cold COMFORT THE SECRET LIFE OF AFRIcaN ScoPS-OWLS Text by Ben Smit & Andrew McKechnie adio-tracking owls near a vulture restaurant on a midwinter’s night in the Kalahari is not as much fun as it may sound. By 3 a.m., the temperature is -5 °C R and dropping, the caffeine from the cup of coffee you had two hours ago has long worn off, and the neurons of your sleep-deprived brain are firing much too slowly to work out a comfortable sleeping position in the front seat of a pick-up truck. During the intervals between data-recording sessions, the only indication that time is not, in fact, standing still is the layer of ice becoming progressively thicker on the vehicle’s roof. When you do eventually fall into a cramped, restless sleep, you are soon jolted back to frozen reality by the none-too-subtle aroma of a week-old zebra carcass. Every rustle around the carcass, every sound of a bone being crunched, and every carnivore eye reflected in the moonlight causes your imagination to run wild. African Scops-Owl WARWICK TARBOTON Some consolation for your prolonged discomfort is offered by the infinite number of stars glistening overhead, the moon rising majestically between the branches of a dead tree, and the faint beep…beep…beep that your telemetry receiver emits every time you stagger out of the vehicle and point the antenna into the darkness. Somewhere among the ghostly grey camel thorns, an African Scops-Owl is foraging for the slim pickings a cold desert night has to offer, and the miniature transmitter affixed to it is providing new insights into the ecology and physiology of this charming but secretive little bird. 42 AFRICAN SCOPS-OWL SHEM COMPION he African Scops-Owl Otus The distinctive prrrup of senegalensis is the smallest owl in southern Africa. Widespread African Scops-Owls belongs as much to humid lowveld in sub-Saharan savannas, it is evenings after summer thunderstorms as it does to Tparticularly common in parkland dot- ted with large trees. However, when cold, cloudless Kalahari nights not proclaiming its presence vocally, this species’ secretive roosting behavi- a pair of yellow eyes appear against a Pearl-spotted Owlets, which remained our and nocturnal habits mean that it branch within the tree’s canopy. On extremely vocal and active in this period, is often overlooked by all but the most such occasions, scops-owls were appar- particularly during daylight hours. dedicated observers. Globally, scops- ently unfazed by the frantic activity of In mid-August, as daytime temperatures owls are the most species-rich group of the mobbers, and the latter were com- began to climb, the Kalahari’s nocturnal owls, with a remarkable 20 per cent of pletely oblivious to the little owl’s close sounds changed once again. We heard the world’s 222 owl species belonging proximity. the tek-tek-tek clicks of barking geckos, to the genus Otus. This diverse group The distinctive prrrup of African Scops- and the scops-owls began proclaiming occurs throughout the Old World, with Owls belongs as much to humid lowveld their territories once more, this time in the exception of Australasia, where it is evenings after summer thunderstorms as preparation for breeding. In Molopo, a replaced by the ecologically similar but it does to cold, cloudless Kalahari nights. pair of African Scops-Owls typically de- more distantly related owlet-nightjars. In prime scops-owl habitat, an observer fends a territory of about 30 hectares year- In the Americas, 26 species of screech- will often hear the calls of a multitude round. In summer, from around January, ROBYN BRUYNS owls were formerly considered part of of individuals at regular intervals from the number of individuals calling in the Otus genus, but they have recently By radio-tracking owls around the clock, many points of the compass. A scops- each territory increases as the youngsters been re-classified as Megascops. we obtained new insights into their behav- owl usually perches in a favourite tree, that hatched between September and Scops- and screech-owls are small, feed iour and patterns of thermoregulation. and may remain there for hours on end November add to the nocturnal sym- mostly on invertebrates (including scor- ‘chatting’ with a mate or neighbouring phony. By April, Molopo nights literally pions), and have highly cryptic plumage albitrunca trees, provide superb habitat territory-holder. Their calls, produced at reverberate with scops-owl calls. coloration. They occupy a remarkably for these two owls, as well as a host of intervals of about five seconds, are used wide variety of habitats, from the trop- Kalahari endemics. By attaching tiny, to keep in contact with mates, as well as ical rainforests of South-East Asia to cool, temperature-sensitive radio transmit- to audibly proclaim territories. high-altitude coniferous forest in North ters to several owls of each