North American Birds

VOLUME 69 NO3 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/778845

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Figure 4. Part of the northward expansion of Black-necked Stilt, these in southeastern Chicago, Illinois were noted 9 May 2015 but did not linger there. Photograph by Sam Burckhardt. N O R T H A M E R I C A N B I R D S 344 T H E C H A N G I N G S E A S O N S : R E T R O S P E C T ous variables. Studies of the actual and po- tential impacts of the warming planet were still in their infancy when I began work with National Audubon Society Field Notes two decades ago, but studies have prolifer- ated since that time, and the recent litera- ture paints a picture both intricate and dire: both the impacts already documented and those predicted to occur vary tremendously, but widespread extinctions of numerous plant and animal species are now thought to be highly likely (Barnosky et al. 2011, Bellard et al. 2012, Ceballos et al. 2015). According to the State of the Birds report for 2016: "One-third of all North Ameri- can bird species need urgent conservation action. These 432 species of high conser- vation concern are on the Watch List and are most at risk of extinction without sig- nificant action." It stands to reason, of course, that species already in steep decline, such as Tricolored colder-than-average winters, not uniformly milder weather from year to year. Neverthe- less, in species whose natural history favors expansion in this era of warming—general - ists with regard to habitat and feeding in par- ticular—we have seen northerly records of many sorts, whether we call them vagrants, pioneers, or prospectors, and we are likely to continue to see an increase among many species in the future. Looking back: 1996 William B. Robertson, Jr., writing this col - umn in 1980, lamented: "the big trouble with writing The Changing Seasons is that the seasons don't change enough." We find ourselves in envy of such a statement, from what were perhaps the halcyon days of bird- ing, when only Carl Sagan (1980) dared warn us of what might lie ahead. It is a testament to how rapidly our pas- time has changed, and how rapidly bird Blackbird, Mountain Plover, Black Rail, are less likely to be found in range expansion, and those species whose habitat require- ments are specific and limited (Red-cock- aded Woodpecker, Lesser Prairie-Chicken, Golden-cheeked Warbler) likewise cannot simply or easily expand their ranges. Look - ing at the map of observed temperature changes for the United States (1991-2012 is the most recent available, Figure 1), we see that the warming trend itself is not uni - form, with what we used to call the Central Southern region closer to (or even below) long-term averages in this period, though the period 2002-2012 was above average there as well. The Northeast, Great Lakes, West (especially Alaska), and southern Florida and Texas have shown the greatest departures from average. And so we should by no means expect to see anything like a uniform pattern of range expansion; climate change involves upheavals, including some

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