdo each other with these displays. Successful males might mate with several females. The females then go off to build nests and raise the chicks on their own. So that's polygyny. In the polyandrous breeding system, the situation is reversed. Females compete with each other for the attention of males.

A female will breed with multiple males, and it's the males who incubate the eggs and raise the chicks. The three phallarope species, Wilson's, red, and red-necked, exhibit varying levels of polyandry. Females in these species are larger and have flashier breeding plumages than males. Females compete aggressively to mate with males.

After the eggs are laid, it's dad who incubates them, and its dad who raises the baby fowleropes. This breeding system, Polyandri, is relatively rare in the animal kingdom, including among birds. But the spotted sandpiper, one of the best-known scolopacids in America, is also Polyandrus. Sometimes all of these breeding systems can be found in a single species. Remember the little stint? Quite possibly the world's smallest shorebird?

Well, those little buggers can be monogamous, polygynous, or polyandrous. They're all over the place. Depending on the situation, it might be the female or the male who raises the chicks. In any case, once a pair of sandpipers has sorted things out and mating is over, it's time to build a nest. And I use the term build rather loosely. Most species nest on the ground. That's especially true for all those Arctic breeders. Not so many trees up there.

The nests are simple scrapes, just shallow depressions on the bare ground. Some birds may augment their nest with a bit of vegetation. Four eggs to a nest is typical. After about three weeks of incubation, the eggs hatch and out-pop some fuzzy, insanely cute, chicks. Most Sandpiper species have hatchlings that are precocial. They're born covered in fuzzy down and their eyes are wide open. They leave the nest after a few hours and they get busy feeding themselves. This is like what you see with baby chickens and ducks.

Young sandpipers fledge after two or three weeks. Not long after that, their parents say Sayonara and abandon them to their fates. The adults usually depart to fly south in the autumn before the juveniles. So the young birds have to find their own way the first time they make their epic migration. No adults are there to guide them, so they have to follow their instincts. Amazingly, these birds are born genetically programmed with the knowledge of when to fly south and in what direction and for how long. This inborn ability is one of the marvels of the avian world. Migration is strenuous and full of peril, however, so many juvenile

birds don't survive to see the next summer. But the hardy ones that endure, they might live 10 to 15 years. That's a fair amount of time. It's enough time to perforate lots of mudflats with your pointy bill, to chase countless waves on the beach, and to fly back and forth across the planet dozens of times. Well, there you have it. That's my version of an intro to Sandpiper Ology. We covered a lot, from the least sandpiper to the most sandpiper and lots of other birds in between. As usual, there's much more to be said about a family of birds like this. But I hope you've found this episode informative and at least mildly pleasing.

Thanks a lot for listening and for your interest. If you haven't subscribed to the Science of Birds podcast, I recommend you find that subscribe button and tap away on it. You wouldn't want to miss the next episode, would you? If you have something you'd like to share with me, either about the show or about your position on strawberry ice cream, say, please shoot me an email. The address is Ivan at Scienceofbirds.com.

You can check out the show notes for this episode, which is number 26 on the Science of Birds website, scienceofbirds.com. This is Ivan Philipson. Thanks again, and I look forward to our time together on the next episode. Peace.