Bird populations

[Bill Hall <>]

Bird counts dwindling

Yellow-headed blackbirds. Even some familiar species, such as blackbirds and starlings, are declining. JACK DYKINGA/NPL/MINDEN PICTURES

A sobering study has documented an almost 30% drop in the number of North American birds since 1970, with common birds such as sparrows and blackbirds declining as well as rarer species. The losses have raised fears that many species could go the way of the passenger pigeon, a species once so abundant that its extinction in the early 1900s seemed unthinkable. Habitat losses and ecosystems under stress from pollution, climate change, and development are among the leading causes.

U.S. and Canadian researchers combined data from annual spring censuses, the Audubon Christmas Bird Count, an international assessment of shorebirds, and aerial studies to look for population changes in 529 species. Thanks to conservation efforts, waterfowl and raptors are thriving. But birds living along shorelines are not doing so well—sanderlings and plovers are down by about one-third—and the number of birds that inhabit grasslands has declined by about 50% over the past 50 years. Even the most familiar birds are in trouble: Nineteen common species have each lost more than 50 million birds since 1970.

All told, North America now has 3 billion fewer birds, but the situation is not hopeless, researchers say. Reversing habitat loss could stabilize populations. And simple steps, such as keeping cats indoors and planting native plants, can help, says a coalition of conservation groups that has come up with policy recommendations and an action plan for citizens.

— Elizabeth Pennisi

References

K. Rosenberg et al., Decline of the North American avifauna, Science, Vol. 365, p. 1228, 20 September 2019

E. Pennisi, Billions of North American birds have vanished, Science, Vol. 365, p. 1228, 20 September 2019