Random Bird Thursday: A Highly Vocal Species With Female Helpers

0:00Hello and welcome. This is The Science of Birds. I am your host Ivan Phillipson. The Science of Birds podcast is a light-hearted exploration of bird biology for lifelong learners. It's that time again, it is Random Bird Thursday. Random bird Thursday episodes are relatively short and sweet. And in these episodes, what I'm doing is highlighting a bird species that most likely I won't really talk about at length in any normal episode, my longer standard form episodes. The world is crawling with over 11,000 bird species and so by doing these random bird Thursday episodes, this gives us a chance to celebrate maybe some of these birds that would otherwise

1:04be overlooked. So let's find out who we are talking about today. I'm going to push the random bird selector button and here we go. Ah cool. We've got the white-throated magpie J, cyanocorax formosis. This is a great bird. It's found in the Mesoamerican region in Mexico and Central America. The white-throated magpie J. And it goes by different names in Spanish in the places where it's found. For example, in Honduras, this bird is known as Uraca Cololarga, which I guess is yet long-tailed magpie. Uraca, not sure I'm saying that, exactly right, but Uraca, Uraca, U-R-R-A-C-A. And in Mexico, it's Uraca Carablanca, white-faced magpie. So different people are choosing different features to highlight.

2:07White-faced, long-tailed, white-throated in English. But of course, the scientists all agree that it is cyanocorax formosis. And here we go. Let's get into it. Now, this is a very charismatic bird. It's quite attractive and large. It's got a very noticeably long tail. And on the head, there's a thin, curly, recurved crest, curving forward. So for a corvid, this is a very distinct bird. Now, that long tail is graduated. So that means that the outer feathers, the outer rectacies, are the shorter feathers. And then as you move to the inward feathers, they get longer, longer to the middle. The wings aren't particularly long. They're more rounded and broad, as is typical for a bird that flies around among trees.

3:09And as I said, this is a fairly large bird. So we're talking from big to tail, 17 to 22 inches, or 43 to 56 centimeters. But a lot of that length is actually the tail. In at least the nominant or primary subspecies, males have a average tail length of about 12 inches long, or 31 centimeters. So that can be half or more of the total body length. The bill in adults is pretty dark overall, dark, grayish, black. But it changes at the bill coloration changes throughout the life of the bird. The nestlings have pale, flesh-colored bills. And then it gets more grayish or plumbious as they become fledglings. And after about three or four months, the bill is all black. But also the color of the inner beak or mouth changes. Starting off as bright red or pink, and then it transitions to black over maybe four years. And perhaps there's a signaling component there, right?

4:12The color of the inside of the mouth may mean something to other magpie jays. And the bill, the shape of the bill, is strong and stouts very typical for a Corvid. So as I said, an attractive bird, it's got that crest on the head, it's got a long tail. The upper parts, so the wings, the mantle, the back of the tail, they are more or less sky blue or a bluish gray, and they might even have a little bit of a lavender tinge. The under parts that throw the cheeks, the sides of the head are white. And then there's this narrow band of black at the base of the throat separating the throat and the breast, sort of a necklace-like structure of black. Very distinct. And that black necklace meets the nape and there's kind of a black line that follows up the back of the head on the sides of the head. Now as I mentioned, the tail feathers are graduated, they're shorter on the outer edges and then

5:12they get longer and longer towards the middle. And the outer most rectarcy's tail feathers are tipped with white, so it's very distinct when the bird flies. So again, the bill is black as are the legs and feet, at least in adults. Then in the eye color, the iris is dark brown in adults and juveniles. Now in terms of dimorphism, females have somewhat shorter tails and there's also dichromatism right, so differences in coloration or patterning between the sexes. So the females have a narrower black chest band, that necklace. But females have more black in the auricular or ear area, as well as in their crowns, in the front part of their crown and in their crest feathers. Okay, so let's talk about the voice. Now for a corvid, this bird has a really astonishingly complex array of vocal sounds, pretty impressive for a corvid. There's at least 14 distinct functional call types, but within those or across those, there's

