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

Predicting winter irruptions: Correlating Red-breasted Nuthatch, Pine Siskin, and Red Crossbill winter invasions with previous years’ snowfall

I can almost do it; I’m just wrong this year.

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Pine Siskins in fall 2015 during the “superflight”. Davis, California.

Boreal seed-eating birds are notoriously unpredictable in their winter wanderings. Unlike a certain distinctive Dark-eyed Junco that once returned to my small apartment patio in Davis, California several winters in a row, these birds of the northern forests have no such allegiance to any patch of land. A Pine Siskin once banded in winter in Quebec turned up in California during a subsequent winter; other Pine Siskins banded in winter in New York and Tennessee spent a later winter in British Columbia; an Evening Grosbeak banded in winter in Maryland spent a later winter in Alberta; a Eurasian Siskin banded in winter in Sweden was later found in Iran; a Common Redpoll once wintered in Belgium, and later in China; another Common Redpoll banded in winter in Michigan was found during a later winter in Siberia (Newton 2006). In other winters, they hardly migrate at all. While up to 90% of band recoveries for many winter-banded species are pretty much where they were banded, that rate fall to about 1% for irruptive boreal species (ibid).

There’s a rich literature focusing on cone crop failure and irruptions of crossbills, redpolls, Clark’s Nutcrackers and other species (Reinikainen 1937, Lack 1954, Svardson 1957, Davis and Williams 1957 and 1964, Ulfstrand 1963, Evans 1966, and Eriksson 1970). To quote Newton (2006), “Clear evidence has emerged that major emigrations follow periodic crop failures.” Most recently, Wilson and Brown (2017) confirmed that Red-breasted Nuthatches are not fleeing bad weather nor are they attracted to specific food elsewhere; they are spreading across the land “because of failure of conifer seed production on the breeding grounds.” They are famine refugees. Other research has shown that, “despite the presumed benefits of irruption as an adaptive response to food shortage when population levels are high, negative population consequences can ensue.” Large irruptions are correlated with smaller numbers on Breeding Bird Surveys the following summer; they don’t all make it back (Dunn 2019).

Another factor, however, is high population densities of the birds (Bock and Lepthien 1976). Koenig and Knops (2001) reached some specific conclusions when they examined 30 years of Christmas Bird Count (CBC) data, focusing on multiple species, and compared it with data on cone crops. They found that Red-breasted Nuthatch, Black-capped Chickadee, Evening Grosbeak, Pine Grosbeak, Red Crossbill, Bohemian Waxwing, and Pine Siskin irruptions were “correlated with a combination of large coniferous seed crops in the previous year followed by a poor crop.” In short, a good year causes a pulse in reproduction, followed by a lean year with causes the expanded population to suddenly roam in search of food. There was some variation, with the good year or the bad year playing a more dominant roll for different species, but for most species, it was both. (And for Purple Finch, it seemed to be neither.) They concluded that “seed crops of boreal trees play a pivotal role in causing eruptions for a majority of boreal species, usually through a combination of large seed crop resulting in high population densities followed by a poor seed-crop, rather than seed-crop failure alone.”

RBNU Davis 10-12-15

Red-breasted Nuthatch, also in Davis in fall 2015.

A year previously, Koenig and Knops (2000) studied just the trees, and concluded that various tree species often boom and bust in sync. They noted that “the large geographic scale on which seed production patterns are often synchronized, both within and between genera, has important implications for wildlife populations dependent on the seeds of forest trees for food. In general, resident populations of birds and mammals dependent on mast are likely to be affected synchronously over large geographic areas by both bumper crops providing abundant food and, perhaps even more dramatically, by crop failures.” Newton (2006) reported synchrony in boreal conifer seed production in forests 1000 km apart. Strong et al (2015) links Pine Siskin irruptions to continent-wide winter climatic patterns.

