North American Birds

VOLUME 68 NO4 2015

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/605532

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V O L U M E 6 8 ( 2 0 1 5 ) • N U M B E R 4 467 T h e c h a n g i n g s e a s o n s : o d d d u c k the steady increase in oversummering Greater White-fronted Geese (Figure 1) has gone hand in hand with increas- ing numbers of both wintering western birds in the Southeast and Greenland birds in the Northeast in particular. The more wintering, the more stragglers and injured birds left behind in summer. The same seems to be true of Snow and Ross's Geese over much of Canada's southern tier and the Lower 48 United States. And what about summering Eurasian Wigeons late- ly? They seem to be detected a bit farther south over the past few years. In addition to records from the Atlantic Provinces of Canada, singles this summer were at South Porcupine near Timmons, Ontario 1 June; in Sandusky County, Ohio 1-19 June; at Carleton, New Brunswick 13 June; at Hill- man Marsh Conservation Area, Ontario 14 June; at Bowdoin National Wildlife Refuge in eastern Montana 14 June (Fig- ure 2); at Bells Corners 2-6 July and at nearby Ottawa, Ontario all summer; at Hull, Québec 9 July; at Montezuma Na- tional Wildlife Refuge in upstate New York all summer; and at Lake Josephine, Maine all summer. Two were at Medicine Hat, Al- berta 3 June, and two were at Churchill, Manitoba as late as 17 June. How many of these summer Eurasians are fnding Amer- ican Wigeon mates and breeding in North America? Surely a few. One male at Cape from these three states are of single birds or very small groups, as refected in eBird checklists. A roster of odd summering ducks is a feature common to many regional re- ports, and in recent seasons, we have noticed increases, not just in the Mid- west and Great Lakes but also in Gulf coastal states, and in summer 2014 even in western Texas. In particular, counts and varieties of extralimital bay ducks (Aythya) are up, especially of Lesser Scaup and Redhead and even Canvas- back, which were detected far south of breeding range in summer 2014, to the Gulf Coast and even down to Hondu- ras and Costa Rica in the case of Lesser Scaup. (An exception to this trend, Ring- necked Ducks, once the most wide- spread of summer bay ducks south of breeding range, seem to have declined a bit since the 1990s.) These summering birds, though far fewer in number than the scoters, also follow several winters in which these species have been detected in unprecedented numbers in Mexico, Central America, and the Caribbean. A new publication presenting data on div- ing ducks, especially sea ducks, Ecol- ogy and Conservation of North American Sea Ducks (Savard et al. 2015), presents much food for thought. Birders tend to think of waterfowl in terms of our tra- ditional seasonal expectations, but they are a very dynamic group, able to capi- talize rapidly on changing opportunities for feeding and breeding—and changing their migration patterns to ft these re- sources. We are still very much ignorant as to whether new patterns indicate re- silience/adaptability or rather debility/ susceptibility. Are the Black Scoters in the Atlantic attempting, with mixed suc- cess, to summer far south of usual areas? Is this an attempt to adjust to changing food availability farther north? It's frus- trating not to have a clear understanding of whether we're observing exploitation of resources or desperation. In some cases, records of summering waterfowl ft with patterns that we are comfortable with or expect. For instance, Coral, Florida all summer "was thought to be of captive origin"—but perhaps an out- lier or injured bird? Certainly, numbers on the Atlantic coast of Florida have been in- creasing recently, as seems to be the trend in many parts of the East. We have always been quick to call the odd duck a potential escapee, but it's not just geese that seem to be thriving in the warmer northern sum- mers: Common Shelduck populations are burgeoning as well (Figure 3). In the past two decades, the tiny nesting population in Iceland has increased manyfold, from a few pairs in the early 1990s to a few hun- dred by 2014. Maybe it's time to give these records a second look? In some cases, such as that of Common Mergansers, those suspicious single sum- mer birds end up being nesters—and what is a happier sight than a female Common Merganser with her dapper ducklings in tow? West Virginia, and much of Appala- chian Pennsylvania, Maryland, Virginia, Tennessee, and Ohio, have recorded sum- mer birds that turned (thanks to careful scrutiny) into nesting records. This is es- sentially a reoccupation of former breed- ing range in many cases, possibly because of improving environmental conditions in some river systems, but it is a welcome bit of news and perhaps unexpected during a period of climate change, when many species' ranges appear to be contracting Figure 3. This Common Shelduck discovered 2 April 2014 on St. Vincent's Beach, Avalon Peninsula, Newfoundland is part of a small but increasing pattern of records in the northeastern part of North America. Photograph by Yvonne Dunne.

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