A number of recent academic papers have described northward shifts of bird species in both North America and Europe, driven by climate change. These papers usually present aggregated results from dozens of species; they rarely provide details for any specific species. These maps are intended to offer that.
While there are tremendous species-specific differences, non-migratory resident birds (such as Northern Cardinal, Carolina Wren, Tufted Titmouse, and Red-bellied Woodpecker) appear to be the most adaptable and have expanded their ranges the most. This seems to be primarily driven by warmer winters and, for some species, is further augmented by bird feeders.
I created these maps using eBird, so the usual caveats apply– they don’t necessarily include all records (though many historical out-of-range records are indeed included), and eBird reporting, which became widespread only after 2010, continues to increase dramatically each year. To draw the lines, my intent was to capture the primary range area — and more — but I deliberately excluded the furthest ten to fifteen outliers for each line.
Two of the academic papers that report climate-driven range expansions in eastern North America are listed below, along with their abstracts.
Prince, K. and B. Zuckerberg. 2016. Climate change in our backyards: the reshuffling of North America’s winter bird communities. Global Change Biology 21(2): 572-585.
Much of the recent changes in North American climate have occurred during the winter months, and as result, overwintering birds represent important sentinels of anthropogenic climate change. While there is mounting evidence that bird populations are responding to a warming climate (e.g., poleward shifts) questions remain as to whether these species-specific responses are resulting in community-wide changes. Here, we test the hypothesis that a changing winter climate should favor the formation of winter bird communities dominated by warm-adapted species. To do this, we quantified changes in community composition using a functional index–the Community Temperature Index (CTI)–which measures the balance between low- and high-temperature dwelling species in a community. Using data from Project FeederWatch, an international citizen science program, we quantified spatiotemporal changes in winter bird communities (n = 38 bird species) across eastern North America and tested the influence of changes in winter minimum temperature over a 22-year period. We implemented a jackknife analysis to identify those species most influential in driving changes at the community level and the population dynamics (e.g., extinction or colonization) responsible for these community changes. Since 1990, we found that the winter bird community structure has changed with communities increasingly composed of warm-adapted species. This reshuffling of winter bird communities was strongest in southerly latitudes and driven primarily by local increases in abundance and regional patterns of colonization by southerly birds. CTI tracked patterns of changing winter temperature at different temporal scales ranging from 1 to 35 years. We conclude that a shifting winter climate has provided an opportunity for smaller, southerly distributed species to colonize new regions and promote the formation of unique winter bird assemblages throughout eastern North America.
Saunders et al. 2022. Unraveling a century of global change impacts on winter bird distributions in the eastern United States. Global Change Biology
One of the most pressing questions in ecology and conservation centers on disentangling the relative impacts of concurrent global change drivers, climate and land-use/land-cover (LULC), on biodiversity. Yet studies that evaluate the effects of both drivers on species’ winter distributions remain scarce, hampering our ability to develop full-annual-cycle conservation strategies. Additionally, understanding how groups of species differentially respond to climate versus LULC change is vital for efforts to enhance bird community resilience to future environmental change. We analyzed long-term changes in winter occurrence of 89 species across nine bird groups over a 90-year period within the eastern United States using Audubon Christmas Bird Count (CBC) data. We estimated variation in occurrence probability of each group as a function of spatial and temporal variation in winter climate (minimum temperature, cumulative precipitation) and LULC (proportion of group-specific and anthropogenic habitats within CBC circle). We reveal that spatial variation in bird occurrence probability was consistently explained by climate across all nine species groups. Conversely, LULC change explained more than twice the temporal variation (i.e., decadal changes) in bird occurrence probability than climate change on average across groups. This pattern was largely driven by habitat-constrained species (e.g., grassland birds, waterbirds), whereas decadal changes in occurrence probabilities of habitat-unconstrained species (e.g., forest passerines, mixed habitat birds) were equally explained by both climate and LULC changes over the last century. We conclude that climate has generally governed the winter occurrence of avifauna in space and time, while LULC change has played a pivotal role in driving distributional dynamics of species with limited and declining habitat availability. Effective land management will be critical for improving species’ resilience to climate change, especially during a season of relative resource scarcity and critical energetic trade-offs.
Like so many species, the Carolina Wren is expanding northward. And, like many of those species, this expansion started decades ago, before any measurable climate change, but has exploded in the past decades with climate change.
