In addition to major changes in the physical environment, rising temperatures will bring dramatic shifts in the habitats of countless species, most notably in the semi-arid American West, esnl‘s own habitat for the last six decades.
From the U.S. Geological Survey:
With temperatures projected to increase approximately 6 degrees Fahrenheit in the Southwestern United States and precipitation projected to decrease between 5 and 20 percent this century, habitat for some bird and reptile species may be negatively affected, according to new research [open access] by scientists from the U.S. Geological Survey, University of New Mexico and Northern Arizona University.
“This study identified better tools and strategies to conserve and sustain wildlife habitats in the Western U.S. using specific information about climate change consequences from models the authors developed,” said Dr. Charles van Riper III, senior research ecologist with the USGS and report co-author. “In conducting this study, we coupled existing global climate change models with newly developed species distribution models to estimate future losses and gains of Southwestern bird and reptile species.”
“Resource managers need scientific products and tools to inform planning and decisions under climate change and habitat alteration,” said Dr. Stephen Jackson, director of the Department of the Interior’s Southwest Climate Science Center. “This study will help managers assess the potential consequences of climate change for bird and reptile species, identify vulnerable species and populations and develop robust plans for climate adaptation.”
Fifteen species of birds and 16 reptile species comprised the study, including well-known species such as the Gila monster, horned lizard, chuckwalla, Sonoran desert tortoise, pinyon jay, pygmy nuthatch, sage thrasher and black-throated sparrow.
Projected changes in bird and reptile ranges varied widely among species:
- One-third of the ranges are predicted to expand, while two-thirds are predicted to contract.
- Several reptile species are projected to lose between 25 and 72 percent of their range, including the Gila spotted whiptail, Arizona black rattlesnake and ornate box turtle.
- Numerous bird species are projected to lose between 78 and 85 percent of their range, including Williamson’s sapsucker, sage thrasher, red-naped sapsucker and pygmy nuthatch.
There’s more, after the jump. . .
An important finding by the authors was bird or reptile species that currently occupy warmer locations in any season may experience range gains, whereas species that currently occupy wetter spring or summer locations may experience range contractions.
Another key finding by the authors was that the more fragmented bird and reptile ranges are under today’s conditions, the more vulnerable they appear to the future effects of climate change. The more fragmented a species’ current range, the greater the magnitude of possible future decline.
“Proactive land management actions that enhance landscape connectivity and conserve core areas might lessen the severity of range contractions projected over the coming century for birds and reptiles,” said James Hatten, lead author and research biogeographer with the USGS. “Land management actions that reduce the distance between habitat patches, increase connectivity, and enlarge core areas could be helpful for bird and reptile species across the landscape.”
Numerous studies have examined the vulnerabilities of wildlife to climate change without considering coexistence of plants and wildlife. After plants were incorporated into their models, future predictions for birds and reptiles became even more severe.
When the authors modeled the assumption that reptiles will not be able to disperse fast enough to escape a shifting climate (think of animals with tiny or no legs), all their future ranges contracted. When the authors assumed reptiles can disperse as fast as the climate shifts, such as birds, over half of reptile species’ ranges expanded, but the authors think this is highly unlikely given the life histories of many reptiles. In contrast, several desert-scrub bird species (black-throated sparrow, gray vireo and sage sparrow) are projected to increase their future ranges by over 30 percent.