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

Contents of this Issue

Navigation

Page 35 of 211

Figure 6. Great-tailed Grackle was added to the Alberta list when this male showed up at Spring Hill, south of Fort McLeod, some time in mid-May 2015. The bird remained into June (here 6 June). Photograph by Gerald Romanchuk. N O R T H A M E R I C A N B I R D S 346 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 poorly seen dark ibis unidentified to spe- cies; increasing hybridization is one conse- quence of climate change that is generally underappreciated (see the notes by Tony Leukering and Matt Fraker in the Colorado & Wyoming regional report). What we have noticed over the decades is a shift from patterns of spring "over - shoots" or late-summer "post-breeding wanderers" to larger and larger flocks of ibis arriving in extralimital contexts appar - ently in search of breeding sites. To be sure, some White-faced Ibis have probably been re-colonizing former range, after decades of population loss attributed to pesticides. And both species, like many wetland birds, are highly mobile, seeking out new wet - lands when local ones have dried. Although categorical conclusions about the ultimate drivers of range expansion are usually elu - sive (Patten and Lasley 2000), a strong as- sociation with warming climate has been established reasonably well in multiple in - stances. Breeding successes, coupled with increasing availability of habitat and food (and niche) beyond core range, are often factors cited as necessary for expansion. But as with so many other species, we are certainly seeing a northward trend in all categories of records and also changes in seasonality of records, not just in our con - venient but imprecise categories of "over- shoot" or "vagrant." And it is reasonable to attribute this part of the trend to increas - ing average temperatures, which "open up" higher-latitude and higher-elevation areas earlier in spring (on average, three days earlier each decade) and keep them open later into autumn. One recent paper (Chen et al. 2011) calculated the northward shift to be 16.9 kilometers per decade (and 11.0 of which are reported by people who don't consider themselves birders at all. In the late 1980s and early 1990s, for instance, we began to see a remarkable increase in records of extralimital Glossy Ibis (Fig- ure 2), a familiar species to birders in the Southeast and East but a novelty elsewhere twenty years ago. At just about the same time, its western counterpart, White-faced Ibis, began to turn up in areas north and especially east of usual range, notably as a vagrant in the East and around the Great Lakes (Sabo 1992, Patten and Lasley 2000). Through years of abundant water and of extreme drought, the ranges of both White- faced and Glossy Ibises have continued to expand, irregularly, in multiple directions, and many regional reports in this issue still put the Plegadis ibis front and center, with significant 2015 records from the Dakotas, West Virginia, Tennessee, Illinois, Pennsyl- vania, Indiana, and Québec (where breed- ing now?). Though now expected in many areas, unexpected vagrants are still turning up; Panama had its first White-faced in 2016. Some state and provincial commit- tees have moved the dark ibis off the review lists in many places where the birds were once genuinely rare, despite the difficulty in identification and despite the apparent increase in hybrids between them. Com- mendably, more and more observers leave But we must bear in mind, as we con- sider the examples: expansion into new areas does not mean that a species' overall population is growing, as many species have become scarce or absent in other parts of range in recent decades, and for northern species, the ability to shift northward is lim- ited: the landmass ends at the Arctic Ocean or Hudson Bay (Virkkala et al. 2008). We have a tendency to notice what is new but oftentimes seem to forget about species that have vanished in our areas. For my stomp- ing grounds, Upland Sandpiper, Bewick's Wren, Bachman's Sparrow, and more recent- ly Henslow's Sparrow and Black Rail, seem to have all checked out, and Loggerhead Shrike and Golden-winged Warbler hang by a thread. Psychologically, it is natural that we not spend our days in mourning, but the memory of what has been lost should stay with us, reminding us that these absences may presage much greater losses in the fu- ture. Little research has been done into the psychological effects of declining biodiver- sity (Clark et al. 2014), but for people such as ourselves, it is clearly very painful to lose even a few cherished species. In this age of changing climate and birds' ranges, small, secretive species tend to re- ceive less notice, as they are difficult to de- tect; we see new patterns more quickly and clearly in the larger, showier species, some Figure 7. Vermilion Flycatcher has been spreading steadily northward in New Mexico for several years; this male was at Maxwell National Wildlife Refuge, Colfax County 23 April 2015. Photograph by Leann Wilkins.

Articles in this issue

Archives of this issue

view archives of North American Birds - VOLUME 69 NO3 2016