Photo: California 1917
New report (August 2018) – Mojave birds crashed over last century due to climate change
Bird communities in the Mojave Desert straddling the California/Nevada border have collapsed over the past 100 years, most likely because of lower rainfall due to climate change, according to a new University of California, Berkeley, study.
A three-year survey of the area, which is larger than the state of New York, concludes that 30 percent, or 39 of the 135 bird species that were there 100 years ago, are less common and less widespread today. The 61 sites surveyed lost, on average, 43 percent of the species that were there a century ago.
“Deserts are harsh environments, and while some species might have adaptations that allow them to persist in a desert spot, they are also at their physiological limits,” said Kelly Iknayan, who conducted the survey for her doctoral thesis at UC Berkeley. “California deserts have already experienced quite a bit of drying and warming because of climate change, and this might be enough to push birds over the edge. It seems like we are losing part of the desert ecosystem.”
The collapse could have an impact on desert plants that rely upon birds to spread their seeds and for pollination, she said, as well as on a host of creatures that prey on the birds.
Though the decline has happened across the entire Mojave Desert, sites with available water saw less decline, suggesting that dehydration is a major factor. To halt further losses, the authors suggest, it may be necessary in the short-term to create additional water resources and limit groundwater pumping, which depletes desert springs. The best long-term solution is to reduce greenhouse gas emissions and reverse climate change, the authors say.
The loss of bird species has happened even though much of the Mojave Desert is protected national park or preserve, including Death Valley National Park, one of the nation’s largest.
“This is a shot across the bow of our nation’s national jewels, telling us that climate change is already having an adverse impact even in our largest national parks and wilderness areas, and that we have got to reduce dependence on fossil fuels by smartly employing green energy,” said Steven Beissinger, senior author of the study and a UC Berkeley professor of environmental science, policy and management.
Iknayan and Beissinger report their findings this week in the journal Proceedings of the National Academy of Sciences, Collapse of a Desert Bird Community over the Past Century Driven by Climate Change:
“Climate change has caused deserts, already defined by climatic extremes, to warm and dry more rapidly than other ecoregions in the contiguous United States over the last 50 years. Desert birds persist near the edge of their physiological limits, and climate change could cause lethal dehydration and hyperthermia, leading to decline or extirpation of some species. We evaluated how desert birds have responded to climate and habitat change by resurveying historic sites throughout the Mojave Desert that were originally surveyed for avian diversity during the early 20th century by Joseph Grinnell and colleagues. We found strong evidence of an avian community in collapse. Sites lost on average 43% of their species, and occupancy probability declined significantly for 39 of 135 breeding birds. The common raven was the only native species to substantially increase across survey sites. Climate change, particularly decline in precipitation, was the most important driver of site-level persistence, while habitat change had a secondary influence. Habitat preference and diet were the two most important species traits associated with occupancy change. The presence of surface water reduced the loss of site-level richness, creating refugia. The collapse of the avian community over the past century may indicate a larger imbalance in the Mojave and provide an early warning of future ecosystem disintegration, given climate models unanimously predict an increasingly dry and hot future.”
Mojave Desert Bird Species Have Declined By Almost Half – The Mojave Desert has gotten hotter and drier over the past 100 years, and this change has been especially hard on birds. (State of Nevada, August 2018)
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At this point I wish to emphasize what I believe will ultimately prove to be the greatest value of our museum. This value will not, however, be realized until the lapse of many years, possibly a century, assuming that our material is safely preserved. And this is that the student of the future will have access to the original record of faunal conditions in California and the west, wherever we now work.
– Joseph Grinnell, 1910, The Uses and Methods of a Research Museum (source)
— UC Berkeley (@UCBerkeley) August 6, 2018
— PNAS (@PNASNews) August 10, 2018
— Shaun McKinnon (@shaunmckinnon) August 8, 2018