With synchronized cone crop failures, one would expect synchronized irruptions across bird species. The literature on this is supportive but mixed. Bock and Lepthien (1976) provide nice annual maps by species illustrating “generally synchronous” irruptions in many (but not all) years. Koenig (2001) offers the most comprehensive analysis, exploring synchronous irruptions among all combinations of 15 species, including multi-year lagged effects. (Here it’s important to understand correlation coefficients, or Pearson’s r. For guidance in interpreting r, 1.00 would be a perfect match, 0 would mean no correlation, and -1.00 would mean they do the exact opposite of each other.) Koenig’s highest correlation coefficients between two species were generally between 0.30 and 0.50. He also shreds an earlier assertion from Bock (1999) that there is strong correlation between Common Redpoll and Pinyon Jay irruptions; there was, but it didn’t last long.

Here I examine 49 years of CBC data (1970-2018) for Red-breasted Nuthatch, Pine Siskin, and Red Crossbill from the northern Central Valley of California, centered around Sacramento. I used data from eight CBCs: Caswell-Westley, Folsom, Lincoln, Marysville, Rio Cosumnes, Sacramento, Stockton, and Wallace-Bellota. I didn’t have any data on cone crops, but I assumed they might be correlated with precipitation the previous year, so I looked at snowfall. In short, I find some support for Koenig and Knops, but I wouldn’t bet more than a beer on it in any given year.

Here are the results.  CLICK TO ENLARGE.

irruptiongraph

First, there are no units for the vertical axis. That’s because the units I used for the birds is basically an index. I converted them all to natural log (ln) because the numbers of siskins, which often occur in large flocks, dwarfed the nuthatches and crossbills. Converting to natural logs put them all more on a level playing field. What you’re seeing is the natural log of total individuals across all eight CBCs each year. (In most years, most birds were in the Sacramento CBC.) The blue circles are the water content (in inches) of the deepest observed snowpack from winter snow surveys at Upper Carson Pass from the previous winter. For example, the large irruption (or “superflight”) in 2015 occurred in the fall and winter of 2015-16, and the very low blue circle on that column is associated with the snowpack from the winter of 2014-15. In general, the snow surveys occurred in Jan-Apr and the CBCs in December of the same year.

A few quick observations from the chart:

  • Red Crossbills only occurred in six of the 49 winters, but 4 of those were during nuthatch/siskin irruptions. The only large crossbill irruption occurred in 2015, on top of the largest combined nuthatch/siskin invasion. The 2015 superflight also coincided with the lowest snowpack the previous winter, which came at the end of a four-year drought. So 2015, as an extreme event, tells us a few things. Previous snowpack is important, and correlation across species does occur.
  • Most of the other highest irruption years (1981, 1987, 1992, 2012) all came after low snowpack years, and all had higher snowpack the year before that, exactly what Koenig and Knops would predict.

And now for some math:

  • The correlation coefficient between nuthatches and siskins is 0.32, so they do tend to irrupt together-ish, but not always and certainly not in the same magnitude. Koenig writes, “For Red-breasted Nuthatch and Pine Siskin, synchrony over different 10-year periods varied from a high of 0.82 (1965-1974) to a low of 0.24 (1987-1996).” His sample included eastern North America, which he showed follows different patterns than the West.
  • I then looked at correlation between the cumulative nuthatch/siskin/crossbill irruptions (in natural log, so the full blue, yellow, and red columns in the graph) and a variety of other parameters. Here are the results:
    • Correlation with previous winter’s water content from snowpack (the blue circle): -0.44.
    • Correlation with water content more than 5″ below average: 0.41.
    • Correlation with multiple years of drought: 0.37.
    • Correlation with a 10″ drop in water content from the year before that (thus going from a good year to a worse year): 0.38.
    • Correlation with the same 10″ drop in water content, but only if the recent year was below average (thus, going from a good year to a bad year): 0.40.

So these correlations all lean in the right direction, supporting Koenig and Knops’ notion that bad years are bad, and bad years after good years are even worse. I would also add that bad years after bad years (a drought) are also bad.

These correlations come with some caveats. First, the correlation between snow water content and cone crop is imperfect. Koenig and Knops (1999) state that, while recent precipitation is indeed an important variable, it’s not the only one. Spring and summer temperatures play a role in cone development, as well as previous seasons. After a really good year, trees need a break, regardless of rainfall, and will produce less. An example might be 1984, where there was an irruption after an average snow year, but two really heavy precipitation years preceded that.

