Tag Archives: Climate Change

The Limpkin explosion: Like an invasive species in a changed world

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When this field guide was published in 1966, it was clear from the range map that, if I wanted to see a Limpkin in the US, I had to go to Florida.

Limpkin species account from 1966 Golden Field Guide.
The Limpkin range map from this popular 1966 field guide.

Growing up as a kid birder in the 1970s, this was one of my first field guides. I did not see my first Limpkin until decades later, in 2005. At that time, this freshwater snail and mussel specialist was still largely a Florida bird, with only a scattering of records north of their usual range.

Limpkin records north of Charleston, SC up thru 2015
Extra-limital records up thru 2015 (on eBird).

Between 1956 and 2015, eBird shows only 18 Limpkin sightings north of Charleston, South Carolina, though presumably some historical records have not been entered. Suffice it to say, a Limpkin in this region was a rarity. There were no Gulf Coast records in Texas, Louisiana, Mississippi, or Alabama, and only a few in the Florida panhandle west of the Tallahassee area.

Suddenly, all this changed. 2019 saw records from Illinois, Ohio, Virginia, and coastal Louisiana, in addition to dozens of records from Alabama, Georgia, and South Carolina. 2020 and 2021 added a scattering of records from Texas to Minnesota(!) to Maryland.

Extralimital Limpkin records across the eastern US in 2022 and 2023 (so far)
The remarkable Limpkin invasion so far.

In 2022, they simply exploded, with first state records across much of the continent. 2023 looks like it is picking up where last year left off.

This kind of rapid range expansion is typically seen in invasive species who are introduced into a new ecosystem. They either die out or explode. The Limpkin invasion, however, is not because they have just arrived in Florida — they are a native species — but because the ecosystem north of Florida has been transformed by a warming climate. It is as if they have landed on a new continent. They are following food — an invasive apple snail, as well as freshwater mussels.

This kind of poleward range expansion is predicted with climate change and has already been documented in hundreds of species. See, for example, my posts here:

And these scientific papers:

  •  Amano et al. 2020. Responses of global waterbird populations to climate change vary with latitude. 10: 959-964.Chen et al. 2011. Rapid range shifts of species associated with high levels of climate warming. Science 333 (6045): 1024-1026.
  • Devictor et al 2008. Birds are tracking climate warming, but not fast enough. Proc. R. Soc. B 275, 2743–2748.
  • Hitch and Leberg. 2007. Breeding distributions of North American bird species moving north as a result of climate change. Conservation Biology 21(2): 534-9.
  • Langham et al 2015. Conservation status of North American birds in the face of future climate change. PLoS ONE 10(9): e0135350.
  • La Sorte, F.A., and F.R. Thompson III. 2007. Poleward shifts in winter ranges of North American birds. Ecology 88(7):1803–1812.
  • La Sorte FA and Jetz W. 2012.  Tracking of climatic niche boundaries under recent climate change.  J Anim Ecol. 81(4): 914-25.
  • Prince, K. and B. Zuckerberg. 2015. Climate change in our backyards: the reshuffling of North America’s winter bird communities. Global Change Biology 21(2): 572-585.
  • Stephens et al 2016. Consistent response of bird populations to climate change on two continents. Science 352(6281): 84-7.
  • Virkkala, R. and A. Lehikoinen 2014. Patterns of climate-induced density shifts of species: poleward shifts faster in northern boreal birds than in southern birds. Global Change Biology 20: 2995–3003.

[A more complete list of academic papers about birds and climate change, with highlighted abstracts, is available in the Documents section of the Birds and Climate Change Facebook group.]

Like many birds with expanding ranges, Limpkins have been slowly recovering for decades from historic habitat impacts. There are historic records (from the 1800s) from Georgia, which they did not occupy again meaningfully until 1994. Likewise, expansion into the Florida panhandle was not until the late 1980s. This fits the typical climate change pattern, with ecosystem changes beginning in the mid to late 1980s. Range expansions, however, can be variable, with different species crossing ecological and climatological thresholds at different times.

eBird status map for Limpkin
The current eBird status map for Limpkins shows them as regular from Houston to North Carolina.

Like most of the species shifting their ranges, Limpkins are generally non-migratory, though may have some seasonal movements based on water levels and foraging conditions. Most the recent northern records have been in summer. It is not known if these birds return south in fall, or die, not being able to withstand the winter. That said, they are undoubtedly establishing year-round presence in southern Louisiana (where the first state record was in 2018), and likely from Texas to South Carolina. There are recent winter records from Iowa, Ohio, Oklahoma, Kentucky, and Virginia.

Limpkin southward expansion in Argentina and Chile
The Limpkin may be one of the few species expanding poleward in both directions.

The Limpkin also ranges south into Central and South America. Its scientific name is Aramus guaranauna, the latter part being the Tupí name for it. Until 2018, it did not occur south of Bahia Blanca, Argentina (at least not in eBird). Its core range ended closer to Buenos Aires. However, with a record in 2018 and four more in 2020 (based on eBird, which is used less in South America), it has spread up to 700 miles south, mimicking its poleward spread in North America. Northern Ohio is also about 700 miles from the Limpkin’s core range in Florida. The southernmost record, found dead at Puerto Deseado, Argentina, is at 47.8 degrees south latitude. The northernmost record, just north of Minneapolis, is at 45.2 north latitude. Like a true invasive species, one even crossed the Andes!

