This work was done with a combination of funding from the US national science foundation and Japan's JSPS (see acknowledgements) and doesn't involve the NIH dir

This work was done with a combination of funding from the US national science foundation and Japan's JSPS (see acknowledgements) and doesn't involve the NIH directly. PubMed/PMC are hosted there, though. That said, animal models are extremely common for NIH-funded work, and birds feature prominently in studies of language and auditory processing.