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Ptilopsis grantisouthern white-faced owl

By Amanda O'Farrill

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. ("Ptilopsis granti (Southern white-faced scops-owl, White-faced owl)", 2000; König, et al., 1999)

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. (Duncan, 2003; "Ptilopsis granti (Southern white-faced scops-owl, White-faced owl)", 2000; Sinclair, et al., 2005)

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. (Duncan, 2003; König, et al., 1999; Smit, et al., 2008)

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. (Bouglouan, 2008; König, et al., 1999)

There is little sexual dimorphism between sexes; the only noticeable difference being size. Females generally weigh more than males. (Bouglouan, 2008; König, et al., 1999; Weick, 2006)

  • Sexual Dimorphism
  • female larger
  • Range mass
    185 to 275 g
    6.52 to 9.69 oz
  • Range length
    20 to 24 mm
    0.79 to 0.94 in
  • Range wingspan
    191 to 206 mm
    7.52 to 8.11 in
  • Average basal metabolic rate
    0.06 cm3.O2/g/hr

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. (König, et al., 1999)

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. (Bouglouan, 2008; Duncan, 2003; "Ptilopsis granti (Southern white-faced scops-owl, White-faced owl)", 2000; König, et al., 1999)

Age at sexual maturity is not reported in the literature.

  • Breeding interval
    Southern white-faced owls typically produce one clutch per year.
  • Breeding season
    Southern white-faced owls breed between May and November, with a peak during the dry season (July through August).
  • Range eggs per season
    2 to 4
  • Average time to hatching
    30 days
  • Average fledging age
    4 weeks
  • Average time to independence
    6 weeks

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. (Bouglouan, 2008; "Ptilopsis granti (Southern white-faced scops-owl, White-faced owl)", 2000; König, et al., 1999)

  • Parental Investment
  • precocial
  • male 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 Ptilopsis leucotis is 30 years in captivity. (Marwell Wildlife, 2011)

Behavior

Due to the recent separation of Ptilopsis 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.” ("Ptilopsis granti (Southern white-faced scops-owl, White-faced owl)", 2000; König, et al., 1999)

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. (Duncan, 2003; König, et al., 1999; Weyden, 1973)

  • Other Communication Modes
  • duets

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. (Duncan, 2003; "Ptilopsis granti (Southern white-faced scops-owl, White-faced owl)", 2000; König, et al., 1999)

  • Primary Diet
  • 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. (Grossman and Hamlet, 1964)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

These birds prey heavily on small mammals (consisting of 81% of their diet) and thus aid in rodent population control. ("Ptilopsis granti (Southern white-faced scops-owl, White-faced owl)", 2000)

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. (Bouglouan, 2008; "Ptilopsis granti (Southern white-faced scops-owl, White-faced owl)", 2000)

  • 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. ("Ptilopsis granti (Southern white-faced scops-owl, White-faced owl)", 2000)

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. (Duncan, 2003; König, et al., 1999)

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. (Wink, et al., 2009)

Contributors

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

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

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

acoustic

uses sound to communicate

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

duets

to jointly display, usually with sounds in a highly coordinated fashion, at the same time as one other individual of the same species, often a mate

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

male parental care

parental care is carried out by males

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

young precocial

young are relatively well-developed when born

References

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.

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.

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