The Eastern Towhee, a bird of scrub and thickets, is a common resident in the southeast United States. One subspecies migrates north in summer.
They are a prime example of a species that is considered “Least Concern” by the International Union for Conservation of Nature (IUCN), but “High Risk” in National Audubon’s assessment of birds under climate change. In their 3.0 C scenario, they predict it would lose 83% of its current breeding range, while gaining only 23%.
These projections are consistent with recent literature showing poleward shifts of species ranges– of the northern edge of their range, of the southern edge, and of their range’s geographic center. The predictions for Eastern Towhee are among the most dramatic.
Recent research also suggests that non-migratory and short-distance migrants are more adaptable to climate change than are long-distance migrants, and more able to shift their ranges. Indeed, we are already seeing that with Eastern Towhee. The Audubon projections appear to be in progress.
Based on Breeding Bird Survey (BBS) data, the Eastern Towhee breeding population in Florida has declined over 50% since the late 1990s. The timing of this is consistent with worldwide ecological shifts which began in the mid-1980s.
The white-eyed subspecies appears to be already in trouble. eBirders in Florida in May and June are encountering the species half as often as they were just six years earlier.
Not all range shifts are due to climate. As a scrub specialist, the Eastern Towhee prefers habitat that is in the act of regrowth, such as after a fire or being cleared. But they don’t want a forest either. To quote the Birds of the World species account for Eastern Towhee: “As farmland is abandoned, successional changes produce suitable midseral habitats that towhees favor, and their numbers increase. But, successional time is against towhees, and their numbers decrease as seres age.” That may be the explanation for the Georgia data (orange dots), which show a decline in the late 60s and early 70s, possibly due to forest growth or land clearance for development, and then a leveling off.
As the climate warms, many species are expanding north and/or declining in the southern part of their range. But these need not happen simultaneously. Opportunities for suitable habitat may open doors in the north, and doors may close in the south, at different times. There is evidence of Eastern Towhee expansion in Minnesota, but look at the vertical axis; it does not compare with the losses in Florida.
In Florida, the white-eyed subspecies faces extinction based on National Audubon’s 1.5C scenario. They appear to have declined dramatically in the past two decades.
Backyard bird feeders bring nature close to people, increase appreciation for the natural world, and, in winter, help birds survive. But research also documents some adverse effects, such as the potential to spread avian diseases and to inflate the population of nest predators. There’s a lot of attention on the former, but the latter issue probably does a lot more harm.
Close to half of all bird nests fail due to predation. Corvids (ravens, crows, jays, and magpies) play a big part in that; they are among the most voracious nest predators, taking other birds’ eggs and chicks. Squirrels and rats are also major nest predators. Open cup nesters are especially vulnerable.
Corvids are part of the natural ecosystem, but the problem goes beyond “natural” because many corvid populations are artificially higher due to anthropogenic food subsidies – human garbage, bird feeders, scraps, etc. In short, corvids are often what biologists call human-subsidized predators. Millions of restoration dollars have been spent trying to protect declining species from corvids (e.g., Marbled Murrelet, Least Tern, Snowy Plover, Piping Plover, and Desert Tortoise). Additionally, local populations of otherwise common species are known to be at risk from corvids (e.g. Common Murre, Red-capped Plover). And research shows they can depress bird populations in residential neighborhoods.
By providing food, humans have a remarkable ability to inflate corvid populations. Brunk et al (2021) examined efforts to reduce Steller’s Jay densities at campgrounds in Big Basin State Park in California in order to protect endangered Marbled Murrelets. Jay densities within the campgrounds were nine times higher than in the surrounding forest. Previous research documented that the Steller’s Jay juvenile survival rate in the campgrounds was over 90%, possibly the highest figure ever recorded for a bird; 50% is more typical. After the installation of new garbage cans, food lockers, as well as extensive camper education, the jays disbursed and densities fell to natural levels. I’m proud to have been a part of that project.
There is a long list of papers that show the depressing impact that high numbers of jays and crows can have on the productivity and populations of other birds. Here are a few examples focusing on songbirds:
Jokimäki et al (2020) looked at nest predation rates in nine European cities, finding that cats and corvids had a significant impact on other birds’ nest success in urban and suburban areas.
Hanmer et al (2017) experimented with artificial thrush nests with quail eggs placed in a natural context but in the vicinity of bird feeders that were offering peanuts. Nests near active feeders were far more likely to be depredated than nests that were far away from peanut feeders. The predators were jays, magpies and squirrels.
