The Science of Birds - The Birds of Alaska

Episode Date: July 20, 2021

Alaska is a truly amazing place that is still dominated by nature. It’s a wonderful region to explore for anyone who loves birds and charismatic megafauna. Many of Alaska’s vast natural areas are relatively intact. They offer endless opportunities for visitors to immerse themselves in raw nature.I recently returned from leading a birding tour in Alaska and I was inspired to make a podcast episode about the Birds of Alaska. We’ll first get a sense of Alaska’s geography, then we’ll consider the major ecosystems of the region, and then we’ll get into some of the overall characteristics of the birdlife of Alaska.~~ Leave me a review using Podchaser ~~Link to this episode on the Science of Birds websiteThanks to my newest Patrons for your pledges to support this podcast! I deeply appreciate your help and generosity. Cheers to: Michael R, Justin T, Anette S, David K, Jennifer, Henri-Claude B, Diana H, Jesse M, Pamela G, Carole P, Christine B, Teal, Vero, Emily R, Donna A, and Susan W!Support the show

If you've ever been to Alaska, you were probably left with some powerful impressions of the place, because, well, Alaska is impressive. Visitors to the state are met with range upon range of snow and glacier-clad mountains. The forests and tundra extend to the horizon in many places with few, if any, signs of human influence. The rugged coast teems with marine mammals, salmon and wheeling flocks of seabirds. If you've never been to Alaska, you might picture some of these same things. Or perhaps you envision a frozen wasteland

populated by only penguins and polar bears that guzzle Coca-Cola by the gallon. Sorry if this comes as a shock to you, but there are no penguins in Alaska or anywhere else in the Arctic. Penguins are confined almost entirely to the southern hemisphere, with only one species found just north of the equator.

There are polar bears up in Alaska, but they much prefer the taste of human flesh to that of any saccharine brown liquid that comes from a bottle. It turns out we can't believe everything we see on TV. But Alaska is, like, for real, a truly amazing place that even today is dominated by nature. It's a wonderful region to explore for anyone who loves birds and big shaggy mammals.

Many of Alaska's vast natural areas are relatively intact. They offer endless opportunities for visitors to immerse themselves in raw nature. I recently returned from leading a birding tour in Alaska, and I was inspired to make a podcast episode about the birds of Alaska. The trip was super awesome. My group and I explored Kenai Fjords National Park, Denali National Park, and the remote region around the town of Nome in the far west.

In Nome, we were only about 175 miles or 280 kilometers from Russia. Some bird songs that created a sonic backdrop to our adventure in Alaska included the song of the gray-cheeked thrush. and this is the golden-crowned sparrow and here's the golden-crowned sparrow. We heard and saw lots of other great birds on our trip, including some species that I had never encountered before. For example, I got to see my first King Ider, Aleutian Turn, and Blue Throat.

So how about we take a little field trip up to the great state of Alaska to learn a few things about the birds you can find there? 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. Before we dig into today's topic, I want to correct a little error I made in the last episode. We were talking about the shoe bill.

in episode 30, and when we got around to reproduction in this species, I had a momentary brain short circuit. I said I was puzzled because if only one shoebill chick per brood survives on average, shouldn't the shoe bill population decline over time? But what I forgot was that, duh, shoebills typically have multiple broods over the 30 to 50 years that they live. If the pairs of shoe bills in a population leave behind two offspring on average over their lifetimes, the population should be stable, more or less. I had been thinking in only the very narrow sense of a single breeding event, a single brood. I should have been thinking about the lifetime reproductive success of the breeding shoebills. I credit an astute listener of this podcast with helping me

realize my error. So thanks to Sarah from Yorkshire, England, for listening, for paying close attention, and for gently letting me know that I goofed up. Anyway, today, today we're taking a look at the birds of Alaska. I'm sure I won't say anything stupid in this episode, or ever again, really. That's all behind me now. For this episode, we'll first get a sense of Alaska's geography, then we'll consider the major ecosystems of the region, and then we'll get into some of the overall characteristics of the bird life of Alaska. This is the first episode of the Science of Birds where I'm focusing on the birds of one geographic region. I hope you enjoy it and I look forward to making more episodes like this.