Limpkins are not the only waterbird associated with Southeast wetlands that are expanding north. Birders have noticed northward range expansions among the following:

  • White Ibis
  • Neotropic Cormorant
  • Black-bellied Whistling Duck
  • Purple Gallinule
  • Anhinga
  • Roseate Spoonbill
  • and even Snail Kite, Swallow-tailed Kite, and Mississippi Kite
Limpkin

Many of these are actually declining in Florida (or Louisiana) as they increase in the north.

Indigenous Americans relied on observations of nature to provide information about weather, or when certain plants could be planted or harvested, or when certain fish or game were available. An Anhinga in New York, a Purple Gallinule in Ohio, White Ibises nesting in New Jersey, all of which have happened in this year – would be portents of change – or doom.

Miners kept canaries in coal mines to monitor the atmosphere. A sick or dead canary meant dangerous conditions in the mine. But imagine their surprise if their mine was suddenly invaded by a hundred canaries. That would mean something was amiss outside. Limpkins are becoming those canaries.

BREAKING: One day after posting this, a first record for Ontario, Canada.

UPDATE IN JULY 2023: Limpkin has reached Pennsylvania.

eBird Trends maps reveal dramatic northward range shifts in Eastern species

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Over a year ago, on a webinar hosted by the Washington Ornithological Society (WOS), John Fitzpatrick of Cornell Lab of Ornithology teased us with some screenshots of eBird Trends maps. I was mesmerized. Now, they have been released here at the eBird Science tab. These remarkable maps illustrate population trends for each species across their range, showing exactly where they are increasing (blue dots) or decreasing (red dots).

They do more than that, actually. The color of the dot is correlated to the rate of change — the % change between 2007 and 2021. Dark blue means really increasing; dark red really declining. The size of each dot is correlated to the size of the population in that area (or “relative abundance” in eBird lingo). Big dots mean there’s a lot of birds there, regardless of whether they are increasing or decreasing. If you hover over a dot, the actual numbers pop up. White dots mean the data are inconclusive or show no trend. You can read more of the details at the site, and perhaps I’ll discuss methodology on a later post.

Here’s the amazing thing — each dot represents a 27 x 27 km (16.7 x 16.7 mile) grid square, so just a bit larger than a Christmas Bird Count circle, which are 15 miles in diameter. That’s a remarkable level of detail. I joke that there’s more information in these maps than in all the ornithological research in the last ten years. That’s an overstatement, of course, because professional ornithologists study things that eBirders don’t. Nevertheless, these maps take crowdsourced data collection and present it in ways that are instantly useful for understanding species population trends at a granular level. This has profound implications for targeting conservation.

So, on to my first of probably many posts looking at these maps. My first peruse suggests they strongly support what the climate change research has been saying — that resident and short-distance migrants are shifting their ranges north. Let’s start with some common eastern species.

CLICK TO ENLARGE

To examine each map in detail, go to eBird’s Trends page, type in the species name, and then click “Trends” to the right of the species’ name.

Until now, most of the published literature on northward range shifts have been meta-analyses with conclusions such as “non-migratory species are shifting north by so many km per year”, but no maps, nor even mention of species by name. Here, we get the details in bright colors, at the species and even county level. Wow.

A few observations. For many species, they are declining where they are still common (the red dots are large), and increasing where they are less common or even rare (the blue dots are small). This probably implies that their overall population is declining. It also suggests that climate change may be hurting them in the south faster than it is helping them in the north. It takes time to establish new populations, and/or the new regions may not be as suitable as their old home. Note also that each of these species have different transition isoclines (if that’s what one would call it). For example, Red-bellied Woodpecker and Carolina Wren are increasing in Tennessee, but Tufted Titmouse are declining there.

Here are some relevant papers regarding range shifts in eastern species, but again, these maps communicate their results in new and vibrant ways:

Prince, K. and B. Zuckerberg. 2016. Climate change in our backyards: the reshuffling of North America’s winter bird communities. Global Change Biology 21(2): 572-585. We conclude that a shifting winter climate has provided an opportunity for smaller, southerly distributed species to colonize new regions and promote the formation of unique winter bird assemblages throughout eastern North America.

Rushing, C.S. et al. 2020. Migratory behavior and winter geography drive differential range shifts of eastern birds in response to recent climate change. Proceedings of the National Academy of Sciences, 117(23), pp.12897-12903. Since the early 1970s, species that remain in North America throughout the year, including both resident and migratory species, appear to have responded to climate change through both colonization of suitable area at the northern leading edge of their breeding distributions and adaption in place at the southern trailing edges.

Saunders et al. 2022. Unraveling a century of global change impacts on winter bird distributions in the eastern United States. Global Change Biology We conclude that climate has generally governed the winter occurrence of avifauna in space and time, while [habitat] change has played a pivotal role in driving distributional dynamics of species with limited and declining habitat availability.

The maps also support some of my previous blog posts: such as the northward expansion of Northern Cardinal, Carolina Wren, Tufted Titmouse, and Red-bellied Woodpecker, the crash of Florida’s white-eyed Eastern Towhees, certain range expansions of the Lesser Goldfinch and California Scrub-Jay, the expansion of many species from California into the Pacific Northwest, and the failure of oak-dependent species (e.g. Oak Titmouse and Nuttall’s Woodpecker) to go anywhere.

In future posts, I’ll look at range shifts in resident birds of the West, the impact of California’s fires (many encompassing several of these Trends dots), long-distance migrants, nationwide species, waterbirds, and seabirds, among other things.

Heading south for winter, more birds are choosing the Pacific Northwest

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Many papers predict that bird ranges will shift northward with a warming climate (Wu et al 2018, Langham et al 2015).

Many studies have already documented that this is happening (Illán et al. 2014, Virkkala, R. and A. Lehikoinen 2014, Hitch and Leberg 2007, and La Sorte and Thompson 2007).

