Can Birds Help us Predict El Niño Weather Patterns?

It’s here—one of the biggest El Niños of all time. El Niño is part of a pattern of ocean-atmosphere interactions by which sea surface temperature in the tropical Pacific Ocean varies from below-normal (La Niña) to above-normal (El Niño). These changes in equatorial waters off the coasts of Peru and Ecuador result in global weather effects.

Climatological models can predict El Niño six to eight months out, but can birds provide an El Niño indicator years in advance? Since 2012 eBird reports of some species highlight major and irregular movements of certain species: for example, Elegant Terns have spread up the Pacific Coast from California to Washington, and Black-vented Shearwaters have spread from San Diego to Oregon.

The northward expansion of these seabird species coincided with the gradual warming of waters in the equatorial Pacific. But this expansion also coincided with warming sea surface patterns in the Gulf of California, far to the north of the Equator. Is the arrival of Elegant Terns in Puget Sound correlated with a coming El Niño or is it simply the local conditions spawning these movements? Can such movements add precious months to our predictive models’ abilities? Such research questions about birds and weather cycles are still being investigated.

But one thing is for sure: El Niño affects birds in profound ways.

The Big Birding Winters of ’82-83 and ’97-98

The journal North American Birds documents how birders have delighted in unusual irruptions and wayward rarities during past  winters.

During the warm winter of 1982–83, some Rose-breasted Grosbeaks skipped migration and stayed put in the eastern United States, Ospreys overwintered from the Great Lakes region to the Pacific Coast, and Varied Thrushes were seen in the Great Plains and Northeast. On a more somber note, a major Gulf Coast die-off of Common Loons was attributed to an El Niño-related epidemic caused by imbalances of saltwater and freshwater.

The winter of 1997–98 was the most recent big El Niño, and like this current cycle, the preceding autumn witnessed a large population movement of Elegant Terns up the Pacific Coast. The strangely warm winter in the Great Plains (50°F in Minot, North Dakota, on January 1) kept many waterfowl from migrating out of the Prairie Pothole region. In the Northeast, 14 species of warblers—including Ovenbird and Black-throated Blue Warbler—were recorded in winter. Red-winged Blackbirds and American Woodcocks arrived in Ontario well ahead of schedule. And on February 13, birders in British Columbia were startled to see Red-winged Blackbirds arriving on early northbound migrations.

Later in the spring, more than a dozen Bristle-thighed Curlews—which typically migrate from the South Pacific to Alaska—were blown off course and deposited along the California to Washington coast. On Attu Island—the legendary birding outpost at the end of the Aleutian Islands—41 Asian species were recorded in spring 1998, including the only Yellow-throated Bunting (a bird that breeds in Japan) ever seen in North America.

Ebird’s First El Niño

El Niños can be catastrophic for humans. The El Niño of 1997-98 caused drenching rains and devastating drought that wreaked global economic costs of $33 billion, $4 billion in the United States alone. The costs include impacts to commerce. Palm-oil production in the Philippines typically declines during El Niño, as does the squid catch off the California coast. Early warnings can help government and industries around the world plan for a year of weird weather.

“The potential uses of advance information are almost limitless,” says Michael H. Glantz of the National Center for Atmospheric Research. For example, the coffee industry could benefit from pre-planning for the El Niño droughts that affect coffee harvests in Brazil and Indonesia, thereby creating a greater demand for Kenyan coffee.

Could the addition of bird distributions improve our predictions? We may find out after this winter, which will mark the first strong El Niño since eBird’s launch in 2002. For the first time, scientists will have access to a database of millions of bird observations to analyze shifts in bird distribution before, during, and after the event.

Real-time reports in eBird will garner great interest from birders wanting to see El Niño rarities. But more meaningfully, these accumulated data could garner great interest from scientists wanting to understand more about complex climatological patterns.