The maddening truth: Feeding crows and jays harms other birds

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.

Crows and jays are especially fond of peanuts. Feeding them may depress other bird populations.

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.

The Research

Sign from Big Basin State Park. Corvid-control measures may include removal (killing or transferring elsewhere), camper education, improved food storage, and food waste management and garbage control, among other measures. There is a vast literature on the topic.

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.

In the Santa Cruz Mountains of California, eggs painted to look like Marbled Murrelet eggs are injected with a chemical that causes jays to vomit. This has trained some jays to avoid them.

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.

Hanmer et al (2017) examined the fate of artificial nests placed 5 and 10 meters away from feeders with peanuts, feeders with peanuts and a protective cage guard to exclude predators, and empty feeders. Approximately 90% of nests near empty feeders survived the first day, and 50% remained a week later. Near active peanut feeders, these numbers fell to 50% and just 10%. Guarded feeders only slightly reduced the impact.

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).

A good sentinel species may be the American Robin. If your neighborhood is devoid of breeding robins, and especially fresh juvenile robins, it may be due to excessive numbers of jays or crows.

References

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 2021, Shutt and Lees reminded us that we (humans and jays and warblers) are all connected:  “Generalised provisioning is enthusiastically promoted by many conservation organisations as a means to foster connection with nature and help wildlife. However, such a vast input of additional resources into the environment must have diverse, ecosystem-wide consequences. Direct effects…  are generally positive in leading to increased survival, productivity and hence population growth. However, we argue that the wider implications for the recipients’ non-provisioned competitors, prey and predators are underappreciated and have the potential to generate pervasive negative impacts for biodiversity.”

Restoring Southeast Farallon Island thru mouse eradication: Yes

Islands are special

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.

I’ve had the privilege of being on Southeast Farallon twice. It’s a magical place, home to thousands of seabirds and marine 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.

A new 4-minute video by Point Blue, summarizing the project.

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.

Scripps’s Murrelet nest success on Anacapa Island, before and after rat eradication.

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.

Here’s the 4-minute version about Anacapa restoration ten years after rat eradication.

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.

Locations of all of the recorded eradications of invasive vertebrates from islands for which location data are available (n=664). 

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.

Scripps’s murrelet on Anacapa.

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.

Supporters

Here is a list of organizations and experts in support of the project:

  • National Audubon Society
  • Audubon California
  • American Bird Conservancy
  • BirdLife International
  • 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
  • Island Conservation 
  • Oikonos
  • 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
  • Freshwater Life
  • Marin Conservation League
  • Marine Endeavors
  • 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 farallonislands@coastal.ca.gov. The deadline for letters is 5pm on Friday, December 10.

Related reports and videos

Here are some videos and reports about past similar projects:

Paper: The Global Islands Invasive Vertebrate Eradication Database: A tool to improve and facilitate restoration of island ecosystems

Article: 169 Islands that Offer Hope for Stemming the Extinction Crisis: Nearly 10% of island extinctions can be prevented through the eradication of invasive mammals on 169 islands

Anacapa Island Rat Eradication

Achieving Balance: Anacapa Island Ten Years After the Removal of the Black Rat (15 min)

Final Report: Responses by Breeding Xantus’s Murrelets Eight Years after Eradication of Black Rats from Anacapa Island, California  

All the reports on the Anacapa rat eradication

Short documentaries/reports of rodent eradications from islands around the world

Night Birds Returning: eradication of rats by Haida Nation and Parks Canada

The Rakiura Titi Islands Restoration Project: Community action to eradicate rats for ecological restoration and cultural wellbeing

Million Dollar Mouse: the eradication of mice from Antipodes Island

Macquarie Island Pest Eradication Project – documentary trailer

Rat Eradication – South Georgia Island

Eaten alive: Tristan Albatross chick massacred by invasive mice on Gough Island [WARNING: GRAPHIC]

Operation: Desecheo National Wildlife Refuge, Puerto Rico       

Southeast Farallon looking down from the summit. The steep hillside below hosts half the world’s population of Ashy Storm-Petrels.

