11.   Falling world fish catches, rainforest depletion, reduced energy efficiency, disappearing bird species and increasing global temperatures also give cause for concern.

12.   The overfishing of herring and other fish has caused problems for bird species dependent on these stocks, particularly in wintertime.

13.   Indeed, neither bird species seems to have developed echolocation to such a pitch of sophistication as bats have.

14.   Almost as prolific as bird species and birders are places to camp along the copious birding trails.

15.   Among many bird species, males and females share nesting duties.

16.   Being exceedingly beautiful, or even notably clever, proved deadly for some other bird species.

17.   Besides its predilection for crows, robins, chickens, hawks and other common bird species, West Nile virus has another feature that worries public health authorities.

18.   Being an ornithologist, she sits in the Prado with her binoculars to study the dozens of bird species in the triptych.

19.   A number of bird species are dependent on these varieties of marine life, and they may well be affected different ways.

20.   Agencies fielded complaints from a wide variety of people, from those planning vacations to national parks to those seeking the status of bird species.