6:18maybe up to 150 different distinct calls. And ornithologists have sorted these into several functional classes, the first of which is a group of calls that are associated with predators. So these are defense calls, things like mobbing calls, raptor alarm, distress call. And there's something called the loud call made primarily by males and we'll talk a little more about that in a moment. Another class is the food associated signals. And the more common calls here would be begging calls often made by females to solicit food. And then the third class is social integration and courtship. So these are social sounds, territorial sounds, described as churs, CHIRRS, that's one type, or flight buzzes, there's the soft song, the whisper song, these are all social sounds. Now I do have some recordings for you and I wish I could tell you which type of call

7:21or class of call each of these is. I can't say for sure I suspect a number of them are alarm calls, probably in response to the person recording them, the human. But yeah, let's check these out. So the first we have is from Guerrero, Mexico. This next recording was made in El Salvador.

8:23And then the recording we have from the furthest south, this one was from Costa Rica. Now given all of the diverse vocal array, the repertoire that these birds have, you wouldn't be surprised to hear that they are very social. This is a gregarious social species, they're very conspicuous and noisy, they travel around in groups. And they're very active during the day when they're out foraging, they cover vast distances. And when they're forging in a local area, they're hopping around on the ground or perching out prominently in the tree tops or on branches. And from the human perspective, these birds are again, pretty loud, not lousy, loud and conspicuous, anything but lousy.

9:26And they get pretty worked up when people approach them, they make a lot of sound, get all excited and agitated. But they will also get used to people and come in to be fed at feeders and things. These are smart birds, they're corvids of course, so they're highly intelligent, adaptable. Birds of these groups will roost together at night in a communal roost. They also show a lot of social behaviors like alopraining. This is where one bird grooms another bird, right? This occurs within these cooperative groups and even siblings start doing this when they're just three to twelve weeks after fludging. They start to aloprain each other. Okay, so so far we've covered what the white-throated magpie J looks like. But it sounds like in some of its primary or most important behavioral characteristics. But there's a lot more to talk about. First off, the name. So white-throated magpie J, pretty straightforward.

10:28The magpie part comes from having that long tail with contrasting patterns like other magpies. So pretty straightforward common name, even in English and Spanish. Now the scientific name is again Sianocorax Formosis and Sianocorax is spelled C-Y-A-N-O-C-O-R-A-X. That comes from a Greek word, Kuannos, which means dark blue and corax means raven. So Sianocorax, dark blue raven. And then that leaves us with the specific epithet Formosis, the second part of the scientific name. That comes from Latin and it means beautiful. So we have a beautiful dark blue raven. Cool. Now as I've mentioned, this is a corvid, meaning it belongs to the family corvidi. That family includes 136 species across the planet. And yes, we will definitely do an episode on corvidi. I know that's going to be very exciting for all of us.

11:31Corvidis are among the most loved birds and the most fascinating. So stay tuned for that episode. But anyway, so the genus is Sianocorax and there are 18 other species in that genus. And it was recently expanded. So these birds used to be, the Magpie J's used to be in another genus, Calositta. But they have been now included in Sianocorax. And so among those birds in the genus Sianocorax, who are the closest relatives of our white throated Magpie J. Well if you looked at the list, you probably would guess that the black throated Magpie J, Sianocorax coli-i is the closest relative. And you would be right. The black throated Magpie J lives in Mexico. It has a smaller range and it's found more to the north. But within the white throated Magpie J, there are three subspecies. And they differ primarily in that the nominate subspecies has a triangular blue-blues.

12:34Black patch below its eye and the other two subspecies don't have that. The white throated Magpie J is one of the better studied corvids in the new world. So we do know a little bit about its evolution. There are some fossils, so there have been a couple extinct species that have been discovered. And those appear to be ancestral to our modern Magpie J's. Those fossils were dated to around the Pleiocene and Lake Pleistocene. So maybe four to about a million years ago, something like that. And ornithologists looking at genetic data from DNA have been able to use the molecular clock approach to estimate when the white throated Magpie J, and its closest relative, the black throated Magpie J, split. When did their lineages go from one to two? Well the genetic data tells us that the estimate for that is about three million years ago. In a late Pleiocene epoch.

