By George Beccaloni, March 2018
Wallace collected an impressive total of 212 new bird species during his collecting expeditions to Amazonia (1848-52) and the "Malay Archipelago" (1854-62) (Beccaloni, 2017). Given that around 10,000 bird species are currently recognised, this means that he was responsible for discovering about 2% of the entire World bird fauna. Of the new birds he discovered, he personally named 105 species, making him one of the most prolific describers of bird species after Linnaeus (Ernst Mayer, for example, 'only' named 26 species during his lifetime).
Birds were one of main focuses of Wallace's collecting. He wanted specimens for his private collection for personal study, and he sold his "duplicates" to collectors and museums in order to fund his collecting trips. Sadly for him and for science, many of his Amazonian specimens were destroyed when his ship caught fire and sank on his way back to England in 1852. Fortunately, however, most or all of the specimens he collected in South-East Asia survived the journey back. During his trip to the Malay Archipelago he collected 8050 bird specimens, keeping about 3,000 of them (representing about 1,000 species) for his private collection. Twenty-three of the new species and subspecies he collected were named after him by other taxonomists, including the one new Bird of Paradise he found - Semioptera wallacii (Wallace's Standardwing Bird of Paradise).
Paradisea (Semioptera) wallacii
Not only was Wallace (with the help of paid assistants) a prolific collector of birds, but he was the first Westerner to observe and document the spectacular mating displays (leks) of male Birds of Paradise. He was probably also the first European to eat them, but he didn't rate them very highly, saying that "The flesh…is dry, tasteless, and very tough—to be eaten only in necessity." (he often ate birds after skinning them because he was frequently short of food). Wallace's contributions to the study of Bird of Paradise behaviour were lauded by Daniel Giraud Elliot, who dedicated his important 1873 book A Monograph of the Paradiseidae to Wallace.
Wallace was able to identify the bird species he collected in Asia and Australasia using Charles Lucien Bonaparte's book Conspectus Generum Avium. Rather incredibly it contains only brief Latin descriptions of the birds and lacks any illustrations. Wallace obviously had a good knowledge of Latin and a remarkable grasp of the distinguishing characteristics of birds, since using the brief descriptions in this book he was able to visualize exactly what the species looked like. He later claimed that thanks to this book he “…could almost always identify every bird already described, and if I could not do so, was pretty sure that it was a new or undescribed species” (Wallace, 1905: 327).
It was Wallace's observations and knowledge of the geographical distribution of birds which led him to discover what is now called the Wallace Line. This is an invisible boundary that separates the zoogeographical regions of Asia (to the west of it) and Australasia (to the east). The line runs through the Lombok Strait between the islands of Bali and Lombok, then northwards up between Borneo and Sulawesi and beyond. The significance of the line is that it identifies a major (though not entirely abrupt) faunal discontinuity: many major groups found to the west of the line do not extend east of it, and vice versa.
Wallace discovered 'his' line in 1856 when he crossed from Bali to Lombok and found that the two islands, although within sight of one another, had very different bird faunas. In a letter to his agent Samuel Stevens in August 1856 he wrote:
"The Islands of Baly & Lombock…though of nearly the same size, of the same soil[,] aspect[,] elevation & climate and within sight of each other, yet differ considerably in their productions, and in fact belong to two quite distinct Zoological provinces, of which they form the extreme limits. As an instance I may mention the Cockatoos, a group of birds confined to Australia & the Moluccas, but quite unknown in Java[,] Borneo[,] Sumatra & Malacca. One species however…is abundant in Lombock, but is unknown in Baly, the island of Lombock forming the extreme western limit of its range & that of the whole family. Many other species illustrate the same fact..."
Wallace published his observations in a 1857 article, "On the natural history of the Aru Islands" and further refined them in his 1863 article “On the physical geography of the Malay Archipelago”.
Wallace published many other original observations on the behaviour of South-east Asian birds and was the first to describe visual mimicry in birds based on his observations in the Moluccas (Wallace, 1869). He suggested that orioles (Oriolus, Oriolidae) avoided attack by hawks by mimicking the aggressive friarbirds (Philemon, Meliphagidae). While he was still in the Malay Archipelago he produced an important early paper on bird evolution and classification, in which he used unrooted tree diagrams to show the evolutionary relationships of groups of birds (Wallace, 1856). Notably the distance between groups on his diagrams were intended to indicate the degree to which the groups were related.
One of the two evolutionary trees of bird families in Wallace's 1856 paper.
Beccaloni, G. W. 2017. Introduction. pp. xix-xliii. In: Wallace, A. R. The Malay Archipelago. UK: Folio Society. 665 pp.
Bonaparte, C. L. 1850-56. Conspectus Generum Avium. Part 1. May – November 1850, 543 pp. Part 2. October 1854 – May 1856, 232 pp. Leiden: E. J. Brill.
Wallace, A. R. 1856. Attempts at a natural arrangement of birds. Annals and Magazine of Natural History, 18 (2nd series): 193–216.
Wallace, A. R. 1857. On the Natural History of the Aru Islands. Annals and Magazine of Natural History, Supplement to vol. 20 (2nd series.): 473-485.
Wallace, A. R. 1863. On the physical geography of the Malay Archipelago. Journal of the Royal Geographical Society, 33: 217-234.
Wallace, A. R. 1869. The Malay Archipelago; The Land of the Orang-utan and the Bird of Paradise; A Narrative of Travel With Studies of Man and Nature. 2 vols. London: Macmillan & Co.
Wallace, A. R. 1905. My life. A Record of Events and Opinion. 2 vols. London: Chapman and Hall.