And some have documented poleward range shifts specifically for wintering ranges (Saunders et al 2022, Hampton 2019, Paprocki et al 2017, Prince and  Zuckerberg 2016, and Paprocki et al 2014).

I’ve previously written about an increase in insectivore bird species in winter associated with a warming climate in the Sacramento Valley. As the Putah Creek Christmas Bird Count (CBC) compiler, it was hard not to notice the trends. Cassin’s Vireo, Black-throated Gray and Townsend’s Warblers, and Western Tanagers were becoming more expected in winter. We had crossed a threshold; we didn’t get freezes anymore. My bougainvillea and cape honeysuckle, which previously clung to life in winter, were now growing and blooming year-round. Fruit and insects were available to these birds.

Now in Port Townsend, Washington, we set a local CBC record for Yellow-rumped Warblers last year. This caused me to take a closer look at the data, focusing on Passerines that are rare or uncommon, and at the northern edge of their wintering range. They are: Hermit Thrush, Cedar Waxwing, Lincoln’s Sparrow, White-crowned Sparrow, Orange-crowned Warbler, and Yellow-rumped Warbler. For each of these, the PNW is at the northern limits of their wintering range.

I looked at their numbers and trends on the Portland, Olympia, Seattle, Bellingham, and Vancouver BC CBCs since the 76th CBC (winter 1975-76). I’ve got more notes on my methodology at the end.

Results

All have increased since 1975, generally with the uptick beginning in the 1990s. Here are the results of my inquiry.

The range maps are from eBird’s Abundance Maps. Red=summer; blue=winter; purple=year-round; yellow=migration. The graphs show the birds per party hour across the five CBCs, taking the total number of birds and dividing by the total number of hours across all five counts.

Hermit Thrush

Hermit Thrush has been increasing at a rate of 4.2% per year across all the CBCs. It has been increasing across all five of the counts, most strongly in Vancouver (4.1% annual growth) and most tepid in Seattle (0.6%). It is most common on the Portland count, which has averaged 26 Hermit Thrushes per count since 2009.

Cedar Waxwing

Of the six species I focused on, Cedar Waxwing showed some of the most erratic growth, averaging only 2.5% per year. That said, it has been above average 8 of the last 9 years. To illustrate the unpredictable nature of waxwings, they have actually been declining on the Olympia (-2.3%/yr) and Vancouver (-4.1%/yr) counts. They are increasing the most on the Portland count (3.0%/yr).

Lincoln’s Sparrow

Lincoln’s Sparrow has been increasing steadily, from near zero, at an overall rate of 3.6% per year. To put this in perspective, these five CBCs tallied 5 or fewer individuals, summed across all counts, in each of the first five years of this analysis. In each of the last five years, these counts, in aggregate, tallied between 34 and 52 individuals. Growth has been strongest on the Olympia count (4.6%/yr) and weakest on the Bellingham count (1.7%/yr).

White-crowned Sparrow

Despite the eBird map, White-crowned Sparrow is a regular overwintering species in the PNW. The five counts, in aggregate, tally between 100 and 750 individuals each year. They’ve been increasing at a rate of 1.8% per year, strongest in Seattle (3.1%/yr) and weakest in Vancouver (-2.5%/yr, the only count with declining numbers).

Orange-crowned Warbler

Orange-crowned Warbler has seen dramatic increases, averaging 5.0% per year, highest in Olympia (7.2%/yr) and lowest in Bellingham (3.2%/yr). The numbers, however, are still small. Aggregate numbers across all counts were zero five of the first eleven years of this analysis (easily seen on the graph). Double digits were not reached until 1999. The last ten years, however, have averaged 15 individuals across all the counts, making this an expected species in winter now.  

Yellow-rumped Warbler

Yellow-rumped Warbler wins the award for poster child of species increasing in winter at the northern edge of their wintering range. They’ve been increasing at a rate of 5.3% per year. Interestingly, this growth is concentrated in the south. Portland (3.7%/yr), Olympia (3.4%/yr), and Seattle (6.1%/yr) have seen the most growth, while Bellingham (-0.5%) and Vancouver (-5.0%) have seen declines. Perhaps those Fraser River winds are too cold for warblers. 

Methodology

The data includes bird per party hour for the Portland, Olympia, Seattle, Bellingham, and Vancouver BC Christmas Bird Counts from the 75th count (winter 1975-76) to the 120th count (winter 2019-20). The 121st count was impacted by the pandemic.

CBC (and Breeding Bird Survey) data is uniquely advantageous for looking at long-term trends such as climate change, as they both go back many decades with generally similar effort over time (for certain well-established counts). Nevertheless, there were some issues with this data:

  • I did not use the Portland data from the 76th thru the 82nd count, due to aberrantly low party hours relative to later counts.
  • The following data was missing entirely from the Audubon CBC database: Olympia 76th, 77th, 78th, 84th, 104th, and 110th counts; and Seattle 91st count.
  • The following counts had no (or obviously incorrect) data for party hours: Portland 104th count; Bellingham 111th, 112th, and 119th counts. Because they did have bird numbers, I approximated the party hours based on their counts in nearby years. I used 230 party hours for the Portland count and 200 party hours for the Bellingham counts.

Other climate-related bird changes in the Pacific Northwest

I’ve previously blogged about climate change and birds in the Pacific Northwest:

The invasion of the Pacific Northwest: California’s birds expand north with warmer winters looks at northward range expansions of Great Egret, Turkey Vulture, Red-shouldered Hawk, Anna’s Hummingbird, Black Phoebe, Townsend’s Warbler, and California Scrub-Jay, with some discussion of others as well. Note that Townsend’s Warbler, as a migrant that winters rarely in the PNW, fits with the group of birds described in this post.