Okay, it's time to grab our binoculars and strap on our boots. We're heading north into the wilds of Alaska. Alaska is, by far, the largest of the 50 U.S. states. Its land area is about 572,000 square miles, or almost 1.5 million square kilometers. If you're like me, you can understand that, sure, those are some big old numbers, but you don't have a mental image of how much land that is. Put another way, Alaska is bigger than the next three largest states combined, Texas, California, and Montana. It's 6.67 times larger than my home state of Oregon. And the island of Great Britain is a

wee bit more than one-tenth the size of Alaska. What's more, if you superimpose Alaska on a map of the lower 48 U.S. states, Alaska spans the entire width of the U.S. It's ridiculous. Of course, that's only if you include the very long Aleutian Island chain that extends Alaska far to the west. But why wouldn't you include the Aleutian Islands? And because I know you're wondering, Alaska is about as big as the Ottoman Empire was in about 1914. That probably gives you a nice mental image, I'm sure. Okay, so Alaska is friggin' big. Got it? Good. Alaska's enormous This size is one feature that contributes to its importance to birds and other wildlife. There's a lot of habitat up there.

Alaska also represents the far northwestern edge of North America. It sits at high latitudes and is practically touching the eastern fringe of Eurasia. Only the narrow, bearing straight separates the two continents. This unique geographic position has strongly influenced the mixture of bird species that breed in Alaska. The Arctic Circle passes through the top third of Alaska. North of that line of latitude, the sun stays up for 24 hours on at least one day every summer. In other words, the summer days are super long in Alaska. The further north, the more days you have where the sun never sets.

For example, the northernmost town in the United States is Utkiadvik Alaska, formerly known as Barrow. It sits at a latitude of 71 degrees, 17. minutes north at the edge of the Arctic Ocean. The sun doesn't set in Utkiadvik for 83 days in the summer. It's a great place to be a breeding bird in the summer, but slightly less great if you're a vampire. On the flip side, of course, winter nights above the Arctic Circle are long, dark, and cold. If you think of Alaska as a snowy, chilly place in general, you aren't wrong. Many parts of Alaska range from cool to icy cold for large portions of the year. Huge ice fields blanket some of the mountain ranges,

feeding a multitude of glaciers. Glacial ice covers about 5% of Alaska. Alaska's interior, that is the part that's away from the coast, experiences a continental climate. It's super cold there in the winter, but it also warms up a lot in summer. Around the city of Fairbanks, for example, summer temperatures can get up over 80 degrees Fahrenheit, or about 27 degrees Celsius.

But in winter, the average low temperature in January is minus 17 degrees Fahrenheit, which is minus 27 degrees Celsius. Several major mountain ranges extend across the state. These include the Mighty Brooks Range and the Alaska Range. The latter chain of mountains includes the highest peak in all of North America, Denali, at 20,310 feet or 6,190 meters. All of this high country in Alaska represents some pretty extreme and barren habitat, which only a few bird species can make use of. You find more species along the coasts, or across the lowland tundra and in the river valleys.

Speaking of rivers, over 12,000 of them flow across the state. Alaska has a lot of water, and it holds over 40% of America's freshwater supply. The longest of Alaska's rivers is the Yukon. It flows almost 2,000 miles from Canada across the entirety of Alaska to the Bering Sea. And there are at least 3 million lakes and countless smaller ponds. Freshwater habitats like this are incredibly important to Alaska's birds. Another important feature of Alaska's geography is its human population. density, or the lack of it, actually. This is America's least densely populated state,

and it's the third least populous, with only about 732,000 people. Most of these people are concentrated in a few cities. That means the state has plenty of vast open space with relatively few of us pesky humans to disturb the birds. Now let's look at some of the the major ecosystems that are important to birds in Alaska. First off, there are the forests. There are two main types of forest in Alaska, boreal forest and temperate rainforest. Boreal forest, also called Taiga, T-A-I-G-A,

is widespread across the state, especially in the interior. White and black spruce are the dominant trees in this forest type, with some birch and willow mixed in. plants, birds, and the other wildlife of this ecosystem all have to endure cold temperatures and long dark winters. Permafrost is common here. Forest fires are also a regular occurrence in the dry months of summer. Some quintessential birds of the boreal forest are spruce grouse, American three-toed woodpecker, northern hawk owl, boreal owl, northern gosshawk, boreal chickadee, pine grosbeak, and blackpole warbler.

