The Science of Birds - Parental Care: How Birds Raise Their Young

Episode Date: June 22, 2023

This is Episode 78 and today we’re doing an overview of parental care in birds. How do birds raise their babies?Parent birds feeding their chicks in a nest is an iconic image. It’s a symbol of the spring and summer seasons and of the annual rejuvenation of nature.To the casual observer, birds generally come across as caring, attentive parents. Similar to the way mammals demonstrate good parenting behavior. We humans approve of this sort of thing. It makes us feel all warm and fuzzy inside.I mean, the behavior of birds and mammals is way better than what amphibians and reptiles do, right? Those cold-blooded critters just crank out a bunch of babies and then leave them to fend for themselves. No parental care to speak of. Despicable!But to be fair, birds aren’t always the paragons of parental love that we might think they are. They sometimes do pretty messed up things when it comes to raising their offspring.And this highlights the fact that humans like to project our own cultural values onto animals. If, for example, we see a pair of adult geese dutifully tending to their adorable, fuzzy chicks, we might think, “Aww… What a cute little family. They all love each other.”And when we hear about a female Blue-footed Booby that did nothing and just sat there indifferently while the older of her two chicks murdered its younger sibling… Well, in that case, we’d probably think that booby is a bad mommy. She should be locked up in bird prison, if there were such a thing.I’ll admit I’m often guilty of this sort of thinking. I like to think that birds love their babies. I’m a total sucker for heartwarming scenes of parental care in birds.But I also know it’s not really fair for us to judge birds based on human ideas of right and wrong. Birds are just being birds. They do whatever it takes to survive and reproduce in a challenging and mostly unpredictable world.Support the show

Hello and welcome. This is the Science of Birds. I am your host, Ivan Philipson. The Science of Birds podcast is a lighthearted exploration of bird biology for lifelong learners. This is episode 78, and today, Today, we're doing an overview of parental care in birds. How do birds raise their babies? Parent birds feeding their chicks in a nest is an iconic image.

It's a symbol of the spring and summer seasons and of the annual rejuvenation of nature. To the casual observer, birds generally come across as caring, attentive parents, similar to the way mammals demonstrate good parenting behavior. We humans approve of this sort of thing. It makes us feel all warm and fuzzy inside. I mean, the behavior of birds and mammals is way better than what amphibians and reptiles do, right? Those cold-blooded critters just crank out a bunch of babies and then leave them to fend for themselves. No parental care to speak of.

Despicable. Okay, yes, I know. Some amphibians and reptiles show parental care. I was exaggerating a little, for comedic effect. But to be fair, birds aren't always the paragons of parental love that we might think they are. They sometimes do pretty messed up things when it comes to raising their offspring. And this highlights the fact that humans like to project our own cultural values onto animals. If, for example, we see a pair of adult geese dutifully tending to their adorable fuzzy chicks, we might think,

Aw, what a cute little family! They all love each other. And when we hear about a female blue-footed booby that did nothing and just sat there indifferently while the older of her two chicks murdered its younger sibling, well, in that case, we'd probably think that booby is a bad mommy. She should be locked up in bird prison if there were such a thing. I'll admit I'm often guilty of this sort of thinking. I like to think that birds love their babies. I'm a total sucker for heartwarming scenes of parental care in birds.

But I also know it's not really fair for us to judge birds based on human ideas of right and wrong. Birds are just being birds. They do whatever it takes to survive and reproduce in a challenging and mostly unpredictable world. So today I'll try to keep my mushy emotions in check to maintain a mostly scientific perspective as we look at how birds raise their families. At the most basic ever,

evolutionary level, the reason birds have babies is so they can get more copies of their own genes passed down to the next generation. That's it. That's all that matters. The parenting behaviors we observe in a bird are mostly hardwired instincts. These behaviors help to maximize the number of surviving offspring the parent bird has. The number of surviving offspring in a single breeding season, yes, but more importantly, the number of offspring across the entire lifetime of the parent bird. The more offspring you have over your life, the more copies of your genes you've successfully passed down. Different types of birds have evolved different strategies to achieve this same goal. So there's a spectrum of parental care, ranging from none on one end to a whole heck of a lot

