When I tell my non-birding friends that we saw quite a few owls in Costa Rica, many of them are surprised.  The common perception is that owls are indeed woodland creatures, but that’s “normal” woods — not, you know, the “jungle.”  I suspect this monolithic concept of owls — where “owl” pretty much equals “great horned owl” — arises in part from our being exposed from early on to things like halloween images of owls perched in leafless trees over tombstones, defining owls glibly as creatures not only of the night, but of deciduous woodland.  For many, it even takes some getting used to think of owls as desert creatures, living in and on saguaros, and eating scorpions and other Sonoran fare.

So the concept of tropical owls takes many people by surprise.  Of course, owls are at home in rain forests as much as woodlands and wetlands and tundra.  Just not the same owls in all of those places, for the most part.  There are in fact many species of tropical owls in central America, some endemic to Costa Rica, others widespread in tropical habitats from Mexico to South America.

One of the latter is the aptly named Black and white owl (Ciccaba nigrolineata).  They are birds of moist forests.  They also can be found in urban and suburban habitats within that range, much the way Great horned owls successfully exist in proximity to human settlements.

<< Black and white owl scratching its itchy face (digiscoped by C.Gómez)

This Black-and-white owl was roosting in the central city park in the town of Orotina CR, high in a tree it was sharing with a sloth, spending the middle of the day preening itself and scratching its face with its strong-toed yellow foot. It could only be seen by standing directly below its branch and looking straight upward.

From an owl’s viewpoint, a city park is a good place to hunt large insects, like cockroaches, and small mammals, like mice and bats.  From a human point of view, it was humorous to be enjoying such an excellent owl in such an urban setting: we were surrounded by ice-cream vendors, mothers strolling their babies, pan-handlers, too-cool teenagers eyeing each other, and romping, boisterous children, as we craned upward in broad daylight at an owl who seemed to care nothing for all the traffic noise and people far below it. The owl’s primary concern seemed to be that its face itched. As it scratched like a cat, rapidly kicking at its facial disc with a talon or two, bits of down fluff, owl dander, and even a contour feather drifted down unnoticed onto the activity and bustle in the park below.

To say that pygmy owls are sparrow-like isn’t entirely true.  But it’s almost true.

To start with, there’s their size: they are Very Very Small (the technical term).  Almost sparrow-sized.  Perched in a conifer, they look like a tiny pinecone. Also, like sparrows, they’re largely diurnal, and can frequently be found glaring down from a high branch in daylight hours.

Ferruginous pygmy owl, San José CR.  (photo A.Shock) >>

Then there’s their fierce, predatory nature.

OK, that’s not like a sparrow at all, unless you’re a seed.

But then, there’s their population density: they’re almost as numerous as sparrows.  Of course this is hyperbole too, but, for a predator, whose numbers are usually limited, they are fairly numerous.  In a walled garden of our hotel in San José, Costa Rica, we encountered (heard or seen) at least three if not more Ferruginous pygmy owls, simultaneously responding to their own staccato calls, recorded and played back to them. (By contrast, in Arizona, Ferruginous pygmy owls reach their maximum northward range in the southern part of the state; they’re not terribly numerous.  In fact, the Cactus ferruginous pygmy owl is endangered in the state)

<< Here’s another pygmy owl in Costa Rica, making its repetitive “poop” call, at the rate of about 3 per second, each note accompanied by a slight lift of its tail, showing the whole-body effort that goes into making a noise that’s pretty loud coming from such a small entity. (Photo A.Shock)

Costa Rica is especially well-supplied with pygmy owl species: Ferruginous, Costa Rican (endemic to the country), and Central American pygmy owl all make their homes there, varying slightly in appearance and voice, but not overlapping much in range.

[This is a Spot the Bird, although it’s less of a quiz than a photo series. All photos A or E Shock.  Click to enlarge.]

Here are some feral date palms, growing wild at a substantial oasis in Death Valley, CA.  The date palm is Phoenix dactylifera (“finger-bearing”), but in this case we could call it P. bubifera, “owl-bearing.”  There’s an owl in this palm, although you can’t see it. >>

Owls seem to like roosting in palms.   Every birder the world over checks palms for owls.  Great horned, Barn, Grass, whatever the local species are — if there are owls and palms together in a habitat or region, they are likely to be acquainted.  This is because palms (like pine trees) provide what owls like: concealing, sturdy roosts, and habitat and food source for prey items.  An owl perched hidden in palm fronds has a grand view of scurrying, foraging rodents at its feet — imagine regularly finding dinner on your very own kitchen floor… or, to quote Homer: “Mmmm, Floor Pie!”  (that’s the epic Homer Simpson, not Homer the epic poet).