13:34Another interesting thing about the evolution of these birds is that there is a very narrow secondary contact hybrid zone in Haleesco, Mexico, where the white throated and black throated Magpie J's meet. And they interact and they interbreed, and so there are hybrids there. But it's a narrow hybrid zone. And apparently it's a very stable hybrid zone. It hasn't really moved from its geographic location between historical specimens that were collected prior to 1973 and modern data has been collected since 2005. And even though their habitat has been changed by human machinations in that area, the birds have maintained this hybrid zone, which is really interesting. I'm imagining somebody's out there studying that. So we have another feature of the evolution of these birds that's unique and really interesting. So we're going to talk about the breeding system in the species pretty soon. But basically it is a female dominated social system and breeding system.

14:38And these birds are philopatric so they don't move around, they don't migrate. And the females are the ones who defend territories. So males, unlike in other bird species, many other bird species, the male white throated magpie jays aren't able to defend resources as a way to attract females. So evolution being what it is, being creative through the process of sexual selection, which I did an episode on, the predator alarm calls made by males have been co-opted into something that is attractive to females. So the males make these diverse loud calls. So that's what they're called, the loud call. And it's a display that the males make when there's a predator in the area of a certain type, and they also make these loud calls at dawn. And even though corvids are technically songbirds, as you know, they don't tend to make very elaborate

15:39songs. But in this case, these birds do make fairly elaborate vocalizations. And so it's thought to be that this is a sort of secondary evolution of song in this group. So these are the purpose of made attraction. So these loud calls, there are 134 distinct types that have been classified, at least. And these include chirps and whoops, pops, yells, clicks. They've been described, some of them have been described as pow, uir, pio, and rolling trills. So lots of different sounds. And these are often accompanied by some flight display. And again, the birds are making this sound. They'll do it at dawn, but they'll also do it in the presence of a predator. Okay, so they see a predator. And this needs to be a predator that's like a mild predator, like a mid predator that's not super threatening. A Magpie J-Mail, he's the predator, starts making these loud calls. And this is a way to attract the attention of females and to, I guess, impress them.

16:44Because the females aren't going to be visiting the males territory because the male doesn't defend the territory. The females do that. And they do that cooperatively. So the male needs to advertise to females somehow and do that when the females are alert and paying attention. So if the male is screaming like, hey, there's a predator over here. Look out. There's a predator. Hey, look over here. He's getting the females attention. And then he's doing this loud thing where he's putting himself at risk. Now, as I said, the males only do this for these kind of mid-level, mid-tier predators. But then if a high-threat predator comes around, something like an owl, the Magpie J's scale way back and they stop making their loud calls, they're like, hey, oh, yeah, let me just, whoa, let me just quiet down here and make myself a little less conspicuous. And so they're able to switch like that, depending on the predator that's approaching. Okay. So hopefully that makes sense.

17:44There's a lot more, of course, we could get into. This is random bird Thursday. So I'm not trying to make an hour-long episode here, even though the white-throated Magpie J is a very interesting species. We should probably move on to talk about distribution and habitat. So again, this is a Mizo American species found primarily on the Pacific side, the Pacific slope of middle America, ranging from Holesco, Mexico, all the way down to Costa Rica. It does occur in some locations on the Caribbean or Atlantic side, but just a few little isolated areas. Interestingly, this species appears to be expanding its range northward, southward, and moving up in elevation. So expanding its elevation range. And across its range, its habitat is pasture lands, cattle pastures, open savannah-like areas with brush and small fire-resistant trees. Breeding pairs of Magpie J's select isolated trees in the middle of pastures, or sometimes

18:47near human habitation, to build their nests. And one idea behind why they do that, to have these isolated trees, or to build their humans, is to minimize the predation of the nest by monkeys. As everyone knows, monkeys are the worst. At least in terms of being nest predators there, yeah, they can be pretty bad. Now in terms of foraging, the white-throated Magpie J's live in woodland habitats. So deciduous or semi-deciduous forest, second-growth forest, gallery forest along rivers, even pine oak forests, mangrove, so whole different assortment of forest types. And during the wet season, the foraging groups tend to spend more time in dense woodlands, whereas in the dry season they spend more time out in those pastures. And as I mentioned briefly, these birds do not migrate, they hang out in the same region, all year round, so they're described as sedentary resident.

