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REDISCOVERY
Rediscovery of Dusky Eagle Owl Bubo coromandus klossii in Thailand INGKAYUT SA-AR, JARUN KUNNARONG & BUNYARIT DECHOCHAI
Plate 1. Dusky Eagle Owl Bubo coromandus klossii perched in a Shorea roxburghii, Thale Ban NP, Satun, Thailand, 28 April 2015.
Plate 2. Dusky Eagle Owl, pale individual, Thale Ban NP, 28 April 2015.
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TETSUYA YOSHIKAWA
Rediscovery On 12 April 2015, after setting up camera traps for a Great Argus Argusianus argus study project at Thung Ya Wang Pra, Thale Ban National Park, Satun province (6.683°N 100.150°E), BD was walking along forest edge by an open field. Three large owls were flushed from a bush; two of them flew deep into the woods but the third bird perched on a tree about 10 m from the ground, although too far away to obtain images. About two weeks later, on 28 April, Vichai Chantawaro and Tetsuya Yoshikawa joined BD in a search for the mystery owls. As they approached the area where the birds were first seen, they saw two large owls perched on a Shorea roxburghii tree and managed to obtain images (Plate 1). The birds were identified as Dusky Eagle Owls, the first record in Thailand for 99 years. On 3 May, IS and others went to collect more data and found two birds. At dusk on 14 May, P. D. Round made sound
TETSUYA YOSHIKAWA
Introduction The Dusky Eagle Owl Bubo coromandus is a large owl, length between 54–58 cm, greyish-brown in colour, with darker upperparts, a dark greyishbrown facial disc, a streaked breast and dark brown wingtips. It has prominent ear-tufts, yellow eyes and a greenish-grey bill. It resembles the Brown Fish Owl Ketupa zeylonensis in general appearance, but has feathered tarsi. Juveniles are creamywhitish with faint darker markings (Robson 2008). Two subspecies are described: B. c. coromandus occurs in much of South Asia, whilst the subspecies klossii (del Hoyo et al. 1999) ranges from southern Myanmar and south-west Thailand to Perak and Melaka in Malaysia (Wells 1999). Information from Thailand is scant, with only three specimens from two localities. A male was collected at Khlong Bang Lai, Chumphon province, in December 1915 (Baker 1920), while a male and female were collected in Prachuap Khiri Khan province in 1916 (Kloss 1918).
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Rediscovery of Dusky Eagle Owl Bubo coromandus klossii in Thailand
BENCHAPOL LORSUNYALUCK
When the images were examined, the two Dusky Eagle Owls were found to be noticeably different in appearance. The first bird (Plate 2) was larger, with more greyish-brown tones and paler underparts. The second bird (Plate 3) was smaller, and its facial disc, belly and upperparts were slightly darker. These differences are thought to be due to sexual dimorphism; in many species of large owls, females tend to be larger (Lynch 2007). In some eagle owl species, such as Barred Eagle Owl B. sumatranus, the size difference between males and females is noticeable: females are estimated to be 15% larger (Foley et al. 2013). The rediscovery was made at the edge of evergreen forest adjacent to an open, seasonally flooded grassland with scattered large trees, predominantly Shorea roxburghii and Syzygium species (Plate 4), at about 160 m, close to a forested hilly ridge.
Plate 3. Dusky Eagle Owl, dark individual, Thale Ban NP, 3 May 2015.
recordings of the pair duetting before they left their daytime roost at dusk; these were deposited with the Avian Vocalizations Center, Michigan State University (http://avocet.zoology.msu.edu/). At the same time a video recording was made by Yotin Meekaeo.
