When biologists at the Wildlife Conservation Society in the Bronx heard last fall that a beaver was making New York City home for the first time in 200 years, they were understandably excited. Unlike some other biologists, however -- say, those who said they had seen an ivory-billed woodpecker in 2005 -- the Bronx group made sure they caught Jose the beaver, on a video everyone could agree was actually a beaver, before announcing it to the press last week. (See Jose here .)

Video of another claimed 'first' last week was a bit more controversial. Iowa State's Jill Pruetz and the University of Cambridge's Paco Bertolani reported in Current Biology that they had documented ''the first account of habitual tool use during vertebrate hunting by nonhumans.'' Specifically, they report observing chimpanzees in Senegal making and using wooden spears to hunt bushbabies in tree hollows. The find was the talk of the blogosophere, with several bloggers using it as an opportunity to boost evolution.

Pruetz and Bertolani did videotape the end of one such hunt -- you can see the videos here -- but the BBC reported that they ''did not photograph the behaviour, or capture it on film.'' That puzzled me, so I asked Pruetz to clarify by Email this weekend. ''There are a number of errors in the popular press about the article...so it does look like BBC got it wrong - sort of,'' she said. She went on to suggest that they may have been referring to the fact that one video only catches the end of the behavior, while two others catch the huntress and then a male eating the bushbaby. She referred me to National Geographic's website, which she said had done a good job editing it. (National Geographic will be featuring her work as part of an upcoming NOVA/National Geographic special on PBS.)

At National Geographic, I read comments by USC anthropologist Craig Stanford, who called ''the 22 observed instances of spearmaking 'good evidence''' but said that the lack of ''visual evidence of the spear being used as a spear - weakens it.'' So I asked him whether he doubted the behavior had actually taken place, or whether he was just expressing skepticism. ''I think it's a fascinating discovery, but the term 'spear' is misleading and inappropriate; there's no evidence that the stick was ever used to actually stab anything - it was seen once to ram a bushbaby, injuring it,'' he told me via Email. ''It was more a ramrod or bludgeon, which chimps have been seen to do elsewhere. The video doesn't seem to me to show much of anything at all.''

There may be a lesson here about being an eager beaver.