Another source of noise in the data is that our birds, especially the siskins, may be coming from much further afield than Tahoe. (I deliberately left out Evening Grosbeak because call types from our last invasion suggested the birds were brooksi from Washington state or somewhere up there.)

Donner Jan20-2015

Donner Pass without snow. January 20, 2015.

While it may seem that the data on irruptions and snowpack tell a compelling story, let’s not forget the present. It’s fall 2019 and we’re in the midst of a significant Red-breasted Nuthatch irruption (and I’ve seen one siskin as well). This year is not on the graph above, but we do already have the snowpack data from earlier in the year. It was way above average. Thus, we’ve just gone from an average snowpack year in 2018 to above-average in 2019, the opposite of what should prompt an irruption. If you bet me a beer, I’d owe you one.

References

Bock, C.E. 1999. Synchronous Fluctuations in Christmas Bird Counts of Common Redpolls and Piñon Jays. The Auk 99: 382-383.

Bock, C.E. and L.W. Lepthien. 1976. Synchronous eruptions of boreal seed-eating birds. American Naturalist 110: 559- 571.

Davis, J. and L. Williams. 1957. Irruptions of the Clark nutcracker in California. Condor 59: 297–307.

Davis, J. and L. Williams. 1964. The 1961 irruption of the Clark’s nutcracker in California. Wilson Bulletin 76: 10–18.

Dunn, E.H. 2019. Dynamics and population consequences of irruption in the Red-breasted Nuthatch (Sitta canadensis). The Auk 136.

Eriksson, K. 1970. Ecology of the irruption and wintering of Fennoscandian redpolls (Carduelis flammea coll.). Annals Zoologica Fennici 7: 273–282.

Evans, P.R. 1966. Autumn movements, moult and measurement of the lesser redpoll, Carduelis flammea. Ibis 106: 183–216.

Koenig, W.D. 2001. Synchrony and Periodicity of Eruptions by Boreal Birds. The Condor 103: 725-735

Koenig, W.D. and J.M.H. Knops. 2000. Patterns of annual seed production by Northern hemisphere trees: a global perspective. American Naturalist 155: 59-69.

Koenig, W.D. and J.M.H. Knops. 2001. Seed-crop size and eruptions of North American boreal seed-eating birds. Journal of Animal Ecology 70: 609-620.

Lack, D. 1954. The Natural Regulation of Animal Numbers. Clarendon Press, Oxford.

Larson, D.L. and C.E. Bock. 1986. Eruptions of some North American seed-eating birds. Ibis 128: 137-140.

Newton, I. 2006. Advances in the study of irruptive migration. Ardea -Wageningen 94: 433-460.

Reinikainen, A. 1937. The irregular migrations of the crossbill, Loxia c. curvirostra, and their relation to the cone-crop of the conifers. Ornis Fennica 14: 55-64.

Svardson, G. 1957. The ‘invasion’ type of bird migration. British Birds 50: 314-343.

Ulfstrand, S. 1963. Ecological aspects of irruptive bird migration in Northwestern Europe. Proceedings of the International Ornithological Congress 13: 780–794.

Wilson Jr., W.H. and B. Brown. 2017. Winter Movements of Sitta canadensis L. (Red-breasted Nuthatch) in New England and Beyond: A Multiple-scale Analysis. Northeastern Naturalist 24.

 

Spring Migration in the Central Valley

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Compared to fall, spring migration is fast and furious. It ramps up thru April, peaks in early May, and then ends abruptly. Birds don’t stay long; they’re in a hurry. Rarities rarely last more than a day. And there are fewer birds than in the fall, winter mortality having taken its toll. But, like this Lazuli Bunting, the birds are in their best dress.

In 2010, after ten years of collecting data on morning “warbler walks” in my local patch in Davis, the Central Valley Bird Club Bulletin published my results. You can read the whole paper here:

Hampton, S. 2010. Passerine migration patterns in Davis, Yolo County—2000-2010. Central Valley Bird Club Bulletin 13(3): 45-61.

Last fall, I posted a re-visualization of the data from that paper with regard to fall migration. Here is the spring version.