The song of the Lesser Goldfinch: Another harbinger of a warming climate looks at increasing records in the PNW in summer.

Mapping the expansion of the California Scrub-Jay into the Pacific Northwest looks at the steady range expansion of this non-migratory species.

References

Hampton, S. 2019. Avian responses to rapid climate change: Examples from the Putah Creek Christmas Bird Count. Central Valley Birds 22(4): 77-89.

Hitch and Leberg. 2007. Breeding distributions of North American bird species moving north as a result of climate change. Conservation Biology 21(2): 534-9.

Illán et al. 2014. Precipitation and winter temperature predict long-term range-scale abundance changes in Western North American birds. Global Change Biology, 20 (11), 3351–3364.

Langham et al 2015. Conservation status of North American birds in the face of future climate change. PLoS ONE 10(9): e0135350.

La Sorte, F.A., and F.R. Thompson III. 2007. Poleward shifts in winter ranges of North American birds. Ecology 88(7):1803–1812.

Paprocki et al. 2014. Regional Distribution Shifts Help Explain Local Changes in Wintering Raptor Abundance: Implications for Interpreting Population Trends. PLoS ONE 9(1): e86814.

Paprocki et al. 2017. Combining migration and wintering counts to enhance understanding of population change in a generalist raptor species, the North American Red-tailed Hawk. The Condor, 119 (1): 98–107.

Prince, K. and B. Zuckerberg. 2016. Climate change in our backyards: the reshuffling of North America’s winter bird communities. Global Change Biology 21(2): 572-585.

Saunders et al. 2022. Unraveling a century of global change impacts on winter bird distributions in the eastern United States. Global Change Biology

Virkkala, R. and A. Lehikoinen 2014. Patterns of climate-induced density shifts of species: poleward shifts faster in northern boreal birds than in southern birds. Global Change Biology 20: 2995–3003.

Wu et al. 2018. Projected avifaunal responses to climate change across the U.S. National Park System. PLOS ONE 13(3): e0190557.

I try to maintain an updated list of references at the Birds and Climate Change Facebook group. At that page, click on Files to find the list.

A Nazca Booby, a tug, a barge, and a pit: A climate parable

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At 9:30am on August 17, that is, yesterday, I got a text from another birder. A Nazca Booby had just been seen from Discovery Point near Seattle. What’s more, we knew exactly where the bird was now; it was perched on the bow of a barge being pulled by the tug Seaspan Raider.

The Nazca Booby, atop the barge, photographed by Matt Stolmeier, captain for Outer Island Excursions.

The Nazca Booby is a tropical seabird that breeds exclusively on the Galapagos Islands. When not nesting, it occurs at sea in the eastern Pacific, generally between central Mexico and northern Peru.

Breeding (orange) and non-breeding (blue) range of the Nazca Booby.

This was Washington’s third record. The first, quite possibly the same bird, was on August 14, 2020, in pretty much the same part of Puget Sound. The second was a few weeks ago also off Seattle. That one was an immature, not an adult, so we know it was a different individual. It then showed up off Victoria, providing Canada with its third record.

The Nazca Booby first arrived in the United States in California in 2013. I actually played a role in that first record, a dead beachcast bird found in the aftermath of an oil spill. Working for the state’s spill response, I brought it to the attention of the California Bird Records Committee and had experts examine the carcass for identification. That bird was not a one-off event; it was the beginning of an invasion. There were a few scattered records in the following years, followed by an explosion of 26 records in 2018 and 21 in 2019. After that, California removed the species from its “review list”. While some of these records may have been the same individuals, it is remarkable that a tropical bird previously unheard-of in the US was suddenly widespread. Oregon got its first two records in 2018 and 2019.

Sea surface temperature (SST) of 66.1F off the Washington/Oregon coast.

Checking sea surface temperatures, I see that the water off the Washington and Oregon coasts is reaching 66F in places, only 4F cooler than on the south side of the Galapagos. Zooming out, it is easy to see a route from there to here where the bird never had to encounter sea surface temps under 60F. The Strait of Juan de Fuca is in the low 50s, but it does approach 60F near Seattle.

I opened the MarineTraffic app and quickly located the Seaspan Raider. It was southwest of Edmunds, northbound at 7.3 knots. I calculated it would arrive off Port Townsend between 1 and 2pm. Birders scrambled, heading to various coastal promontories on both sides of Puget Sound. I headed to Point Wilson, where Puget Sound effectively ends and meets the Strait of Juan de Fuca. The tug, bound for Canada, would have to pass by me here.

Reports came in. The bird had flown off the barge. It was in the water off Edmunds. It took off. It was seen from both sides. No one knew where it was.

Tracking the tug using the MarineTraffic app.

This wasn’t the only booby in the Salish Sea at the moment. A Brown Booby had been photographed a few days earlier near the San Juans. That was yet another tropical seabird that had already invaded the US, with records from over forty states, including Alaska. Two decades ago, this would have been unimaginable. And this summer, 2022, was already noteworthy across the Midwest and East Coast for the mass invasion of waterbirds typically found only in Florida or the Gulf Coast. Limpkins, Wood Storks, White Ibis, Roseate Spoonbills and many others were showing up hundreds of miles north of their previously known ranges.

