#Grinnell Resurvey Project

[scitechman]

California Birds Nesting a Week Earlier Than They Did a Century Ago

A new study suggests that many of the state’s birds are adapting to rising temperatures by breeding earlier than they did a century ago.

A comparison of nesting data recorded in the early 1900s with similar data today for more than 200 species of California birds shows that overall they are breeding five to 12 days earlier than they did 75 to 100 years ago.

Earlier studies found that many but not…

[rjzimmerman]

Excerpt from this story from the Audubon Society:

The Mojave Desert, like many deserts across the world, is getting hotter and drier. Over the last century, it’s warmed by about 3.6 degrees Fahrenheit (2 degrees Celsius), and its already sparse rainfall has declined by 20 percent in some areas. Even before modern climate change, the Mojave’s birds lived at extremes; many desert birds have evolved special drought adaptations to save water. Now they’re facing conditions that exceed their physiological limits, according to new research published today in Science.

The study accounts for changes in the Mojave’s wildlife over the past century using data from the Grinnell Resurvey Project. The research, led by ornithologist Steve Beissinger at the University of California, Berkeley, retraces the steps of famed naturalist Joseph Grinnell and resurveys the hundreds of sites where he and his field staff counted birds and mammals across California between 1908 and 1968. (Grinnell died in 1939.) By comparing the new data with the old, Beissinger and his team can analyze how bird populations have changed since Grinnell's observations.

According to the resurvey data, the Mojave’s small mammal populations are stable. At 90 study sites across the desert, only three lost mammal species; on average, each site lost two and gained two species. Birds, however, saw drastic declines. Bird diversity went down at 55 out of 61 sites, each losing an average of 18 species. That’s a 42 percent decline in bird diversity across the Mojave, and mostly on protected land. Species that experienced the biggest declines include raptors like American Kestrel, Prairie Falcon, and Turkey Vulture; insectivores like White-throated Swift, Western Kingbird, and Violet-green Swallow; and birds lacking desert adaptations like Northern Mockingbird, Western Wood-Pewee, and Chipping Sparrow. The loss is so catastrophic that scientists have deemed it a “collapse” of the Mojave’s birdlife.

[rjzimmerman]

Excerpt:

A growing number of studies suggest a dim future for desert dwellers in the coming decades, as they face warmer, drier conditions. Temperatures in Death Valley in July were the hottest for any month anywhere in the world in 2017, averaging 41.9 °C.

Many biologists think that desert organisms are living at the limits of survival — and that cooler regions may be out of reach for slow-moving or short-lived species. Preliminary results from the Grinnell Resurvey Project corroborate this idea. Of the 135 bird species surveyed in the Mojave Desert, only the common raven (Corvus corax) has significantly expanded its range since the early twentieth century, Beissinger says. The ranges of 38 other species have contracted.

Others on the resurvey project are exploring how hotter, drier conditions might harm birds and mammals, by studying species’ metabolisms and how much water they lose through evaporation. Ecological modellers can combine these findings with the latest population data to better project how the desert ecosystem might fare as the planet warms.

Ideally, scientists would revisit these forecasts in a few decades using fresh data. But fieldwork of this sort is falling out of favour. Staring at the blue mountains on the horizon, Patton says that he doesn’t know who will replace him: very few students today train as naturalists, and museums and national parks are chronically underfunded. “Everyone wants to know how nature is changing and why,” he says. “But there’s almost nobody doing this kind of work.”