on the other. For example, many cuckoo species provide no care for their chicks whatsoever. A female cuckoo just stealthily lays her egg in the nest of another bird species, then she high-tails it out of there never to return. The other birds unwittingly raise her baby for her. This is called brood parasitism, and you can listen to episode 12 of this podcast if you'd like to learn more about that. Beyond making an egg, a female brood parasite makes no investment in her offspring. At the other end of the spectrum are birds like albatrosses, which spend lots of time and effort raising their young. It can take a pair of albatrosses an entire year from when they build their nest to when their single chick finally learns to fly. With such a long breeding cycle,

albatrosses can, at best, raise only one chick every two years. Most birds fall somewhere between these two extremes of parental investment, between cuckoos and albatrosses. In general, raising a brood of chicks is stressful on parents and takes massive amounts of energy. Many birds burn significantly more calories per day during the breeding season than they do during the rest of the year. Such energy demands are one reason raising a family can actually lower the chances of survival for the parents.

They take a risk by having offspring. This means if you're a parent bird, you're forced to make a trade-off. The more of your genes you get out there in the world this season, that is, the more babies you raise successfully, the lower your chances are of surviving to breed again next season. So what do you do? Do you crank out as many babies as you can this year, but then most likely burn out and send yourself to an early grave well before the next breeding season? Or do you have just one or two chicks this year and live to breed again the following year?

Well, these strategies both work, but each works best under a distinct range of conditions. That's why we see variation among bird species in how they approach this tradeoff. consider, for example, a small songbird with an expected lifespan of only three years. It probably makes sense for that bird to put most of its effort into raising a large batch of babies this year. Because there's a good chance that, no matter what, it isn't going to live to see next year. Life is short. But basically, there's no one-size-fits-all approach for how much a parent-beard. bird should invest in its young. It all depends. One thing for certain is that parent birds caring for their young need extra energy. They can get this energy in several ways. First, they can spend

more time foraging for food. Second, they can survive on fat or muscle reserves they built up before the breeding season. Third, and this one's really important, parent birds can rely on each other for help, to share the load. You know, like Sam Gamgee said in the Lord of the Rings. In some species, breeding adults can also share the load with their full-grown offspring from last year. For example, cooperative breeding is common in the pygmy nut hatch, sita pygmia. This small social songbird lives in Ponderosa pine forests in western North America. One-year-old pygmy nut hatches will sometimes help their parents by building the nest, keeping the nest clean, and feeding their newborn siblings. So cooperation between mates,

or less commonly between parents and their grown offspring, is a great way to reduce the burden on any one caregiver. It's no surprise then to learn that most of the world's 11,000 or so bird species are monogamous and have bi-parental care. Two birds pair up, whether for a single season or a lifetime, and they both share in the duties of raising their chicks. There are exceptions, of course, but cooperation is the default situation in birds. But like we talked about earlier, the family lives of birds aren't all cuddles and rainbows all the time. There can be a darker side. Because, although there's plenty of cooperation, there's also conflict. Every individual bird is driven to pass on as many copies of its genes as possible.

Sometimes a bird's interests, to that end, come into conflict with the interests of its mate, or even the interests of its own offspring. And conflicts among siblings are common. This is a complex topic, and we can't get into all the details right now. But just be aware that each individual parent is doing its best to balance its own needs and interests with the needs of its young. At the same time, each individual chick is looking out only for itself. Baby birds are selfish little buggers. To illustrate one form of conflict between the two members of a mated pair,

imagine a couple of, I don't know. Ooh, wait, I'll use my random bird species button. I haven't used that thing in like forever. Here we go. All right, we got yellow-throated laughing thrush, Terorinus Galbanus. Cool. This species lives in northeastern India,

and a bit of Myanmar and Bangladesh. Okay, imagine you've got a hypothetical mated pair of these yellow-throated laughing thrushes. They've got a nest squirming with four hungry babies. If the parents have mated only with each other this season, then each of those chicks is going to share 50% of its genes with mom and 50% with dad. In this case, it makes sense for the parents to cooperate and share the burden of raising the chicks equally. But what if the female snuck off a while back and mated with another male?