19:49And good news, in terms of conservation, this species is in the least concern category as designated by the IUCN, the International Union for the Conservation of Nature. It's a common species and it appears to have a stable or even a slightly increasing population size. It's estimated that the total population increased 7.2% between 2012 and 2022. So in the face of all these changes brought on by humans, the bird seems to be doing fairly well, which is good news. Now there is one threat to this bird faces and that is the caged bird trade. It's common in Mexico for this species to be trapped and then sold in the illegal caged bird trade for a caged bird or a companion bird. And yeah, traveling through Mexico, I saw this at least one time where there was a mag bite J in a cage and yeah, it wasn't to, wasn't thrilled to see that.

20:49And these birds sometimes escape or they get released in places that they are not native to, so places in northern Mexico or in the southwestern United States, these birds show up randomly and they're not vagrants, they are escapees or releases. What does the white-throated magpie J eat? This is a broadly of niverous species, eating a wide range of animal and plant material. They eat a lot of large invertebrates, insects, caterpillars, spiders, but also small lizards, frogs, small rodents. They like to eat the eggs and nestlings of small birds like yellow-winged casheaks. So monkeys aren't the only one out there pillaging nests. You can't point fingers magpie J and these birds will eat fruit and they like to slurp nectar. They'll even pick parasites off the backs of cows and things, so ectoparasites from livestock. Then there's even observations of white-throated magpie J's getting into the nests of crocodiles

21:53and eating the eggs. So the eggs of American crocodiles, and that's pretty wild. All right, as I've alluded to the breeding system in the species is pretty interesting. This is a cooperative breeding species with a complex genetic mating system. And if you'd like to learn more about cooperative breeding, go back and check out the episode I did on that topic. So the social structure of the white-throated magpie J is related to how it breeds. There are these territories that are occupied by a dominant breeding pair. So a primary breeding female and her one lone social mate, the male that she spends most of her time with and builds a nest with and all that. And then this territory is also occupied by one to nine female helpers. On average, there's about three to four. And these are often the females offspring from previous years. And this is unusual because often in cooperative breeding, we see the helpers being males or

22:54maybe a mixture. For example, in the black-throated magpie J, which remembers the closest relative to the white-throated, it too is a social breeder the black-throated is, but unlike the white-throated species, both male and female offspring help in the black-throated species. So again, there's this single female in the territory. And she appears from the outside to be associated with this single male, but in this species, there's lots of polyandry going on. So social monogamy, but genetically highly polyandrous. There's lots of extra pair fertilizations going on where that female will breed with floater males or neighboring males that are paired up with other dominant females. So in any given nest, if you look at the parentage of the nestlings, who their parents were, about 33% of them came from some other pairing, not the dominant pair. So from some rando floater male or a male on a neighboring territory, highly polyandrous.

24:02Sometimes the primary pair, the male and female, will attempt to build multiple nests. And in those cases, sometimes the female helpers will lay, they lay dump eggs, so-called dump eggs in the primary nest. So the number of eggs in that primary nest increases directly with the number of helpers. Clutch size is correlated with the number of helpers. So the female helpers are kind of sneaking around and dropping their own eggs in there. And those helper females will sometimes try to establish their own nests within the territory, they don't really get help from the group and those nests rarely are successful. So for the pairs to form, there is some courtship. When a male is interacting with a single female, he'll make a display flight, which includes these stiff wingbeats, and he holds his head straight ahead and spreads his tail out wide. And then if he's perched on a branch, he'll perform a little courtship dance, leaning forward, sticking up his crest feathers and making a low amplitude soto voce song,