Spot the bird: In the center of this photo, you can see a vague milky blur on the right edge of the darkest dark: the vermiculation, or fine breast barring, of a Great horned owl, Bubo virginianus. >>

It’s nearly invisible because its distinctive yellow eyes aren’t visible; owls roosting in plain sight will often consider themselves concealed by squinting.  When even one eye is revealed, the bird become easier to spot. <<

I’ve checked a lot of palm trees.  I never find owls in them (although I know others who have), but I keep checking.  This repeated optimistic searching is known in our family as checking for lard. The term was coined after a cat named the Beefweasel found an unattended pile of chopped fat on a windowsill in our St. Louis apartment, waiting to be put outside for winter-hungry titmice and chickadees.  Making good her name, the Beefweasel wolfed down the yummy chunks.  Balancing on her hind legs and sniffing hard, she checked that bountiful window-ledge for years hoping for a fatty repeat.  Birders are well-known to check for lard, too: there was a nut tree in St. Louis that was searched every winter by local birders on field trips because once in a decade past it had hosted an out-of-range Bohemian waxwing.  Among birders, places to check for lard are passed down as oral tradition: I knew about that pecan tree, but the waxwing that made it famous alit there long before my time.

So out of habit and hope, I was checking these particular palms with my binoculars, searching the deepest shadows for Good Feathery Detail (vermiculation).  And there was an owl.

>> The bird never fully unhid; this was the maximum best sighting it allowed.

It was a Great horned owl, tucked in out of the breeze, and not at all worried about us (although we didn’t go very close, being equipped with telephoto lenses and optics — owls are like cats; sometimes you have to respect their invisibility, even if it’s just in their heads).

It’s so delightful to luck into a surprise owl (which, mostly, they are), that we talked about it for the rest of the trip.  We referred to this bird as “the Boss in her Office”, because she reminded me of a boss I once had, who lurked invisible at her desk most of the time.  Although she was hidden from us as we scurried around busily, it was never a good idea to forget she was there…

… and we were — always — this Great horned owl (Bubo virginianus) was giving us the eye from our big backyard pine tree, right at sunset tonight.  The Gila woodpeckers, doves, and local hummers — both Anna’s and Black-chinned — were really ticked off at the eminence tigre, and zoomed and hovered threateningly.  I’m unable to report if the owl even noticed.

The noise of the scolding yard birds, and the nervous upward glances of the “wild” African collared dove, Hoover, tipped us off.

<< Great horned owl (Photo A.Shock)

Hiding behind a shred of pine-bough seems to be a mere formality for the large owl.  It’s probably looking for another Desert cottontail, to follow up the one it helped itself to part of on the weekend, leaving the rest of the bunny for the resident raccoons.

…was a Ruru, or Morepork (Ninox novaeseelandiae).

It’s NZ’s only remaining native owl (the Laughing owl was last recorded in 1914), and is fairly common in many habitats, even parks and gardens, but is especially numerous in tracts of native bush.  We heard them several places, mostly in the Kauri Forest while on a night walk looking for Kiwi.  They whinny and whoo and screek, but their main call is, not surprisingly, “More-pore” repeated frequently.  If you live where there are Inca Doves, you know what a Morepork sounds like.  Inca doves’ call is usually transcribed as “whirl-pool” or “no-hope”, but in pitch, frequency, and tone, it’s very much like the owl’s call.  The Māori name, Ruru, is also onomatopoetic, as is the Australian name, (Southern) Boobook.

Ruru is a relatively small (approx 10″ ht), long-tailed owl that takes a range of prey but specializes in nocturnal insects like weta (large crickets — really large crickets!), huhu beetles and moths.

(Photo by Aviceda from Wikimedia Commons)

There’s a property of owls I call “Half-Dome Head.”  It’s a shape that’s noticeable in the profile of all owls, particularly the larger ones.  The Barred Owl to the right is exhibiting major Half-Dome Head.  If Half-Dome Head can be achieved when making owls in clay, the resulting effigies will be Especially Owly.