Maybe one or two of the eggs she laid were fertilized by this other mystery male. Let's call him Larry. This sneaky rendezvous with Larry could be in the interest of the female if it increases the genetic diversity of her brood. The original male in the pair, his name is Melvin, the eggs fertilized by Larry would have none of Melvin's genes, none of his DNA. The female would still be just as invested in those eggs, but Melvin would have no incentive to care for them.

If Melvin even suspects that his lady has been unfaithful, he might reduce his effort to raise any of the chicks in the nest. After all, who knows if any of them are his? Worse case scenario, Melvin might go so far as to kill the nestlings. A slightly less severe response from Melvin would be to stop reading bedtime stories to the nestlings. He leaves most of the child care duties to his female partner. Cooperation has turned to conflict. So the interests of mates can be in conflict, and parents can be in conflict with their offspring.

Siblings in a nest are almost as a rule competing for space, food, and the attention of their parents. Sibling rivalry can be as subtle as one chick begging for food a bit more enthusiastically than its nestmates. But at a more extreme level, one chick can act like a bully and hog all the food for itself, so that its siblings might starve. Or one chick will straight up murder its siblings. Siblicide is common in some species, including certain boobies, pelicans, herons, eagles, owls, and penguins. In fact, there are bird species that have what biologists call obligate sibilicide. That means that within a brood, one chick almost always dominates the nest and kills its smaller sibling. Obligate sibilicide is most often seen in bird species where a clutch has.

two eggs, and where one of them hatches earlier than the other. The older chick ends up dominating its younger sibling. And like the blue-footed booby mommy I mentioned earlier, the parents in species with obligate siblicide generally just sit on the sidelines and let it all play out with no intervention. Or in many situations, they play favorites and take better care of the older, larger chick. Why would such a system evolve in a bird species? It seems like a huge waste of energy for the female parent to lay two eggs only to have one nestling invariably get killed later on.

Ornithologists have come up with several hypotheses to explain why sybilicide exists in birds. We don't have time to dig further into all this today, but I can tell you the leading hypothesis is that the second egg, the one that hatches later, is a sort of insurance policy. Because if the first egg or chick doesn't survive, the second one can take its place. The parents can still raise a chick and get some copies of their genes out into the world in that breeding season. Or if food happens to be especially plentiful in that season, it's possible that there's enough food to go around to feed both chicks. With a surplus of food, the chicks don't need to compete so fiercely.

So a parent bird could say to its nestlings, Mommy has some good news for you. It turns out there are so many fish in the ocean this year that you don't have to murder each other. Isn't that nice? Yay! If under these conditions both chicks survive, then the parents get a big bonus in terms of their reproductive success. How much and what kind of parental care is needed to raise a baby bird depends on how dependent that baby is.

Many freshly hatched birds are as helpless and ugly as newborn humans. They can't walk, they can't see, and they're naked, so they can't keep themselves warm. Do you remember what the technical word is for this kind of baby? I've brought it up in several other podcast episodes. Al-T-R-I-C-I-A-L is the word for chicks that completely depends, on their parents for survival in the first days or weeks of their lives. All birds in the order Paceriformis have Altricial Young. So we're talking robins, finches, wrens, warblers, sparrows, and all of those guys.