Malpass et al (2017) conducted an experiment in seven neighborhoods in Ohio, adding bird feeders during the breeding season to some areas. The neighborhoods with the most feeders had triple the numbers of American Crows and Brown-headed Cowbirds compared to the neighborhoods with the least feeders. American Robin nest success fell to just 1% in the high-feeder neighborhoods, compared to 34% in the areas with the fewest feeders. Northern Cardinals, perhaps because their nests are generally more hidden, managed to avoid these impacts.
Jokimäki and Huhta (2000) looked at bird assemblages across urban, suburban, and natural areas in Finland. They found a dramatically higher nest predation rate in the managed urban parks (53 to 92%) compared to more wild suburban parks (22 to 67%). Additionally, most ground nesting species simply avoided the urban areas. Crows and jays were listed among the primary nest predators.
Stoate and Szczur (1994) reported that corvid removal led to dramatic improvement in the hatching success of thrushes and Chaffinch. Some ground-nesting and thicket-nesting species (Dunnock, Yellowhammer, etc) were unaffected by corvids.
Slagsvold (1980) found that Fieldfare populations (the Scandinavian counterpart to the American Robin) doubled after the removal of Carrion Crows (the counterpart to the American Crow). Smaller songbirds also sought protection and nested near Fieldfares. Many songbirds based nest site decisions on the presence or absence of crows.
There are several meta-analyses, studies of studies, that try to summarize the big picture. Most of these include a wide array of avian and mammalian predators—and most focus on ground-nesting shorebirds and gamebirds, where conservation and hunting interests fuel research funding.
Cote and Sutherland (1997) is typical. It reviews 29 studies, focusing on avian (crows, gulls, grackles) and mammalian (foxes, skunk, marten) nest predation on gamebirds (pheasants, quail, etc) and some songbirds. Removing predators had a large positive effect on the prey species’ productivity and post-breeding population.
It is important to add that not all studies have found a link between corvids and reduced densities of other birds. This seems to be truer in rural contexts. Furthermore, impacts seem to be species-specific. I can imagine, for example, that chickadees and nuthatches, which nest in small cavities, are relatively protected from jay and crow nest predation.
Finally, there is Madden et al (2015), a meta-analysis focusing exclusively on corvids, which caused some confusion. It focused mostly on impacts to gamebirds and did not include jays. It is curious because its summaries and conclusions do not match the data they present. Based on their data, Madden could have concluded with this:
“The presence of crows had a negative impact on other bird species’ productivity in 66% of cases. In 10% of cases, a decline in abundance was also detected. These results suggest that, in certain contexts and for many species, large crow populations may create population sinks or actual declines in the populations of other birds.”
That would have been consistent with other studies, but the paper didn’t end that way. Instead, it summarized the data in ways to bury important results, failed to include some well-known cases involving endangered species, and concluded with this head-scratching statement:
“Our review shows that although there is no consistent pattern with regard to corvid impacts on other bird species, the most commonly reported effect is that corvids have no negative impact on prey species abundance or productivity. When combining experimental and correlative studies (326 cases), most cases (81%, n=264) showed no negative influence of corvids on either abundance or productivity of birds…”
“Most commonly” meant more than 50%. Because they lumped magpies with crows, and lumped abundance with productivity, they were able to say this (barely). I am astonished this paper passed thru peer review with this sweeping, and deceptive, summary intact. Some backyard birders, in defense of laying out a smorgasbord of peanuts on their back patio, have cited this paper on social media.
There’s a lot more I can say about this paper, but suffice it to say their own numbers (see Table 4) imply that two-thirds of studies involving crows found significant impacts to other species’ productivity.
Conclusion: No peanuts, and use caution in the breeding season
Make no mistake—bird-feeders in winter are associated with increased bird survival. There are lots of papers about that. I feed birds in winter (but no peanuts!). In the spring and summer, however, when my juncos and sparrows have departed, those same feeders disproportionately attract jays, crows, and squirrels, as well as House Sparrows, Eurasian Starlings, and Brown-headed Cowbirds. It’s no wonder that open cup nesters have a tough time. In the summer, I maintain hummingbird feeders and have a little pond and fountain that attracts bathing warblers.