The name derives from the famous granitic dome formation, Half Dome, in Yosemite Valley, California, which bears an obvious resemblance to an owl’s head in profile.  The geologic Half Dome is forming largely by weathering: eons of sheet-exfoliation on the fragmented face of an exposed granodioritic batholith gave it the shape we see today.  (Appropriately, one of the most Half-Dome-Headed owls ever, the regal Great Gray Owl, is an uncommon resident of Yosemite Valley, see photo below: the color and texture even match).

In owls, the “Half-Dome Head” effect arises from the front of the Owl’s head (in other words its face, to use the technical term) being shaped like a radar dish, to be efficient at gathering sensory input — in other words, light and sound.  But take away the feathers and an owl’s cranium is shaped pretty much like a hawk’s, or even a chicken’s skull (check out these images).  An owl is after all a bird, albeit a fairly specialized one, so it’s built like a bird.  The forward-oriented flat face that we humans find so fascinating (probably for anthropocentric reasons) is due more to posture and feather-arrangement than underlying skeletal structure: the owl generally holds its bill slightly downward rather than forward like other birds.  This gives prominence to the distinctive “facial disc” — the specialized array of radar-dish-like plumage around an owl’s eyes and ears — and positions it so it functions optimally.

The owl’s Facial Disc is a precise specialization for nocturnal hunters who require every available bit of light and sound directed into their sensory apparatus to ensure the highest possible success rate while hunting.  Several features of the facial disc are noticeable: short flat-lying feathers sweep away from the eyes and “cheeks” so as not to impede forward vision; stiff vertically-arranged feathers edging the facial disc help funnel sound into the ear openings, which are asymetrically arranged on either side of the face behind the eye to create aural parallax (and are nowhere near the cranial tufts we commonly call “ears”); and rictal bristles (“whiskers”), which are specialized sensitive filamental feathers on either side of the gape (the flexible corners of the mouth which allow the beak to open and close), that enable the owl to perform preening and feeding activities — including the feeding of owlets — by feel, since their large eyes are immovable in the skull and so can’t focus efficiently at very close ranges.

But that’s just the flat front of the “Half-Dome”: the round back, the helmet-shaped fullness of feathers on the back of an owl’s head also transmits owliness to our perception.  This is also due to the owl’s skeletal configuration: the bird’s upright posture is possible because its skull is joined to a nearly vertical spine.  Most birds’ backs go off at a more or less right angle to their necks (think of a dove), somewhat shortening the curve at the back of the head.  But the feathers on the back of an owl’s head arc smoothly down to the back, which continues downward steeply.  The photo above shows Half-Dome head creating Owliness in an MLO (Moderately Large Owl) I’m currently working on for a client.

Photos: from top to bottom: IBO barred owl, A.Shock; Half Dome Yosemite, Carroll Ann Hodges, USGS; Great Gray owl, Canada (Sorry; don’t know who to credit this photo to); Three Star Owl “eared” owl effigy in progress, A.Shock.  And finally, a Gratuitous Cranky Owlet chillin’ with the Big Boys…

…a true kindred spirit:

Adult Burrowing owl giving the entire world StinkEye at the Adobe Mountain Wildlife Center display at Boyce Thompson Arboretum‘s “Welcome Back Buzzards Day”. (Photo A.Shock)

Great news!  Sharon Stiteler of Birdchick.com fame ran a contest for guest-bloggers while she’s out of the country, and Three Star Owl is her selection for Friday’s guest post!  Regular Three Star Owl readers will recognize the entry as a post from this web journal, Vertical Napping Bark, which is one of my favorites because of the lucky shot of the Great horned owl with downy chick in a snag, demonstrating the beauty of Owly Invisibility very well.

[The image to the right is a digitally-altered photo of the breast feather vermiculation (= Latin for “wormy pattern”) that makes Great horned owls so invisible.]

If you’ve found your way to Three Star Owl from the Birdchick site, Welcome (Cranky Owlet says Hmph!), and take a look around: there’s lots of birdy art in the Gallery and Shop, and posts at the Journal on a variety of topics like birds, clay art, natural history and more!  Make yourself at home, and come back any time.

Thanks, Sharon, and have a great time in Guatemala!

Oh, and in my excitement, I forgot to mention that Swarovski Optik, makers of excellent binox and scopes, and beeooteeful crystal, is helping Sharon sponsor the contest.