Passerine birds. The opposite of Altricial is precocial, P-R-E-C-O-C-I-A-L. You know, like a precocious child that runs around screaming and causing mayhem. Compared to altricial chicks, precocial chicks are much more independent. From the moment they hatch, they can see, they can walk or swim, they can feed themselves, and they have fuzzy down feathers to help keep them warm. Picture ducklings and baby chickens, quail and sandpipers. You know, the cute ones. So we've got two categories, altricial chicks and precocial chicks. and cute, respectively. But in reality, there are some other categories on the

dependence spectrum. For example, some species have semi-altricial chicks. Newly hatched hawks and eagrits are in this category. They're covered in down and their eyes are open, but they can't leave the nest on their own and they still need to be fed by their parents. They're only semi-helpless, semi-altricial. Parent birds with chicks on the helpless end of the spectrum generally have to work super hard to raise their families. They need to protect their babies from temperature extremes and from predators, they need to feed them, and they need to clean up their messes.

We'll talk about feeding chicks and defense against predators in a moment. But in terms of temperature regulation, we have the behavior of brooding. Parent birds, especially those with altricial young, provide shelter for their chicks under their wings or bodies. Brooding shields the youngsters from the sun, from rain and wind, and from temperature extremes. Parents often take shifts brooding. While one parent keeps the chicks warm and safe, the other flies off to find food for the family. As the nestlings get older, they develop insulating feathers and no longer need to be brood. They can regulate their body temperatures all on their own.

Birds raising a family are lucky because they don't have to spend tons of energy doing things like driving kids to soccer practice and piano lessons, finishing their science projects for them, or fighting with them about brushing their teeth at night. Birds don't have time for that stuff anyway because most of their time and energy is taken up by the task of feeding their babies. For example, songbirds feeding a nest full of hungry chicks routinely make 300 to 500 trips to and from the nest every day. This is usually about 4 to 12 food deliveries per hour. Large seabirds, on the other hand, might feed their chicks only once every few days. But each foraging trip might require the parent bird to travel hundreds or thousands of miles over the ocean.

Altricial young require the most energy to feed, of course, because precocial chicks can usually find their own food. A typical chick's diet in the first few days after hatching is mostly insects, other invertebrates, or maybe fish. Such foods give newborn birds the protein and fats they need. Altricial chicks don't just sit there politely in the nest, assuming mom and dad know how hungry they are. No, the youngsters take matters into their own hands. They beg in order to trigger their parents' instinct to provide food. They manipulate the psychology of their parents to get as much food as they need, and then some. When mom or dad, Dad returns from a foraging trip, the chicks open their beaks wide and make distinct

begging calls. They wobble their bulbous heads around and try to be as conspicuous as possible. In other words, they use visual and auditory signals to get their parents' attention. Here, for example, is the sound of some hungry, scaly-breasted munya chicks begging in the nest. This recording was made in southeastern India. The most obvious visual signal used by an altrucial nestling is the shape and color of its wide-open mouth. If you've ever looked down into a nestful of wiggling chicks, you might have seen one or more diamond-shaped mouths aimed up at you, wide open, rimmed with yellow, and lined with red or orange skin on the inside. A chick's mouth is a boldly colored target that says,

Hey, you, this is where the food goes. All of it. All the food. Put it in here right now. The interior of a bird's mouth is called the gape. The gape of altricial birds is specially adapted for signaling their parents. The corners of a chick's mouth, where the upper and lower mandibles meet, have gape flanges. These swollen, fleshy flanges are often the most brightly colored part of the mouth. And they're sensitive to touch. If a parent bird or meddling human touches a gape flange, the baby bird's mouth will pop open like a jack in the box. Or if you'd prefer a pop culture reference, the baby bird's mouth pops open like a xenomorph egg in the movie Alien. Altricial chicks look to me like little aliens, so this image works for me.

In some types of birds, like finches and waxbills in the family estrildedee, chicks have bold patterns of spots and colors on the roof of the mouth and on the tongue. Each species has a unique gape pattern. And what's more, the chicks of astrilded finch species that nest in cavities, where it's dark, they have the most vibrantly colored gapes, the better to be seen by mom and dad in a dimly lit nest. So, chicks are sending out their visual signals and their auditory signals, and these stimulate the parents to stuff their tiny mouths with food.

