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Otus marshallicloud-forest screech

By Nikki Panos

Geographic Range

Cloud-forest screech owls (Otus marshalli) are endemic to South America, and are dispersed in the Andes Mountains of south central Peru and Bolivia. These owls were first thought to occur on only three concentrated areas in Pasco and northern Peru, in the northern region of Cusco. New studies have projected that range to be larger. This includes alienated subpopulations of the Bolivian Andes located in the northern area of La Paz, into Departamento Conchabambo, as well as the Departmento Pasco. This information may be biased, as much of the joining land between the populations is unstudied. Other recent modeling suggests the populations are more continuous than originally thought. ("Endemic Species Distributions on the East Slope of the Andes in Peru and Bolivia", 2007; Herzog, et al., 2009; Weske and Terborgh, 1981; del Hoyo, et al., 1999)

Habitat

The chief habitat of Otus marshalli is the canopy of the dense cloud forest of Cordillera Vilcabamb. These are forests covered by mist, or low-level clouds. They experience a great deal of rainfall especially during the wet season, and are covered in moss and epiphytes. The forest consists of trees topping out at 40 m with a jagged canopy. Tree ferns and climbing bamboo sweep the forest as well with ferns, mosses, and orchids growing on trees. Light penetrates into the understory fairly well. Cloud-forest screech owls have a range of 12,709 square kilometers. They are found in elevations of 1,920 m and reaching to 2,240 m, but are most abundant between 2,130 and 2,190 m. (Herzog, et al., 2009; Weske and Terborgh, 1981)

  • Range elevation
    1,920 to 2,240 m
    to ft
  • Average elevation
    2,130 to 2,190 m
    ft

Physical Description

Cloud-forest screech owls are of average size for a screech owl, with a standard body mass of around 115 g. Their length can be anywhere from 20 to 23 cm. Their wingspan ranges from 151.5 to 164 mm. The abdomen pattern is made of slanting white spots contrasted by black and rufous streaks and bars. This is sometimes regarded as “ocellated”. Just above the abdomen, it has a buffy-tinted nuchal collar. Rufous, black rimmed facial discs with a partially shrouded white coronal band are distinct. Their eye color is a dark brown, and it boasts a greenish gray bill. The ear tufts are diminutive and made of white feathers with rufous and black tips. The middle dorsal side of the bird usually has four black, irregular, transverse bars against a chestnut base; but the overall coloration is uniform judged against that of close relatives. The outer part of the primaries and secondaries are banded yellowish-brown, with the inner part of the primaries dusky for the total length, except for two pale bands situated distally and have an insipid tawny tip. The tail of the owl is markedly banded rufous and blackish. The black bands become less discrete toward the distal part of the tail. The tarsi are feathered by rufous colored feathers, but the toes are left naked. Males and females both share this coloration, but colors on the female are seemingly less bold. Females also tend to be larger than males. ("Bird Life International", 2010; Herzog, et al., 2009; Weske and Terborgh, 1981)

  • Sexual Dimorphism
  • female larger
  • male more colorful
  • Average mass
    115 g
    4.05 oz
  • Range length
    20 to 23 cm
    7.87 to 9.06 in
  • Range wingspan
    151.5 to 164 mm
    5.96 to 6.46 in

Reproduction

This information is not yet known for cloud-forest screech owls.

Much of the breeding behavior of cloud-forest screech owls is unknown. The breeding season lasts from June to mid-August, but it is unknown how many broods are produced. Young cloud-forest screech owls reach sexual maturity at 1 year of age. (Weske and Terborgh, 1981; del Hoyo, et al., 1999)

  • Breeding interval
    The breeding interval for cloud-forest screech owls is unknown.
  • Breeding season
    Cloud-forest screech owls breed from June to mid-August.
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (male)
    1 years

Parental investment for cloud-forest screech owls is unknown. Like all owl species, it can be assumed that the young are born altricial, feather-less and with eyes closed. When young are born this defenseless, it can also be assumed that a large parental investment is required to incubate, protect, and care for the chicks.

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female

Lifespan/Longevity

Lifespan of cloud-forest screech owls has not been documented.