The Carolina Wren has been expanding north since the 1800s due to habitat recovery after deforestation (Haggerty and Morton, 2020 – the Birds of North America (BNA) species account). What makes the recent Carolina Wren data so interesting is that we can clearly see, in its expansion into Canada, its battle with winter weather conditions.
The species is known for “decimation… by severe winter conditions” (BNA) at the northern limits of its range. The same account notes that “severe winters have apparently been infrequent enough during the 20th century to allow populations to expand and move northward.” Indeed, one of the key conclusions of an analysis of climate change in southern Ontario was that there has been “a decrease in the frequency of cold temperature extremes”. While the wren is aided against cold snaps by bird feeders, the climate trend, at least in Canada, is in its favor. The report noted an overall average increase of 1.5C.
As the wren expanded, certain record-breaking and persistent cold waves knocked the population back, where it restarted. It’s also clear that it is restarting from a higher position each time, thus building its numbers and continuing its expansion.
The cold snaps denoted on the graph were particularly severe in southern Ontario. A more detailed look at weather data may reveal a more complicated pattern and even greater correlation to warmer winters.
This blog post is merely to provide a visual illustration, by way of a map, of the expansion of the California Scrub-Jay across Washington, British Columbia, eastern Oregon, Idaho, and even Montana (one record so far). It is intended to complement my more detailed article, “Tracking Expansion of the California Scrub-Jay Into the Pacific Northwest”, in the Washington Ornithological Society (WOS) News, August-September 2021 edition.
As becomes clear in the article, these are not hard lines. The jays are advancing gradually, not in a solid wave. Typically, a single jay will appear well outside the known range (e.g. Spokane). Within a year or two, there will be several. Then they’ll be breeding. Then they will begin expanding further. Meanwhile, a wave of jays will be backfilling the new territory, with densities increasing annually. The lines in this map are as much art as science, but are intended to show the primary region were jays were “regular and expected”. There were always outliers, pioneer dispersers expanding the range. Records beyond the 2020 line are shown as pale blue dots.
The jay’s expansion, when considered in the context of timing and trends in other species, is likely a function of a warming climate combined with suitable food sources. For more discussion of this, see the WOS article linked above.
It will be interesting to see where the 2030 scrub-jay “contour line” will be. I predict they’ll be on Vancouver Island from Victoria to Campbell River, as well as up the Sunshine Coast, up the Okanagan Valley to Kelowna and possibly Kamloops, and east to Idaho, from Coeur d’Alene in the north throughout the Snake River Valley in the south.
After that, they face some formidable hurdles. The biggest obstacles to their expansion further north and east will be habitat with limited food sources (e.g. high mountains). That said, they’ve already shown some ability to travel up mountain valleys and potentially cross the Cascades north of Mount Rainier.
Looking at Version 8.0.8 (March 12, 2021) of the ABA Checklist, 116 of the 1,123 species, or a little over 10%, are named after people. Of the 116 in the ABA area, two (Bishop’s Oo and Bachman’s Warbler) are considered extinct, one is an introduced species in Hawaii (Erckel’s Francolin), and 32 others are Codes 3, 4 or 5, meaning they occur rarely in the ABA area. The remaining 80 are all Code 1 or 2 and can be expected to be seen in the ABA area regularly. The following analyses focuses on these 80 familiar species.
The first thing to note is that these 80 species come from a wide array of families and species groupings. As with all birds, Passerines are dominant, making up 49% of the list. Digging deeper, seabirds and Passerines with limited ranges (mostly warblers and sparrows) are over-represented—because they were described relatively late in the European discovery process, when honorific naming became more in vogue.
The AOU (American Ornithological Union, the precursor to the AOS) began proposing English names in its first checklist in 1886, but didn’t complete the effort – and the names were not universally accepted – until the 5th edition in 1957. Meanwhile, the Latin scientific names have always followed a clear rule: the Latin name is set by the first published description of a species. The “bird names for birds” movement is focused on English names only.
Eponymous naming was rare in the 18th century, limited to just four of the 80 species, all emanating from Russian/German and British field work, primarily focused on the far north. The four early birds are Steller’s Eider (1769), Blackburnian Warbler (1776), Steller’s Jay (1788), and Barrow’s Goldeneye (1789).
Then, in 1811, Alexander Wilson named a woodpecker and a nutcracker after Lewis and Clark, and honorific naming was off and running, peaking in the mid-1800s.