Scrolling thru the American Birding Association Rare Bird Alert nationwide posts, limited to just mega-rarities, here is what pops up: Brown Booby in Oklahoma, Neotropic Cormorant in North Carolina, Brown Booby in Wisconsin, two Swallow-tailed Kites in Ohio, Limpkin in Wisconsin, Neotropic Cormorant in Michigan, White Ibis in New York, Wood Stork in Pennsylvania, Heermann’s Gull in Alaska, Limpkin in Illinois, Nazca Booby in California, White Ibis in Nebraska, etc. And that doesn’t even get us back to August 1. These are all birds, mostly aquatic birds, well north of their normal ranges.

Our current rate of climate warming hasn’t been seen since the Paleocene-Eocene Thermal Maximum (PETM) 55 million years ago. Then, there were alligators within the Arctic Circle. Kind of like Nazca Boobies are now a thing in Puget Sound. Actually, our current rate of warming is much faster than then. During the PETM, the climate warmed 5C in five thousand years. The current rate of warming is eighteen times faster. Then, no one would have noticed. Now, there is 1C of warming – and, with it, dramatic changes in climate and ecology – within the lifespan of a single bird. Some seabirds are showing us that they can keep up, thanks to their ability to fly long distances. I’m not sure about the alligators. Or birds that depend, say, on oak trees. The birds can fly, but the oaks can’t.

Two hours passed. I was ready to give up and head home, my only consolation being “MAMU CF”, a Marbled Murrelet making a provisioning flight across the Sound, carrying a fish to its single chick somewhere on a moss-covered Doug fir branch a hundred feet above the forest floor, probably in the Olympic Mountains. I’d only seen that once before. Much of their range in California has been lost to fires in the past five years, so this Olympic chick is important.

The original photo of the Nazca Booby on the barge, by Alex Meilleur.

One birder, who was unable to search for the Nazca Booby, called some of the local orca boats, as he worked on some of them. He let them know about the bird, as some were near it. About twenty minutes later, texts came in. They had re-found it! It was back on the same barge, now approaching Marrowstone Point. I spun my scope south. There, beyond the ferry lane, I could make out the red and white structure of the Seaspan Raider, pulling its barge, all blurry and shimmering in the distant heat mirage, slowly chugging toward me.

Taking advantage of the outgoing tide, the Seaspan Raider was now hitting 9 knots. It is powered by two Niigata 6m G25HX diesel engines. I don’t know what kind of gas mileage it gets, but, because it presumably refueled in Washington, most of its fuel is likely conventional diesel, but a small component may be renewable diesel.

Renewable diesel is not the same as biodiesel. Biodiesel can be mixed with conventional diesel, but only in very small amounts, like 2%. Renewable diesel, on the other hand, is molecularly identical to conventional diesel. It’s a relatively new invention. Made from non-petroleum sources, such as plant and animal material, it is to conventional diesel what corn syrup is to sugar; it is a “drop-in ready” alternative fuel. It can be mixed with or substituted for conventional diesel seamlessly, with no change in gas pumps, pipelines, or engines. In fact, it burns slightly cleaner, so engines last longer. It emits fewer particulates and, most importantly, its greenhouse gas footprint is up to 80% less. Its use is already widespread in California, where two of the state’s largest refineries no longer take petroleum crude.

This is the kind of thing that should have been developed thirty years ago, just after James Hansen of NOAA briefed congress on climate change in 1986. Now it’s late. We’ve already had more than 1C of climate warming, with more coming and probably ten feet of sea level rise built into the system. Stopping carbon emissions is no longer a suitable goal. We’ve already pushed the cart down the ramp. It’s rolling. We need to reverse climate change, to change that ramp so the cart rolls back to where it was. That will require actually sucking CO2 out of the air – negative emissions – which will certainly take a hundred years under the most optimistic scenarios. So get ready for more boobies, maybe even Limpkins and alligators.

Aside about Washington: Washington further delayed action a few years ago when the Department of Ecology required an Environmental Impact Statement from Phillips 66 to convert their refinery at Cherry Point to make renewable diesel. That is to say, Phillips needed to jump through major permitting hurdles because they were changing – that is, reducing — their greenhouse gas emissions. Phillips didn’t want to wait the several years required for this, so they promptly moved their operation to California. Governor Inslee tried to intervene and save the project, but it was too late. Now BP is picking up the baton in Washington.

Renewable diesel is already in widespread use in trucks, especially in California. The ferries in San Francisco Bay are powered exclusively by it. Because diesel is similar to jet fuel, and made during the same refining process, refineries also produce what is called sustainable aviation fuel (SAF). Aircraft are currently permitted to fly with up to a 50/50 blend of SAF and conventional jet fuel. Boeing promises jets that can fly with 100% SAF by 2030. We’ll be approaching 1.5C of warming by then. Nazca Booby will almost certainly be off the rare bird review list, at least in California. Brown Boobies will be breeding on the Farallones and prospecting further north.

I watched as orca boats came and went from the barge, photographing the Nazca Booby. I was told it was on the starboard side of the roof of the little structure on the bow. The tug and barge continued up Admiralty Inlet until it was straight out from me, as close as it would pass. Slightly more than halfway across the channel, it remained blurred in heat mirage. I could see fuzzy white dots on the described rooftop, but I couldn’t tell you if they were Nazca Boobies or gulls or volleyballs. In birder’s lingo, this was going to be a ‘dip’, even though I knew exactly where the bird was and was looking at it.

My view of the tug, barge, and bird.

Mathematically, this would be at least the sixth time a Nazca Booby had passed this point, my point, my sea watch. And this time I was here, ready and waiting, and still I couldn’t see it. Were it not for the texts and the orca boats, I’d never know it was there. I kept my scope glued to it, hoping it would lift off in a distinctive flight and head directly toward me, where it would join the Caspian Terns and plunge dive right in front of me as I clicked my camera in ecstasy. But it didn’t. The tug and barge chugged north.

