The Science of Birds - Vermilion Flycatcher

Episode Date: March 7, 2021

The Vermilion Flycatcher (Pyrocephalus rubinus) is a charming bird found in the arid southwest of the United States, as well as in Mexico and down to southern South America.This bright red flycatcher is a favorite of birders and bird photographers. Join Ivan as he introduces you to the basic features of this species. We’ll also take a look at some interesting questions, like “Why are the Vermilion Flycatchers of Lima, Peru so dark and sooty-looking?”Note: Some ornithological authorities have now split this species into several. Under this new classification, the birds found in the US, Mexico, and northern South American are Pyrocephalus obscurus, not P. rubinus.~~ Leave me a review using Podchaser ~~Link to this episode on the Science of Birds websiteSupport the show

ruby crimson maroon scarlet cinnamon rusty these are some of the fun words we use to describe reddish plumage colors in birds but only a few bird species in the world are so brilliantly red that their name includes the word vermilion this elegant word comes from the name of a pigment made from the mineral cinnabar for which the technical name is mercury sulfide Vermilion has been used as a pigment by various human cultures for thousands of years, for all sorts of decorative purposes. One ancient use for it was as a cosmetic, as rouge to color the cheeks or lips. But that wasn't such a great idea, given that vermilion is super toxic, what with the mercury and all. Returning to birds, we've got the vermilion cardinal, the vermilion tanager,

and today's featured creature, the vermilion flycatcher. This little bird perches proudly and conspicuously on top of shrubs or on fence lines, waiting for flying insects to snatch up in mid-air. Vermillion flycatchers are solitary, but you sometimes see them in pairs. It's actually hard not to see these birds out in the field, at least the colorful males. male vermilion flycatchers look like little glowing red orbs sticking out like sore thumbs in their otherwise green and brown habitats. In South America, one colloquial Spanish name for the vermilion flycatcher is Bracita de Fuego.

That translates as Little Ember of Fire. Yeah, that's a pretty fitting name for this outstanding bird. 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. In this episode, we're getting to know the vermillion flycatcher, pyrocephalus Rubinus. This scientific name translates to Ruby Firehead, which, to me, kind of sounds like a character from Harry Potter.

Or maybe I could use Ruby Firehead as my pen name whenever I get around to writing trashy romance novels. Right, on with the show. The Vermilion Flycatcher is a small songbird with a barrel chest and a large head. The head is also a little flat. on top. The bill is straight, broad, and somewhat short. This overall shape or silhouette is typical for members of this bird's family, tyrannity. From the tip of the bill to the end of the tail,

these birds are about 5.5 inches or 12 to 14 centimeters long. Males and females of most species in the family tyrannity have very similar plumage, but not the vermilion flycatcher. This species is one extraordinary exception. The male is the little ember of fire. He has a bright red head and underside. In some individuals or populations, the red can be a deeper shade or even a little orangy. There's a brownish-black mask running through the eye, and the bird's bill and upper parts are this same dark color. The female looks very different. She has a grayish-brown head and back, her underside is whitish and towards the tail it fades to a salmon color. I'll include some photos of these birds, both males and females, in the show notes on the

Science of Birds website. Interestingly, there are some vermillion flycatcher populations on the west coast of South America where many individuals, of both sexes, are a dark, sooty brown color from beak to tail. These birds have few, if any, red feathers. This dark form, or morph, is especially common in the sprawling city of Lima, Peru. The dark morph reaches its highest frequency in the city's heart. As you move outward to the suburbs and then to the countryside, you encounter fewer and fewer dark-colored individuals.

So what's the deal with vermilion flycatchers in Lima? Why are dark-morph individuals so common? there. One idea is that dark plumage provides some camouflage for flycatchers living in the city. You can imagine that vermilion flycatchers with dark plumage are less conspicuous to predators. Bright red birds would get killed more often, whereas dark morph birds would survive to pass on their genes more often. This natural selection would cause an increase in the proportion of dark colored birds in the population over time. Sounds reasonable, but shouldn't this be true everywhere, not just in the city?