Eponyms for the 80 Code 1 and Code 2 species are overwhelmingly honorific. Only six are named after the describer himself (Wilson’s Warbler, Sabine’s Gull, Brandt’s Cormorant, Townsend’s Warbler, Gambel’s Quail, and Cory’s Shearwater), and it’s not clear that even all of them intended for the species to have an eponym; the Latin names for the warbler, cormorant, and shearwater suggest otherwise. Wilson himself called his warbler the Green Black-capped Flycatcher and the western subspecies went by Pileolated Warbler (coined by Pallas) as late as the 1950s.
The namers were widespread – 36 different people provided the 80 names, though four stand out. John James Audubon provided fifteen of the eponymous names, Spencer Baird and John Cassin each provided seven, and Rene Lesson four. Together, these four ornithologists were responsible for 41% (33/80) of the honorific names in this analysis. In addition, many eponymous subspecies were coined by Baird.
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The majority of the namers were connected to each other, with many naming birds after colleagues, who in turn named species after other colleagues. Lesson described Audubon’s Shearwater and Oriole; Audubon described Baird’s Sparrow; Baird described Woodhouse’s Scrub-Jay; Woodhouse described Cassin’s Sparrow; Cassin described Lawrence’s Goldfinch; Lawrence described LeConte’s Thrasher.
There are no examples of a quid pro quo, where two people named birds after each other, unless you count Audubon’s Warbler, described by Townsend in 1837; Audubon returned the favor with Townsend’s Solitaire the following year. Or Coues, who christened a sandpiper after Baird in 1861; four years later, Baird named a warbler after Coues’ sister, Grace.
Despite Audubon’s dominant role in honorific naming, no Americans honored him (excepting Townsend with Audubon’s Warbler); only Lesson, a Frenchman, did.
A third of the species (27 of 80) have Latin names that do not match the honorific English name. In most instances this is because the bird was accidentally described twice. Most often, they were not originally intended to have an honorific name. A person described the species and gave a descriptive Latin name, then later another person described the same species and gave an honorific name. For example, Lichtenstein described A. aestivalis in 1823, then Audubon described it again in 1839, naming it Bachman’s Sparrow. When it was realized the two were the same species, the Latin name provided by the first publication held, but, at least in these instances, the honorific English name was also given—a kind of consolation prize to the second describer. Thus, what was called Pinewoods or Oakwoods Sparrow became Bachman’s Sparrow. It’s apparent that oversight and review of “naming and claiming” was limited.
Among the 80 species in this analysis, this double-describing happened at least 18 times. Curiously, six of these were by Audubon and account for 40% of his honorific bestowments. These are Harris’s Hawk, Bachman’s Sparrow, MacGillivray’s Warbler, Harris’s Sparrow, Brewer’s Blackbird, and Smith’s Longspur. MacGillivray’s Warbler was intended to be Tolmie’s Warbler as described by Townsend; the other five have descriptive Latin names. There is one other double-described species that has a Latin honorific—Scott’s Oriole, Icterus parisorum, originally named after the Paris brothers. Most of the others have descriptive Latin names.
Cassin’s Auklet (P. aleutica) and Cassin’s Kingbird (T. vociferans) were first described, respectively, before Cassin was born and when Cassin was just thirteen. Clearly the original describers did not intend to honor Cassin. However, by the 1886 AOU checklist both carried the Cassin moniker, though there is no record that I could find how or why that came to be (and even a co-author of the auklet’s Birds of North American species account didn’t know the answer).
Interestingly, two species have Latin names derived from indigenous words: pipixcan of Franklin’s Gull is Nahuatl for the gull or possibly the Aztec region in Mexico; sasin of Allen’s Hummingbird is Noo-chah-nulth (Nootka) for hummingbird, a reference to when the species was lumped with Rufous Hummingbird. The gull was described twice, which is how it ended up honoring Franklin. The hummingbird was split, providing an opportunity for another name. Ironically, Allen’s, not Rufous, Hummingbird always bore the Noo-chah-nulth name which emanates from Vancouver Island.
Correlated with the timing, a clear regional pattern emerges. Because the common eastern species had already been described a century earlier, western species with honorific names outnumber eastern ones nearly ten to one. A map plotting the year of description with the core of the species’ range mimics European expansion – and ethnic cleansing of Native Americans – across the continent in the nineteenth century.