Bird names matter: Top ornithologists and organizations endorse name changes for all species named after people

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.

MacGillivray’s Warbler was named by John James Audubon after his friend, William MacGillivray, a Scottish ornithologist who never came to America. Audubon also coined its Latin specific, tolmiei, to honor William Fraser Tolmie, a Scottish employee of Hudson’s Bay Company based at Fort Nisqually during the period of Native removal. Scientific, or Latin names, are subject to international rules and are not the focus of this process.

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.

An FAQ, full list of the panelists, and a video of the Congress can be found at the AOS English Bird Names website. The direct link to the video is here.

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.

The Bird Names for Birds website includes bios of various people memorialized with bird names. For example, Townsend (of the solitaire, warbler, and storm-pretrel) collected Native skulls for his friend Samuel Morton, author of Crania Americana. The November 2020 issue of Birding magazine focused on name changes, with a strong endorsement by ABA President Jeffrey Gordon and a longer article providing historical background. It is available here for ABA members.

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.”

The AOS Congress on English Bird Names was superbly moderated by José González, providing a model for the process ahead.

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.

Does Lawrence’s Goldfinch deserve a better name?

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.

Ross’s Goose

Steller’s Eider

Stejneger’s Scoter

Barrow’s Goldeneye

Gambel’s Quail

Erckel’s Francolin

Clark’s Grebe

Vaux’s Swift

Rivoli’s Hummingbird

Anna’s Hummingbird

Costa’s Hummingbird

Allen’s Hummingbird

Xantus’s Hummingbird

Ridgway’s Rail

Wilson’s Plover

Temminck’s Stint

Baird’s Sandpiper

Wilson’s Snipe

Wilson’s Phalarope

Kittlitz’s Murrelet

Scripps’s Murrelet

Craveri’s Murrelet

Cassin’s Auklet

Sabine’s Gull

Bonaparte’s Gull

Ross’s Gull

Franklin’s Gull

Pallas’s Gull

Belcher’s Gull

Heermann’s Gull

Forster’s Tern

Salvin’s Albatross

Wilson’s Storm-Petrel

Swinhoe’s Storm-Petrel

Leach’s Storm-Petrel

Townsend’s Storm-Petrel

Tristram’s Storm-Petrel

Murphy’s Petrel

Fea’s Petrel

Zino’s Petrel

Cook’s Petrel

Stejneger’s Petrel

Bulwer’s Petrel

Jouanin’s Petrel

Parkinson’s Petrel

Cory’s Shearwater

Buller’s Shearwater

Newell’s Shearwater

Bryan’s Shearwater

Audubon’s Shearwater

Brandt’s Cormorant

Cooper’s Hawk

Steller’s Sea-Eagle

Harris’s Hawk

Swainson’s Hawk

Lewis’s Woodpecker

Williamson’s Sapsucker

Nuttall’s Woodpecker

Nutting’s Flycatcher

La Sagra’s Flycatcher

Couch’s Kingbird

Cassin’s Kingbird

Hammond’s Flycatcher

Say’s Phoebe

Bell’s Vireo

Hutton’s Vireo

Cassin’s Vireo

Steller’s Jay

Woodhouse’s Scrub-Jay

Clark’s Nutcracker

Bewick’s Wren

Pallas’s Leaf Warbler

Blyth’s Reed Warbler

Pallas’s Grasshopper-Warbler

Middendorff’s Grasshopper-Warbler

Townsend’s Solitaire

Bicknell’s Thrush

Swainson’s Thrush

Bendire’s Thrasher

LeConte’s Thrasher

Sprague’s Pipit

Pallas’s Rosefinch

Cassin’s Finch

Lawrence’s Goldfinch

Smith’s Longspur

McKay’s Bunting

Pallas’s Bunting

Botteri’s Sparrow

Cassin’s Sparrow

Bachman’s Sparrow

Brewer’s Sparrow

Worthen’s Sparrow

Harris’s Sparrow

Bell’s Sparrow

LeConte’s Sparrow

Nelson’s Sparrow

Baird’s Sparrow

Henslow’s Sparrow

Lincoln’s Sparrow

Abert’s Towhee

Bullock’s Oriole

Audubon’s Oriole

Scott’s Oriole

Brewer’s Blackbird

Swainson’s Warbler

Lucy’s Warbler

Virginia’s Warbler

MacGillivray’s Warbler

Kirtland’s Warbler

Grace’s Warbler

Townsend’s Warbler

Wilson’s Warbler

Morelet’s Seedeater

