North American Birds

VOLUME 69 NO2 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.

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Page 29 of 139

N O R T H A M E R I C A N B I R D S 204 T H E C H A N G I N G S E A S O N S : C A R B O N C O P Y tiple species "masting" synchronously over enormous areas. Drought certainly has an impact on production, and oaks that have dropped leaves in response to severe long- term drought of course do not produce acorns at all. Drought during spring, when oaks are flowering and acorn production commences, could be particularly impactful, leading to a reduced crop in autumn (Koenig et al. 2013). Indeed, Koenig (2014) writes that the the drought is "perhaps" to blame for the well-below-average acorn production in 2014 for most species, and although many species had very poor production, Oregon Oak, California Black Oak, and Valley Oak had reasonably good production. In think - ing about other fruits consumed by both thrushes and pigeons—fruits of Cascara and Pacific Madrone as well as elderberry, black- berry, snowberry—we have to imagine that all of these important foods were reduced in their availability in the important late summer/early autumn period. Very likely, because exceptional/extreme drought con- ditions prevailed over much of California for a fourth consecutive year, and moderate drought conditions were recorded in Ore- gon, eastern Washington, and southwestern British Columbia, the thrushes and pigeons io—to looking very carefully through urban parks and sewage pond shrubbery, expect- ing to find a species that should be in the tropics during the Christmas Bird Counts and even later. What has changed? My gut tells me that people who watch birds regularly have in - creased tenfold since the 1980s. And certain - seen in such remarkable numbers in central and southern California were likely from populations spanning a very large area of the Pacific Northwest. North of normal This section of the winter Changing Seasons essay has long been considered the oddball corner, the grab-bag of patternless waifs left behind by their conspe- cifics that had migrated farther south for the winter—the "gee whiz" birds, as a few authors have called them. And indeed we still have a fair number of species for which strong patterns of northerly over- wintering are lacking. But we can no longer say of cardinalids such as Rose-breasted Grosbeaks, Sum- mer and Western Tanagers (Fig- ure 8), Indigo and Painted Bun- tings that we are surprised to see them well north of normal range in winter. And we have gone from shock-and-awe about double-dig- it warblers species counts in early winter—whether in Georgia or Newfoundland, Virginia or Ontar- Figure 9. The mild weather in December 2014 allowed this Nashville Warbler to survive until 2 January 2015 at a riverside park in Sainte-Catherine, Québec (here 19 December). Photograph by Pierre Bannon. Figure 10. Found in the Kootenays at Kokanee Creek Park, this White- eyed Vireo provided a long-anticipated first record for British Columbia 4 December 2014. Photograph by Paul Prappas.

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