This month’s eBirder of the month challenge, sponsored by Carl Zeiss Sports Optics, intends to motivate you to get out in the field every day, helping uncover little-known patterns in bird distributions. Around much of the world, this time of year heralds post-breeding movements in numerous bird species. Many of these post-breeding movements (e.g., dispersal) are little-known, and quite fascinating. Many birders just think of late July and most of August as the time of year to look for shorebirds—there is much more to be seen! The eBirder of the month will be drawn from eBirders who submit at least 31 complete checklists during August. That is an average of one checklist a day—we hope you won’t stop at just one! Winners will be notified by the 10th of the following month.
No matter where you are, birds (and birders) respond to shifting seasons. In the Northern Hemisphere, summer is coming to an end. In the Southern Hemisphere, spring is beginning to become a reality, with summer close behind. Closer to the equator, seasons are often marked by periods of wet and dry instead of temperatures; mountain ranges dictating where the rain falls and in what months. Although these wet and dry seasons may be more difficult for humans to understand, we do know one thing: the birds are paying attention. No matter where you are, a changing season means a change in birds—whether the composition of the species or the behavior of the residents.
This time of year is especially interesting in regions where the breeding season is coming to a close. For many species, both the post-breeding adults and the newly fledged young are dispersing—moving from their breeding territories further afield, perhaps just a few miles to a nearby field or forest; or perhaps much further, sometimes hundreds of miles, well beyond their normal range. Birds in this latter category make late summer a period where people in eastern North America look for out of place birds from the southern and western parts of the continent: White-winged Dove; Black-bellied Whistling-Duck; American Avocet, and perhaps even species like Calliope Hummingbird.
However, all of the birds that are doing this dispersal are not the rarities, and these are the ones that often fly under the radar. Many common species engage in these same post-breeding behaviors, and that is what we hope to learn more about through this Challenge. For example, the common North American backyard bird Chipping Sparrow is in the midst of movements across the continent, dispersing to new habitats and areas where they don’t occur earlier in the summer. Many species of warblers are using habitats that they do not breed in—Hooded and Blackburnian Warblers in scrubby field edges or Louisiana Waterthrushes at edges of cattail marshes. Great Egrets and Red-tailed Hawks disperse northward by the hundreds. Swallows are flocking and preparing to migrate, sometimes in massive numbers. Blackbirds are starting to roost communally in large numbers. Your observations will help us learn more about all of these mysterious movements.
It is important to note that this is by no means restricted to North America. In Central America, there are species like Northern Rough-winged Swallow and Black-headed Siskin that are showing altitudinal migration at this time of year—congregating in regions at lower altitudes than they normally breed. Hummingbirds are undergoing seasonal movements; species like Brown Violetear turn up in large numbers at locations they are uncommon at other seasons—in Honduras you can see close to 100 Brown Violetears in a region that hosted only 1-3 per visit just a few months ago.
These same phenomena are happening worldwide—with thrushes and other songbirds dispersing in Europe; altitudinal movements in the Himalayas; and local movements of post-breeding birds across the rest of Asia. In the southern Hemisphere, birds are finishing up their winter, and will soon be starting that most amazing of journeys: migration. So this is the perfect time to get outside and see what is happening near you!
One of the reasons why many of these local dispersal events are not detected by birders is due to how people look for birds. If it is early August and you want to go birding, are you going to go to a nearby marsh/lake/river/beach, or to the edge of a farm field and some forest? The answer will almost always be water-related, but we hope to change that—at least sometimes. Go on out, bird a place that you wouldn’t normally, and see what you’ll find. These observations contributed from your backyard or local birding patch truly make a difference in our global knowledge of birds, helping us collectively understand the complex life cycles of birds across the world.
Each month we will feature a new eBird challenge and set of selection criteria. The monthly winners will each receive a new ZEISS Conquest HD 8×42 binocular.
Carl Zeiss Sports Optics is a proven leader in sports optics and is the official optics sponsor for eBird. “Carl Zeiss feels strongly that by partnering with the Cornell Lab we can provide meaningful support for their ability to carry out their research, conservation, and education work around the world,” says Mike Jensen, President of Carl Zeiss Sports Optics, North America. “The Cornell Lab is making a difference for birds, and from the highest levels of our company we’re committed to promoting birding and the Lab’s work, so there’s a great collaboration. eBird is a truly unique and synergistic portal between the Lab and birders, and we welcome the opportunity to support them both.”
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