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the weighs twice as much as its suspected that it would be 101 years be- Martim captured another three individu- closest relative, further emphasising the fore it was rediscovered in August 1991 als near where Sinclair and Sargeant re- the world’s extent of its gigantism. by a group of birdwatchers that included discovered the . The two sister species apparently di- Dave Sargeant and Ian Sinclair. During the past decade an increas- verged within the past million years, ing number of visits by birdwatchers the grosbeak weighs when São Tomé was experiencing signifi- have led to additional sightings, almost cant volcanic activity. The evolution of twice as much as its all in the same areas where the captures largest the grosbeak’s extreme phenotype in such closest relative, further were made. Concerted survey efforts, a relatively short time span suggests that emphasising the extent of led by Ricardo Lima and BirdLife Inter- strong natural selection drove the mor- its gigantism national, have resulted in a better un- phological divergence of the two species, derstanding of the species’ distribution canary presumably to allow their co-existence by The fact that two of the three specimens on the island (https://doi.org/10.1017/ targeting different food items, and hence collected by Newton were lost in the 1978 S0959270916000241). SÃO TOMÉ GROSBEAK reduce interspecific competition. Selec- fire that destroyed the Natural History The grosbeak is without doubt the most tion appears to have been most marked Museum in Lisbon served to deepen the difficult-to-observe on São Tomé and on the proto-grosbeak population, as the aura of mystery surrounding this spe- although it is clear that it depends on pri- seedeaters on São Tomé differ little from cies, long thought to be extinct and now mary forest, no clear pattern of habitat those found on Príncipe and Boné de classified as Critically Endangered. Apart preference has emerged. The limited ge- Jóquei where there is no grosbeak. from two unconfirmed records in 1997, netic data has shown surprisingly high lev- several individuals were confidently ob- els of variation for such a rare species. This he São Tomé Grosbeak was dis- served again (and photographed) only information, together with the unpredict- covered in 1888, when the Portu- in January 2002 by Martin Dallimer and able location of sightings, gives hope that it guese naturalist Francisco Newton colleagues, close to the area of its redis- might just be a very difficult species to ob- Tcollected a male in the forests of south- covery. In December 2002, Martim Melo serve, perhaps a canopy specialist that only eastern São Tomé; in 1890, he collected discovered a new area, probably close to occasionally comes down to delight us. another two males in the south-western the first place of capture by Newton, and MARTIM MELO, Research Center in forests. Newton reported the species to in January 2003 caught one individual Biodiversity and Genetic Resources, be extremely rare, but he probably never there. In February 2005 and July 2011, University of Porto Alexandre Vaz

above São Tomé Grosbeak being ringed by Martim Melo.

left A large with a massive, parrot-like bill, the São Tomé Grosbeak is classified as Critically Endangered. Precision in all areas. Martim Melo MINOX - he São Tomé Grosbeak Neospiza the link to Amblyospiza in 1962. Genetic species, the Thick-billed Seedeater Crith­ concolor is a contender for being material was needed to confidently clari- agra burtoni. In this it joins other São Tomé Powerful binoculars All-round binoculars with Superior optics one of the most enigmatic bird fy the origins of Neospiza, but that is hard giant endemics like the Giant Sunbird Tspecies on the planet. This Critically En- to come by for a bird that was not seen Dreptes thomensis and the Giant Weaver for the outdoors. open bridge design. “Made in Germany”. dangered species is one of the rarest – or for close to a century. However, during Ploceus grandis (the largest sunbird and MINOX BF-Line MINOX BV-Line MINOX BL HD-Line least observed – in the world, and his research on the origins of the endem- Ploceus weaver in the world), and the its peculiar morphology resulted in it be- ic avifauna of the Gulf of Guinea, Martim Black-capped Speirops Zosterops lugubris ing placed in its own of uncertain Melo captured and bled four individuals and the São Tomé Thrush Turdus oliva­ x44 affinities. between 2003 and 2011. These four sam- ceofuscus, which are the largest representa- BV 8 R 5980 Based on the shape of its head and on ples provided sufficient material to infer tives of their families in Africa. SRP x33 HD its massive bill, the São Tomé Grosbeak the species’ evolutionary history. Of particular interest was the discovery BL 8 was originally placed with the Thick- In a recent paper published in Ibis that the grosbeak shares the São Tomé x42 BF 10 R 8650 billed Weaver Amblyospiza albifrons. In (http://dx.doi.org/10.1111/ibi.12466), forests with a population of its closest SRP R 3450 1903, other traits were used to place it mitochondrial and nuclear sequences living relative, the Príncipe Seedeater SRP in the true (Fringillidae), related confidently identified Neospiza concolor C. rufobrunnea. The seedeater also has to canaries and seedeaters ( sensu as an Old World finch (Fringillidae: Car- populations on the neighbouring island lato). This is the current taxonomic view, duelinae) within the Crithagra seedeater/ of Príncipe and on Boné de Jóquei, an but debate persisted throughout the 20th canary clade. This makes the São Tomé islet two kilometres off the coast of São century about the true relationships of Grosbeak the world’s largest canary, 50 Tomé. The Príncipe Seedeater is the the species, with Ernest Moreau retaining per cent heavier than the next largest fourth largest canary in the world, but L&O Group South Africa Tel: +27 (12) 819 7800/11 | Email: [email protected]

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