species, we To human ears, the call of the African America, as well as the savannas of Africa obtained fascinating insights into how Scops-Owl is highly ventriloquial: the and the stony deserts of the Middle East. they cope physiologically with the harsh direction of the call’s source can be dif- Most species spend the day roosting in desert environment, and were afforded ficult to pinpoint and scops-owls often trees, but a few, such as the Pallid Scops- unparalleled opportunities to track and sound much closer than they really Owl O. brucei of the Middle East, roost on observe them at night. are. On a quiet, windless night, a male the ground on steep, rocky slopes. One Differences in behaviour between scops-owl can be heard from almost of the most remarkable aspects of the these two owl species were dramat- a kilometre away. The calls of males scops-owls’ global distribution concerns ically illustrated in their interactions and females differ in pitch and, when their diversity on Indian Ocean islands, with other birds. A Pearl-spotted Owlet both birds are calling, the female is eas- where almost every archipelago has an perched in the upper branches of a camel ily distinguished by her slightly higher endemic species. In the past decade, a thorn late in the afternoon would often pitched vocalisations. Another fairly new and highly distinct species restricted ensure top-class birding entertainment. loud, single-noted call, heard less often to Sri Lanka, the Serindib Scops-Owl The owlet’s piercing whistles invariably and which seems to be used mostly by O. thilohoffmanni has been described, attracted a commando of small birds, females, sounds like the low squeak of a and the number of known species more often than not with a vanguard of bicycle pump: puet, with a similar call- may well increase further. shrieking Scaly-feathered Finches flut- ing interval to the usual call. tering in a thorny tangle of branches Scops-owl vocalisations can be sea- uring 2007 and a few metres below the pearlie. Within sonal. In June 2007, when the owls in in early 2008, minutes, Crimson-breasted Shrikes, Molopo suddenly became silent and Dwe studied the Fork-tailed Drongos and White-browed stopped responding to imitations of physiology and ecology Sparrow-Weavers would join the protest. their calls, just as we were about to start of African Scops-Owls and On several occasions, scops-owls that we data collection, our initial thought was Pearl-spotted Owlets in the were tracking would remain motionless that they had moved out of the area for Molopo Nature Reserve in in the midst of the chaos, undetected the winter. However, after several bit- African Scops-Owls feed KALAHARI North West Province. Falling by the mobbing birds. Only after the terly cold nights of intensive searching, DESERT predominantly on insects, within the Kalahari Desert bi - harassed pearlie headed for more peace- we discovered that they were still there, Pearl-spotted Owlets, unlike the more but also include scorpions, ome, Molopo’s undulating plains ful hunting grounds, the twittering of but at lower densities and very reluctant secretive and completely nocturnal scops- spiders, and other arthro- of dry shrub savanna, dotted with the finches had died down and calm to call. Throughout June and July, they owls, are frequently conspicuous and active pods in their diet. camel thorns and magnificent Boscia was restored to the camel thorn, would kept a low profile, in contrast to the during the day. WARWICK TARBOTON (2) 44 AFRICAN SCOPS-OWL AFRICA – BIRDS & BIRDING OCTOBER/NOVEMBER 2008 AFRICAN SCOPS-OWL 45 Just after sunrise on cold Kalahari mornings, the body temperatures of scops-owls that had recently returned to their daytime roosts would gradually drop about 10 degrees below normal levels very few insects are active on cold winter One of the fascinating aspects of the nights and nutrient-rich dung will in all patterns of torpor we observed in the likelihood be one of the most reliable scops-owls concerned the way in which places to find prey. they re-warmed after each torpor bout. Many birds and small mammals warm up ur study’s major question, how- to normal temperatures by rapidly meta- ever, concerned what scops-owls bolising fats and carbohydrates, produc- Odo during the day, when they ing heat as a by-product of these chemical are not foraging, calling or engaging reactions. The amount of heat generated in any other activity. Unlike nightjars can be astounding: the metabolic rate of and their allies, owls as a group do a hummingbird perched motionless on a not appear to use torpor, an energy- twig while re-warming from torpor can saving strategy during which metabolic be similar to when it is hovering in front rate and body temperature are reduced of a flower, beating its wings tens of times far below normal levels (see Africa – per second.