The temperate rainforest ecosystem dominates the coastal region of southeast Alaska and extends north along the coast to the south central part of the state. Gargantuan citca spruce and western hemlock trees dominate this type of forest. Trees here are many times larger than their counterparts in the boreal forest. That's because moderate maritime temperatures and ridiculous amounts of rain make for great growing conditions in the rainforest. Also, there's no permafrost here, or very little of it, and fires are far less frequent. In the temperate rainforest, some common resident birds you'll find are the varied thrush, Stellars J, Bald Eagle, and Pacific Ren. As you move higher in elevation, growing conditions for trees become more challenging.

Tree line, the elevation above which trees don't grow, is relatively low in most of Alaska's mountain ranges. Mountains form another sort of ecosystem, one of wind, even colder temperatures, rocky, snowy terrain, and sparse low-growing vegetation. Some mammals that frolic around in the mountains include dolls sheep, mountain goats, and wolverines. Bird diversity is pretty low in the mountains, But still, there are some charismatic kick-ass raptors up there, like the Golden Eagle and the jeer falcon. There are also birds like rock tarmigan and even some plucky shorebirds, such as the surfbird that nests on the ground in high rocky places.

Tundra is another treeless ecosystem. Tundra dominates the landscape in places where some combination of conditions makes it impossible for trees to thrive. Cold temperatures, a short growing season, low precipitation, permafrost, and fierce winds can all play apart. Low-growing mat-like plants blanket the tundra. Many of them produce berries, which is an important late-summer food for some birds. In the far north, the Arctic tundra ecosystem provides nesting habitat for a large number of bird species, including sandpipers, plovers, yeagers, geese, swans, loons, loons, and snowy owls. Lakes, ponds, wetlands, and estuaries offer another set of important ecosystems.

These tend to be places in Alaska where bird diversity is at its highest. In spring and early summer, there can be huge numbers of shorebirds or waterfowl cavorting at the muddy mouth of a river or splashing around in a boreal wetland. Freshwater and estuarine ecosystems like this provide lots of aquatic vegetation and aquatic insects or other invertebrates for birds to eat. These places can be especially thick with nesting waterfowl. For example, the vast Yukon-Kuska-Quim Delta

hosts about a million ducks and a million geese during the breeding season. Last, I want to mention the near-shore marine ecosystem. ecosystem. Where the sea meets the land in Alaska, the cold, nutrient-rich waters are teeming with plankton, kelp, fish, and marine invertebrates like crabs and mussels. Numerous bird species depend on this bounty from the sea. Birds that nest and forage on the coast include puffins, gulls, and sea ducks like scoters and iders. And there's a whole heck of a lot of this near-shore marine habitat. Alaska has something like 46,000 miles of coastal habitat. That's about 74,000

kilometers. Alaska has more coastline than all the lower 48 states combined. So it's a great place for birds who make a living at the interface of the ocean and the land. I want to tell you now about some of the the large-scale patterns or characteristics we see in Alaska's avian fauna. In episode three of this podcast, I talked about the latitudinal diversity gradient. This is the global pattern found in birds and many other organisms, where the greatest number of species lives near the equator, and species diversity decreases as you move toward the poles.

So given that Alaska is in a far northern part of the globe, and knowing what we know about the latitudinal diversity gradient, we shouldn't be shocked to hear that Alaska doesn't have all that many bird species. I mean, that's if we compare it to a similarly sized chunk of land in the tropics. Alaska has 530 or so naturally occurring bird species. But the country of Peru, for example, is only 75% the size of Alaska, and it has about 1,800 bird species. A few groups dominate Alaska's bird diversity. These are groups with a relatively large number of species in the state. These are, one, the ducks and geese of the family Anatidae, two, sandpipers of the scolopacety family, and three gulls and turns of the family Laridie. Sure, there are a bunch of other

types of birds in Alaska, but those three families are among the most strongly represented. Now, of the 530 bird species recorded in Alaska, a bunch are rare, accidental, or casual, and a handful are quote-unquote unsubstantiated. Alaska is sort of an intercontinental crossroads where birds from wildly different parts of the world come together. It's like Constantinople back in the day, or Venice. We'll come back to this idea in a few minutes. If you ignore those rare species and only consider the birds with well-established populations in Alaska, you're left with about 230 species.