But parent birds aren't just acting like mindless robots, acting purely in response to the signals they get from their offspring. A parent bird can make its own decisions, at least to some extent. Remember, it has to balance its own needs and interests with those of its young. There are many decisions to be made. For example, there's favoritism. Parents might choose to invest most of their efforts in feeding one particular chick. Most often, this is the largest chick or the one with the biggest gape.

But in other situations, the parents might make sure each chick gets fed more or less the same amount. The availability of food in a local environment might influence a parent's decisions of how many chicks to feed, or how much to feed the brood overall. If food is scarce, like during a drought, for example, a parent will sometimes cut and run, just give up and let an entire nestful of chicks starve. Rather than risk its own survival in what might be a lost cause, the parent bird will just try again during the next breeding season. That's pretty harsh, I know, but so it goes.

The way parent birds feed their chicks differs by the type of food brought to the nest. Bald eagles, for example, might drop a large fish or duck in the nest. The adults tear off small pieces of meat and then pass these to the baby eagles, the eglitz. Common kingfishers, on the other hand, bring tiny fish to their chicks. In this species, each chick gets handed one entire fish at a time, and that fish gets swallowed whole. Songbird nestlings, like those of the American Robin, may be fed by regurgitation for their first few days after hatching.

Parents cough up soft-bodied invertebrates like beetle grubs and earthworms into the gaping mouths of their chicks. Some seabirds, like we talked about in the last podcast episode, will regurgitate partially digested fish or other seafood like small crustaceans to their young. This paste-like substance gets injected directly into a chick's mouth or it gets deposited on the floor of the nest. And speaking of injections, a female hummingbird sticks her long bill deep into the gullets of her chicks to deliver a delicious injection of bugs and hot flower nectar. A few birds can actually make their own food to feed their young. This is what

mammals do, right? Mammals are famous for having mammary glands which make milk to feed their babies. Well, some birds make a substance called crop milk. It gets secreted by cells in the parent bird's crop, which is part of the esophagus in the digestive tract. Pigeons and doves do this, so do flamingos and so do male emperor penguins. In pigeons, crop milk is a semi-solid substance that looks sort of like cottage cheese. But the crop milk of flamingos looks like blood. It's not blood, but it's red because it's packed with carotenoid pigments. You know, the stuff that makes flamingos pink.

Now, what about water? Water is kind of important, right? How do young chicks, especially those confined to a nest, stay hydrated? Most of them get plenty of water from the food they eat, from juicy insects, worms, fish, or berries. But some birds, like crows and ravens, will dip food items in water before delivering them to their babies. Dunking like this provides some extra hydration and may also soften the food up a bit. But the most amazing water delivery service found among birds has to be what we find in sand grouse. Sand grouse are all the birds in the family Teroclody.

There are 16 species found across southern Europe, Africa, and Asia. They look sort of like grouse, yes, but they're much more closely related to pigeons. These birds live in deserts and other super arid environments. We're talking places like the Sahara Desert. A typical sand grouse brood has three precocial chicks. Water is usually nowhere to be found near the nesting site. And the seeds these birds eat contain basically no water. The chicks won't survive without some supplementary water.

So it's daddy sand grouse to the rescue. He makes regular flights from the nest to a water source. and this is usually many miles away. Male sand grouse have specially adapted belly feathers that are super absorbent. Oounce for ounce, these feathers can hold up to four times more water than a dish sponge. The male jostles his belly around in a pool of water, soaking up about two tablespoons of water in his feathers. Then he flies home to his family. The chicks run dad's belly feathers through their bills, ringing out to the furthers.

drops of precious water and everyone rejoices. Amazing stuff, right? Another less glamorous aspect of parental care in birds is the job of sanitation. Parents of precocial chicks don't really need to worry about cleaning up the droppings of their chicks since these birds are constantly moving from place to place. But a nest full of helpless altricial chicks can get messy really quickly if no one makes an effort to clean it. Poop is going to pile up. In some species, however, chicks have an instinct to aim their butts away from the center of the nest to eject their feces outward.

