A good summary of why at least one quarter of these birds are in decline and 25 species are threatened with extinction.
(at least one quarter of these birds; are; in decline and 25 species) (A good summary of why at least one quarter of these birds are in decline and 25 species; are threatened; with extinction)
at least one quarter of these birds A good summary of why at least one quarter of these birds are in decline and 25 species
are are threatened
in decline and 25 species
with extinction