As for the honorees, most were naturalists, either doing field work or promoting it (70 of 80), most were Americans (55 of 80) or at least had spent some time in North America (add ten more). French collectors dominated the hummingbirds.
Only six species honor women—or girls. Blackburne is the early outlier, a British naturalist honored by one of the German ornithologists in the late 1700s. Neither spent time in North America; the type specimen comes from South America. Curiously, the eponymic title is not in the possessive form (e.g. Blackburne’s Warbler). For reasons unknown to me, the Latin name was changed from blackburniae to fusca before 1910.
During the surge of honorifics in the mid-1800s, the only females honored were friends or family, and they only got first names. Anna, age 27 when the hummingbird was named in her honor, was the wife of an ornithologist and a lady-in-waiting in the court of Emperor Napoleon III’s wife. She was described by Audubon as a “beautiful young woman, not more than twenty, extremely graceful and polite.” Virginia was the wife of William Anderson, the original collector; she was honored by Baird at Anderson’s request. Grace, also honored by Baird, was Elliot Coues’s sister. Lucy, age 13, honored by James G. Cooper, was Baird’s daughter.
We don’t return to female scientists – and last names – until the 1900s, with Scripps, who was honored in 1939, and her bird didn’t reach species status until 2012.
Most of the honorees have no obvious indications of a checkered past (66 of 80), though most of these were quite comfortable associating with, or honoring with bird names, those who were slaveholders, white supremacists, or actively involved in killing or removing Native Americans, even while these actions were hotly debated and contested at the time among whites—and universally opposed by Blacks and Native Americans. As early as 1920, the entire concept of eponymous bird names was challenged.
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The dominance of western species among honorific names with morally objectionable pasts is no accident. Many of the ornithologists working in the West were attached to US military expeditions or other surveys of colonization, such as railroad surveys or the border survey after the Mexican-American War. They often served as doctors while doing naturalist work on the side. Many were likely looking for a vehicle to get into the field.
Others were active combatants, with the naturalist work coming on the side. William Clark, after the famous 1803 expedition, played a leadership role in the ethnic cleansing of Native Americans for three decades. Abert served as a soldier under John Fremont’s Third Expedition and likely participated in the Sacramento River massacre of Wintu families, deemed horrific by their contemporaries. General Winfield Scott, not a naturalist in any way, was honored by Couch with an oriole precisely for his role as the Commanding General of the US Army, which included overseeing the arrest, detainment, and expulsion of the Cherokee during the Trail of Tears.
But why did they turn to honorific naming when their predecessors did not? Was it the spirit of conquest, of erasing the former occupants of the land, that gave them the presumption and bravado to name even the birds after each other? After all, mountains, rivers, valleys, and large regions of land were all being re-named and claimed as European.
White supremacy permeated the sciences. Crania Americana was published between 1839 and 1849 by Samuel Morton, a colleague of several of the naturalists. Townsend collected skulls for him. During the same era, to support the Indian Removal Act and other similar policies, the Mound Builder Myth, asserting that Native Americans were not actually native, but that North America was originally populated by Europeans, was widely taught in grade schools across the land. The land was originally European, so the story went. This theory was eventually laid to rest thanks to the efforts of John Wesley Powell, but only after most Natives were detained in concentration camps.
In short, the scientific fields were permeated with white supremacy and a sense of white ownership. Ornithological research found itself interlocked with US military endeavors and, on the Western frontier, far from Eastern progressive voices advocating abolition and respect for slaves and Natives. In this climate, honorific naming eventually ran amok, often foundering on the rocky shores of slavery and ethnic cleansing, aka manifest destiny.
Caveat: Researching the origins of species’ names is challenging, especially for those described more than once or subject to taxonomic revisions. Corrections from knowledgeable readers are much appreciated. Regardless of errors, the larger picture, the trends regarding time and place, still hold.
Note: Updated June 2, 2021 to include Blackburnian Warbler.
There are a lot of reasons why I’m moving from California to Washington, including family and other personal considerations. But one reason, one big reason, is California’s rapidly changing climate.
It was late February in the Coast Range of northern California when I was wearing shorts and a t-shirt. Dust swirled around my car in the dirt parking lot at Cold Canyon. The car thermometer, warmed by a sun that felt imported from Palm Springs, said 87 degrees; it was actually only 77. A hint of ash, omnipresent since The Fire last summer, remained in the air.
