A hollow trill echoes in the night, reverberating deeply over the high-pitched stridulations of katydids and the guttural thuds and “whoops” of anurans. Although the trill was so distinct and occurred repeatedly, it was incredibly difficult to spot who was producing the call. At times, I would get just a handful of meters away from the sound, gazing up into the leaves and epiphytes to no avail. It wasn’t until one day I searched at dusk, that I found two small round figures perched low above the vine thickets. At first, I thought they were too tiny to be owls, but as I got closer, their sharp talons and stout proportion became more obvious— and couldn’t possibly belong to anyone else. Navigating through the vegetation as quiet as possible, I would periodically look up to the two owls, worried that they would have already vanished into the forest silently. But at last, hardly four meters away, both of them finally acknowledged my presence, turning to reveal bright yellow irises and expressive large round pupils. Two small tufts of feathers arose on each feathery ball, revealing one of the diagnostic characters for screech owls of the genus Megascops. More specifically, they were vermiculated screech owls (Megascops guatemalae vermiculatus), one of the smallest owl species in Costa Rica.
At a mere 8 inches in height, they eclipse only three species of pygmy owls in the genus Glaucidium and the unspotted saw-whet owl (Aegolius ridgwayi). These two individuals, however, appeared to be juveniles and were easily the smallest owls I’ve ever seen in my life. It’s possible that because the owls were young, they allowed me to approach so closely, resorting to a more cryptic antipredator strategy. I’ve also heard that screech owls tend to be less skittish than larger owls, but I have few observations of my own to give insight into their demeanor. In the U.S., I’ve been fortunate to encounter and observe barred owls regularly, though only once an eastern screech owl (Megascops asio) made its appearance— almost hitting me in the head while I was out biking.
Very little is known about the ecology and behavior of vermiculated screech owls. Most information is inferred from observations of other owls in the same genus, and two reports in the literature concern occurrence through playbacks and more simply, anecdotal praise of their “pure musical trills.” A few decades ago, a brief note was made of a nest site in Mexico, in which a pair had situated within a shallow and narrow cavity previously made by a trogon and produced two glossy spherical eggs. Next time I visit Costa Rica, I’ll keep peering into those small tree holes in hopes of not solely boas and bats, but also the nests of these adorable little owls.
Photographed in situ