Bird feeding in spring and summer, and especially offering peanuts which disproportionately attract crows and jays, likely depresses the populations of other songbirds in the vicinity. This is probably a big reason why many suburban neighborhoods can be largely devoid of cup nesters (e.g. warblers, vireos, flycatchers) while still having cavity and thicket nesters (e.g. chickadees, nuthatches, wrens, towhees).
Benmazouz et al. 2021. Corvids in urban environments: A systematic global literature review. Animals.
Brunk et al. 2021. Reducing anthropogenic subsidies can curb density of overabundant predators in protected areas. Biological Conservation.
Cote and Sutherland. 1997. The effectiveness of removing predators to protect bird populations. Conservation Biology.
Hanmer et al. 2017. Provision of supplementary food for wild birds may increase the risk of local nest predation. Ibis.
Jokimäki et al. 2020. Land-sharing vs. land-sparing urban development modulate predator–prey interactions in Europe. Ecological Applications.
Jokimäki and Huhta. 2000. Artificial nest predation and abundance of birds along an urban gradient. The Condor.
Madden et al. 2015. A review of the impact of corvids on bird productivity and abundance. Ibis.
Malpass et al. 2017. Species-dependent effects of bird feeders on nest predators and nest survival of urban American Robins and Northern Cardinals. The Condor.
Shutt and Lees. 2021. Killing with kindness: Does widespread generalised provisioning of wildlife help or hinder biodiversity conservation efforts? Biological Conservation.
Slagsvold. 1980. Habitat selection in birds: on the presence of other birds species with special regard to Turdus pilaris. Journal of Animal Ecology.
Stoate and Szczur. 1994. Game management and songbirds. The Game Conservancy Review of 1993.
In contrast to continents, their ecosystems have much fewer moving parts. It’s not unusual for an island to have only a few plant species and often no land bird or mammal species. All of New Zealand has no native land mammals except for bats. The Channel Islands off southern California have only a native deer mouse and the island fox, and that’s only on some of the islands. Southeast Farallon Island has no native land mammals.
Yet islands are critical refuges for marine mammals and seabirds. It’s not unusual for over 90% of a single species to come from a single island, or just a few islands. For example, over 99% of the world’s Heermann’s Gulls breed only on Isla Raza, a 1.5 acre postage stamp in the Sea of Cortez. 95% of the world’s Black-vented Shearwaters breed only on San Benito Island off Baja California. 99% of the world’s Scripps’s Murrelets come from four islands off southern California and Baja California. And probably 50% of the world’s Ashy Storm-Petrels nest in burrows on a single hillside on Southeast Farallon Island. There are similar examples from all over the world.
Islands are vulnerable
This gets us to the final characteristic about islands; they are vulnerable to perturbations. Add one more moving part, and things can fall apart quickly. 75% of all bird, mammal, amphibian, and reptile extinctions have occurred on islands. More bird species have gone extinct on the Hawaiian Islands than on North America, South America, Europe, Africa, Asia, and Australasia combined.
The introduction of a single non-native species, such as rats or mice or cats or even rabbits, can result in massive changes to an island’s ecology, leading to the extinction of native or breeding species. Rats, arriving as stowaways on ships, are the number one cause of bird extinctions worldwide.
When I worked for the California Department of Fish and Wildlife, I was involved in over 300 restoration projects. The best one, the one with the most obvious and dramatic benefits, was when we eradicated non-native black rats from Anacapa Island. In addition to benefitting Scripps’s Murrelets, other seabirds such as Cassin’s Auklets began nesting on the island. The native lizard and even the sea stars and mussels and vegetation rebounded; the rats had been eating them all out of house and home.
The mouse problem on Southeast Farallon Island
Today, the non-native house mouse is impacting the Farallon Islands, one of the most important seabird nesting colonies south of Alaska.
Southeast Farallon Island, the main island, is infested with the mouse. In fact, there are higher densities of house mice there (more than one per square foot) than anywhere in the world. They eat seabird eggs and spread the seeds of non-native weeds around the island. More significantly, they attract a few migrating Burrowing Owls each fall. The owls, lost over the ocean, would normally stop on the island and then leave. But with the mice there, the owls stay and feast. When the winter rains come, the mouse population crashes and the owls begin to starve. Right about then, the declining Ashy Storm-Petrels begin returning to the island to nest. The owls catch them and stack them like cordwood. (In the most recent review, they were not listed an “endangered” based on the assumption that this project would be implemented.)