Conservation status The seasonal status of Dusky Eagle Owl in Thailand has long been regarded as uncertain; there are no nesting records (Lekagul & Round 1991). However, the pair in Thale Ban National Park is assumed to be resident since no seasonal movements have been reported elsewhere, and its status as a resident in Peninsular Malaysia was recently confirmed—in January 2011, a pair of Dusky Eagle Owls was reported using an old Wallace’s Hawk Eagle Nisaetus nanus nest in Bukit Wang Forest Reserve, Kedah state (Robson 2011). The Dusky Eagle Owl is considered to be of Least Concern (BirdLife International 2015). However, in Thailand, Sanguansombat (2005) categorised klossii as
INGKAYUT SA-AR
Plate 4. The habitat in which the Dusky Eagle Owls were discovered: lowland evergreen forest edge adjacent to seasonally flooded open fields with scattered large trees, predominantly Shorea roxburghii and Syzygium species.
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Critically Endangered, whilst Wells (1999) reported no more than four skins in Malaysia, all of which were collected from Melaka and Perak in the midnineteenth century. However, recently, Dusky Eagle Owls have been recorded in Selangor, Perak and Kedah—two of these sites were degraded lowland peatswamp bordering wetland areas (D. Bakewell pers. comm.), somewhat similar to the habitat at Thung Ya Wang Pra. The association of this species with wetlands or well-watered lowlands prevails throughout its range (del Hoyo et al. 1999, König & Weick 2008, D. Wells in litt.). The spread of records in Peninsular Thailand, from about 12°N to the Malaysian border, suggests there may be undiscovered populations in the intervening areas. However, given the species’s preference for flat lowlands, much of which has been converted to rubber and oil palm, few suitable sites now remain, so that any surviving populations of Dusky Eagle Owl in the Thai-Malay Peninsula are almost certainly small and fragmented due to habitat loss and degradation. There is little information on the population of klossii in Myanmar and assessment of its status throughout its range might yet result in a reclassification by BirdLife International. It is perhaps also threatened by the illegal wildlife trade, as is the case with many species of raptors and owls in the region.
Robson, C. (2008) A field guide to the birds of South-East Asia. London: New Holland. Robson, C. (2011) From the field. BirdingASIA 16: 117–119. Sanguansombat, W. (2005) Thailand red data birds. Bangkok: Office of Natural Resource and Environmental Policy and Planning, Thailand. Wells, D. R. (1999) The birds of the Thai-Malay peninsula, 1: London: Academic Press.
Ingkayut SA-AR Bird Conservation Society of Thailand 221 Mu 2, Soi Ngamwongwan 27 Ngamwongwan Road Bangkhen, Muang Nonthaburi 11000, Thailand Email:
[email protected] Jarun KUNNARONG & Bunyarit DECHOCHAI Thale Ban National Park, T. Wang Prachan A. Khuan Don, Satun 91160, Thailand
Acknowledgements Thanks go to Phil Round, David Wells, David Bakewell, Wichchayanan Limparungpattanakij and Utain Pummarin for comments and improvements to the original manuscript. We are most grateful to Benchapol Lorsunyaluck and Tetsuya Yoshikawa for their images, and to Vattikorn Sophonrat, Vichai Chantawaro, Chan Tosinthiti and Khemthong Tonsakulrungrueng for their help. References Baker, E. C. S. (1920) Notes on a collection of bird-skins formed by Mr. E. G. Herbert (part 3). Nat. Hist. Bull. Siam Soc. 4: 25–43. BirdLife International (2015) Species factsheet: Bubo coromandus. Downloaded from http://www.birdlife.org on 10/05/2015. Foley, C., Thor L. W., Sheng L. J. & Hui T. K. (2013) Breeding Barred Eagle Owl Bubo sumatranus in Johor, Malaysia. BirdingASIA 19: 34–37. del Hoyo, J., Elliott, A. & Sargatal, J. (1999) Handbook of the birds of the world, 5. Barcelona: Lynx Edicions. Kloss, C. B. (1918) On birds recently collected in Siam. Part 1. PhasianidaeEurylaimaidae. Ibis 60: 76–114. König, C. & Weick, F. (2008) Owls of the world. London: Christopher Helm. Lekagul, B. & Round, P. D. (1991) A guide to the birds of Thailand. Bangkok: Saha Karn Bhaet. Lynch, W. (2007) Owls of United States and Canada. Baltimore, Maryland: Johns Hopkins University Press.
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