Birds, bees, bats and other species that pollinate North American plant life are losing population, according to a study released Wednesday by the National Research Council. This "demonstrably downward" trend could damage dozens of commercially important crops, scientists warned, because three-fourths of all flowering plants depend on pollinators for fertilization. American honeybees, which pollinate more than 90 domestic commercial crops, have declined by 30 percent in the past 20 years. This poses a challenge to agricultural interests such as California almond farmers, who need about 1.4 million colonies of honeybees to pollinate 550,000 acres of their trees. By 2012, the...