And dozens of those species fly to Alaska only to breed in the spring in summer. When summer ends, they're like, Peace out, losers! And they return to warmer regions in the south. The real die-hard Alaskan birds are the ones that tough it out up there all year long. Coastal areas are more mild and support more species in the winter than the frigid interior or the Arctic tundra. Tough buggers that live year-round in the interior in the boreal forest include ravens, owls, eagles, woodpeckers, and a handful of songbirds like red poles, chickadees, bohemian wax wings, and white-winged crossbills. When we consider the geographic distribution of birds, as you and I are doing right now,

we might wonder what species are unique to the region in question. Are there any endemic species? The answer for Alaska is yes. There is a grand total of one endemic bird in Alaska, and that is Mackay's Bunting, Plectrophenax hyperboreous. McKay's Bunting is a cute little songbird that lives on only two. two remote islands in the Bering Sea. It's a close relative of the snow bunting, Plectrophenax Nevalia. Both species are in the family Calcareity, which also includes the long

spurs. The ancestors of McKay's bunting were probably snow buntings who found themselves isolated on those islands at the end of the last glacial maximum, when the sea level rose and drowned most of the land bridge that once connected Eurasia and North America. But interestingly, most of these birds, the McKay's buntings, fly to mainland Alaska in the winter and return to their little islands to breed in summer. So it's not like they're isolated by an inability to fly long distances. Researchers have suggested that McKay's buntings maintain their genetic distinctiveness from snow buntings, their closest relatives, because the two species breed at different times,

even where their ranges overlap. We don't know a whole lot about the biology or the behavior of McKay's bunting, but it does have one other claim to fame. No other North American songbird has plumage that's as white as that of the male McKay's bunting. It looks like a snowball magically came to life and started flitting around, eating seeds and causing mischief. I feel like this bird needs a cooler name, but the name Snowbunting is already taken. And maybe you've heard of the movement to get rid of honorific bird names. You know, birds named after some dude. So instead of McKay's bunting, maybe we could go with bleached bunting or blizzard bunting or

McFlurry bunting. I don't know, something like that. As for the snow bunting, that species gives us an example of another pattern we see among Alaskan birds. Snow buntings breed at high latitudes all across North America, Asia, and Europe. So this species has what we call a circumpolar distribution. Birds with circumpolar distributions are found in Arctic and sub-Arctic regions around the globe. After my recent birding tour in Alaska, I went over to Iceland to run a tour there. It was kind of strange, like deja vu, because I got to see several of the same bird species in both places, including red-throated and common loon, jeer falcon, rock tarmigan, red-necked fallow rope, arctic turn, northern weedier, and, yes, snow-bunting.

Alaska and Iceland are far apart, sure, but as you move closer to the North Pole, the distance between the eastern and western hemispheres gets shorter and shorter, doesn't it? At the actual North Pole, the distance reduces to zero. So it's not that crazy for birds, other animals, and plants to disperse all across the Arctic region. There are quite a few other birds in Alaska with circumpolar breeding distributions. Birds like snowy owl, common myrrh, Lapland Longspur, and so on. So we've been looking at some patterns or characteristics of Alaskan birds here. We talked about the number of bird species in Alaska, of which only one is endemic.

And then there's the presence of a bunch of circumpolar breeders. Migration is also an enormously important part of the story for Alaska's birds. As I mentioned, relatively few birds spend the entire year in Alaska. Waterfowl and shorebirds come to Alaska by the millions every summer. These birds are often the most numerous and conspicuous animals you'll encounter in the wild. Well, other than mosquitoes, that is. The arrival of all these migrant birds is a dramatic event, and it's super important for the ecosystems of Alaska. Shorebirds and waterfowl play vital roles in the food webs of freshwater, coastal, and tundra ecosystems.

They eat ungodly amounts of vegetation and invertebrate biomass. They fertilize the soil and water with their nitrogen-rich droppings. And, of course, they end up as meals for furry predators like foxes and weasels. Circle of Life and all that, yada, yada. Lots of migrant species spend the summer on the tundra or in Alaska's wetlands. These are essential breeding habitats for migrant birds. But there are also specific places along migratory pathways that are nearly as important. On their long-distance journeys, migrants need to stop to rest and refuel.