The hillsides were green with the new growth of non-native grass, which was responding to a recent heavy rain. That was deceptive. More than half the rain we’d had in the previous eight months came in that single event. We had six inches of rain in all of 2020. Looking beyond the grass, nearly every tree – blue oaks and gray pines – on the hillsides was dead, burnt black and orange monuments to a previous era. For our local blue oak woodland, that era ended last year and, given that recruitment of saplings is unlikely due to heat, fire, and cattle, it was an era that will never return.
Massive die-offs are eliminating blue oaks from the southern third of their range. Black oaks are marching up the Sierra, displacing Ponderosa pine, which are marching up, displacing firs. Everyone is on the move. Oak woodlands are becoming oak savannahs, oak savannahs are becoming grasslands, grasslands are becoming rocky high deserts. Arizonification is happening quickly, thru heat, drought, and ultimately, thru fire.
Virtually all of the east slopes of the Coast Range between San Francisco Bay and the Trinity Alps has burned in the past ten years. In the Sierra, one can practically predict where the next fire catastrophe will happen, because it hasn’t burned yet (hint: Lake Almanor, Placerville, Arnold).
It was a beautiful day—for April. But February has become April, April has become May, and June, July, August, September, and even October and November have become unrecognizable. Every year more heat records are broken. Hottest summer, hottest month, most days over 100, most days over 90. The list goes on, each year breaking the records set the previous year. Weather data is normally highly variable; now it is a straight line—warmer and warmer. And smokier.
My cape honeysuckle and bougainvillea, both planted with a degree of optimism outside their recommended zone, used to die back so badly in the winter that each spring I was tempted to declare them dead and pull them out. Now they bloom year-round, looking like they’re in a courtyard at a hotel in the tropics. We haven’t had a real freeze in seven winters.
The songs of lesser goldfinches on my street are a depressing warning. I can’t take two steps outside without seeing or hearing a bird that reminds me that our climate has seriously changed. Western tanagers, house wrens, and turkey vultures are regular in winter now. The lesser goldfinches have come out of the arid hills and are quickly becoming one of the most ubiquitous nesting birds in Davis. (I know this definitively because one included an imitation of a canyon wren in its song.) What’s more, at least four Say’s phoebes, essentially a high desert species, are scouting for nests in town now. A fifth arrived on my block last week, singing as if on territory. They’ve been doing this for a few years and their numbers are growing.
I’m leaving. I’ve lived in California fifty-five years but it’s no longer the state I grew up in.
We’re headed to the Olympic Peninsula in Washington. We are fortunate to be able to do so.
I feel like a frog in a boiling pot. I’m getting out. I’m saying goodbye to California, but I feel it has left all of us without saying goodbye to anyone.
I do believe that Homo sapiens may ultimately win the climate battle and bring atmospheric CO2 back down to 300 ppm or something. But that’s a hundred years off. And there’s no guarantee we can stop the tide of Greenland and Antarctic ice melt to prevent sea level rise. In the meantime, in the next 50 to 100 years, it’s going to get a lot warmer. And we may ultimately lose New York City, Singapore, Mumbai, and every other low-lying coastal city. My new home is fifty feet above sea level. Well, probably forty-nine and a half now.
Two recent papers concluded that many breeding bird species in southern California and Nevada deserts have declined dramatically due to climate change.
In their abstract, Iknayan and Beissinger (2018) summarized, “We evaluated how desert birds have responded to climate and habitat change by resurveying historic sites throughout the Mojave Desert that were originally surveyed for avian diversity during the early 20th century by Joseph Grinnell and colleagues. We found strong evidence of an avian community in collapse.”
Of 135 species assessed (which included some wintering and migrating species, as well as breeding species), 39 had significantly declined; only one (Common Raven) had increased. This was in stark contrast to similar assessments they conducted of Sierra and Central Valley sites, where more species had increased than decreased and there were no overall declines (not to say there weren’t winners, losers, and range shifts within those regions).
Detailed analyses suggested less rainfall and less access to water was the primary driver. Habitat change only affected 15% of the study sites and was of secondary importance. They found no evidence of expansion of species from the hotter, drier Sonoran Desert (e.g. Phainopepla, Verdin, Black-throated Sparrow) into the Mojave Desert.
