Presumably they took lots of other specimens. This bird is probably the one that is the strongest rationale for collection, because it is a virtually unknown species with no males in collections and its collection does not appear based on the data presented to endanger populations. A lot could be done with this specimen in comparing it to related species, confirming it is actually the male related to the females in collections through molecular work, and preventing other collections in that people know there is now a male available which they could compare photographs to, as well as more detailed studies into feather, bill and skeletal morphology which are not possible in the field. Are people not more concerned about the somewhat tasteless press piece by AMNH, which does not mention that the lovely bird in the photo was then promptly asphixiated?
If you want to point to difficult-to-justify instances of collecting new species, then this one, where 17 specimens including 3 fledglings were collected, looks a questionable one in terms of numbers. This being of a "new species" already known in collections from at least 35 specimens cited in a previous paper whose existence was played down through non-designation of those 35 other specimens as paratypes.
http://www.museum.lsu.edu/cuervo/pubs_files/Scytalopus.perijanus_Auk.2015.pdf . In our more recently inked paper on S. griseicollis subspecies it was actually really useful to have juvenile specimens, as they show plumage differences (which can only really be studied well in Scytalopus with specimens), so that aspect is less bothering to me than the very large number of new adult specimens, when 1 or 2 to link the sound recordings to a specimen and compare to the other 35 that exist is probably all that would be necessary.
Or the guys from a U.S. museum who a couple of years ago "allegedly" obliterated pretty much every bird in a nature reserve in Peru with guns and nets, including Tinamous and Antpittas who had been trained to come to feeders, undoing years of hard conservation and ecotourism promotional work.
Having the collecting discussion focused on new and poorly known species, or specimens from regions lacking material where new specimens are often critical to taxonomic studies, is probably the wrong discussion. Such collecting is pretty easy to justify unless you take the view that no specimens should ever be taken on moral grounds. That is a valid position if you are a vegetarian (like me), but I don't subscribe to it. Think of all the fish that were saved by collecting this Kingfisher. Or think of the junvenile coots who would not be subject to infanticide if you collected their mother. The wild world of animals is not always an entirely moral one either... Unfortunately the world seems to fall into a "kill 'em all, make bigger the collections, they are useful [and who are you to say on morals]" or "you have no right" camp. Probably the right answer is somewhere in the middle.
