Helping Shorebirds in California's Central Valley
Plus Fighting Invasive Mustard, Biodiversity at the UN, Hope for Fireflies and the Western Monarch Butterfly, and Elephants
California’s Central Valley
Mountains run the length of California, from Oregon down to the border with Mexico, Yet right in the middle of this rugged terrain is a big, very flat expanse called the Central Valley. From Yuba City in the north down to Bakersfield, the Central Valley covers about 20,000 square miles. That’s about the size of Vermont and New Hampshire put together.
California is a land of extremes. The highest point in the 48, Mount Whitney (elevation 14,505 feet) is in California, as well as the lowest, Badwater (elevation -282 feet), in Death Valley. The Central Valley is another of these extremes. In a state with high tech and billionaires, the Central Valley has some of the most extreme poverty in the country.
Besides being big and flat, the soil is fertile in the Central Valley, and farmers can ship in water, so it’s where folks grow a lot of food. More than 250 crops are grown in the valley, worth an estimated $17 billion per year. One-quarter of all of the food in the U.S. is produced in California’s Central Valley.
It can be a curious thing to zoom in to this valley with Google Earth to a large Mondrianesque expanse of human-made rectangles and see how we have transformed the landscape. The weather there is also greatly affected by humans. A lot of the water that irrigates the crops evaporates and then condenses, producing large fog banks. One day many years ago, I think I drove through about 150 miles of fog.
Helping Shorebirds in the Central Valley
Before the 1850s, the Central Valley had more than 6000 square miles of wetlands. More than 90 percent of that is now gone. Yet the Central Valley continues to be a habitat for migratory birds in the remaining wetlands and even in some of the farms. It is estimated that almost five million waterfowl live among the wetlands and farms through the winter, and more than half a million shorebirds representing over 30 species—including dowitchers, plovers, sandpipers, black-necked stilts, and avocets—rely on the habitats of the Central Valley during their spring migration, from April through May.
The habitats these birds use include corn and rice fields that farmers flood after their fall harvests. For a shorebird, if an area is filled with shallow water, they don’t know or care if rice or corn had been grown there weeks before. To them, it looks like habitat.
These wetlands are important to the birds. Without them, there aren’t a whole bunch of other places along their flyways for the birds to stop. Without these places—where the birds can rest and eat—migration may be impossible, jeopardizing their existence. The managed wetlands in the Central Valley are reliable habitats for the birds.
One of the wetlands areas is the Grasslands Ecological Area (GEA), a 160,000-acre multi-habitat preserve in the Central Valley located mostly within Merced County. About 30 percent of the land in the GEA is privately owned and farmed. Though they flood their wetlands, farmers have typically drained their farmlands in February and March, before the majority of shorebirds pass through the valley in mid-April.
A team of scientists had a simple question. What if the farmers delayed the onset of drainage and drained the lands more slowly than the one-to-three weeks of traditionally managed farmlands?
They had some farmers give it a try for three years. During this time the scientists monitored 107 areas that were drained slowly and 73 traditionally drained areas. In all, they completed 1,245 bird surveys of all the areas.
The scientists found no big surprise. The shorebirds used the slowly draining land to a much greater degree than the traditionally managed land. They found overall 21 times as many birds in the slowly drained land than in the traditionally drained lands. Ninety-six percent of the shorebirds were observed using the slow-draining farmlands. The scientists published their results in the Journal of Fish and Wildlife Management in December 2020.
The scientists suggest incentives for the farmers to drain their lands later and more slowly in the Central Valley. Adopted on a large scale, shorebirds could continue migrating through California much as they have for thousands of years.
Invasive Mustard and Climate
One of the invasive plants that scourge the landscapes where I live in southern California is black mustard (Brassica nigra). Yes, it is the same plant used to make mustard, the condiment we slather on our hot dogs and hamburgers. But at least here, it’s a pest.
The invasive mustard can be really bad. I’ve seen where it has taken over entire hillsides, nothing but invasive mustard from one side of the hill to the other. Once it gets established, it can be really hard to remove. I work as a native plant horticulturist, and nonnative mustard crops up somewhere in my landscaping every year.
Where I work we landscape exclusively with plants native to coastal southern California. One thing that I’ve noticed over the years is that during very dry years, some of which might be described as drought, the native plants fare better than many of the nonnative and invasive plants, including the nonnative mustard. During the dry years, our native sunflowers and sages will begin to turn green and bloom far quicker than the invasive black mustard. Last year we had a lot of rain, and we had a lot of mustard. This year has been notably drier, and I’ve hardly had to contend with any invasive mustard at all.
Germany is scourged by another species of mustard plant called warty cabbage (Bunias orientalis), which has been introduced to the country in the last 30 to 40 years. It was just a nuisance found along roadsides 30 years ago, but now it has invaded Germany’s orchards, vineyards, and even made its way into remote areas.
Scientists took a look at how the weather affects this mustard, specifically the wetter weather that is expected to accompany climate change in Germany. They examined the germination of warty cabbage seeds in both disturbed and undisturbed grasslands. They mimicked the expected wetter weather by heavily irrigating some of their study sites, and conducted surveys of the invasive plant over three years.
The scientists found that drier weather tends to help the warty cabbage, but the wetter weather that is predicted for Germany due to climate change, actually hindered the invasive. Seeds of the plant germinated at less than half the rate under wetter conditions than drier. In this case, climate change may have an ironic silver lining. The scientists published their findings in Frontiers in Ecology and Evolution on March 18, 2021.
Would any scientists like to look into how the weather affects the invasive mustard here in southern California? I have a sense that the dry weather impedes the plant, but that is simply my casual observation. If anyone wants to look into this, please leave a comment.
Threats to Biodiversity Threaten Human Health and Survival
Panelists at a recent UN forum pointed out that threats to biodiversity threaten human existence as well. While humans are far from being an endangered species, the COVID-19 pandemic reminds us that the health of biomes affects human health. The forum reaffirmed its commitment to preserving 30 percent of the planet. I hope they are successful! (UN News)
Conservation Assessments for Fireflies
When I was a kid growing up in West Virginia, the local fields glowed at dusk with millions of fireflies. By the time I was in junior high, their numbers had very obviously dwindled.
Now, the Xerxes Society—working with the International Union For Conservation of Nature and ABQ BioPark, a combined zoo, aquarium, and botanical garden in Albuquerque, New Mexico—performed the first extinction risk assessment for North America’s 128 species of fireflies.
The researchers found that 14 species, 11 percent of the assessment, are threatened with extinction, with insufficient data to make a good assessment for half of the species. More fireflies might be threatened, researchers just couldn’t tell. (Xerxes Society)
Funding and Hope for the Western Monarch Butterfly
The population of the Western Monarch butterfly has plummeted by 99.9 percent in recent years. Two bills were introduced in Congress this last week to enhance funding for conservation efforts for this critically endangered butterfly: the Monarch Action, Recovery, and Conservation of Habitat Act and the Monarch and Pollinator Highway Act. The first bill would provide $12.5 million a year for conservation projects and the same amount of money for a full, comprehensive plan. The second would provide money for planting native grasses, wildflowers, and milkweed along highways. (Xerxes Society)
My goal with this newsletter is to spotlight environmental news that does not make it to the regular press. This story made headlines, but I wanted to include it because of how strongly it affected me when I read it a few days ago. There are two species of African elephant. Both species are now endangered, and one, the forest elephant, is critically endangered. (National Geographic)