They do this predictably in the same places year after year. These places are called stopover sites or staging. areas. For example, the Copper River Delta in south-central Alaska is an enormous wetland that serves as a stopover site for birds like Western Sandpiper and Dunlin. They stop to feed on the mudflats of the Delta before flying much farther north to their breeding territories. So why is Alaska so attractive to migratory birds? Why do they bother flying all that way to breed in far-flung, seemingly desolate landscapes. Why not just stay in the tropics where everything is sort of more pleasant? Biologists have different hypotheses to explain this. But in general, it's thought that

the habitats of the far north are great places for birds to breed because, one, there is an explosion of insect life every summer. This superabundance represents tons of food to feed growing chicks. Two, there's a lot of open space, which means there might be less competition for nesting and foraging habitat. Three, the days are super long, so there's plenty of time for courtship, nest building, and finding food for your insatiable young ones. And four, compared to more tropical places, birds breeding in high latitudes may also have fewer predators, parasites, and diseases to deal with.

It's easy to understand that many migratory birds that breed in Alaska fly south in the autumn, using flyways across North America. After all, Alaska is just an extension of that continent. Depending on the species, these birds might then spend the winter somewhere in the lower 48, in Mexico, the Caribbean, or even South America. But some birds that breed in Alaska head west in winter, instead of east or south across North America.

A great example is the northern weedier, a songbird in the Old World Flycatcher family. This species nests in boulder fields and on rocky slopes on the Alaskan tundra. But in late summer, northern weediers fly over the Bering Sea, then across Asia, and all the way down to sub-Saharan Africa. This is an incredible journey for such small birds to make, and they do it year after year. So the northern weed ears I recently saw in Alaska will soon be heading to Africa. Pretty crazy. Some other outstanding migratory superheroes that leave North America in winter are the

bar-tailed godwit and bristle-thied curlew. These are both members of the Sandpiper family, Scolopacety. Bar-tailed godwits that breed in Alaska fly all the way to New Zealand and eastern Australia for the winter. Bristle-thied curlews end up in Hawaii and some other Pacific Islands. Pretty amazing. Now remember that I said Alaska is like an intercontinental crossroads? This is another major characteristic of Alaska's bird diversity. Birds in Alaska are a mix of species, some with evolutionary ties to North America and others of Eurasian origin. Not surprising given that the two continents are practically touching each other here. Some species with deep connections to the Eastern Hemisphere are regular breeders in Alaska. You can expect them in significant

numbers every summer. These are birds like the Northern Weadier, Arctic Warbler, and Blue Throat. They represent bird families that are found almost entirely in the old world. But earlier I mentioned those rare, casual, and accidental species that have been recorded in Alaska. These birds are the ones that pad the species list for Alaska, bringing it up to 530. Like, for example, there are only two records of an Oriental Pratton Coal being seen in Alaska, back in the mid-1980s. Other species may show up every few years, something like that. This sort of phenomenon happens fairly often on the westernmost peninsulas and islands of Alaska.

Time and time again, these outposts have been visited by wayward birds from Asia. The birds, for some reason or another, get off course during their migration. and end up in Alaska. One of these vagrant birds makes landfall, probably exhausted and be draggled, and then it finds the nearest gas station to ask for directions. But the birds at the gas station speak another language. The birds don't understand each other.

They're all just squawking and flapping their wings in a frustrating effort to pantomime what they're trying to get across. The vagrant bird ends up as a stranger in a strange land, and who knows if it will ever find its way home again. Let's take a closer look now at a couple specific groups of birds that live in Alaska. To keep this episode from going on for hours and hours, I won't dig into every family of birds you'll find in Alaska. I'm just going to single out a couple, the tarmigans and the ox. Did he just say ox?

