As common wisdom has it, bird flocks in the Northern Hemisphere move from northerly locales in the summer to southerly ones in the winter. For many species, such as the White-throated Sparrow, this notion holds basically true. A closer look at the details of this bird’s movements, however, is much more intriguing, as you can see in this 25-second animation created by eBird, a citizen science project organized by the Cornell Lab of Ornithology and the National Audubon Society. For birders, the information offers a wealth of new insights. Ornithologists, too, can use such data to learn more about migratory behavior, the impact of climate on migration and variables affecting population sizes. In addition, such animations can be useful for conservation biologists and scientists in other fields seeking indicators of climate change as well as for studies of biodiversity shifts and other markers of evolution.
As you will see in the clip, these sparrows spend nearly all their time from June through September either in Canada or in northern areas of New England, New York, Wisconsin and Minnesota, along with Michigan’s Upper Peninsula. That's useful information at a simple level for fanciers like me. I won't go looking for any White-throated Sparrows where I live, in New York City, in the warm months. And strangely, these birds never foray far into Florida, my winter stomping grounds, although they can be found in large numbers at that time in eastern Texas and throughout Louisiana, Mississippi, Alabama and Georgia.
The animation is mesmerizing, and eBird has created such graphics for more than 300 bird species. Nearly as amazing, amateur scientists (maybe some of you reading this story) played a large part in creating them. Thousands of volunteers with the eBird project have been collecting and sharing up to millions of bird observations each month for the past 10 years. Without such armies of laypeople as observers, such data sets would otherwise be out of reach or impossible to obtain. (For more about this burgeoning field and its impact on science, read Hillary Rosner's feature, “Data on Wings,” in the February issue of Scientific American.) Those eBird data have been combined with remote-sensed information on climate, habitat, night flight calls and other variables to generate spatiotemporal exploratory models (aka migration forecasts) as well as more static “birdcasts” (weekly migration forecasts for birders focusing on seasonal species and the impact of weather), estimates of how far birds fly, and myriad other insights.
For two more fascinating examples of how eBird’s real-time migration forecasts illustrate the travel complexities of our feathered friends, you might enjoy these videos of the Willow Flycatcher and the Upland Sandpiper Their long, complex round-trip journeys each year put human "snowbird" excursions to warmer climes to shame.