The end result might be a thick ring of white guano encircling the nest, while the center stays relatively clean. The nestlings of passerine birds have an interesting adaptation that makes nest sanitation a lot easier for their parents. They make something called a fecal sack. That's SAC. This is a thin mucous membrane that completely envelops the baby bird's poop. It's like the bird makes its own diaper or something. Each time the chick poops, everything comes out bundled up nicely into a fecal sack. It's usually white and really conspicuous in the nest. Mom or dad sees the sack and then picks it up and carries it away from the nest. The nest stays nice and clean. Well,

that's what the parents do once the chicks are a little older anyway. Before that, when the chicks are very young, the parent birds will often eat the faecal sacks. Yes, they eat baby bird poop. Gross, I know, but those little white bundles actually contain a fair amount of valuable nutrients. That's because young nestlings aren't all that efficient at digesting their food yet. Some nutrients pass all the way through their systems and come out the other end. The stressed out and overworked parents benefit from a few extra doses of nutrition. Now, I know what you're thinking. Wouldn't it be great if dogs made their own fecal sacks?

You could take your dog out for a walk and it would just pop out these nicely, little self-contained, poop-filled balloons. Easy to clean up. No must, no fuss. Pet owners could save hundreds of dollars every year because they wouldn't have to buy those little plastic poop bags anymore. It would be brilliant. But enough of that. Let's move on to talk a little about how parent birds defend their babies from predators. To a hungry predator, a baby bird is probably irresistible. It's a plump little ball of soft, tasty meat, one that's easy to catch and easy to dispatch. It's no surprise then that a wide assortment of animals are predators of young birds.

These include snakes, rats, cats, squirrels, raccoons, monkeys, foxes, weas, and many types of avian predators. The latter include hawks, jays, crows, and owls. Keeping young birds out of the bellies of critters like these is a full-time job for their parents, as if feeding their chicks wasn't demanding enough. As you can imagine, precocial young aren't as vulnerable to predators as altricial young. Precocial chicks can run, hide, or scatter. A Fox, for example, might be able to catch one sandpiper chick, but that chick's siblings are likely to get away. This is in contrast to what happens to many altrucial chicks, clustered together as they are in a nest. A snake or raccoon or whatever that gets lucky and finds the nest,

well, that predator is probably going to gobble up every last one of those nestlings. Many small passerine birds can't do much to defend their chicks once the nest has been infiltrated by a predator. They can perch nearby and make alarm calls all they want. The predator probably won't care. The best strategy small passerine birds have is to keep predators from ever finding their nests in the first place. They build their nests in hard-to-reach places,

they camouflage them, and they try to be stealthy and inconspicuous. as they make trips to and from the nest. But other birds, especially larger ones, can take action to defend their chicks. Hawks, eagles, owls, and falcons have powerful bills and talons to strike out with. They can kick butt and do some serious damage to a predator with these weapons. Ostriches, cassowaries, swans, and geese are also notorious for aggressively defending their fuzzy precocial chicks. Even some smaller bird species can effectively defend the territory around their nest from lurking predators.

For example, Australian magpies, Jim Narina Tobison, are famous for their swooping behavior in the breeding season. In suburban Australia, people are sometimes terrorized by the swooping attacks of male magpies. Signs are posted in areas with high levels of agro magpie behavior. One sign has a bulleted list that reads, Avoid the area, do not run, wear a hat or carry an umbrella, wear glasses to protect your eyes. And to confuse the magpies, pat your head and rub your belly simultaneously while walking backwards and whistling the national anthem of Turkmenistan.

Okay, maybe that last one I made up. But now, in case you're wondering, the National Anthem of Turkmenistan sounds a little something like this. truly inspiring. The truth is that thousands of people in Australia have been injured by swooping magpies. It seems this species has come up with an effective nest defense strategy. You know you're doing something right when you force people to make warning signs and carry umbrellas. There's another way some parent birds try to protect their young, and that is by using a distraction display. This is a behavior of the parent bird that gets the attention of an approaching predator, intending to draw the predator away from the nest or chicks.