Ox? I've heard there are musk ox in Alaska. Is that what he means? Musk ox? But those aren't birds? I'm so confused. Yes, there are musk ox in Alaska, as I can attest from having recently seen those shambling beasts up close with my very own eyes. They're super cool and their calves are insanely cute. But no, I'm not talking about musk ox. I'm talking about ox. A-U-K-S. Ocks are all the birds in the family Alcadie. These are the puffins, mers, merlets, ocklets, gillimots, and other such characters. They're chunky, fish-eating seabirds that swim around underwater like miniature penguins. They aren't closely related to penguins at all, but they've evolved to have a similar lifestyle and appearance. But unlike penguins, ox can still fly. I'll do an entire episode

on the family Alcadi at some point. But for now, I just want to point out that Alaska is kind of like ock heaven. There are about 17 ock species found there, not too shabby considering there are only 24 ox species in the world. These birds nest on Alaska's rocky coastlines, but spend the rest of the year far out to sea. The most famous of Alaska's ock species are the tufted puffin and the horned puffin. These are charming birds with bold, colorful markings on their bills and heads. I mean, who doesn't love a puffin? right? Show me a man who doesn't like puffins, and I'll show you a man who really needs to take a good look in the mirror and ask himself, what have I become? When did I stop finding joy in the world? Why am I

such a miserable wretch? And to repeat my earlier public service announcement, there are no bloody penguins in the Arctic, not one, no penguins. But luckily, this lack of penguins is more than made up for by the multitudes of adorable ox. So if the marketing geniuses at Coca-Cola had only done their homework, they could have made a series of biologically accurate commercials by showing polar bears palling around with puffins instead of penguins. Moving on to tarmigans. Tarmigans are chicken-like birds in the family Phasianity. Chickens themselves are in this same family, along with pheasants and turkey, and all of those sorts of guys.

Tarmigans are the sole members of the genus Lagopus. There are only three tarmigan species in the world and you'll find them all in Alaska. There's the Willow Tarmigan, rock tarmigan, and white-tailed tarmigan. These birds are superbly adapted

for life in cold places. Their plumage is pretty much solid white in winter and their legs are fully feathered all the way down to their toes. They also have skated. on their toes that help spread their weight over the snow, so they have built-in snowshoes. They also burrow in snow to keep warm at night or when the weather is especially frigid. Tarmigan's molt in spring as the snow melts. They lose their white feathers to become a

speckly, modelled brown or gray. This makes them really well camouflaged in their shrubby or rocky habitats. All three Tarmigan species are herbivores, and they really love to eat the buds, leaves, and twigs of willows. These plump birds are pursued and devoured by a wide range of predators, from Arctic foxes, wolverines, and polar bears, to jeer falcons, snowy owls, bald eagles, and others. Thus, a tarmigan's need for good camouflage in both winter and summer. The willow tarmigan, legapus, legapus, is common throughout Alaska

and has a circumpolar distribution. It's actually the state bird of Alaska. School kids in Alaska voted in 1955 to choose the Willow Tarmigan. That was four years before Alaska was even officially recognized as the 49th state. So I say those kids had their priorities right. First things first, birds are awesome, so we better choose a state bird right away. Then we'll worry later about how to become a state and all that. I really love Willow Tarmigans.

They're good-looking birds and they have a lot of personality. And the male's song is absolutely ridiculous and it's wonderful. Check this out. This is the song of the male Willow Tarmigan. The first part of the song is given in flight and it finishes as he lands. Tell me this isn't just a fantastic sound. So that's a little bit of natural history regarding Alaska's birds. There's much more we could talk about, as always.

For example, I could go into the topic of conservation. Alaska's birds face many challenges, especially with respect to climate change. Spoiler alert, it's mostly bad news. But we'll have to save all that for another day. I'm trying desperately to keep this episode on the short side. Maybe you've been to Alaska, and you can remember seeing and hearing some of these wonderful birds. Or if you've never been to Alaska, maybe I've given you a taste of what it's like up there. If you're into birds and birding, and you also want to see charismatic megafauna like musk ox, bears, moose, and whales,

I think you'd have a great time exploring Alaska. It's an incredible, wild place. Thanks for listening today and going on a mental journey to Alaska with me. I hope you learned something new. If you have thoughts or feelings about the show that you'd like to share, or if you'd like to suggest a better name for McKay's Bunting, shoot an email to Ivan at Science of Birds.com. You can check out the show notes for this episode,

which is number 31 on the same. Science of Birds website, Scienceofbirds.com. This is Ivan Philipson, and I hope you have a glorious day. Cheers.