Consistent with a community collapse, declines were greatest among species at the top of food chain — carnivores such as Prairie Falcon, American Kestrel, and Turkey Vulture. Insectivores were the next most impacted, and herbivores the least. But the declines affected both common and rare species, both generalists and specialists.
A follow-up study by Riddell et al (2020), also involving Iknayan and Beissinger, focused on the thermoregulatory costs — the water requirements to keep cool — for the declining species. They found that “species’ declines were positively associated with climate-driven increases in water requirements for evaporative cooling and exacerbated by large body size, especially for species with animal-based diets.” Larger species get much of their water from the insects they eat. They estimated larger species would have to double or triple their insect intake to meet their water needs, though insect abundance is lowest July thru September.
Iknayan and Beissinger conclude, “Our results provide evidence that bird communities in the Mojave Desert have collapsed to a new, lower baseline. Declines could accelerate with future climate change, as this region is predicted to become drier and hotter by the end of the century.”
The ponds at the Davis Wastewater Treatment Plant have been one of the top birding spots in Yolo County for over 50 years. With 212 species reported via eBird, only two other sites in the county have recorded more (Yolo Bypass Wildlife Area and Davis Wetlands).
Here’s a short video clip from October 2020 illustrating the amazing bird life. A family of Sandhill Cranes walks among thousands of geese, ducks, and shorebirds while the calls of curlews filled the air. A Peregrine Falcon and a Northern Harrier buzzed past. Though the ponds are no longer part of the water treatment plant operations, they still collect rain water and provide habitat. Over 14,000 ducks have been counted on them during the annual Christmas Bird Count. The list of rarities includes everything from Slaty-backed Gull and Arctic Tern to Vermillion Flycatcher.
But it’s not too late to try to stop it. Here’s what you can do:
1. Call or email each City Council member and ask them to rescind their original vote. Their phone numbers are available here. We need three of them to overturn the original decision. Will Arnold has expressed regret for his vote and Gloria Partida was skeptical at the outset. We also may have an opportunity after the election with new Council member to overturn this decision.
Gloria Partida — firstname.lastname@example.org
Will Arnold — email@example.com
Dan Carson — firstname.lastname@example.org
Brett Lee — email@example.com
Lucas Frerichs — firstname.lastname@example.org
2. Call or email Valley Clean Energy Alliance board members and ask them to reject the bid from BrightNight for a new power contract. Their emails are here:
Angel Barajas — email@example.com
Dan Carson — firstname.lastname@example.org
Lucas Frerichs — email@example.com
Gary Sandy, Vice Chair — firstname.lastname@example.org
Don Saylor — email@example.com
Tom Stallard, Chair — firstname.lastname@example.org
Birds, because of their mobility, are considered to be fairly adaptable to climate change. They evolved in the aftermath of two of the world’s most catastrophic warming events (the K-T extinction and the Paleocene-Eocene Thermal Maximum), spreading to the Arctic, crossing continents, and evolving along the way. While those warming events took place over tens of thousands of years, the current warming is happening in the space of a couple hundred, with noticeable changes in climate within the lifespan of a single bird.
There will be winners and losers. Generalists, and species that enjoy warmer weather, are likely to be winners. Those with narrow food or habitat requirements, especially those dependent on the ocean or the Arctic/Antarctic, will likely be losers. Although counter-intuitive, it is primarily non-migratory resident species that seem to be more adaptable to a changing climate.
Studies of climate impacts on western North American birds using past data are limited, but some focusing on California were recently published. Iknayan and Beissinger (2018) showed that, over the last 50 years, “bird communities in the Mojave Desert have collapsed to a new, lower baseline” due to climate change, with significant declines in 39 species. Only Common Raven has increased. Furnas (2020) examined data from northern California’s mountains, showing that some species have shifted their breeding areas upslope in recent years. Hampton (myself) (2020) showed increases in many insectivores, both residents and migrants (from House Wrens to Western Tanagers), in winter in part of the Sacramento Valley over the last 45 years. These changes, particularly range shifting north and out of Southwest deserts, is predicted for a wide number of species.
The invasion of the Pacific Northwest
Here I use Christmas Bird Count (CBC) data to illustrate that some of California’s most common resident birds have expanded their ranges hundreds of miles north into Oregon, Washington, and British Columbia in recent years. The increases are dramatic, highly correlated with each other across a wide range of species, and coincide with rapid climate change. They illustrate the ability of some species to respond in real time.
