Owls of Peru – Part 2: Arid Habitats

Western Peru experiences a formidable rain shadow, which creates a remarkable diversity in habitats. Simply put, all the moisture from the Amazon basin being pushed up the Andes (the prevailing winds are from southeast in this region) gets sucked out on the eastern side as moist air rises and condenses into rain (or snow). This leaves almost nothing for the west side, the leeward side, i.e. as air descends the western slope of the Andes there is no moisture left in it. Maybe your first image of Peru is of lush jungles, but if you are west of the Andes, it should be more like desert and arid scrub or tropical dry forest. So, you might not be expecting to see species like Burrowing Owl as my first Peruvian owl, but the smallish, pale desert subspecies nanodes is common here (much more common than this species is where I live in Manitoba, Canada)...

In the tropical dry forests along the coast (west of the Andes), one of the most common owl species is the diurnal Peruvian Pygmy-Owl. This species comes in a range of colour morphs – here a greyish bird, a brown bird and a rufous bird to show some of the range in colouration.

The Peruvian Pygmy-Owl like all of their congenitors in the genus Glaucidium is tiny (about 16cm though even this dwarfs the Long-whiskered owlet in my previous post which measures a mere 13cm). This photo of a Peruvian Pygmy-Owl being mobbed by an Amazilia Hummingbird should give you a sense of the size.

But don’t be fooled by their size – these little birds pack a lot of punch and can take prey much larger than they are. Can’t you see the feisty personality in their eyes?

As with so many owl species, females are larger than males (female is the lower bird in this pair). In this pair the female has a stronger rufous plumage colour wheras the male is browner but note that colour is not indicative of sex generally.

There are nocturnal owl species in the dry forests too. The Tumbes Screech-Owl (Megascops pacificus) occurs in dry coastal forests of northwestern Peru and southwestern Ecuador. Some authors consider this to be a subspecies of the Peruvian Screech-Owl (Megascops roboratus). This photo shows a grey morph bird (apparently the rufous morph is rare).

While out at night in Chaparrí, we heard a descending hoot call that struck me as being very similar to one of the alarm calls of Eastern Screech-Owl (a series of descending hoots is given and will escalate to “barks”, rattling calls and bill snapping if a threat persists). Sneaking up slowly, I spotted the owl perched about four feet off the ground and looking straight down. The bird was so intently focused on the ground and giving the alarm call persistently. This lead us to conclude that there must have been something like a snake in the leaf litter that was stressing the owl. We never did see a snake so this is only a guess but we got fantastic looks at the owl, who was so focused on the ground that they seemed oblivious to our presence. Here are a few examples of the photos I got…

Over near Jaén, we had much briefer looks at the Peruvian Screech-Owl, the interior species (or subspecies) that is found in dry intermontane river basins and hillsides, especially in the Marañon Valley. Not a great photo though but compare this bird, which is larger and has a proportionately longer tail, with the previous photos of Tumbes Screech-Owl. There are also differences in song…

The dry forest also extends to considerable elevation along the western slope of the Andes and the intermontane valleys. Up above 1800m ASL, the forests are much more “temperate” than tropical in appearance and this is the home to the very little known Koepcke’s Screech-Owl, discovered by great Neotropical ornithologist Maria Koepcke (she thought this taxa to be a race of Peruvian Screch-Owl) but not described until after her death and named in her honour. Koepcke’s Screech-Owl is very poorly known and very patchily and sparsely distributed, so seeing a pair of Koepcke’s Screech-Owls roosting by day was one of the highlights of this trip. The fact they were in, of all things, an introduced eucalyptus tree, only softened the high ever so slightly…

Since we spotted them in the late afternoon, we waited around for them to get active. They began allopreening (preening each other) and calling softly towards dusk.

These owls were high up in the eucalyptus and in amongst many cluttered twigs and branches. As it turns out my best opportunity to see them up close and personal came about an hour before dawn, when I found this bird out on the prowl. Notice, for example, the heavier markings on the breast and belly (also against a whiter base colouration) compared with Peruvian and Tumbes Screech-Owls. You will also notice the paler bare part colouration. Needless to say I was elated to get these photos of this secretive species.

In the dry Apurimac Valley (Abancay area) there is a currently undescribed taxon of screech-owl that has some consider conspecific with Koepcke’s Screech-Owl, but others favour treatement as a full species (awaiting further study). This taxon is nicknamed the Apurimac Screech-Owl and is paler in colouration and shows differences in voice. Another highlight for me was to see this bird after having seen Koepcke’s Screech-Owl (seeing an undescribed species/taxon is always a thrill even if you are not the one to discover them). So, let me introduce you to the Apurimac Screech-Owl…

Certainly a beautiful bird but is this a full species? Well, the song and calls I heard were similar in pattern to Koepcke's but did seem faster and of a higher frequency and there were some plumage differences (colder grey overall, lacking brown tones and also lacking the ochre/greenish tones in the tarsi and with greyer bare part colouration… though none of these mean very much in and of themselves). Since recently more and more authors are coming to accept that Tumbes and Peruvian Screech-Owls function as reproductively isolated species, it will be interesting to see what the conclusion on the Apurimac versus Koepcke’s Screech-Owls is in the long run. So, I end this post with this photo of a most handsome pair of Apurimac Screech-Owls – one of the mysteries of the Peruvian night!

Stay tuned for some owls of Peru’s humid forests…