North American Birds

VOLUME 69 No1 2016

A Quarterly Journal of Ornithological Record Published by the American Birding Association. The mission of the journal is to provide a complete overview of the changing panorama of our continent’s birdlife.

Issue link: http://nab.aba.org/i/629070

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N O R T H A M E R I C A N B I R D S 44 T H E C H A N G I N G S E A S O N S : O U T P O S T S Anna's (or hybrids?) seem to be on the upswing. Over the years, banding recoveries of a num - ber of individual vagrant hummingbirds have produced some startling results. The same Broad-billed Hummingbird turning up in both Louisiana and Oklahoma a number of years ago is one such example. In 2014, a Rufous Hum - mingbird banded in Wisconsin on 23 October was subsequently recaptured on 22 November in North Carolina! But it was an individual Blue- throated Hummingbird that most astounded this year. Initially banded in its normal range at Portal, Arizona, in July 2013, it then turned up briefy in the San Bernardino Mountains east of Los Angeles in September 2014—for a third Cal - ifornia record—and then was found yet again, to the south in San Diego County in December 2014, where it collided with a window and need - ed rehabilitation before being returned to Portal! Identification and documentation in the digital age Back in the early 1980s, this essay raised the un- comfortable subject of the uncritical (or errone- ous) reporting of several long-distance Neotropi- cal migrant passerines in the United States and southern Canada during the late-autumn and winter months (Lehman 1983, 1984). Heading the list for late autumn were Eastern and West - ern Wood-Pewees, Gray-cheeked and Swain- son's Thrushes, and Veery, as well as Blackpoll Warbler (probably misidentifed Pine Warblers and a few straggler Bay-breasteds?) and Yellow- throated Vireos (probably mostly male Pine Warblers). Some of these reports came from Christmas Bird Counts, and most were from the only other Hooded Oriole record for east - ern Canada (late November 1998), and it lies neatly along that trajectory. Away from the west - ern edge of the Gulf, there are no other Hooded Oriole records in the American East, and the few Great Plains (and Kentucky) records lie nicely along the Southwest-to-Northeast lines. Is New England, with its many birders (hummingbird feeders, gardens), situated too far east of this trajectory to anticipate a Berylline Humming - bird? Is it in the "shadow" of the Gulf of Mexico when it comes to such mostly Mexican species? New England does have a very few such bird records (Painted Redstart, Lucy's Warbler), but most such records in the northern tier of the United States or southern tier of Canada fall far - ther west. Whatever the mechanisms involved, it is interesting to note how many such species' vagrancy records appear to ft these lines, even stealth/ultra-rare species like Ruddy Ground- Dove, with a few records from central Texas and one from northwestern Mississippi (2004). Of course, this vagrancy vector is only one of many in North America. The Broad-billed Hummingbird in Washington, Ruby-throated in Nevada, and both Ruby-throated and Anna's in the Yukon took different tacks to reach their points of discovery. In some cases, such birds could be mirror-migrants (likewise birds like Orchard Oriole and Blue-gray Gnatcatcher in the Pacifc Northwest). Ruby-throated is prov - ing to be an increasing "stealth" fall vagrant in the West, with additional single individuals this season in both northern and southern California (Figures 19, 20). Is this a new development, or are more hardcore birders in the West now put - ting out more feeders? The Yukon bird, in the wilderness well north of the small community of Beaver Creek (Figure 21), is astonishing: who would imagine that anyone way up there would think to put out a hummingbird feeder in such a remote location? Anna's Hummingbird popula - tions in the West continue to grow and expand. They are much more numerous and widespread than just a few years ago in the Pacifc Northwest, vagrant records in Alaska are increasing and are coming from a wider variety of seasons than pre - viously (when mostly just found a late fall and early winter), and records from the East continue to mount—including one this season in Florida. Displaying Anna's are now regularly reported well into Mexico, as far southeast as Coahuila. The recent increases and altitudinal spread of breeding Anna's in the core range in California is thought to be having a negative effect—at least locally—on populations of both Black-chinned and Costa's there. One wonders if that trend will have an impact on extralimital records: data points are scant, but Black-chinned vagrants seem to be in a lull in the East lately, whereas ma around 3 October and later (as predicted! Brinkley 2014). Regional editor Peder Svingen wonders whether the post-tropical remains of Hurricane Norbert, which arrived in Michigan 12 September, and those of Odile, which arrived about 20 September, could be connected to these state-frst hummingbirds, for which there was scant precedent, though wayward Costa's were reported this season from Colorado and Alaska, and a Costa's or Costa's x Anna's hybrid (Figures 17, 18) was in Oklahoma. Before one dismisses the idea of hurricane remnants trans - porting hummingbirds, it's important to bear in mind that birders in the mid-Atlantic have of - ten observed hummingbirds (presumed Ruby- throateds) moving northward inside the bands of tropical storms and hurricanes, right along with aerial insectivores such as swifts, swallows, and martins. Of course, these storm remains are no longer tropical storms by the time they're crossing the continent—and we routinely credit the southwesterly winds of baroclinic storm sys - tems with helping to transport birds from the Southwest to the Northeast. The surfeit of rare southwestern/Mexican hummingbirds in Michigan (Broad-billed, White-eared, Berylline, Costa's, plus eight Green Violetears) seems odd. Just a lucky coincidence? Are there more hummingbird feeders in, say, Grand Marais than in other lakeshore hamlets? Or could this phenomenon too be a function of geography? When one looks at a map of North America, and draws 45º lines from the South - west and Mexico across the continent, the lines drawn from southwestern Arizona begin to hit Minnesota, and the lines from the rest of Ari - zona and western Mexico hit the central Great Lakes—Michigan and Ontario in particular. Both have received startling Mexican/southwest - ern specialties in recent years, with Michigan's Lucy's Warbler coming to mind and Ontario's Phainopepla, Pyrrhuloxia, Painted Redstart, Varied Bunting, and two Hooded Orioles having top billing. As one continues these lines farther east in Mexico and into Texas, the lines break at the coast of the Gulf of Mexico. So if one hypoth - esizes that southwesterly winds are important for transportation of fall migrants to the Great Lakes, including some hummingbirds, then Michigan's (and Ontario's) remarkable fortune seems to make more geographic sense, at least if the Gulf of Mexico poses a barrier to birds mov - ing northeastward out of Mexico. If we assume that these birds are coming not from Mexico but only from the southwestern United States, then we still see that the western and central Great Lakes are the frst big bodies of water that break the lines drawn northeastward. Continuing the lines, we fnd that they reach New Brunswick and adjacent Québec—of course, Matapédia has Figure 19. This juvenile female Ruby-throated Hummingbird visited feeders at a residence in Eureka 3-10 (here 3) September 2014, providing the second record for Humboldt County, California. Photograph by Brad Elvert.

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