The enigmatic São Tomé grosbeak is a giant seedeater

We have finally published the first piece of the puzzle about the critically endangered São Tomé grosbeak Neospiza concolor in the ornithological journal Ibis. So what is special about the São Tomé grosbeak? Pretty much everything:

  • It is among the rarest species on Earth
  • It was not seen for over 100 years
  • Taxonomists have fought about what kind of bird it really is

In 1888, the Portuguese naturalist Francisco Newton collected a specimen of an unknown bird species on São Tomé. Two years later, he found another two specimens, and with its large size and massive bill it was originally described as a weaver (family Ploceidae). However, not everyone agreed, and there was an argument about whether it was really a weaver or a finch (family Fringillidae). Eventually, most authorities agreed that it was probably a finch, but its affinities were unclear and it was rewarded its own genus, Neospiza – the new finch.

São Tomé grosbeak. Photo (c) August Thomasson.

A rare sighting! This female São Tomé grosbeak (Neospiza concolor) was photographed during our field work on São Tomé, in July 2011. Photo (c): August Thomasson (

The type specimen is held at the Natural History Museum ornithology collections in Tring, whereas the two others were destroyed in a fire in 1978 at the National Museum of Natural History in Lisbon. After Newton’s initial collections, the São Tomé grosbeak was not sighted again for over 100 years, until it was found by Dave Sergeant three other birders in 1991! Even after its rediscovery, sightings remain very scarce. Until recently, the official population size estimate has been less than 50 individuals, but recent censusing efforts by Ricardo de Lima and colleagues suggest that it might not be just that bad. Continue reading