Birds from Mt. Benom, Pahang, the Kledang Hills, Perak, and the islands of Penang, Tioman and Aor. F.N. Chasen and C.B. Kloss. Records of the Raffles Museum, No. 34
F. N. Chasen and C. Boden Kloss published this ornithological list in 1928 as Record No. 34 of the Raffles Museum, reporting bird specimens collected from five localities across the Malay Peninsula: Mt. Benom (Pahang), the Kledang Hills (Perak), Penang Island, and the offshore islands of Tioman and Aor. The paper documents the first systematic avifaunal surveys of several of these sites and identifies insular differentiation in several species on the Tioman Archipelago.
Summary
The paper addresses a persistent gap in the ornithological knowledge of the Malay Peninsula: the absence of reliable species lists for highland and insular localities. Mt. Benom, at 6,916 feet, had never before yielded birds from its higher elevations; Evans’s March 1923 ascent produced twenty species whose composition closely parallels those recorded at comparable altitudes on Mt. Tahan and the Main Range, confirming the ecological continuity of the western Pahang highlands (p. 70). The Kledang Hills, at roughly 2,600 feet, had never been examined for birds before Seimund’s December 1927 visit, and the authors note the complete absence of true mountain species, with the resident avifauna being entirely normal for lowland Perak (p. 70).
Penang Island, rising to 2,700 feet, had previously been documented only from its lowlands; Chasen’s summit collections in December 1927 revealed nothing unexpected, the notable species being common winter visitors such as the thrush, warblers, and shrike (p. 70). The most ornithologically significant material comes from Tioman and Aor, where the authors confirm the existence of well-marked insular races—Stachyris tionis, a differentiated Orthotomus, and a large Treron vernans allied to the Anamba Islands form adina—and demonstrate that several species on the Tioman group cannot be separated from those of the southern peninsula, Singapore, and the Anambas (pp. 74–75).
The paper thus functions as a baseline faunal inventory, establishing which localities harbour insular differentiation and which are ecologically unremarkable, while simultaneously anchoring the biogeographic affinity between the Tioman Archipelago and the Anamba Islands across the Strait of Johore.
Key Findings
- Mt. Benom (6,916 ft) yielded 20 species from its upper levels in March 1923, the first such records from the mountain; the assemblage matches that of Mt. Tahan and the Main Range at equivalent altitudes (p. 70).
- The Kledang Hills (~2,600 ft) contain no true mountain birds; the only migrants beyond usual warblers and king crow were Delichon urbica dasypus (second mainland record) and Cyornis rubeculoides anak, suspected to be the winter form of glaucicomans (pp. 70, 72).
- Treron vernans from Tioman (wing 160 mm, male) is assigned to the Anamba Islands race adina, indicating a shared insular lineage across the strait (p. 74).
- Stachyris nigiceps tionis (wing ♂ 63 mm, ♀ 58 mm) is confirmed as a well-marked insular race of Tioman, with two additional specimens corroborating the original 1927 diagnosis (p. 74).
- Gracula javana prasiocara from Tioman averages large (wings 186–192 mm), matching the Anamba Islands population, while Dissemurus paradiseus platurus from Tioman and Aor cannot be separated from birds of the southern peninsula, Singapore, and the Anambas (p. 75).
- Orthotomus atrigularis major from Tioman (wing ♂ 48–49 mm) is allied to the Anamba Islands race, reinforcing the pattern of insular differentiation in the tailors (p. 75).
Conclusion
Chasen and Kloss establish that the Tioman Archipelago supports a distinct insular avifauna with multiple differentiated races, most closely aligned with the Anamba Islands rather than the mainland, while the highland sites of Mt. Benom and the Kledang Hills prove ecologically unexceptional. The paper’s lasting value lies in fixing the biogeographic boundary of insular differentiation in the southern peninsula and providing the first reliable species lists for localities that had previously been undocumented.
Context
- The paper draws on specimens held in the Raffles Museum (Singapore) and the F.M.S. Museums, representing the standard institutional collections of the Straits Settlements and Federated Malay States at the time.
- Historiographically, the paper is a typical product of the early-twentieth-century “Records of the Raffles Museum” series, which served as the primary vehicle for publishing new species and subspecies from the region before the establishment of more formal taxonomic journals.