Southeastern Asia

Mr. Arthur S. Vernay, a Trustee of the AMNH, sponsored several zoological expeditions to northern Burma (Chindwin region) during the period 1932-1936, with Maj orJ. K. Stanfordinchargeofbirdcollecting. E. Mayr, whowas askedtostudy the collectionsgiven to theAMNH publishedthe resultsin The Ibis of 1938 and 1940-41 (with J. K. Stanford supplying field notes). Several British ornithologists had been rather unhappy that an inexperienced American colleague who had never done any work in this region should study this important collection. However, eventually they admitted that they themselves could not have done a better job.

An interesting example of discontinuous geographic variation of alternative plumage colors (white, gray, black) is presented by the Black Bulbul (Hypsipetes madagascariensis). The populations are fairly uniform, where they are isolated on high mountains (Fig. 4.9). However, hybrid populations develop where several of these forms come in contact with one another, which occurs from northeastern Burma into China south of the Yangtze River (Mayr 1941n, 1942e: 83-84).

Mayr's real triumph of working up the Burma collection provided the colorful minivets (Pericrocotus) (Fig. 4.10). Two exceedingly similar species were always confounded under the name P. brevirostris until Mayr (1940e) discovered a sibling species mixed in with the series of brevirostris. A name (ethologus) was already available for the newcomer. The two species co-exist over a wide range from Sikkim eastward. At first Mayr's finding was doubted by Ticehurst, Whistler, Kinnaer,

Fig. 4.9. Black Bulbul (Hypsipetes madagascariensis). Discontinuous geographical variation of alternative plumage characters in populations of northeastern Burma (Myanmar) and southwestern China. Rather uniform (stabilized) hybrid populations (3-5) inhabit isolated mountains between the ranges of four well-differentiated geographical subspecies (1 leucocephalus in S and SE China, 2 leucothorax, 6 concolor, 7 nigrescens, 8 psaroides); hybrid populations: 3 stresemanni, 4 sinensis, 5 ambiens). Plumage characters: Blank-white, shaded-gray, solid-black. Sketches of birds by R.T. Peterson. From Mayr (1941n, 1942e: 83)

Fig. 4.9. Black Bulbul (Hypsipetes madagascariensis). Discontinuous geographical variation of alternative plumage characters in populations of northeastern Burma (Myanmar) and southwestern China. Rather uniform (stabilized) hybrid populations (3-5) inhabit isolated mountains between the ranges of four well-differentiated geographical subspecies (1 leucocephalus in S and SE China, 2 leucothorax, 6 concolor, 7 nigrescens, 8 psaroides); hybrid populations: 3 stresemanni, 4 sinensis, 5 ambiens). Plumage characters: Blank-white, shaded-gray, solid-black. Sketches of birds by R.T. Peterson. From Mayr (1941n, 1942e: 83)

and Baker, the experts on the birds of this region, but eventually they accepted it. E. Stresemann in Berlin was working on a collection of birds from Sikkim obtained by Ernst Schäfer in 1938-1939, when he received the letter from Mayr (dated 23 May 1940) describing his two sibling species of minivets. Stresemann had already determined Schäfer's specimens of Pericrocotus as belonging to one species (P brevirostris) only and answered:

Fig. 4.10. Two sibling species of cuckooshrikes (Campephagidae), the Long-tailed Minivet (Pericrocotus ethologus, left) and the Short-billed Minivet (P. brevirostris, right) which are sympatric over a wide range from the Himalayas to western Yunnan. Ernst Mayr (1940e) discovered their distinctness as species. Illustrations of adult males from MacKinnon and Phillipps (2000)

Fig. 4.10. Two sibling species of cuckooshrikes (Campephagidae), the Long-tailed Minivet (Pericrocotus ethologus, left) and the Short-billed Minivet (P. brevirostris, right) which are sympatric over a wide range from the Himalayas to western Yunnan. Ernst Mayr (1940e) discovered their distinctness as species. Illustrations of adult males from MacKinnon and Phillipps (2000)

"Your data convinced me that I hadn't noticed anything, which should not have happened! You are a tremendous fellow and have picked unfading laurel with this discovery. I could kick myself to have slept right through. The matter is crystal clear once it is understood. Schäfer collected in Sikkim 27 brevirostris and eight ethologus [...], ethologus breeds at 2,750 m, brevirostris in the subtropical zone, between 560 and 1,900 m" (19 June 1940; transl.; see Haffer 1997b: 517 and Stresemann, Ornithologische Monatsberichte 49 (1941): 9-10, footnote).

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