I mean, a glowing red bird is going to be conspicuous in pretty much every environment, the woods, the city, or wherever. Okay, maybe a vermilion flycatcher could hide in a field of red poppies, or among the gaudy ornaments on your living room Christmas tree, but in most places this bird is going to draw a lot of attention. So why would the vermillion flycatcher's need for camouflage be different in the city of Lima? One explanation I came across has to do with kids in Lima, killing birds with slingshots. A red or light morph flycatcher would be like a living, breathing bullseye, an easy target.

So these kids would be acting as the predators, and they would be the agents of selection. Presumably, there are more of these evil bird-murdering children running around in the heart of the city, so the less conspicuous dark-morph birds would have better chances of survival there. As far as I know, no one has tested this punk kid with slingshot hypothesis, so who knows if there's any truth to this scenario. But there has been some actual research on these dark-morph flycatchers. Carl Jonathan Schmidt did his master's thesis at the University of New Mexico on this population of vermilion flycatchers in Lima.

He did a lot of work and made some interesting discoveries. Schmidt figured out that the dark plumage in this population results from a dominant mutation in a gene that affects the production of the pigment melanin. The variant of this gene, in other words the allele that causes the dark morph, has a frequency of 60% in the city center and drops to 5% way out in the suburbs. Schmidt found evidence that this spatial gradient is the result of natural selection. What's driving the selection? It's still hard to say. Maybe it's kids with slingshots. Who knows? More research is needed.

As I mentioned, the vermillion flycatcher is, is a member of the family, Tyrannity. This is the tyrant flycatcher family of North and South America. With about 420 species, no other bird family in the world is more diverse. Most members of this family are drab compared to our little ruby firehead, pyrocephalus rubinus. We find vermilion flycatchers in the dry southwestern part of the U.S., as well as throughout Mexico and all the way down to Argentina. But they're mysteriously scarce in Central America.

These birds are mostly residents, hanging out in more or less the same place all year. But some birds in the northernmost populations are migratory, flying south for the winter. And there's a large population of vermilion flycatchers in southern South America that migrate north to spend the cooler non-breeding months in the Amazon basin. So those birds are what we call austral migrants.

That's Austral A-U-S-T-R-A-L. Across its range, the Vermilion Flycatcher prefers open, brushy habitats where there are some scattered trees and bushes. You also find them in farmlands and man-made places like suburban parks and golf courses. There's usually some water nearby. Riperian woodlands are especially. attractive to these birds. Vermillion flycatchers in the United States live in arid environments like Southern California and Arizona.

But in deserts and scrublands, these birds tend to hang around streams and rivers, where there are trees like willow, sycamore, cottonwood, and mesquite. This bird has become more and more common in parks, on fancy pants golf courses, and on college campuses. Green places like these offer reliable water and abundant trees for nesting. The best explanation for why vermilion flycatchers are expanding into such artificial environments is that they've lost a lot of their natural habitats. Riparian woodlands along the lower Colorado River and elsewhere in the southwest have been destroyed by flood control projects, livestock, and groundwater extraction.

Despite habitat loss in some regions, the species as a whole seems to be doing okay. The IUCN, the International Union for the Conservation of Nature, lists the Vermilion flycatcher in the category of least concern. No one has yet come up with a good estimate of the total number of these birds, but it's reasonable to assume that there are still well over a million vermilion flycatchers flitting around in North and South America. Honestly, I was just looking for an excuse to say million vermilion. But all is not necessarily hunky-dory for our little flaming orbs of excellence.

There's one place where vermilion flycatchers are having a really hard time. That place is the Galapagos Islands of Ecuador. When Darwin visited the archipelago in 1835, these flycatchers were living on all the major islands. But in the last 50 years, the birds have gone extinct on the islands of San Cristobal and Floriana, and they're almost gone from Santa Cruz Island. These three islands are all inhabited by humans. Coincidence? Nope. The cause of the flycatcher's decline on the islands is probably a combination of habitat destruction

and the ravages of invasive species, such as cats and rats. There's also an introduced parasitic fly whose larvae eat the blood and flesh of baby flycatchers. These flies cause high mortality in the nest. If we lose the vermilion flycatchers of the Galapagos Islands, we might be losing more than a subspecies or a unique population. A genetic study published in 2016 showed that the birds found on the islands are distinct enough

from those on the mainland that they probably should be treated as a separate species. And, in fact, several ornithological authorities now recognize the Galapagos birds as their own species. It's called Darwin's flycatcher, pyrocephalus nanus. This species is in a far more precarious position than its mainland counterpart. That 2016 genetic study was based on data from mitochondrial and nuclear, DNA collected from individuals all across North and South America. This research motivated a couple other changes to the taxonomy and classification of our little red flycatchers, but I won't drag you into all of that right now.

