On a collection of birds from N.E
Robinson and Kloss (1919) present a detailed taxonomic account of a large bird collection assembled by the Dutch planter Heer A. C. F. A. van Heyst across the Deli, Serdang, Simeloengan, and Langkat districts of N.E. Sumatra, spanning altitudes from sea level to 1,390 m on the Karo Plateau. The paper describes 242 species, erects four new taxa, and records four species for the first time from Sumatra, while systematically comparing the N.E. Sumatran populations with those of the Malay Peninsula, Borneo, and Java.
Summary
The collection was gathered over approximately two years (1916–1918) at fourteen localities ranging from coastal mangrove at Laboean to the montane forest of the Sibajak Mountains near Brastagi. Van Heyst’s own locality descriptions, reproduced in full, provide valuable ecological context for each site, noting the interplay of tobacco estates, rubber plantations, secondary jungle, lalang grassland, and primaeval forest that characterised the Deli landscape under colonial cultivation. The authors’ primary task was subspecific determination: for each species they compared the N.E. Sumatran specimens with series from the Malay Peninsula (held in the Federated Malay States Museums), Borneo (Sarawak Museum), and Java, assigning them to existing races or proposing new ones where warranted.
The taxonomic work is framed by a broader argument about the distinctness of Sumatran avifaunal populations. Robinson and Kloss repeatedly challenge the view that apparent differences between Javan, Bornean, Sumatran, and Malayan birds are merely age-related variation, as had been asserted by Stuart Baker for the red-headed fruit dove. Their examination of over seventy specimens of Macropygia ruficeps from multiple localities led them to recognise four subspecifically distinct forms. Similarly, their work on the grey drongo Buchanga leucophaea and the woodpecker Brachylophus chlorolophus demonstrates careful attention to plumage detail, size, and bill morphology in distinguishing populations that previous authors had lumped together.
The paper also serves as a corrective to earlier literature. Robinson and Kloss explicitly identify errors in Hartert’s 1902 list for the region, challenge Oberholser’s subspecific splits in several groups (kingfishers, nighthawks, swifts), and note that Pycnonotus aurigaster, which they initially reported as new to Sumatra, had in fact been recorded by Parrot from a Martin specimen of 1894. An addendum also concedes that their name Bhringa remifer attenuata for the Malayan drongo had been antedated by Stuart Baker’s B. r. peracensis (1918).
Key Findings
- Four new taxa are erected: Macropygia ruficeps sumatranus (subsp. nov., type from Gunong Talaman, W. Sumatra, 1,300 m), Brachylophus chlorolophus vanheysti (subsp. nov., types from Bandar Baroe and Gunong Talaman), Cyornis vanheysti (sp. nov., type an adult male from Toentoengan, Deli, 10 February 1918, wing 78 mm), and Buchanga leucophaea batakensis (subsp. nov., types from Bandar Baroe, 10 October 1917) (pp. 73, 77–78, 97, 104, 125).
- Four species are recorded for the first time from Sumatra: Collocalia linchi cyanoptila, Collocalia innominata, Geocichla citrina citrina, and Machaeramphus alcinus (the latter a crepuscular barn owl feeding largely on bats, collected at Helvetia estate, wing 375 mm) (pp. 73, 82, 90, 119).
- The collection comprises specimens from 14 localities at elevations ranging from 0 m (Laboean coastal mangrove) to 1,390 m (Brastagi, Karo Plateau), with the Deli Toewa and Toentoengan estates (150–200 m) and Bandar Baroe (860 m) yielding the greatest diversity of montane and lowland species respectively (pp. 73–74).
- Cyornis vanheysti is described as a heavy-billed form with the adult male entirely deep indigo-blue above and sapphire-blue on the breast, the immature male ferruginous with dusky wing coverts; it is noted as possibly referable to C. ruecki Oustalet (1881) from Kessang, Malacca, known only from types in Paris (p. 104).
- The authors demonstrate that Macropygia ruficeps populations from Java, Borneo, Sumatra, and the Malay Peninsula are all subspecifically distinct, rejecting Stuart Baker’s 1913 claim that observed differences were merely those of age; the Sumatran form differs from the Bornean in having a paler cinnamon-buff head, more barred back, reduced amethystine gloss, and more pronounced black breast markings (pp. 77–78).
- Pycnonotus aurigaster, initially reported as new to Sumatra, is confirmed in the addendum to have been previously recorded by Parrot (1907) from a Martin specimen collected in 1894, and the two van Heyst skins prove identical to freshly collected Javan specimens in both size and colour (p. 133).
Conclusion
The paper establishes that the N.E. Sumatran avifauna, while broadly overlapping with that of the Malay Peninsula, contains a significant number of subspecifically distinct forms that had been overlooked or misassigned in earlier literature. Robinson and Kloss’ systematic comparison of large series from multiple islands provides the empirical foundation for recognising Sumatra as a distinct biogeographic unit in several taxonomic groups, and their four new taxa—particularly the entirely new species Cyornis vanheysti—represent meaningful additions to the known diversity of the region.
Context
- The collection was assembled by a Dutch colonial planter (van Heyst) working in the Deli tobacco and rubber district; the locality descriptions reflect the landscape as transformed by colonial plantation agriculture, with primaeval forest surviving mainly on estate boundaries and in higher ground.
- The authors draw on the Federated Malay States Museums (Kuala Lumpur) and the Sarawak Museum for comparative material, and their 1918 paper on the avifauna of Korinchi (Journ. Fed. Malay Museums, vol. VIII, part II) is cited throughout as a companion study providing more detailed synonymy for the same region.