In parts of Oregon and Washington, it is now not unusual to encounter Great Egret, Turkey Vulture, Red-shouldered Hawk, Anna’s Hummingbird, Black Phoebe, and California Scrub-Jay on a single morning—in winter. A few decades ago, this would have been unimaginable. Some short-distance migrants, such as Townsend’s Warbler, are also spending the winter in the Pacific Northwest in larger numbers.
The following graphs, showing the total number of individuals of each species seen on all CBCs in Oregon, Washington, British Columbia, and (in one case) Alaska, illustrate the range expansions. Adjusting for party hours scarcely changes the graphs; thus, actual numbers of individuals are shown to better illustrate the degree of change. The graphs are accompanied by maps showing predicted range expansions by the National Audubon Society, and recent winter observations (Dec-Feb) from eBird for 2015-2020.
These range expansions were predicted, though in some cases the recent trends exceed even projected scenarios under 3.0C increases in temperature.
Average nationwide winter temperatures deviation from average.
Great Egrets on Oregon CBCs have increased from near zero to nearly 900 on the 119th count (December 2018 – January 2019).
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But their expansion, which took off in the early 1990s into Oregon, is now continuing in Washington, with a significant rise beginning in the mid-2000s. Great Egrets occur regularly in southern British Columbia, but so far have eluded all CBCs.
They have not quite fulfilled the full range predicted for a 1.5C increase, but are quickly on their way there.
Turkey Vultures began increasing dramatically in winter in the Sacramento Valley of California in the mid-1980s, correlated with warmer winters and a decrease in fog. Prior to that, they were absent. Now, over 300 are counted on some CBCs. That pattern has been repeated in the Pacific Northwest, though about 20 years later. Both Oregon and British Columbia can now expect 100 Turkey Vultures on their CBCs. Curiously, Puget Sound is apparently still too cloudy for them, who prefer clear skies for soaring, though small numbers are regular in winter on the Columbia Plateau.
Red-shouldered Hawks have increased from zero to over 250 inviduals on Oregon CBCs, taking off in the mid-1990s.
Twenty years later, they began their surge into Washington. It’s a matter of time before the first one is recorded on a British Columbia CBC.
While their expansion in western Washington is less than predicted, their expansion on the east slope, in both Oregon and Washington, is greater than predicted. This latter unanticipated expansion into the drier, colder regions of the Columbia Plateau is occurring with several species.
If this invasion has a poster child, it’s the Anna’s Hummingbird, which, in the last 20 years, have become a common feature of the winter birdlife of the Pacific Northwest. Their numbers are still increasing. While much has been written about their affiliation to human habitation with hummingbird feeders and flowering ornamentals, the timing of their expansion is consistent with climate change and shows no sign of abating. Anna’s Hummingbirds are not expanding similarly in the southern portions of their range. The sudden rate of expansion, which is evidenced in most of the species shown here, exceeds the temperature increases, suggesting thresholds are being crossed and new opportunities rapidly filled.
The expansion of the Anna’s Hummingbird has now reached Alaska, where they can be found reliably in winter in ever-increasing numbers.
The range expansion of the Anna’s Hummingbird has vastly outpaced even predictions under 3.0C. In addition to extensive inland spread into central Oregon and eastern Washington, they now occur across the Gulf of Alaska to Kodiak Island in winter.
Non-migratory insectivores seem to be among the most prevalent species pushing north with warmer winters. The Black Phoebe fits that description perfectly. Oregon has seen an increase from zero to over 500 individuals on their CBCs.
With the same 20-year lag of the Red-shouldered Hawk, the Black Phoebe began its invasion of Washington.
The figure below illustrates two different climate change predictions, using 1.5C and 3.0C warming scenarios. While nearly a third of the Pacific Northwest’s Black Phoebes are in a few locations in southwest Oregon, they are increasingly populating the areas predicted under the 3.0C scenario.
Migrant species tend not to show the dramatic range expansions of more resident species – and short-distance migrants show more range changes than do long-distance migrants. Townsend’s Warblers, which winter in large numbers in southern Mexico and Central America, also winter along the California coast. Increasingly, they are over-wintering in Oregon and, to a lesser degree, Washington. This mirrors evidence from northern California, where House Wren, Cassin’s Vireo, and Western Tanager are over-wintering in increasing numbers. These may be next for Oregon.
Townsend’s Warblers are already filling much of the map under the 1.5C warming scenario, though their numbers on CBCs in Washington and British Columbia have yet to take off.
