Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Strigiformes Strigidae

Scientific Name: Otus thilohoffmanni
Species Authority: Warakagoda & Rasmussen, 2004
Common Name(s):
English Serendib Scops-owl, Serendib Scops Owl
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Lynx Edicions BirdLife International.
Taxonomic Notes: Described as new to science by Warakagoda and Rasmussen (2004).
Identification information: 16.5 cm. A small, short-tailed scops-owl, lacking true ear-tufts. Quite uniformly rufescent, paler below, with small dark markings all over. Central belly and undertail coverts paler and unspotted. Weakly defined facial disk, and yellow to orange irides with a black outer ring. Iris more yellow in female. Tarsi feathered for less than half their length. Similar spp. In range, only the rufous morph of the Sri Lankan race of Oriental Scops-owl Otus sunia leggei, which is slightly larger, and has obvious ear-tufts, tarsi feathered to base of toes, and obvious whitish spots on scapulars. Voice Female gives a short, piping, tremulous pU'U'u, rising and falling in pitch. Male gives a lower pitched, shorter, less tremulous version. Vocalisations most common in the hours just after dusk and just before dawn.

Assessment Information [top]

Red List Category & Criteria: Endangered B1ab(ii,iii,v); C2a(i); D ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Kaluthota, C., Sirivardana, U. & de Silva Wijeyeratne, G.
Facilitator/Compiler(s): Bird, J., Pilgrim, J. & Taylor, J.
This species is listed as Endangered because it has a very small range and correspondingly small population, both of which are undergoing a decline owing to habitat loss and degradation.

Previously published Red List assessments:
2008 Endangered (EN)
2006 Endangered (EN)
2004 Not Recognized (NR)
2000 Not Recognized (NR)
1994 Not Recognized (NR)
1988 Not Recognized (NR)

Geographic Range [top]

Range Description: Otus thilohoffmanni is endemic to the wet zone of Sri Lanka, where it is known only from Kitugala, Sinharaja, Morapitiya-Runakanda, Kanneliya and Eratna-Gilimale, despite investigation of c.75% of suitable habitat (Warakagoda and Rasmussen 2004, U. Sirivardana in litt. 2006). It escaped detection until 1995 due to its unobtrusive and rather ventriloquial call. Fewer than 100 individuals have now been located in the five known sites (U. Sirivardana in litt. 2006), but it is likely that others remain undetected (Warakagoda and Rasmussen 2004), and it may well occur at additional sites in the wet zone rainforests. On present knowledge the global population is believed to number c.200-250 individuals (Warakagoda 2006), although given its elusive nature the true figure may be somewhat higher.

Countries occurrence:
Sri Lanka
Continuing decline in area of occupancy (AOO): Yes
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 240
Continuing decline in extent of occurrence (EOO): Unknown
Extreme fluctuations in extent of occurrence (EOO): No
Number of Locations: 5
Continuing decline in number of locations: Unknown
Extreme fluctuations in the number of locations: No
Lower elevation limit (metres): 30
Upper elevation limit (metres): 530
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Extensive surveys have located 100 individuals and led to a global population estimate of 200-250 individuals. However, given the species's elusive nature and its ability to remain undiscovered for so long the true population size is likely to be somewhat higher. Therefore, it is probably best placed in the band 250-999 individuals. This equates to 167-666 mature individuals, rounded to 150-700 mature individuals here.

Trend Justification:  The species appears to be intolerant of habitat loss and severe fragmentation, and so is suspected to be declining as the very few remaining unprotected areas of forest are slowly lost. The likely rate of population decline has not been estimated.
Current Population Trend: Decreasing
Additional data:
Number of mature individuals: 150-700 Continuing decline of mature individuals: Yes
Extreme fluctuations: No Population severely fragmented: Yes
No. of subpopulations: 2-100 Continuing decline in subpopulations: Unknown
Extreme fluctuations in subpopulations: No All individuals in one subpopulation: No
No. of individuals in largest subpopulation: 1-89

Habitat and Ecology [top]

Habitat and Ecology: It occurs in larger areas of lowland rainforest, at 30-530 m altitude (Warakagoda and Rasmussen 2004). It appears to be generally rare, but locally common (Warakagoda and Rasmussen 2004), and pairs occupy large territories (U. Sirivardana in litt. 2006). All locations where the bird has been found so far have been disturbed areas with tall, dense secondary growth (Warakagoda and Rasmussen 2004). For the two hours after dark, it hunts for prey in the undergrowth, later foraging higher; between the undergrowth and subcanopy (Warakagoda and Rasmussen 2004). During the day it roosts 1-2.5 m above the ground, sometimes in pairs within a territory and it will adopt a cryptic posture mimicking wood when threatened (Warakagoda and Rasmussen 2004, Warakagoda 2006). The breeding behaviour of this species is not yet known.

Systems: Terrestrial
Continuing decline in area, extent and/or quality of habitat: Yes
Generation Length (years): 3.7
Movement patterns: Not a Migrant

Threats [top]

Major Threat(s): It has not been found in forest patches smaller than 8.2 km2 in extent, indicating that it is sensitive to habitat loss and fragmentation, which has been severe in Sri Lanka (Warakagoda and Rasmussen 2004). Habitat loss is still continuing owing to pressure from settlement, encroachment on protected forests from subsistence logging and small-scale mining operations.

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
All five known sites are protected as Forest Reserves or Proposed Reserves, administered by the Forestry Department (Warakagoda and Rasmussen 2004).

Conservation Actions Proposed
Complete surveys for this species in other wet zone forests (Warakagoda and Rasmussen 2004), and smaller patches (C. Kaluthota in litt. 2005). Protect any other sites where it is found. Continue research into the ecology of, and threats to, this species. Estimate its population size.

Citation: BirdLife International. 2012. Otus thilohoffmanni. The IUCN Red List of Threatened Species 2012: e.T22732040A38010618. . Downloaded on 08 October 2015.
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