25:07so a soft song. And so one courtship is successful, the pair will work together to build their nest. And it is a large bulky thing, at least on the outside, it's got this framework of sticks, rough sticks, and then the inside is woven from wiry roots and fibrous plant material. Again, the nest tends to be made in these isolated tall trees standing out in pastures or near houses. To keep the monkeys at bay, capuchin monkeys are the worst. I mean, that's common knowledge, right? Everybody knows capuchin monkeys are the worst, but just to be clear. The nest is placed 20 to 100 feet in the air up in a canopy, or six to 30 meters, and it's often the tree species chosen as often a thorny species. Again, probably trying to deter pesky monkeys. So the pair build a nest together, but sometimes the helpers that are hanging around those females will come by and bring some small sticks and be like, I'm helping look, here's a stick. I helped. A for effort. So these social groups

26:13are quite territorial. They're going to defend a large, permanent year-round territory. Not just breeding, but it's an all-purpose territory also for foraging. At least in one study in Costa Rica, the average territory size was about 46 acres, or 18.7 hectares, but the territory size is going to correlate with the group size. So those female helpers, the offspring from earlier seasons, they're going to be the ones that primarily do the territorial defense. And that means that the primary male and female, they kind of just get to go about their business. They're not as engaged in defense. A normal clutch is about three to four eggs, and those eggs are laid one per day, but again, clutch size might be higher in the cases where there are those female helpers that are dumping eggs into the nest, surreptitiously. Only that dominant female incubates the eggs, and incubation lasts about 20 days. The female stays on the nest

27:17most of the time, and she begs pretty much constantly, making specific begging calls. And that elicits the helpers and the male to bring her lots of food. In one study, the female was fed 47 times within 13.7 hours. So she can just sit on the eggs, incubate, and doesn't need to do any of her own foraging. In terms of parental care, well, it's more than that because after hatching everybody in the group, the breeders and the helpers cooperate to bring food to the nestlings, as well as to remove their fecal sacs. So the equivalent of diapers basically being removed from the nest, and everybody aggressively defends the nest against predators. The chicks are naked, they're basically outrichial, and they're going to spend about 23 days in the nest before they fledge. And life in the nest for a white-throated magpie J. Chick is precarious. There's a lot of egg predation and nestling predation. Studies have estimated a 72% failure rate for nests. Again, we can

28:25really blame those capuchin monkeys, they're the worst, but we also have crested caracarras as nest predators, collared forest falcons, and even spiny-tailed iguanas. So assuming the chick's survive into the fledging stage, they will continue to beg and to be fed up until about day 71, and that's when their independence is achieved. But they will hang around with their family groups, so independence with regard to feeding themselves, but they do hang around for a while. These birds are shown to require lots of learning. They learn from other individuals in their group to acquire all of their adult foraging skills. So social learning is very important. There have been these experiments where ornithologists have found that naive group members can learn their foraging skills by watching experienced individuals in the group. Learn skills like opening a complex puzzle box in this experiment. So the female offspring are strongly

29:28philipatric. They show natal philipatri, and philipatri again is spelled P-H-I-L-O-P-A-T-R-Y, and that is the tendency to stay in the area where you were born. So females will tend to stay on their natal territory for several years as helpers, but the males they are going to disperse. They tend to take off after about four or two, maybe two years to go live as floaters, unattached floaters, or to become the dominant breeding male in their own territories. The white-throated magpie J is a relatively long-lived bird. Adult annual survival is estimated between 0.84 and 0.9, so that's the proportion of adults that survive from one year to the next. Adult survivorship is going to be a lot higher than young bird survivorship, but once they become mature, they have a good chance of surviving maybe up to 20 years, which is the maximum recorded lifespan. So I mentioned that I've seen this bird in a cage in Mexico, but thankfully I've

30:33also seen this bird in the wild on numerous occasions in Mexico. So this is a bird I have experienced with. It's always exciting to see them. They are really jazzy with the crest and the long tail and the raucous, loud vocalizations and the fact that they're often in groups. So yeah, always a pleasure to see the white-throated magpie J. They are in the black-throated magpie J. How about you? Do you have an experience with these birds? Yeah, let me know. I'm always curious to hear these stories. My email addresses Ivan at scienceofbirds.com. That, my friends, was the white-throated magpie J, cyanocorax, foremosis. Thanks for being here today and we'll see you in the next episode.