Due to problems with CBC data-availability, I have no graph for the California Scrub-Jay. Their northward expansion is similar to many of the species above. Their numbers on Washington CBCs have increased from less than 100 in 1998 to 1,125 on the 2018-19 count. eBird data shows they have filled the range predicted under the 3.0C scenario and then some, expanding into eastern Oregon, the Columbia Plateau, and even Idaho.
Other species which can be expected to follow these trends include Northern Mockingbird and Lesser Goldfinch. (See more on the expansion of the Lesser Goldfinch here.) White-tailed Kite showed a marked increased in the mid-1990s before retracting, which seems to be part of a range-wide decline in the past two decades, perhaps related to other factors.
Curiously, three of the Northwest’s most common resident insectivores, Hutton’s Vireo, Bushtit, and Bewick’s Wren, already established in much of the range shown on the maps above, show little sign of northward expansion or increase within these ranges. The wren is moving up the Okanogan River, and the vireo just began making forays onto the Columbia Plateau. Both of these expansions are predicted.
Likewise, some of California’s oak-dependent species, which would otherwise meet the criteria of resident insectivores (e.g. Oak Titmouse), show little sign of expansion. Oaks are slow-growing trees, which probably limits their ability to move north quickly. Similarly, the Wrentit remains constrained by a barrier it cannot cross—the Columbia River.
Call it the invasion of the Northwest. Call it Californication. Call it climate change or global warming. Regardless, the birds of California are moving north, as predicted and, in some cases, more dramatically than predicted.
Of the top 20 birding sites in the entire United States, based on the number of species reported on eBird, six of them are in south Texas. Two of them, Bentsen-Rio Grande Valley State Park and Santa Ana National Wildlife Refuge, are threatened by Trump’s proposed wall.
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The map above, taken from an excellent article illustrating all of the natural resources at risk from California to Texas, includes the bird totals for the eBird hotspots associated with the at-risk parks and wildlife refuges. The wall is often constructed hundreds of yards north of the actual border (the Rio Grande River). It typically includes a swath of cleared land on each side of it. At Bentsen and Santa Ana, the wall threatens to destroy critical remaining habitat and strand the parks in “no-man’s land”, preventing public access. Dozens of articles have been written regarding the impacts to everything from butterflies to ocelots.
Sabal Palm is unique, in that the natural area is south of the wall. Visitors pass thru the wall in order to visit the park. However, there is no guarantee this arrangement will be made at other sites. Should public access be denied at Bentsen, the park could revert back to the Bentsen family per a historical agreement. The national wildlife refuges are especially at risk. As they are already federal properties, the Administration doesn’t have to deal with acquiring private property. Thus, they are the easiest places to build.
Window strikes kill hundreds of millions of birds each year. It’s a terrible feeling when you’ve set up a feeder just so you can watch the birds and it becomes a death trap, luring birds into food, only to be followed by a sharp “thunk” against your window, resulting in a stunned and sometimes dead bird.
My falcon decals look great from the inside, but they are nearly impossible to see from the outside. Since they don’t move, they don’t attract attention. They did little to stop window strikes.
Here I present one solution from my backyard. The key is something in front of the window that allows the birds to see it and realize what it is. Moving objects, like ribbons that move in the wind, work best. Still objects, like falcon decals and plastic owls, work poorly. Additionally, the maximum range of effect of a window marker is only about 18 inches. I’ve had birds hit my window within 18 inches of the falcon decoy.
Here is my solution, which is quite effective. Tack a shiny ribbon to the top middle of each window, hanging down most of the length of the window. I had a name brand mylar ribbon designed for the purpose (probably a Father’s Day gift), but any shiny ribbon will probably work. There are other similar brands on Amazon. The key is that it moves in the slightest breeze, reflecting off and revealing the window behind it.
This 8-second video illustrates how the slightest wind moves the ribbons, making the windows apparent. Note the falcon decals are still there, just hard to see.
Finally, here’s a view from inside the house with the ribbons in place. From the inside, they are much less noticeable than the decals. From the outside, it’s a different story.
Another thing to experiment with is the placement of your feeders. I once hung a thistle feeder very near the windows. This resulted in several goldfinch deaths, as they tend to flush from the feeder in a fast direct flight. I moved the feeder back ten feet, which made a huge difference, apparently giving them time to see their options while flushing.