Many species have anti-preditor distraction displays, but one of the more famous examples is given by the kill deer, Caradreus vociferous. This is a familiar North American species in the Plover family, Caradreidae. It nests on the ground and has precocial chicks. Kill deer parents have several distraction displays in their repertoire, but probably the most dramatic is the injury feigning display. When a predator like a fox comes sniffing around, one of the kill deer parents contorts its body to look like it has a broken wing. It moves away from the nest or the chicks trying to get the fox to follow. The keel deer is like, oh no, clumsy old me. It seems I went and broke my wing again. Ow. See, look, my wing is just a mess. I guess now I'm as

helpless as a jellyfish on a trampoline. Oh my, I hope nobody tries to eat me. The idea is that the predator will hopefully see this seemingly injured adult bird as an irresistible, easy meal. Lurching along the ground, the displaying killdeer keeps just out of reach of the fox or whoever. The bird keeps moving away until it decides the coast is clear for its babies. Then it promptly runs or flies away, leaving the predator confused, disappointed, and embarrassed. If mom and dad have done their job, job, if they've kept their chicks protected from the elements and predators, and they've fed them plenty of food, if they've done all that, the time will come when the young birds fledge. Their feathers

grow in and they leave the nest. But at least for many passerine species, the parents aren't off the hook yet. The fledglings just spread out into some nearby foliage to find perches. They wait for their parents to come around, then they vibrate their wings, open their mouths, and make begging calls. Or they might chase their parents around and beg more aggressively. It's often easy to tell a fledgling passerine from an adult because the young bird still has obvious gape flanges at the corners of its mouth. The flanges are downturned, so the fledgling looks like it's frowning, like it's in a grumpy mood. I find this hilarious. I love the little grumpy faces of fledglings. As the chick matures, the flanges will get reabsorbed.

The feathers eventually become fully functional and the young birds learn to fly. Meanwhile, their parents feed them less and less. The youngsters figure out how to find their own food and they become independent at last. For passerines, the typical time from hatching to full independence is about, a month. But larger non-passerine birds with altricial or semi-altricial chicks might have to care for their babies for three to six months. It's an enormous challenge for birds to raise a family. At the end of the breeding season, when the chicks have flown off to the horizon, I can just imagine the relief the parents must feel. They can finally get some rest and some alone time.

no more fecal sacks, no more deafening begging calls, no need to feign injury to trick predators, and no more frowny little faces with their yellow gape flanges, just peace and quiet. But unlike most humans, birds don't raise a family just once and then take it easy for the rest of their days. No, a pair of birds raise a family, then they raise another one, and another one year after year for a long as they can. As exhausting as this must be, it makes sense if their ultimate, instinctual goal is to maximize the number of their genes that get passed down to later generations. You've got to get those genes out there. That's all that matters. All right, party people. That's a wrap on episode 78. There are countless other

fun facts I could talk about under the banner of parental care. But those will have to save for another time. I do want to point out that this being the 21st century, humans like you and me have some great opportunities to watch the dramas of parental care and birds play out in real time, because there are countless live nest cams on the internet that we can check out. Eagles, Osprey, falcons, herons, hummingbirds, chickadees, puffins, albatrosses, take your pick. If you get lucky, you might even see one of the parents eat a fecal sack. Woo-hoo! But seriously, just type in something like live nest cam on YouTube, and all sorts of good stuff will pop up.

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you can check out my Patreon page at patreon.com slash science of birds. There should also be a support-the-show link in the show notes. You can shoot me an email if you have something you'd like to share with me, some deep thoughts about birds or about the podcast, or maybe you'd like to tell me what kind of distraction displays you've used to get out of tricky situations. me, for example, if I'm accosted on the street by a well-meaning person with a clipboard

and some survey questions, I scream and flail my arms over my head as I run through traffic to the other side of the street. Works every time. Anyway, my email address is Ivan at Scienceofbirds.com. You can check out the show notes for this episode, which is number 78, on the Science of Birds website, Scienceofbirds.com. I'm Ivan Philipson, and I wish you a most excellent day. Peace.