The bird was last seen at Partridge Point on Whidbey Island, still riding the barge. It was off the barge by Rosario Inlet. I’m guessing it jumped ship and headed toward Victoria or Smith Island.

The barge’s destination was the Lafarge Texada Quarrying Ltd. limestone mine north of Vancouver. Limestone is critical to making cement. The cement-making process is responsible for 8% of the world’s carbon emissions. Part of that is from the energy used in production, which requires a kiln heated to 1,400 degrees Celsius. But most of the emissions comes from the limestone itself. Forty percent of the weight of limestone is CO2, and this is burned off in the process. There are efforts to improve the cement-making process, to make it less dependent on limestone, to reduce its carbon emissions. That’s all coming in the future.

The limestone mine at Beale Cove, the barge’s destination.

I’m wondering about the ancient Nazca civilization in what is now Peru. It was dependent on a remarkable network of underground aqueducts that delivered mountain water to their arid home. There’s a theory that they over-harvested a certain tree, which led to erosion of riversides during heavy rains, destroying their water delivery system. I wonder if they had meetings about the problem, if they had new policies in effect, at least at the end, when it was too late.

It’s supposed to be 95F in the Seattle suburbs today. I’m not worried about missing this Nazca Booby. There will be more.

The Nazca Booby on the bow. I’m sure the scope views were better. Photo by Laura Brou.

Eastern Towhee: Can the white-eyed subspecies survive even 1.5C climate change?

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Pale-eyed and red-eyed forms diverged approximately 18,000 years ago.
Photo by Melissa James/Macauley Library.
eBird abundance map for Eastern Towhee. It is resident in the southeast, but expands north in summer.

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%.

This is National Audubon’s projection for the Eastern Towhee’s breeding range under just a 1.5C scenario. This would spell extinction for the white-eyed birds of Florida and the deep South.
Their winter range is not anticipated to change much.

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.

eBird data from Florida, focusing on frequency of lists reporting the species during the May-June period, shows that the maximum frequency has fallen from 18.3% in 2015 to 8.6% in 2021.

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.

Photo from National Audubon website that provides range change projections under 1.5C, 2.0C, and 3.0C scenarios.

For more on climate change impacts on birds, I invite you to join the Birds and Climate Change Facebook group.

Mountain Bird Network seeks eBirders heading into the hills

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The east side of the Olympics is a staircase of thrushes. The low country is for American Robins. As you get into woodsy habitat, you’ll hear the spiral song of Swainson’s Thrushes. After that, among the tall old growth along the streams, the ethereal Varied Thrush. Finally, up near timberline, you’ll hear singing Hermit Thrushes. Freeman and colleagues are tracking how these ranges are shifting with the climate.

Two 5-minute point counts at each stop as you gain elevation. June 1 to July 15. Entered into eBird. Shared with the Mountain Bird Network.

That’s all Ben Freeman, a post-doc at University of British Columbia, is asking for. And it can be any mountain, any canyon, any road.

The details are here: Mountain Bird Network.

An example of the data and analysis.

And have a great time!

Northward expansion of Northern Cardinal, Carolina Wren, Tufted Titmouse, and Red-bellied Woodpecker

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A number of recent academic papers have described northward shifts of bird species in both North America and Europe, driven by climate change. These papers usually present aggregated results from dozens of species; they rarely provide details for any specific species. These maps are intended to offer that.

While there are tremendous species-specific differences, non-migratory resident birds (such as Northern Cardinal, Carolina Wren, Tufted Titmouse, and Red-bellied Woodpecker) appear to be the most adaptable and have expanded their ranges the most. This seems to be primarily driven by warmer winters and, for some species, is further augmented by bird feeders.

I created these maps using eBird, so the usual caveats apply– they don’t necessarily include all records (though many historical out-of-range records are indeed included), and eBird reporting, which became widespread only after 2010, continues to increase dramatically each year. To draw the lines, my intent was to capture the primary range area — and more — but I deliberately excluded the furthest ten to fifteen outliers for each line.

CLICK TO ENLARGE GRAPHICS

Northern Cardinals (once called Kentucky Cardinals) have been expanding north for decades, but have increased their rate.
Carolina Wren is a classic example of a species knocked back by harsh winters, finding some refuge around bird feeders, and then continuing to expand in warmer winters. See a graph of this at my previous post here.
Like many species, Tufted Titmouse has especially expanded northeast up the St. Lawrence River corridor.
To get a feel for what this expansion actually looks like in one place, see the graphs below from Christmas Bird Counts. Similar graphs could be made for all of these species.

For some examples of western species expanding north from California and southern Oregon into the Pacific Northwest, see this post: The invasion of the Pacific Northwest: California’s birds expand north with warmer winters.

I invite you to join the Facebook group dedicated to this topic: Birds and Climate Change.

Two of the academic papers that report climate-driven range expansions in eastern North America are listed below, along with their abstracts.

Prince, K. and B. Zuckerberg. 2016. Climate change in our backyards: the reshuffling of North America’s winter bird communities. Global Change Biology 21(2): 572-585.