Just know that the vermilion flycatcher, as we have known it, probably represents several species in reality. Some authorities have already recognized these in an official sense. Anywho, let's go ahead and talk about something a little less abstract, the diet and foraging behavior of the vermilion flycatcher. This flycatcher is a sit-and-weight predator. It watches for passing prey while perched on a branch somewhere between three and 20 feet off the ground.

Often this is beneath the canopy of a riparian woodland. The bird sits and waits patiently for an insect to fly by. When it spots a butterfly or other winged bug, the flycatcher darts out to snatch its prey in the air. It may also grab insects and spiders off the ground. After its attack, successful or not, the bird will usually swoop right back to the same perch. This behavior of flying out and returning to the same spot is called sallying.

We see this a lot. rallying among birds in the family tyrannity. If the captured prey animal is large, like an obese grasshopper, the bird may whack it against a branch a few times before swallowing it. One study of the vermilion flycatcher's feeding behavior found that breeding males spend 87 to 92% of their day sitting around waiting. Only 4 to 11% of their time is spent chasing prey. This sounds sort of like my typical day.

At least the sitting-around part anyway. How are millions of vermilion flycatcher chicks hatched from eggs every year to perpetuate the species? In other words, how do these birds breed? This species is socially monogamous. Socially monogamous birds pair up and stick together to raise a brood or two each season. But vermillion flycatchers aren't now. necessarily sexually monogamous. There's evidence that when no one is looking, these birds will

sometimes mess around with other individuals. This can result in what we call extra pair offspring. These are babies made with mates outside of the socially monogamous pair. This pattern of social monogamy, combined with some extra pair shenanigans on the side, is common among songbirds. Vermilion flycatchers form their pair bonds each spring. One of the most important parts of this process is the male's spectacular flight song and display. To impress his would-be mate, the male makes a bouncing butterfly-like flight above the treetops. Near the peak of each undulation in his flight path, he belts out his flight song. As a further enticement, the male may offer the female a big showy insect to eat, such as a butterfly.

If the female approves of the male's gifts and all his fancy flying and singing, the pair will copulate and then move on to making a nest. The female builds the nest, but the male is the one who takes the one who, chooses the nest site. This is often in the horizontal fork of a tree branch. The male tries to convince his mate to start making a nest with a quote unquote nest site showing display. One researcher described the display this way. Quote, the male would crouch in a potential nest site, make slight nest forming movements, and flutter his wings close over his back in a small amplitude movement while calling. End quote. So the mail is like, hmm, this looks like a nice spot for a nest. Hey, babe, check this out. Hey, babe, over here. See, I'm fluttering my wings. What if we build a nest right

here? Yeah, there's a nice view, it's in a great school district, and the property taxes are pretty reasonable. I think we should go for it. What do you think? You agree? Awesome. Okay, go ahead and get started. Time's a wasting. I'm going to go take a nap. Let me know when you're finished. The female lays two to four eggs and incubates them on her own. The male hangs around and brings food to the nest. The eggs hatch after about two weeks. The pair aggressively defend their nest territory from any other birds that get too close, whether the interlopers are crafty predators or just looky-lose. The young birds leave the nest after another two weeks or so. Soon after that, they're off on their own. The parents wave goodbye to their kids,

and in a good season, they might immediately get to work raising a second brood. If a young vermillion flycatcher can avoid the dangers of feral cats, wayward golf balls, and sadistic children with slingshots, it might live for three or four years, long enough to find a mate and raise a few of its own little embers of fire. Thanks a lot for listening to this episode on what I hope you agree is a beautiful and interesting species. If you enjoyed the episode, I encourage you to consider subscribing to the show so you don't miss any new episodes. If you have thoughts or feelings about the show or want to share an amusing anecdote about a vermilion flycatcher, shoot an email to Ivan at Scienceof Birds.com.

You can see the show notes for this episode, which is number 24 on the Science of Birds website, science of birds.com. This is Ivan Philipson, and I'll catch you next time. Peace.