There are also several hybrids (e.g. Brewster’s and Lawrence’s Warblers), prominent subspecies (e.g. Thayer’s Gull and Audubon’s Warbler), and superspecies (e.g. Traill’s Flycatcher) that are used in some databases. It is not clear if these will be addressed at this time.

Mojave Desert bird populations plummet due to climate change

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.”

They re-surveyed 61 sites originally surveyed by Grinnell teams in the early 20th century (primarily between 1917 and 1947).

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).

Figure 1B from Iknayan and Beissinger (2018). Every study site had fewer species than previously– on average each site had lost 43% of their species.

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.

Figure 1B from Iknayan and Beissinger (2018), which I’ve augmented with species labels from the database available in the supplementary materials. Other significant losers (red dots), in order of degree of decline, included Western Kingbird, Western Meadowlark, Black-chinned Sparrow, Lawrence’s Goldfinch, Bushtit, Ladder-backed Woodpecker, and Canyon Wren. The yellow dots are newly invasive species: Chukar, Eurasian Collared-Dove, Eurasian Starling, and Great-tailed Grackle.

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.

American Kestrels were among the biggest losers in the study, struggling to meet their cooling needs.

Intriguingly, they found that 22 species had actually declined in body size over the last century, consistent with Bergmann’s Rule, and had reduced their cooling costs up to 14%. These species fared better. Current climate change, however, is at least ten times more rapid than any previous warming event, during which many species evolved. They estimated cooling costs have already increased 19% and will reach 50% to 78% under most scenarios, far outstripping any species’ ability to evolve through the current rapid warming.

These results stand in stark contrast to the Pacific Northwest, where many of the same bird species (e.g. Anna’s Hummingbird, Turkey Vulture, Northern Mockingbird) are increasing. This is consistent with projections which generally show individual declines along species’ southern edge and expansions at the north edge of their range (see Audubon climate projection maps for individual species).

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.”

Keep Davis Water Treatment Ponds wild

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.

Earlier this year, the Davis City Council voted 4-1 to lease these ponds to BrightNight solar to convert these ponds into a solar array. Aside from the obvious risk of bird mortality from panel strikes, the project would eliminate one of the best bird habitats in the county. The City Council’s decision has been criticized for its impact on wildlife, for the improper process bypassing the Natural Resources Commission, and for its poor financial terms (the city got ripped off). Gloria Partida, Dan Carson, Will Arnold, and Brett Lee approved it. Only Lucas Frerichs voted against the deal.

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 — gpartida@cityofdavis.org
  • Will Arnold — warnold@cityofdavis.org
  • Dan Carson — dcarson@cityofdavis.org
  • Brett Lee — blee@cityofdavis.org
  • Lucas Frerichs — lucasf@cityofdavis.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 — angel.barajas@cityofwoodland.org
  • Dan Carson — dcarson@cityofdavis.org
  • Lucas Frerichs — lucasf@cityofdavis.org
  • Gary Sandy, Vice Chair — gary.sandy@yolocounty.org
  • Don Saylor — don.saylor@yolocounty.org
  • Tom Stallard, Chair — tom.stallard@cityofwoodland.org
  • Duane Chamberlain, alternate — duane.chamberlain@yolocounty.org
  • Xochitl Rodriguez, alternate — xochitl.rodriguez@cityofwoodland.org

3. Join the effort to increase transparency in City government that would have prevented this travesty. You can see more on that here.