Behavior

Cloud-forest screech owls often do not fly from branch to branch, opting instead to climb and weave around the branches and epiphytes. Few observations have been made of the birds acting naturally, and their nocturnal habitats make it even more difficult to observe. Researchers often play audio recordings of cloud-forest screech owl calls to lure the birds in for observation. This method gives little reward, as the owls may take several hours to approach the source of the calls. They are skulking birds, and thus are very secretive and adept at remaining hidden in the thick rain forest canopies. (Herzog, et al., 2009)

Communication and Perception

Cloud-forest screech owls have a few different vocalizations. They produce a "longsong" consisting of incessant monotonic hoots, which begin hushed. The intensity then increases, and ceases suddenly or with a short reduction of intensity for the last couple of notes. Song times range from 2.4 to 9.5 seconds. The last half of the song is slower than the opening half. This owl also infrequently performs a trill-like song which is characteristically short with regular “ii” sounds. This lasts for 2 seconds, in which time, the owl produces up to 23 notes. Because of this species' wide range, songs of different regions have been found to differ slightly with Cordillera Yanachaga populations having a lower pitch than their Bolivian counterparts. Cloud-forest screech owls do respond to playbacks of recorded territorial calls, thus the birds must use calls to define their territory.

Other types of communication have not been studied at this point. Like all birds, cloud-forest screech owls perceive their environment through auditory, tactile, visual, and chemical stimuli. (Herzog, et al., 2009)

Food Habits

Cloud-forest screech owls are seemingly insectivorous, as many insect remains have been found in their pellets (feces). They most likely clamber around tree branches in search of arthropods and insects. (Weske and Terborgh, 1981)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods

Predation

There have been no observations regarding predation on the cloud-forest screech owl.

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

The specific roles of cloud-forest screech owls are not yet known, but they are most likely in conjunction with similar owls of the region including the rufescent screech owls (Megascops ingens), long-whiskered owlets (Xenoglaux loweryi) and rufous-banded owls (Ciccaba albitarsis). They likely impact the insect populations, and any additional dietary organisms, they consume. ("Endemic Species Distributions on the East Slope of the Andes in Peru and Bolivia", 2007)

Economic Importance for Humans: Positive

There are no reported positive economic effects of cloud-forest screech owls for humans.

Economic Importance for Humans: Negative

There are no reported negative economic effects of cloud-forest screech owls for humans.

Conservation Status

Cloud-forest screech owls are listed as 'Near Threatened' under IUCN Red List criteria due to their exceedingly small range, making it extremely vulnerable to dangers which may occur in the future. The owls are currently believed to be uncommon locally, but there are no concrete numbers on population size. Habitat loss due to deforestation is likely the largest danger, as rainforests are constantly being logged for fuel, agricultural fields, and urbanization. ("Bird Life International", 2010; del Hoyo, et al., 1999)

Contributors

Nikki Panos (author), Florida State University, Emily DuVal (editor), Florida State University, Rachelle Sterling (editor), Special Projects.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

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.

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.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

insectivore

An animal that eats mainly insects or spiders.

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).

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.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

sedentary

remains in the same area

sexual

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

tactile

uses touch to communicate

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.

visual

uses sight to communicate

References

2007. Endemic Species Distributions on the East Slope of the Andes in Peru and Bolivia. Arlington, Virginia, USA: NatureServe.

2010. "Bird Life International" (On-line). Cloud-forest Screech-owl Megascops marshalli. Accessed February 11, 2010 at http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid =2204&m=0#.

Herzog, S., S. Ewing, K. Evans, A. Maccormick, T. Valuqui, R. Bryce, M. Kessler, R. MacLeod. 2009. Vocalizations, Distribution, and Ecology of the Cloud-Forest Screech Owl (Megascops marshalli). The Wilson Journal of Ornithology, 121: 240-252.

Weske, J., J. Terborgh. 1981. Otus marshalli, A New Species of Screech-owl from Peru. The Auk, 98: 1-7.

del Hoyo, J., A. Elliot, J. Sargatal. 1999. Handbook of the Birds of the World. Vol. 5. Barn-owls to Hummingbirds. Barcelona: Lynx Edicions.

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