WILD THINGS: THE SECRET LIVES OF YELLOW-BILLED CUCKOOS
It would be tough to be a yellow-billed cuckoo in the Florida Keys if you viewed yourself through the eyes of a birdwatcher, because, well, you’d always just be a damn disappointment.
This is what I was thinking when I saw one fly across the road on Boca Chica the other day.
The disappointment wouldn’t be your fault. It would be the fault of the very similar-looking attention hog, the mangrove cuckoo. That’s the one birdwatchers always want to see.
It’s not because they are terribly beautiful or charismatic creatures – they are various shades of brown and white and always look a little hunched. While some of their brown tones are really quite nice, they’re not in the visually stunning class of, say, flamingos or frigatebirds.
Mangrove cuckoos command the attention of birdwatchers because they’re so rarely seen. The excitement they generate is in exact proportion to their scarcity. They are primarily a Caribbean and South American species. In North America they can only be found in extreme South Florida. Traditionally people come to the Keys to find them, though they can also be found in parts of the Everglades and Sanibel Island.
Their scarcity is compounded by their skulkiness. These sneaky birds spend their lives avoiding attention of any kind. As a result, if you go looking for them, even in a place you know they nest, you are likely to fail.
Arguably the yellow-billed cuckoo is a better looking bird. Where the belly of a mangrove cuckoo is kind of a dingy, tobacco-tinged taupe, the yellow-billed cuckoo’s is a clean, dress-shirt white. Where the mangrove cuckoo’s wingtips are a slightly dark shade of umber, the yellow-billed cuckoo’s are reddish and tinged with a warm cinnamon glow. (The wingtips are usually my go-to for telling them apart.)
Yellow-billed cuckoos are a bit less skulky and a lot more common, breeding across the eastern two-thirds of the US, from the Keys to the Canadian border. I’ve actually seen hundreds of them in a single day during migration.
Disappointing birdwatchers with their commonness probably doesn’t bother yellow-billed cuckoos much. As the kids say, they DGAF. They’ve got their own lives to live.
The cuckoo family is a cosmopolitan one, with species of cuckoos found on every continent but Antarctica. The name comes from the call of the common cuckoo of Europe, which is probably the most well-known bird call in the world – two simple, clear notes that sound just like the name, and are easy to replicate with small bellows and pipes inside an ornately carved clock. Even before the clocks, though, the name was somehow associated with craziness and mental incapacity, which always struck me as strange, as there are so many bird calls that sound so much crazier. (See: pretty much any species of gull. Also: Peacocks.)
While cuckoos are not, in actuality, innately prone to delusions or diminished mental capacity, they can be viewed as devious, immoral creatures – at least in human terms. Consider their oft-used breeding tactic of brood parasitism, or laying their eggs in the nests of other species of birds and tricking them into raising them.
Fifty-six of the 127 cuckoo species in the world practice this to varying degrees. The common cuckoo, for instance, is all in. It doesn’t build nests and it doesn’t form pair bonds, instead mating with multiple partners. (The word “cuckold” is derived from this fact, though inaccurately and no doubt somewhat misogynistically, it’s used as a pejorative for males being cheated on by females.) The female common cuckoo expends far more energy scouting suitable host nests than worrying about who it mates with.
Common cuckoos are known to lay their eggs in the nests of over 100 different species of birds. To ensure the success of their chicks they use a few evolutionary dirty tricks – the cuckoo chicks hatch earlier and grow more quickly than the host species’ chicks. The cuckoo chicks then often lift the other eggs up with their rumps and push them out of the nest, thus ensuring a greater share of care and feeding from the duped parents. A common cuckoo will lay eggs in 12 to 22 different nests each year.
Here in the Keys, mangrove cuckoos may or may not be brood parasites. They are so secretive, and so little is known about their lives and habits, it is impossible to say.
At first glance yellow-billed cuckoos live largely respectable lives of avian domesticity. They’re thought to be monogamous, or at least serially monogamous. Males and females build the nest together, usually selecting a site well concealed by foliage. The female usually lays between one and six eggs, and the parents split brooding duties during the day, taking two-hour shifts, unless it is raining. Then they wait for it to stop before switching. (The males tend to do the brooding at night.)
The parents also share the job of feeding their young, though not for long. These birds can raise a clutch in just 17 days – eggs are incubated for 9 to 11 days, and the fledglings depart the nest 7 to 9 days after that. It’s mind-bogglingly fast.
This speed allows them to live a double life as “facultative, interspecific brood parasites,” a.k.a. birds that lay their eggs in other species’ nests, but only when the situation is right. Yellow-bills have been known to hijack the nests of American robins, gray catbirds, wood thrushes, other songbirds, and several species of doves.
What triggers this is still unclear, but it is thought to occur when there is an unusual abundance of food – for instance, during the hatch year of 17-year cicadas.
It makes you think, maybe they deserve a little more attention than they get in these parts.
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