Ptilopsis granti

Geographic Range

Southern white-faced owls, also known as southern white-faced scops owls, are found from southern Uganda, Kenya, and the Dominican Republic of the Congo to South Africa. They are most common in Namibia, Botswana, Zimbabwe, Mozambique, and northeastern South Africa.

• Biogeographic Regions
• ethiopian ethiopian
  • native native

Habitat

These owls occupy a wide variety of habitats but prefer more open areas that still provide shelter and cover, such as dry savannahs with scattered tree cover and thorny shrubs. They also appear in semi-forested areas or forest/clearing borders that are close to rivers.

• Habitat Regions
• temperate temperate
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland
• scrub forest scrub forest

Physical Description

Southern white-faced owls and their northern counterparts, northern white-faced owls , are almost identical in appearance. Southern white-faced owls are generally darker grey; however this is not reliable as both species vary in color. Southern white-faced owls range from 20 to 24 cm long and can weigh between 185 and 240 g in males and 215 to 275 g in females. Wingspans are between 191 and 206 mm and tails are 88 to 100 mm long. The basal metabolic rate, according to Smit et al. (2008), is 0.06 cubic centimeters of oxygen per hour. The coloration is generally grey, with pronounced white and black facial markings. The face is white to pale grey with a prominent black rim on either side. The eye color of these owls differs from the typical yellow of most scops owls and are orange-red to red. The ear tufts are long and are the same color as the crown, with black streaks. The upperparts are dark grey with black streaks and the feathers of the crown, nape, and mantle have obvious black shaft-streaks along with many fine vermiculations. The flight and tail feathers have bars of light and dark coloration. The underparts are lighter grey with white bases and are decorated with fine black streaks and spots. The feathers on the legs are pale grey and extend to the basal half of toes. These owls have pale, creamy colored bills and dusky, grayish-brown toes tipped with blackish-brown claws.

The feathers of chicks are downy-white in color and their eyes are yellow-grey. By the time they are fledged, they have similar coloration to parents with less pronounced plumage patterns, are smaller, and have eye color closer to the vibrant orange of adults.

There is little sexual dimorphism between sexes; the only noticeable difference being size. Females generally weigh more than males.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger

Reproduction

Southern white-faced owls are monogamous and will not mate with another during a breeding season. They prefer to nest in natural holes of tree trunks or branches, but at times the nests of larger birds will work as well. Males sing intently, mostly around dusk, but can often be heard throughout the night to attract a mate. Once together, the female will sing a duet, and later the female answers the male with a faint shriek of her own. After pairing, both males and females work together to raise and protect their young.

• Mating System
• monogamous monogamous

Eggs are laid between May and November with a peak from July to August. On a rare occasion eggs will be laid in February and May. The clutch size ranges from 2 to 4 eggs that are white and measure 38.1 to 42.4 mm by 31.3 to 34.5 mm. When chicks hatch, males exclusively feed the chicks and both parents hunt for prey. At 4 weeks the young fledge and begin to leave the nest, remaining in the surrounding bush for 2 to 5 days until they can fly well. Two weeks after that, when the young are approximately 7 weeks old, they leave the nest completely.

Age at sexual maturity is not reported in the literature.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous oviparous

Southern white-faced owls spend a great deal of time and energy raising their young. Females incubate the eggs, while males hunt and bring food to the nest for their mate. Occasionally males can be seen incubating eggs on occasion to give females a brief break. After the chicks hatch, males provide food for them as well as the female for the first 2 weeks. After that point both males and females hunt and provide food.

• Parental Investment
• precocial precocial
• male parental care male parental care
• female parental care female parental care
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • male
    • female
• pre-weaning/fledging
  • provisioning
    • male
  • protecting
    • male
    • female
• pre-independence
  • provisioning
    • male
    • female
  • protecting
    • male
    • female

Lifespan/Longevity

The lifespan of southern white-faced owls has not been examined in detail. However, reported lifespans of Otus leucotis is 30 years in captivity.

Behavior

Due to the recent separation of Otus leucotis into two species, differences in behavior have not been adequately explored and investigated. Southern white-faced owls are strictly nocturnal and hunt prey by flying from perch to perch until they locate something. Once prey is spotted, they fly to the ground and snatch it up in their powerful talons. As a defense mechanism, they have been known to puff out their feathers to change their apparent size. This behavior gives them the nickname “transforming owls.”

• Key Behaviors
• arboreal arboreal
• flies
• nocturnal nocturnal
• motile motile
• sedentary sedentary
• solitary solitary

Home Range

Home range size is not reported in the literature.

Communication and Perception

Vocalizations of the two African white-faced owls are what set them apart as species ( southern white-faced owl call ; northern white-faced owl call ). Southern white-faced owls communicate through a series of short, staccato notes followed by a longer and higher pitched ‘hoot’. Songs are used extensively during breeding season and pairs of owls will sing together. There is little information on communication between individuals outside of breeding.

• Communication Channels
• acoustic acoustic

• Other Communication Modes
• duets duets

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

White-faced owls prey on rodents, birds, shrews, squirrels, scorpions, spiders, beetles, other insects, and small reptiles. The largest recorded prey were brush squirrels ( Paraxerus ) and doves ( Streptopeia ). The majority of the diet is small rodents, representing up to 81% of the diet. The talons of these owls are strong and allow for them to hunt and capture larger prey and to hold their food while it is picked apart with the bill. White-faced owls hunt by moving from perch to perch, searching the ground and trees for possible prey to snatch up and carry away. They have been known to fly long distances to grass fires to prey on rodents and insects that are fleeing from the fire.