The invasion of the Pacific Northwest: California’s birds expand north with warmer winters

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.

Recent studies

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.

Let’s begin with the climate. Canada as a whole has experienced 3.0C in temperature increases in winter. British Columbia has experienced an average of 3.7C increase in Dec-Feb temperatures since 1948. The greatest increases have been in the far north; increases in southern British Columbia, Washington and Oregon have been closer to 1.5C.

winter temps in Canada.jpg

Average nationwide winter temperatures deviation from average.

Great Egret

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

GREG OR graph.jpg

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.

GREG WA graph.jpg

They have not quite fulfilled the full range predicted for a 1.5C increase, but are quickly on their way there.

GREG maps.jpg

Turkey Vulture

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.

TUVU CBC graph.jpg

TUVU maps.jpg

Red-shouldered Hawk

Red-shouldered Hawks have increased from zero to over 250 inviduals on Oregon CBCs, taking off in the mid-1990s.

RSHA OR graph.jpgTwenty 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.

RSHA WA graph.jpg

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.

RSHA maps.jpg

Anna’s Hummingbird

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.

ANHU CBC graph.jpg

The expansion of the Anna’s Hummingbird has now reached Alaska, where they can be found reliably in winter in ever-increasing numbers.

ANHU AK graph.jpg

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.

ANHU maps.jpg

Black Phoebe 

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.

BLPH OR graph.jpg

With the same 20-year lag of the Red-shouldered Hawk, the Black Phoebe began its invasion of Washington.

BLPH WA graph.jpg

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.

BLPH maps.jpg

Townsend’s Warbler

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.

TOWA WA OR graph.jpg

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.

TOWA maps.jpg

California Scrub-Jay

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.

CASJ maps.jpg

Other species

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.

ANHU CBC graph.jpg

Magic from Isla Mocha: Pink-footed Shearwater conservation thru soccer and children’s theatre

PFSH1Many 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.

PFSHmigration

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.

PFSHcup

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.

PFSH2

Three-acre beach restoration project produces first nesting Snowy Plovers in nearly 70 years

SMbeach2

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.

SMbeach1

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.

0V2A5362 - Copy

Snowy Plovers, a state and federally listed species, nest on sandy beaches, often putting them in conflict with human recreation.

 

Two of the nation’s top birding spots threatened by the wall

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.

CLICK TO ENLARGE

RG border map

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.

 

 

The decline of Mountain Plovers in two graphs

I live in Yolo County, California, near Sacramento, where Mountain Plovers used to be an annual winter specialty. Searching for “dirt clods with legs”, we used to be able to find dozens of these unique shorebirds, sometimes over a hundred.

Those days are over. They are now “irregular”, meaning we don’t find them every year. We’ve struck out five of the last eleven years. Before that, we averaged a high count of 72 individuals. The first graph, built from records in the Yolo Audubon Society newsletter, emails to the Central Valley Birds listserv, and eBird, shows the high count each winter in Yolo County.

CLICK TO ENLARGE

MOPL Yolo

This second graph backs out a bit in space and time, looking at all Mountain Plovers worldwide, starting in 1980. They are a bird of the steppe, breeding mostly on the Great Plains between the Rockies and the flat lands, between the Canadian and Mexican borders. They winter in open country in a vast arc west and south of there, mostly in California, Arizona, New Mexico, and Texas.

MOPL cbc

All the Christmas Bird Counts nationwide, plus Mexico, averaged 728 birds per count thru 1994, but have never hit that mark since. Fewer than 200 individuals have been enumerated six of the last ten years. Adjusted for party hours, the graph basically looks the same.