One thing to know about Ashy Storm-Petrels is that they are long-lived and slow-reproducing, like most seabirds. With the owls killing the adults, the storm-petrel population cannot recover.
Eventually, the owls starve to death. Then the mouse population rebounds in the spring and the cycle starts over, while the storm-petrel population spirals down. This happens every year on the Farallones.
Restoring the island thru mouse eradication
The plan is to eradicate the house mouse from Southeast Farallon Island, as we eradicated rats on Anacapa, and as has been done on over 600 islands worldwide.
The key is to get every last mouse—thousands of them. The only way to do this is to use rodenticide bait pellets. It will be done in the late fall, when the mouse population is at its low point, and when there are very few birds or mammals on the island. The few gulls present can be hazed with a laser (we’ve tested this). Any pellets that fall in the water will quickly decompose. On Anacapa, there were few secondary impacts; the benefits were far greater than we ever dreamed.
This project has been researched by dedicated biologists who know and love the island. We have explored all alternatives. (Contraceptives are not feasible. Introducing more raptors is NOT the answer.) We have researched possible harms and benefits. We’ve seen the amazing restoration of the ecosystem on Anacapa and on 600 islands worldwide, and we’ve worked with experts from New Zealand.
Here is a list of organizations and experts in support of the project:
National Audubon Society
American Bird Conservancy
The Nature Conservancy
California Native Plant Society
California Invasive Plant Council
David Ainley; author of Seabirds of the Farallon Islands; Ashy Storm-Petrel species account in Birds of North America
Peter Pyle; Institute for Bird Populations; author of Identification Guide to North American Birds and over 100 journal articles
Peter Harrison; author of Seabirds: An Identification Guide.
Mark Rauzon, Marine Endeavors; author of Isles of Amnesia: The History, Geography, and Restoration of America’s Forgotten Pacific Islands.
Hadoram Shirihai, Tubenoses Project; author of A complete guide to Antarctic wildlife: the birds and marine mammals of the Antarctic continent and the Southern Ocean; Whales, dolphins and seals: A field guide to the marine mammals of the world; The Macmillan birder’s guide to European and Middle Eastern birds.
Debi Shearwater, Shearwater Journeys, 44 years of offshore experience; co-author of Distribution patterns and population size of the Ashy Storm-Petrel
Dianne Feinstein, US Senator
Point Blue Conservation Science (formerly Point Reyes Bird Observatory)
Institute for Bird Populations
Pacific Seabird Group
Agreement on the Conservation of Albatrosses and Petrels
California Academy of Sciences
California Institute of Environmental Studies
Oiled Wildlife Care Network
International Bird Rescue
Golden Gate Audubon Society
Marin Audubon Society
Monterey Audubon Society
San Diego Audubon Society
Sequoia Audubon Society
Marin County Supervisor
Santa Cruz County Supervisor
National Refuge Association
Save the Bay
Farallon Islands Foundation
Citizens Committee to Complete the Refuge
Coastal Conservation Action Lab
Marin Conservation League
Natural Heritage Institute
South Georgia Heritage Trust
More details about the project and the public process
More details about the project, the process, and all relevant documents can be found here. The project will come before the California Coastal Commission on Dec 16, 2021. Letters to the Commission should be emailed to email@example.com. The deadline for letters is 5pm on Friday, December 10.
Related reports and videos
Here are some videos and reports about past similar projects:
At the American Ornithological Society (AOS) Congress on English Bird Names on April 16, 2021, a host of prominent organizations and individuals endorsed “bird names for birds”, a widespread effort to rename eponymous or honorific species names with more descriptive names, focusing on their physical or ecological attributes. For example, Wilson’s Warbler could become Black-capped Warbler, Townsend’s Solitaire might become Northern or Juniper Solitaire, and Kittlitz’s Murrelet would probably be re-named Glacier Murrelet.
While specific new names have not yet been chosen, representatives of the American Birding Association (ABA), National Audubon Society, as well as David Sibley and Kenn Kaufmann, all heartily endorsed developing a process to make the changes, noting that new names would engage a larger audience, contribute to greater equity and inclusivity among birders and the interested public, and could aid in public communication and conservation efforts.