I’ve divided it into two graphs, one for more common species (peaking at 1 to 4.5 birds per survey), and another for less common migrants (less than 1 per survey).

CLICK TO ENLARGE.

DavisMigrants1spring

CLICK TO ENLARGE.

DavisMigrants2springThe same caveats apply:

  • A “survey” here is basically a morning walk lasting about 35 minutes.
    This was for my little route in north Davis (where the eBird hotspot is “North Davis Farms Subdivision”). For other locations in the Central Valley, even nearby ones, I would expect the numbers and relative abundance to vary a little. For example, I see a lot more flycatchers at Babel Slough and Grasslands Park than are reflected here.
  • Putah Creek near Pedrick Rd, a current favorite of birders, generally has more birds than is shown here because it’s a larger area, birders spend more than 35 minutes when they visit, and the habitat is slightly different.
  • A large portion of the birds in my data are “heard only”.
  • For additional details, see the full article linked above. I’m happy to provide my Excel spreadsheets of this data to anyone interested.
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Some species are more common in spring than fall. These include Hermit Warbler (above), Townsend’s Warbler, and Swainson’s Thrush (with a very narrow migration window in mid-May).

I’ve also linked lots of the bird literature specific to Yolo County at my Yolo County Birding website; see the list of papers in the lower right corner of that page.

On these graphs, I’ve left out the rarer birds, species that occur at a rate of less than 0.2 birds/survey (less than 1 out of every 5 surveys). These include Hammond’s and Dusky Flycatchers. It also includes Willow Flycatcher, House Wren, MacGillivray’s Warbler, Common Yellowthroat, and Chipping Sparrow, all of which are quite regular in the fall but rarely seen in spring migration.

Hell in Paradise: Why the Camp Fire was the largest climate-induced mass mortality event in modern history

fires Paradise

The Camp Fire was started by downed power lines, spread from a forest, and then became a structure-to-structure urban fire in which houses burned but many trees did not.

I grew up in southern California on the edge of the San Fernando Valley. Fires, usually fueled by Santa Ana winds on dry grasses in the hills, were a fact of life. I evacuated. I ran the pump to squirt water from the pool onto the roof. I helped neighbors on the edge of the hills water their roofs. Back in those days, in the 1970s, fires over 100,000 acres (~150 square miles) were rare. The worst fires destroyed 200 to 300 homes. Rarely, someone died. That was then.

fires infographic

Infographic prepared in 2013, before most of the recent mega-fires.

Twelve years ago, four researchers examined a comprehensive database of all large wildfires in western United States forests since 1970. They detected a signal and concluded that “large wildlife activity increased suddenly and markedly in the mid-1980s.” Looking at weather data and land-use history, they concluded the driving factor was “increased spring and summer temperatures and an earlier spring snowmelt”. Forest management, on the other hand, had “relatively little effect”. Published in the journal Science in 2006, they had found the “force multiplier” that climate change brings to the West. We all knew that forests had been mismanaged for nearly a century, and that too many homes and towns had been built up against wildlands.  But now there was a new factor driving fires—longer hotter drier summers. If you’re looking for numbers, the data show that fires really ramped up in 1987.  The so-called “force multiplier” of climate change was big—about 3 or 4. That is, wildfire frequency was triple in dry years when compared to moderate years, and quadruple that in wet years. Ominously, they noted the effect was non-linear, meaning that, in warmer years, fires really increased. Thus, the multiplier was not just a constant number—it increased with temperature and lack of rain. The Berkeley Tunnel fire, which was exceptional because it killed 24 people trying to evacuate and was the first fire in California history to burn over a thousand homes (it actually burned over 2,000 homes), occurred in 1991.

In the twelve years since the Science article, mega-fires, in terms of acres burned, structures destroyed, and people killed, have gone off the charts—literally. When it comes to fires that burn more than 200,000 acres (~300 square miles), destroy more than a thousand homes, and kill dozens, if not hundreds of people, climate change is not really a “force multiplier”, it’s an on-off switch. Such fires were very rare or non-existent before the year 2000. Now, they appear to be annual.