• Primary Diet
• carnivore carnivore
  • eats terrestrial vertebrates

• Animal Foods
• birds
• mammals
• reptiles
• insects
• terrestrial non-insect arthropods

Predation

White-faced owls are often preyed on by larger owls. To protect themselves from these predators, they hide in hollow trees or dense foliage during the day. When a potential predator is detected, they react in one of two ways . If the predator owl is about 35 to 75 cm tall, white-faced owls expand their feathers and crouch down, swaying side to side, to appear bigger and more intimidating. If the predator owl is more than 75 cm tall, then white-faced owls stretch out as tall as possible, holding their wings close to the body with their eyes half closed. Using their grey coloring, they blend into their surroundings and resemble a branch stub.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

These birds prey heavily on small mammals (consisting of 81% of their diet) and thus aid in rodent population control.

Economic Importance for Humans: Positive

Southern white-faced owls are not common in areas with increased human populations. They help to control rodent populations through their predation and are found commonly in areas with abundant rodent populations.

• Positive Impacts
• controls pest population

Economic Importance for Humans: Negative

These owls have no reported negative effect on human populations. White-faced owls tend to avoid and in general have little contact with humans.

Conservation Status

White-faced owls are not considered threatened by the International Union for Conservation of Nature (IUCN). Although White-faced owls are locally common, except in areas were pesticides are used.

Other Comments

Southern white-faced owls and their northern counterparts were considered conspecific as Otus leucotis until recently, when they were separated due to DNA and vocalization differences. Based on DNA data and morphological characteristics, white-faced owls were not as closely related to other Otus owls as previously thought; thus they were placed into a completely new genus Ptilopsis . Tests have also shown that the genus Ptilopsis is a sister group to the genus Asio .

Additional Links

Encyclopedia of Life

Contributors

Amanda O'Farrill (author), Northern Michigan University.

Mary Martin (editor), Northern Michigan University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

References

Bouglouan, N. 2008. "Southern White-faced Scops-Owl Ptilopsis granti" (On-line). Oiseaux-birds.com. Accessed February 17, 2011 at http://www.oiseaux-birds.com/card-white-faced-scops-owl.html02 .

Duncan, J. 2003. Owls of the world: their lives, behavior and survival . Buffalo, New York: Firefly Books. Accessed February 17, 2011 at http://books.google.com/books?id=8R8zpn8w54EC&printsec=copyright#v=onepage&q&f=false .

Grossman, M., J. Hamlet. 1964. Birds of Prey of the World . New York: Bonanza Books.

Jakobsen, O., N. Krabbe. 1977. "Northern White-faced Owl Ptilopsis leucotis" (On-line). Xeno-canto: Sharing bird songs from around the world. Accessed February 17, 2011 at http://www.xeno-canto.org/browse.php?query=northern+white+faced+owl .

König, C., J. Becking, F. Weick. 1999. Owls: a guide to the owls of the world . New Haven: Yale University Press.

Marwell Wildlife, 2011. "White-Faced Scops Owl (Otus leucotis)" (On-line). Marwell Wildlife: Animal Encyclopedia. Accessed April 18, 2011 at http://www.marwell.org.uk/zoo_guide/animal_detail.asp?id=98&css=0 .

Sinclair, I., P. Hockey, N. Arlott. 2005. The larger llustrated guide to birds of southern Africa . Cape Town: Struik Publishers.

Smit, B., M. Brown, C. Downs. 2008. Thermoregulatory responses in seasonally acclimatized captive Southern White-faced Scops-owls. Journal of Thermal Biology , 33/2: 76-86. Accessed February 17, 2011 at http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T94-4R7J8D6-1&_user=10&_coverDate=02%2F29%2F2008&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=7bff34ba3db3eb211804aec34380be6c&searchtype=a .

Solomon, D. 2009. "Southern White-faced Owl Ptilopsis granti" (On-line). Xeno-Canto: sharing bird songs from around the world. Accessed February 17, 2011 at http://www.xeno-canto.org/browse.php?query=southern+white+faced+owl .

Weick, F. 2006. Owls (Strigiformes): annotated and illustrated checklist . New York: Springer. Accessed February 17, 2011 at http://books.google.com/books?id=PLhOcUhUR20C&dq=owls+%28strigiformes%29+annotated+and+illustrated&source=gbs_navlinks_s .

Weyden, W. 1973. GEOGRAPHICAL VARIATION IN THE TERRITORIAL SONG OF THE WHITE-FACED SCOPS OWL OTUS LEUCOTIS. Ibis , 115/1: 129-131.

Wink, M., A. El-Sayed, H. Sauer-Gürth, J. Gonzalez. 2009. Molecular Phylogeny of Owl (Strigifores) Inferred from DNA Sequences of the Mitochondrial Cytochrome b and the Nuclear RAG-1 gene. Andrea , 97/4: 581-591. Accessed February 17, 2011 at http://www.bioone.org/doi/full/10.5253/078.097.0425 .

Iziko Museum of Cape Town. 2000. "Ptilopsis granti (Southern white-faced scops-owl, White-faced owl)" (On-line). Biodiversity Exporer: The web of life in Southern Africa. Accessed February 17, 2011 at http://www.biodiversityexplorer.org/birds/strigidae/ptilopsis_granti.htm .