An official website of the United States government
The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before
sharing sensitive information, make sure you’re on a federal
government site.
The site is secure.
The https:// ensures that you are connecting to the
official website and that any information you provide is encrypted
and transmitted securely.
Barber I, Arnott SA, Braithwaite VA, Andrew J, Huntingford FA.Barber I, et al. Among authors: arnott sa.Proc Biol Sci. 2001 Jan 7;268(1462):71-6. doi: 10.1098/rspb.2000.1331.Proc Biol Sci. 2001.PMID: 12123300Free PMC article.