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The Rocky River Heron

Joan Jett of Blackhearts and The Runaways fame first sang, “I love rock and roll so put another dime in the jukebox baby!” Weird Al’s twist on that classic 80s rock tune says, “I love rocky road! So weren’t you gonna buy half a gallon baby?”

When visiting California Gulch or some roads in Costa Rica or so many other off beat places we go for birds, the song gets changed to, “I love rocky roads so put another wrench in the toolbox baby!” However, if the Fasciated Tiger-Heron could croon, if that rocky river loving bird could put words to the tune, it might say, “I love rocky flows so put another fish in the eddy baby!”

If you ever wondered what the Fasciated Tiger-Heron does, that lyric just about sums up how it spends most of its time. Unlike so many other herons, this species doesn’t visit marshes, doesn’t wade in estuaries or fly along any ocean shore. It doesn’t even stalk the shallows of slow, steady-flowing tropical lowland rivers. In the nations where our rocky river bittern ranges, those habitats are used by the related Bare-throated Tiger-Heron and the Rufescent Tiger-Heron. At some period in evolutionary history, we can only assume that in occupying and become more adapted to rocky forested rivers, the ancestor of the Fasciated became the bird that it is today.

Like other Trigrisoma herons (the tiger-herons), the Fasciated is a fair-sized bird with a thick, and powerful neck, sharp beak, and medium-length legs. In other birding words, its more or less shaped like a bittern, like a compact, modern dinosaur. However, unlike bitterns, the Fasciated and other tiger-herons don’t bother to hide themselves in the grass, don’t make any noises that sound like a water pump.

No, these birds are too rough and tough characters for any of that quaint country stuff. More in keeping with their dino ancestors, tiger-herons stalk where they wish, make growling noises that sound like some scary predator of the night, and eat baby crocodiles. At least the Bare-throated and Rufescent eat young crocs. The Fasciated doesn’t but I bet that’s only because saurians don’t inhabit the bird’s cold, rocky river habitats.

In fact, the Fasciated is so adapted to rocky streams and rivers, it just can’t seem to live anywhere else. Ranging from Costa Rica through much of the tropical Andes, the Fasciated Tiger-Heron uses rocky streams and rivers that flow through forested landcapes. As one might gather, this special heron also has a morphological feature or two that help it survive in its rushing river home. A bit stockier than other herons, like a feathered goat, it has shorter legs that may help it find better balance on slick river rocks. Its slightly blunter bill might help it catch more crayfish or other prey items peculiar to its cold, splashing home.

Although it’s far from being the only heron that patiently waits in place to eventually catch unwary prey, the Fasciated T. seems to be especially adept at practicing stillness. This river bird stands in place for so long, it can seem more like a garden statue, just another rock in the river than an actual living bird. With water constantly rushing and splashing past it, the heron seems to be making some natural Zen statement. Compared to herons of lowland tropical places, keeping still for long periods of time might be a necessary adaptation to catch enough food in places with fewer prey items. Being “Zen” also probably helps to avoid predators as does another of its characteristic features; its cryptic plumage.

Check a stream for this heron species and you might need to do a double take. Look carefully at the river with binoculars and don’t be surprised if one of those many “rocks” turns into a bird that was hiding in plain sight. Coupled with its art of being still behavior, the mottled gray plumage of the adult helps it blend in remarkably well with the surrounding river rocks and rushing water. The orange and black plumage of the juvenile is another story and raises the question of why the adult seems to be more camouflaged than young birds; a situation typically the other way around.

If you feel like pondering such questions while birding Costa Rica, come visit and scan rocky rivers and streams in rainforest for Fasciated Tiger-Herons. On account of the bird’s natural stealth and likely low density populations, it might take a while to find one. But don’t give up! Think like the heron, check the river with care because you can bet that the birds are somewhere on that waterway. They might be standing just around the bend, or keeping still on the other side of a big river rock, being Zen, hiding in plain sight.