CA fires 2b

We’ve crossed a threshold, tripped a wire.  In 2017, after the astounding loss of 6,000 homes in Santa Rosa, we hoped that was an outlier, a blip in the data. A few months later, in December, when fires were previously unheard of, the Thomas Fire became the largest in state history. Barely six months later, the Carr Fire made Redding “the new Santa Rosa”. After that fire I posted a chart showing that 16 of the state’s largest 20 fires had all occurred in the past 20 years. We had a reached a “new abnormal”. Then, a few months after that, in November, when by all historical standards the fire season should be over, the Camp Fire literally wiped out the entire town of Paradise, population 26,000. Hospitals, high schools, stores, and houses, all gone. The death toll is without historical precedent. While that was burning, the Woolsey Fire became the largest and most destructive fire in the history of the Los Angeles area. At the present rate, next year the Paradise inferno will be surpassed by some hell unimaginable.

CA fires 2a

When I say the Camp Fire is the largest climate-induced mass mortality event in modern history, I’m not counting hurricanes. Hurricanes, even large hurricanes, have always occurred and always will. A Category 5 hurricane striking a major city is an inevitability. Yes, climate change has made hurricanes larger and more numerous, thus increasing the risk, but nothing like the change we’ve seen with fires in the West. Thus, attributing any one hurricane to climate change is like attributing a single specific cancer case to an environmental contaminant causing a cluster of cases.

CA fires 2c

When I say the Camp Fire was caused by climate change, I’m not saying that future destructive fires are inevitable. The fires will come, but we can do things to mitigate the

science-fires-1

Graphic from fivethirtyeight.com

destructive aspects. A full post-mortem on the Camp Fire and other recent mega-fires is of course required. Such analysis should look beyond the political rhetoric of Trump, exclusively blaming management practices in national forests. Most of these fires in these graphs, spreading across dry grass and oak woodland, had nothing to do with forests. Furthermore, in the face of massive tree death from drought, simply removing dead trees from forests has serious feasibility limitations. To quote a forest fire expert colleague, “Yes, fuels reduction is needed same as 30 years ago, but the mills are all full from the tree mortality supply, much of the fuels are not merchantable, and we are not going to cut our way out of longer fire seasons and deadly MegaFires.”

In the short run, we can’t stop the changing climate, the record low humidity and record high dry vegetation, or the longer summers. We can’t shorten the fire season, now 80 days longer than in 1970s. But we can modify power lines, conduct preventative burns, revise urban fire perimeter requirements, and re-evaluate evacuation routes. Those things won’t turn off the switch we’ve triggered, but they might at least save some homes and lives in the coming years.

CalFiredamage

The CalFire damage inspection map of Paradise. The latest interactive map can be found here

The 2018 flight of the Buff-breasted Sandpipers: Data from the West Coast

Buff-breasted Sandpipers breed on the Arctic tundra from western Alaska, across northern Canada, to Baffin Island. They winter eight thousand miles to the south, on the grasslands of the River Plate Basin in Argentina, Uruguay, and Paraguay. Their primary migration corridor is east of the Rockies, through the central United States. A secondary route is along the East Coast. They are always rare in fall migration along the West Coast, with four to fourteen individuals counted each fall between 2014 and 2017. In spring, they are almost unheard of (there is one record in eBird from Arcata, California in May, 1980).

Fall migration in 2018 was exceptional on the West Coast, with sixty-five individuals reported, five to ten times the norm. The figure below summarizes eBird data from the past five years in southern British Columbia, Washington, Oregon, and California.

CLICK TO ENLARGE.

BBSA

A few interesting points:

  • While fall migration generally spans from mid-August thru late September, the timing of records within that period are not strongly correlated with latitude.  That is, it does not appear that birds are moving from north to south through the period. Each season’s latest records, from mid or late September, may come from British Columbia or Washington as easily as from southern California. That said, in 2018, the latest records are indeed from southern California. Moreover, the very few October records over the years (not included in the graph) are from southern California.
  • They are most reliable in the Pacific Northwest, only reaching California in years of relative abundance, such as 2018. The only location with records from every year is Salmon Arm Bay of Shuswap Lake, in the interior of British Columbia. Other sites, with records in all but one year, are Boundary Bay, British Columbia, and the south coast of Washington (e.g. Ocean Shores, Gray’s Harbor vicinity).
  • The vast majority of records are of single individuals. The only time more than four birds were documented together during these years was in 2018, with five birds at once at Sauvie Island, Oregon, and a remarkable thirteen at Boundary Bay.
  • In the years 2014-2017, Buff-breasted Sandpipers first appeared between August 15 and 19. In 2018, they did not appear until August 23, and most were relatively later than birds in previous years.
  • In 2018, there were several records from offshore California: one from the Farallons, two from San Clemente Island, and two birds seen together from a pelagic trip one hundred miles off southern California. These were all relatively early in migration, between August 25 and September 1. In contrast, most 2018 records from the Oregon coast were from the first week of September.

 

 

California apocalypse again: Large wildfires increasing with climate change

smoke

Sunset from the Central Valley, looking toward the Coast Range through the smoke of a million trees.

As I write this, helicopters are passing overhead in a dim gray-brown sky. The sun is a pink orb over the western horizon. It is 97 degrees at 7pm. The people of California sit like frogs in a slowly boiling pot.

Average temperature for July and August, here in Davis, is 93 degrees. But in the past 34 days, it was only below that six times. July 2018 was the hottest month in the history of the state.

Such climate change was predicted, with great accuracy, by both oil companies and government scientists back in the 1980s, and even earlier.  The consequences of this included more extreme weather, more drought, shorter rainy seasons, earlier snow melt, longer fire seasons, and larger fires. All that is coming to pass in such dramatic fashion that new records are set each year.

[CLICK TO ENLARGE GRAPHS]

Note: There were more mega-fires in November, 2018, shortly after I wrote this. These graphs are updated in a more recent blog post “Hell in Paradise: Why the Camp Fire was the largest climate-induced mass mortality event in modern history”

CA fires1In 1988, scientists were excited– and alarmed– to see the first indications of a warming climate. Now, graphs illustrating climate change need no statistical analysis. They are obvious to a child, ramping steeply up with each passing year.

CA fires2

A conservative talking point seems to be that this dramatic increase in fires is not due to climate change, but to poor forest management. While this has been an issue for over a hundred years, this question was the prime focus of Westerling et al 2006 in Science, where he concluded that longer hotter summers and shorter drier winters were indeed to blame. There were increased fires even in areas without poor management– or any management at all. Where there has been poor forest management, climate warming has acted as a “force multiplier” to make fires even worse. One could only imagine how easy it would be to write that paper now, twelve years later, with plenty of new eye-popping data points.  Thirteen of California’s 20 largest fires have occurred since Westerling sent his paper to the publisher.

Perhaps the best illustration of the combined effect of poor forest management and climate change comes from this 14-minute Ted talk given by Paul Hessburg in 2017.

Using a useful forest diagram, he explains how Native Americans regularly burned underbrush and maintained an open forest/meadow ecosystem that effectively prevented large wildfires. In the late 1800s, with the ethnic cleansing of Native Americans, the advent of cattle that ate the grass, and the US Forest Service suppressing fires and logging the largest trees, our forests changed from a mosaic of tough old trees surrounded by natural fire breaks to a solid crop of young growth. Add drought, heat, and an ignition source, and you see the results above.

CA fires3

The solution, regardless of how much you attribute large fires to climate change or management, is the same. We need to re-create the balance of the past thru the protection of large trees and prescribed burns. We need to create meadows and healthy forests. Some Native communities in northern California are planning to do this.

This all assumes that we get enough rain in winter and cool temps in summer to allow re-growth. Otherwise, the current fires may be transforming California’s mountain habitats into something resembling the mountains of Nevada and Arizona in the span of a decade.

Birders detect dramatic changes as Davis climate warms

[A version of this was originally published in the Davis Enterprise.]

In 2002, the cover of The New York Times Magazine featured a silhouetted man standing on frosty mauve ice and staring through binoculars into a rosy polar sky. The title read, davis1“Watching the World Melt Away: The future as seen by a lonely scientist at the end of the earth.” The article was about seabird biologist George Divoky and his decades of work studying the black guillemot, a high arctic seabird, on Cooper Island off the coast of Barrow, Alaska. The guillemots were struggling to feed their chicks. Their preferred food, Arctic cod, lived at the edge of the sea ice. In the past, this was five miles from the island. Now it was thirty. Divoky, moreover, found himself sharing his tiny island with several hungry polar bears stranded by the vast expanse of open water. At the time, the story was one of the first concrete examples of climate change impacting an ecosystem in way that was easily seen and understood.