Much of the recent changes in North American climate have occurred during the winter months, and as result, overwintering birds represent important sentinels of anthropogenic climate change. While there is mounting evidence that bird populations are responding to a warming climate (e.g., poleward shifts) questions remain as to whether these species-specific responses are resulting in community-wide changes. Here, we test the hypothesis that a changing winter climate should favor the formation of winter bird communities dominated by warm-adapted species. To do this, we quantified changes in community composition using a functional index–the Community Temperature Index (CTI)–which measures the balance between low- and high-temperature dwelling species in a community. Using data from Project FeederWatch, an international citizen science program, we quantified spatiotemporal changes in winter bird communities (n = 38 bird species) across eastern North America and tested the influence of changes in winter minimum temperature over a 22-year period. We implemented a jackknife analysis to identify those species most influential in driving changes at the community level and the population dynamics (e.g., extinction or colonization) responsible for these community changes. Since 1990, we found that the winter bird community structure has changed with communities increasingly composed of warm-adapted species. This reshuffling of winter bird communities was strongest in southerly latitudes and driven primarily by local increases in abundance and regional patterns of colonization by southerly birds. CTI tracked patterns of changing winter temperature at different temporal scales ranging from 1 to 35 years. We conclude that a shifting winter climate has provided an opportunity for smaller, southerly distributed species to colonize new regions and promote the formation of unique winter bird assemblages throughout eastern North America.

Saunders et al. 2022. Unraveling a century of global change impacts on winter bird distributions in the eastern United States. Global Change Biology

One of the most pressing questions in ecology and conservation centers on disentangling the relative impacts of concurrent global change drivers, climate and land-use/land-cover (LULC), on biodiversity. Yet studies that evaluate the effects of both drivers on species’ winter distributions remain scarce, hampering our ability to develop full-annual-cycle conservation strategies. Additionally, understanding how groups of species differentially respond to climate versus LULC change is vital for efforts to enhance bird community resilience to future environmental change. We analyzed long-term changes in winter occurrence of 89 species across nine bird groups over a 90-year period within the eastern United States using Audubon Christmas Bird Count (CBC) data. We estimated variation in occurrence probability of each group as a function of spatial and temporal variation in winter climate (minimum temperature, cumulative precipitation) and LULC (proportion of group-specific and anthropogenic habitats within CBC circle). We reveal that spatial variation in bird occurrence probability was consistently explained by climate across all nine species groups. Conversely, LULC change explained more than twice the temporal variation (i.e., decadal changes) in bird occurrence probability than climate change on average across groups. This pattern was largely driven by habitat-constrained species (e.g., grassland birds, waterbirds), whereas decadal changes in occurrence probabilities of habitat-unconstrained species (e.g., forest passerines, mixed habitat birds) were equally explained by both climate and LULC changes over the last century. We conclude that climate has generally governed the winter occurrence of avifauna in space and time, while LULC change has played a pivotal role in driving distributional dynamics of species with limited and declining habitat availability. Effective land management will be critical for improving species’ resilience to climate change, especially during a season of relative resource scarcity and critical energetic trade-offs.

Carolina Wren + Climate Change vs the Polar Vortex

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Like so many species, the Carolina Wren is expanding northward. And, like many of those species, this expansion started decades ago, before any measurable climate change, but has exploded in the past decades with climate change.

This phenomenon is most obvious – and even dramatic – among non-migratory species and short-distance migrants. The same thing is happening in the West (e.g. Anna’s Hummingbird, Turkey Vulture, Red-shouldered Hawk, Great Egret, California Scrub-Jay, Black Phoebe, Townsend’s Warbler, and others).

The Carolina Wren has been expanding north since the 1800s due to habitat recovery after deforestation (Haggerty and Morton, 2020 – the Birds of North America (BNA) species account). What makes the recent Carolina Wren data so interesting is that we can clearly see, in its expansion into Canada, its battle with winter weather conditions.

The raw number of Carolina Wrens reported on Christmas Bird Counts in Canada. Over 95% of these come from southern Ontario. The cold waves marked on the graph were particularly record-breaking and long-lasting.

The species is known for “decimation… by severe winter conditions” (BNA) at the northern limits of its range. The same account notes that “severe winters have apparently been infrequent enough during the 20th century to allow populations to expand and move northward.” Indeed, one of the key conclusions of an analysis of climate change in southern Ontario was that there has been “a decrease in the frequency of cold temperature extremes”.  While the wren is aided against cold snaps by bird feeders, the climate trend, at least in Canada, is in its favor. The report noted an overall average increase of 1.5C.

eBird abundance map. The Carolina Wren has primarily been a species of edge habitat associated with moist southern forests.

As the wren expanded, certain record-breaking and persistent cold waves knocked the population back, where it restarted. It’s also clear that it is restarting from a higher position each time, thus building its numbers and continuing its expansion.

The cold snaps denoted on the graph were particularly severe in southern Ontario. A more detailed look at weather data may reveal a more complicated pattern and even greater correlation to warmer winters.

Predicted range changes for Carolina Wren by National Audubon under 1.5C scenario. This map is fairly accurate as the bird continues to colonize the St. Lawrence River corridor.
eBird map for December 2021 showing colonization from Toronto to Ottawa and Montreal and nearly to Quebec City.
A Carolina Wren fluffed up against the cold. Pic from National Audubon website.

Mapping the expansion of the California Scrub-Jay into the Pacific Northwest

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This blog post is merely to provide a visual illustration, by way of a map, of the expansion of the California Scrub-Jay across Washington, British Columbia, eastern Oregon, Idaho, and even Montana (one record so far). It is intended to complement my more detailed article, “Tracking Expansion of the California Scrub-Jay Into the Pacific Northwest”, in the Washington Ornithological Society (WOS) News, August-September 2021 edition.