The effort has grown out of the national reckoning on racial equality in the aftermath of the George Floyd killing. Movements to change names are underway with regard to parks, mountains, streets, other wildlife, and even rock-climbing routes. Current names generally go back to the eighteenth and nineteenth centuries during European expansion across North America and recall an era of conquest, when species and landforms were “discovered” – and some named after the individual who documented them, or after their friends and colleagues.
Sibley commented that, the more he learns about the names, “the more they cast a shadow over the bird” and “the name doesn’t mean just the bird anymore. They have baggage.” Out of respect for people and the birds, they “should not have to carry a reminder of our own fraught history.” Choosing between stability and respect, Sibley stated “I choose respect.”
Name changes over social justice concerns began last year when McCown’s Longpsur was changed to Thick-billed Longspur, after widespread outcry because McCown was a Confederate general and involved in the ethnic cleansing of Native Americans. A proposal in 2018 for that name change was roundly rejected.
Name changes for these reasons are not new; most birders can probably recall the switch from Oldsquaw to Long-tailed Duck in 2000. At that time, the American Ornithologists’ Union, the precursor to the AOS, asserted that the name change was not for reasons of “political correctness” but merely to conform with usage elsewhere.
Bird Names for Birds, a group of interested birders, was instrumental in reaching out to the larger organizations to participate in the congress. In their words, “Eponyms (a person after whom a discovery, invention, place, etc., is named or thought to be named) and honorific common bird names (a name given to something in honor of a person) are problematic because they perpetuate colonialism and the racism associated with it. The names that these birds currently have—for example, Bachman’s Sparrow—represent and remember people (mainly white men) who often have objectively horrible pasts and do not uphold the morals and standards the bird community should memorialize.” They describe such names as “verbal statues” that should be removed.
Jordan Rutter of Bird Names for Birds argued that, when reaching out to the public to protect an endangered sparrow, Bachman’s Sparrow has much less appeal than an alternative name rooted in local ecology that the public could identify with. Kaufmann pointed out that Bachmann was a pro-slavery white supremacist and that the species was formerly known as the Pinewoods Sparrow.
In the AOS’s own language, “The Community Congress opens the discussion on the complex issues around eponymous English Bird Names…. The specific aim of the Community Congress is to provide an opportunity for a broad range of stakeholders from the birding and ornithological community to share their viewpoints, including challenges and opportunities from their perspectives, to best inform future next steps to address the issue of naming birds after people.”
Keepers of various ornithological databases also participated in the Congress, including representatives for eBird, Christmas Bird Counts, Breeding Bird Surveys, and the Bird Banding Laboratory. While noting potential complications with name changes (and changes in four-letter banding codes), they all agreed the hurdles were not insurmountable. Indeed, name changes, as well as taxonomic lumps and splits, occur every year, with name changes being the simplest of the three to address in data management. eBird currently supports bird names in 47 languages, including 14 different versions of English. Where Americans see Black-bellied Plover, Brits see Grey Plover.
Marshall Iliff of eBird pointed out that the effort is also an opportunity to clean up old taxonomic messes, pointing out that Audubon’s Shearwater has been used for eleven different combinations of nine different taxa. In this case, he said, fresh names for specific taxa will provide clarity, not confusion. He embraced a worldwide effort to “dig into the essence of each species” to “find inspired and appropriate names.”
For now, the effort will be limited to primary eponymous English bird names. The effort will not include secondary names (e.g., American Crow, named after the continent, which was named after Amerigo Vespucci). Other problematic names, such as Flesh-footed Shearwater for a bird with pink feet, were not discussed.
Many suggested using Native names for species, though most stated this could be challenging because 1) names from Native languages may have been lost, or 2) most bird species’ ranges span multiple historic aboriginal territories and languages, creating a conundrum over which indigenous word to use. The exception to this is Hawaii, where indigenous names are already in widespread use. Among mammals, moose, raccoon, and skunk are all derived from Algonquian.
Looking at Version 8.0.8 (March 12, 2021) of the ABA Checklist, 115 of the 1,123 species, or a little over 10%, are named after people. Of these, 2 (Bishop’s Oo and Bachman’s Warbler) are considered extinct, and 20 others are Code 4 or 5, meaning they occur extremely rarely in the ABA area (though three of these are regular in Mexico, within the AOS area). The remaining 93 are all Code 1, 2, or 3, and can be expected to be seen in the ABA area regularly.
Here are the 113 non-extinct species from the ABA Checklist.
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).
CLICK ON GRAPHS TO ENLARGE
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.