Sac Valley winter avg temps SH

Sixteen years later, birders in Yolo County are now witnessing those kinds of changes at our latitude. Winters are suddenly filled with species previously associated with warmer climates to the south, while some other winter visitors no longer come this far south. In the summer, new species are arriving from more arid regions and have started nesting locally.

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Orchard Oriole in Davis, December 2017

A shift of a few degrees may not seem like much, but a winter above freezing makes autumn fruit and berries available longer, resulting in a plentiful food supply. This past December, birders were astounded to find eight species of warblers and three species of orioles in the county at once. Normal would be three and zero, respectively. These birds are neotropical migrants, spending the summer nesting in the northern United States and Canada, and wintering in Southern California, Mexico, or Central and South America. In the last few years, Cassin’s vireos, black-throated gray warblers, and blue-gray gnatcatchers have been present at many locations throughout the cold months. It is now possible to find hooded orioles and western tanagers year-round. Last winter, rarities like orchard oriole, northern waterthrush, and palm warbler turned up and stayed for weeks or months. The prevalence of unusual over-wintering migrants has enabled birders to rack up quite a winter list. Holly Coates shattered previous “big year” records by tallying 200 species in Yolo County by March 20 this year.

neotrop migrants graphThe Putah Creek Christmas Bird Count, an annual effort to count all the birds in a 15-mile diameter circle near Winters on one day each December, has tracked winter bird populations since 1971. In recent years, the number of neotropical migrants found on the count has swelled. These include warbling vireo and Wilson’s and Townsend’s warblers, in addition to the species mentioned above. Perhaps the most dramatic shift in the count data has been with the turkey vulture. With the absence of tule fog, these birds, which rely on warm thermals to give them some lift, have gone from sparse, rarely more than 15 birds on a count through 1985, to over 150 individuals per count in each of the past eight years.

turkey vulture graphA warming climate is expected to create more increases than decreases in bird life in Yolo County. This is because species diversity is greatest in the tropics. As bird ranges shift north, we expect to see more arrivals than departures. Among the departures are some northern species that are growing scarcer in winter. Most notable is rough-legged hawk, a tundra species that journey south to agricultural areas to eat rodents in winter. They have, however, become decidedly hard to find in recent years, perhaps finding the Willamette Valley and other more northern valleys suitable for their wintering grounds. Another species to watch is the beautiful cedar waxwing, which descend on fruits and berries in the winter months. The more they can find food in the north, the less likely they will come this far south.  They are erratic from year to year, however, so it is too early to identify a trend.

Though less dramatic, our hotter summers have brought some changes as well. Great-tailed grackles have expanded up the Central Valley from the Salton Sea. Say’s phoebes, which previously nested only south of the Delta in the Central Valley, moved into Napa and Solano Counties in 2014. Perhaps they are focusing on certain species of insects. This spring, Michael Perrone found them nesting in Davis and Joan Humphrey discovered them feeding young in Woodland, representing first nesting records for the county.

The Yolo Audubon Society is currently revising its Checklist of the Birds of Yolo County, a useful little booklet that will list all 369 species recorded in the county, each with a bar chart showing their abundance through the year. The last version, published in 2004, had a special section called “Recent Changes” highlighting the wetland restoration projects at the Yolo Bypass Wildlife Area and Davis Wetlands. In the coming 2018 version, the Recent Changes section will focus on two big issues: the expansion of orchards and our changing climate. Perrone, author of that section, states that “winters have become milder. In particular, prolonged periods of cold, all-day tule fog have ceased, giving way to sunnier weather.” Davis birders may not be standing on the edge of the continent looking at retreating sea ice, but nevertheless, in the last few years they have witnessed dramatic changes in bird distributions. A look at the graphs, moreover, suggests these changes began before that article about Alaska was published.