California Scrub-Jays are often first detected at bird feeders in suburban areas. As aggressive nest predators, jays should not be subsidized by anthropogenic food sources. In short, please don’t feed the corvids. Port Townsend, WA. April 2021.

As becomes clear in the article, these are not hard lines. The jays are advancing gradually, not in a solid wave. Typically, a single jay will appear well outside the known range (e.g. Spokane). Within a year or two, there will be several. Then they’ll be breeding. Then they will begin expanding further. Meanwhile, a wave of jays will be backfilling the new territory, with densities increasing annually. The lines in this map are as much art as science, but are intended to show the primary region were jays were “regular and expected”. There were always outliers, pioneer dispersers expanding the range. Records beyond the 2020 line are shown as pale blue dots.

CLICK MAP TO ENLARGE

The expansion of the California Scrub-Jay mimics that of several other species, mostly non-migratory or short-distance migrants, rapidly expanding from California and Oregon into the Pacific Northwest.

The jay’s expansion has already surpassed that predicted by the Audubon Society’s climate model under a 3.0 degree Celsius scenario, shown here.

The jay’s expansion, when considered in the context of timing and trends in other species, is likely a function of a warming climate combined with suitable food sources. For more discussion of this, see the WOS article linked above.

They seem to be particularly taking advantage of warmer winters in the lower Columbia River Basin.

It will be interesting to see where the 2030 scrub-jay “contour line” will be. I predict they’ll be on Vancouver Island from Victoria to Campbell River, as well as up the Sunshine Coast, up the Okanagan Valley to Kelowna and possibly Kamloops, and east to Idaho, from Coeur d’Alene in the north throughout the Snake River Valley in the south.

After that, they face some formidable hurdles. The biggest obstacles to their expansion further north and east will be habitat with limited food sources (e.g. high mountains). That said, they’ve already shown some ability to travel up mountain valleys and potentially cross the Cascades north of Mount Rainier.

Like most corvids, California Scrub-Jays are big time cachers, storing extra food for future use. I took this photo in southern California, October 2017, when a family of jays were repeatedly stripping an oak, two acorns at a time, flying over a nearby ridge to cache them, and then returning again and again throughout the morning.

The causes of California’s megafires: Climate change or 150 years of Euro-American mismanagement? Yes and yes.

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In a very frank and data-rich webinar, fire ecologist Hugh Safford (USDA Forest Service and research faculty at Department of Environmental Science and Policy at UC Davis) offers “Some ruminations on fire and vegetation trends in California”. He explains the causes of the dramatic increase in megafires and what can be done about it.

A 2,500 year-old tree at Sequoia National Park now needs protection from fires.

The webinar was co-sponsored by the Yolo Interfaith Alliance for Climate Justice and Cool Davis and presented on May 5, 2021.

Safford’s presentation starts at 13:23 of the video. The equally enlightening Q&A session begins at 48:20.

Here is a summary of some of the key points:

  • The annual burned area has been rising rapidly since the 1980s, almost entirely in northern California.
  • This is largely due to fire exclusion caused by the removal of Native Americans as land managers and increased drought and record vegetation dryness caused by climate change.
  • Since 1999, burning over a million acres/yr now occurs regularly; this had not happened before 1999.
  • Pre-EAS (Euro-American Settlement) burning by Native Americans totaled up to FOUR million acres/year (but these were low severity fires that primarily burned the understory and smaller trees).
  • “Euro-Americans, when they showed up in the 1850s, and for that matter today, had no idea how important fire was to the functioning of these ecosystems and they feared it and felt like it was something they needed to stop. After a hundred years of that, it’s really biting us in the butt now because now we have jungles of fuels, we’ve cut most of the big fire-resilient trees out of the system, and when we get the ignitions start we can’t stop the fires anymore. Until about the 1990s, it was easy to put fires out in the forests.”
More mature trees are burning; the acres burned by high severity fires (where more than 90% of trees die) have increased 7x since 2001 in northern Sierra Nevada. 35% of the area of current fires are severe (burn most of the trees); under regular Native burning, this was 5-15%.
  • Pre-EAS forests were at least 40% old growth; current forests are only 6% old growth and highly vulnerable to high severity fires, as they are 4-5x denser than pre-EAS.
  • “Every single fire projection we found in the literature predicts bigger fires, more fires, and more severe fires, basically until we’ve burned so much of California that there actually isn’t much woody vegetation left to burn.”
  • Expect the loss of conifers and an increase in non-native grassland.
  • Changes already underway: loss of blue oak woodland, ponderosa, yellow pine, and subalpine pine; increase in hardwoods. Loss of sage scrub and chaparral in southern California. Many burned areas are quickly invaded by non-native grasses and will not recover. Incense cedar and white fir may become more dominant trees in California forests.
  • Fires in the Coast Range are now destroying chamise and blue oaks with limited evidence of re-sprouting.
  • In the short run, there’s not a lot we can do to manage climate, but there’s a lot we can do to manage fuels.
  • There’s been a huge renaissance, especially among Native tribes, to use controlled burns to manage forests. California’s new fire resilience plan supports the use of controlled burns. Northern Australia has had great success allowing Aboriginies to manage forests. Opportunities are limited, however, because of development.
  • The combination of drought cause megafires in the Sierra to produce “Hiroshima-type landscapes”, burning old growth.
  • How to stop fires: Forest thinning is critical, but it’s not economical to harvest small trees, so the government will have to subsidize it. For example, we can use the cut trees for biomass energy, as it done in Scandinavia. This is the only way to save large old growth trees and healthy forests.  “We have to cut a lot of trees. We don’t have a choice…. We can create forests that can handle large fires, or we can sit around and watch it all vaporize.”