Many think of Pink-footed Shearwaters as a relatively common bird on West Coast pelagic trips. I like to call them the “photographer’s shearwater” because they invariably offer great photo ops off the back corner of the boat. But they are considered endangered by Chile, threatened by Canada, and vulnerable by the International Union for Conservation of Nature (IUCN). They could easily be called the Chilean or even Isla Mocha Shearwater, as the entire world’s population comes from just three islands off the coast of Chile, 85% from Isla Mocha, and the remaining 15% from Santa Clara and Robinson Crusoe Islands in the Juan Fernandez group.
The very limited breeding range of the Pink-footed Shearwater is actually pretty typical of seabirds. To use some other West Coast species as examples, about half of the world’s Ashy Storm-Petrels come from one hillside on Southeast Farallon Island, 95% of the world’s Black-vented Shearwaters come from Isla Natividad off the Pacific Coast of Baja, and 99% of the world’s Heermann’s Gulls come from tiny Isla Rasa in the Sea of Cortez.
New research (Felis et al 2019), following 42 satellite-tagged birds, describes their seasonal movements from their breeding colonies in Chile. The new paper focused on threats at sea, especially bycatch by purse seine and drift net fisheries in Peru and Chile. CLICK TO ENLARGE.
And, typical of most seabirds, Pink-footed Shearwaters face some daunting challenges at their breeding colonies. At Santa Clara Island, non-native European rabbits denuded native vegetation, caused erosion, and kicked the shearwaters out of their burrows. When the rabbits were eradicated in 2003, the number of shearwater pairs went up 40% in three years. Native plant revegetation continues. On Robinson Crusoe Island, cattle trampled burrows, but a fence installed in 2011 now serves to keep them away from the colony. Shout out to Oikonos (a non-profit based in California, Hawaii, and Chile) and the Chilean national park service (called Corporacion Nacional Forestal or CONAF) for these projects.
But the real conservation challenge is at the shearwater’s main colony on Isla Mocha. Here, the local fishing community of 800 people are accustomed to harvesting shearwater chicks from their burrows. They’ve done so since the community began in the 1930s. And each pair lays only one egg a year. Chick harvesting has been illegal since 1998, but enforcement within a small community where everyone is friend or family is difficult.
Opening ceremonies of Copa Fardela soccer tournament.
Usually seabird restoration on breeding islands means restoring habitat or, more often, eradicating non-native rats, cats, mice, donkeys, you name it. But on Isla Mocha, Oikonos and CONAF have used another approach: outreach and education designed to reduce chick harvesting. The creative part is the strategy; the goal is for the islanders to identify with the shearwater as a symbol of their unique home, and thus want to protect them. Importantly, the project is led by a local Mochano, tapping into local values and local styles of communication. Thanks to the outreach efforts, school kids now flap their wings and enact dramas of the birds returning home. Adults play in the annual Copa Fardela (Shearwater Cup) soccer tournament.
This 48 minute video (in Spanish) documents the project. The Copa Fardela opening ceremonies, which features a children’s drama showing the shearwaters returning from the sea and producing a chick, begins around 42:00.
The fardela blanca, as they call it, is becoming their shearwater.
Pilot study area after three years of protection and restoration. Plant cover has gone from zero to 5% coverage, which offers enough cover for plover nests.
Sandy beach restoration is simple and effective. A three-acre pilot project at Santa Monica Beach by The Bay Foundation has lead to the first nesting by Snowy Plovers in Los Angeles region in nearly 70 years. This was in 2017. Since then, plovers have remained in the area but not yet re-nested.
This tiny project demonstrated “restore it and they will come.”
In fact, only two acres were actively restored thru not much more than a sand fence to build up sand hummocks and the distribution of native plant seeds to encourage dune vegetation. Add a key final ingredient: the absence of people and “beach grooming” (raking by trucks dragging large rakes). The third acre, on the ocean side of the restored section, was left un-groomed, a rarity in southern California. This leaves the “seaweed” (aka beach wrack), home to invertebrates and food to shorebirds. The cessation of beach grooming has already been correlated with an increase in shorebird foraging.
Furthermore, a new native plant species, or possibly a rare variant, was discovered at the site, having germinated on its on. For a very detailed report on the project, see the project website.
Snowy Plovers, a state and federally listed species, nest on sandy beaches, often putting them in conflict with human recreation.