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Rising Heat Isolated as Main Cause of Desert Bird Declines

Rising Heat Isolated as Main Cause of Desert Bird Declines

Alex Wierbinski's picture

By Alex Wierbinski - Posted on 30 September 2019



Rising Heat Isolated as Main Cause of Desert Bird Declines

Collapse of Desert Bird Populations Likely Due to Heat Stress from Climate change,
University of California - Berkeley, September 30, 2019.


"The team that last year documented a collapse of bird communities in Mojave Desert over the last century -- 29 percent of the 135 bird species that were present 100 years ago are less common and less widespread today -- has now identified a likely cause: heat stress associated with climate change."

Earlier Research: See First Link Below

Virtual Birds vs. Real Declines
A Match
"...comparing levels of species declines to computer simulations of how "virtual birds" must deal with heat on an average hot day in Death Valley, which can be in the 30s Celsius -- 90s Fahrenheit -- with low humidity. These temperatures are, on average, 2 C (3.6 F) hotter than 100 years ago. The birds that the model predicted would require the most extra water today, compared to a 100 years ago, were the species that had declined the most in the Mojave Desert over the past century."

Big Bug Eaters
"The most threatened turn out to be larger birds, and those that have an insect or animal diet."

Model Flexibility
"The virtual bird simulation was unique in allowing the researchers to identify the impact of a daily physiological stressor in the desert -- heat -- as birds leave the shade to forage for food or find mates."

Isolating Rising Temperatures
"Most previous studies have not found a direct physiological connection between climate change and biodiversity change, which is usually mediated through changes in the food web or competing species. Our study points to a direct effect of climate change via increased water demands for evaporative cooling to maintain body temperature in the comfort zone."

Bird Tech
"Like humans, birds regulate their internal temperatures to keep within a comfortable range. But they do not sweat. Like dogs, they pant, but can also vibrate their throat muscles in what's called a gular flutter. The resulting increase in air flow and evaporating water cools them off."

Increased H2O Consumption
"The team calculated that larger birds, like the mourning dove, require 10% to 30% more water today to keep cool because of the 2 C increase in Mojave Desert temperatures over the last 100 years."

Big Bug Eaters
"...birds that eat insects or other animals are more threatened by changes in evaporative water loss because they typically get all of their water from the moisture in their food. They seldom, if ever, drink from surface water sources. A 30% increase in water requirement could mean that larger birds have to catch an extra 60 to 70 bugs per day to survive the increased heat. If those bugs are even around, the birds still have to expend extra energy and time to find them."

Declining Big Birds
"The American kestrel, prairie falcon and turkey vulture, all large and carnivorous, have declined, as have large insect-eaters like the white-throated swift, violet-green swallow, olive-sided flycatcher, Western meadowlark and Western bluebird."

Smaller Bird Problems
"Vegetarian birds, such as seedeaters, face a different problem. Because they can drink from surface water sources -- springs and pools in desert oases, they can supplement the water they get from their food. But that's only if water is around."

Less Water for Smaller Birds
"Death Valley, Joshua Tree National Park and the Mojave National Preserve, where the bird surveys were conducted -- are getting drier from climate change and because of groundwater pumping by nearby cities and agricultural areas. As a result, the seedeaters are also at risk of heat-related death."

"For plant-based eaters, it is more binary: whether or not a species survived at a site over the past 100 years had more to do with the presence or absence of surface water. If you could drink, you were better off than if you couldn't drink."

Birds Doing Everything They Can
"...some birds are adapting to the hotter temperatures by moving northward or up mountain slopes to find cooler habitats, while others are shifting their active nesting periods earlier in the year to avoid hotter summer temperatures. Some species are even becoming smaller, reducing their water needs. But birds can reduce their size only so much."

Grim Present, Grim Future

"...we have seen a 50 percent reduction in species diversity at sites in the desert visited a century ago by Grinnell. This isn't really a question of when will it happen in the future, but understanding what we have already done, what has already happened."

"...larger birds like the mourning dove may require nearly twice their typical intake of water by the end of the century to remain cool enough to survive higher temperatures in the desert."


Desert Bird Migrations

Aug 2018
BIRD NEWS: New Normal of Death & Decline in Mojave


Oct 2018
HEATED CACTUS THREATENS HUMMERS: Desert Migrations Threatened by Shifted Blooming Time


Oct 2018
End of Sleeping Sickness? Zambezi Too Hot for Tsetse Flies?



The Real Problem
Feb 2018
Climate Change News: Nature Losing its Integrated Timing; Life no longer supporting itself



Birds & Bird Migrations

Three Billion Fewer Birds in North America since 1970


April 2019
Great Basin Flyway Drying Out


March 2019
Global Bird Migrations Shifting With Climate


Sept 2018
Trouble in the Cloud Forests, Birds Ascending 23 Feet a Year



Bugs & Birds

Jan 2019
Puerto Rico Bug Decline, & Swallow Decline,
BIRDS & INSECTS, A Shared Decline



Nov 2018
Beetle Fertility Crashing in Heatwaves


Nov 2018
UK Bees, 2018: 2 of 25 Species Extinct, 8 Endangered


Oct 2018
New fly species, Lucilia cuprina, found in Indiana Indicates Changing Climate


And Spiders
July 2018
Allies Against the Bugs: Program and Scorecard for the Battle of "The Birds Vs The Bugs"



Bird News

News of Man & Nature, September 2019








Nature News


Climate Destruction News



Bee News

Bear News

Spider Forum

Bird News

Small Mammals

Frogs and Reptiles

Butterfly News


Health and Fitness

Mountain Safety

Mosquito News

Female Trail

High Sierra History


Astro-Phys, Space, & Science News

High Sierra Geology News

Fish, Oceans, & Water News






birds, bird news, desert birds, declining, due, to, rising, heat, temperatures, Mojave Desert, big birds, insects, water


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