Animals in the Goldilocks zone -- neither too big, nor too small, but just the right size -- face a lower risk of extinction than do those on both ends of the scale, according to an extensive global analysis.
Birds often choose their mates based on song, making it a key factor in separating species. However, analyzing spectrograms can only tell us so much -- the characteristics that birds hone in on when identifying potential mates may not be the same ones scientists notice in audio recordings. A new study uses field experiments to […]
Two birds that look the same, but have songs so different they can't recognize each other, should be considered distinct species, suggests new research. Among 72 related populations of Central and South American birds the researchers tested, they found evidence for 21 new species.