Madeira Barn Owl

Here in the clouds a faint rumbling is all I sense of the sea. A moonbeam penetrates, illuminating distant crests of waves. The island of Bugio in the Desertas near Madeira is one long, sharp ridge, the top trimmed off at this end. Just 50 m wide, the grassy southern plateau is 300 m high or a 90 minute hand-and-foot climb above the sea. I sit in on the leeward side, listening among the crickets. All around me, Desertas Petrels Pterodroma deserta hurtle past, tying the wind in knots. Moaning like the ghosts they threaten to become, they display over their last colony in the world. A few Cory’s Shearwaters Calonectris borealis cry in the distance, and every now and then a Madeiran Storm Petrel Oceanodroma castro circuits the plateau, squeaky chatters marking its path. 

Every few minutes, a Madeira Barn Owl Tyto schmitzi screeches in flight, passes quickly and disappears over the edge. Once it passes so close that the LCD of my recorder lights it up. Its perennial screeches have an unfamiliar shape, a descending overall contour. The ending is weak, less abrupt than in Common Barn Owl T alba. CD1-16 is a medley of five recordings from Bugio, the first ever published of this species. In all but one the call is descending. On Deserta Grande, 14 km to the north, I recorded a neighbour on two successive nights. Its perennial screeches also descended in pitch.

A few months before visiting Bugio, João Nunes and I recorded Madeira Barn Owls on the north side of the main island of Madeira. Lameiros is a small village up the side of a valley where few foreigners venture. So when we visited a pinnacle above two local bars, we attracted quite a bit of attention. João’s colleague Liliano owns one of the bars, and that’s how word got out. Every now and then we heard a rather inappropriate tu-whit, tu-who from down below. 

It was thanks to Liliano that we came to hear about this pair, which he had been hearing most evenings from his home. João is a mountaineer and Liliano had been up the pinnacle years before. The two of them climbed up in no time, tying a rope to make subsequent visits easier. I followed carefully, putting some microphones up top where we hoped they would have a panoramic ‘view’. Unfortunately the owls proved to be rather quiet that night. The few calls that I did record were perennial screeches of the presumed male and soliciting calls of the female, which must have been on eggs or brooding small young. The first perennial screech in CD1-17 is delivered at the nest, the second is in flight and the third is already distant. All three descend in pitch just as on Bugio.

In fact, three out of the five Madeira Barn Owls I have heard gave only descending or uninflected calls. The fourth gave both descending and ascending variants, and the fifth gave just one, which happened to be ascending. In Common Barn Owl descending screeches are much less common, occurring in roughly 10% of individuals, and I have not heard them in Slender-billed Barn Owl T gracilirostris at all so far. 

Considering how slowly vocalisations seem to evolve in barn owls, it is remarkable that an important, long distance signal of Madeira Barn Owl sounds different. Although a descending perennial screech occasionally occurs in Common Barn Owl too, on Madeira this is the most typical variant. It suggests that Madeira Barn has been evolving along its own path, in isolation, for quite some time. 

Even after visiting them in five different months, João and I have never been lucky enough to catch this or any other pair at the height of courtship. We have only recorded a few courtship screeches and never long, intense sequences. Based on the few examples we have, these seem to be higher-pitched than in Common or Slender-billed Barn Owl. CD1-18 is a sequence of just two from Lameiras, and CD1-19 is the longest that we have, recorded at a cliff near the sea.

Most calls of Madeira Barn Owl are easily matched with their equivalents in Common Barn Owl. I recorded the soliciting calls in CD1-20 on April Fool’s Day 2011 when the female was probably incubating. João recorded the mobbing scream in CD1-21 during their next breeding attempt, on 11 January 2012.

It would be fascinating to know which mainland population gave rise to Madeira Barn Owl. Intriguingly, Madagascar Red Owl T soumagnei, a close relative of Common Barn Owl living on an island off the other side of Africa, also has descending screeches (Thorstrom et al 2007, Huguet & Chappuis 2002). Cape Verde Barn Owl T detorta produces them too. Might all these barn owls have descended from a similar-sounding African population? And is it one that still exists?

If you go to Madeira to look for Zino’s Petrel P madeira and other endemics, don’t miss the chance to hear and perhaps see this fascinating barn owl, which survived for thousands of years on a diet of crickets, wall lizards and birds.

>>> Cape Verde Barn Owl Tyto detorta >>>