Recent accomplishments of CDFW's scientific community
California leaf-nosed bats. CDFW photo by retired biologist Andy Moore.
Hundreds of bats in flight. ©Dave Feliz, all rights reserved.
Little brown bat with white-nose syndrome. US Fish and Wildlife Service photo.
Townsend's big-eared bat in flight. National Park Service photo.
The last seven days of October are celebrated each year as Bat Week – a time to learn about the importance of bats in our environment.
Bats are nature’s best pesticide. According to a study by the University of California, Davis, Division of Agriculture and Natural Resources, each of these small mammals eats between half and 100 percent of its own weight in insects every night. Some California species consume as many as 600 insects per hour. Imagine living with all the mosquitoes, flies, midges, moths and agricultural pests that are now consumed by bats!
In monetary terms, the natural pest control that bats provide is extremely valuable to the state’s $54 billion per year agriculture and $450 million timber industries. The bats’ appetite reduces the need for chemical pesticides, reduces crop losses and curtails the spread of crop diseases. According to the US Geological Survey, a recent economic analysis indicated that insect suppression services provided by bats to American agriculture is worth something between $4 billion and $50 billion per year.
California Department of Fish and Wildlife (CDFW) Senior Environmental Scientist Scott Osborn notes the estimate’s wide range makes it hard to know exactly how much money bats save farmers. “But even the low estimate, $4 billion, is an impressive amount,” he said. “Bats are an important part of integrated pest management systems.”
As the wildlife trustee agency in California, CDFW is engaged in several activities to help us understand the conservation status of bats in the state, as well as to address threats to bat populations. At statewide, regional and local scales, our scientists have been deploying acoustic bat detectors to determine the distribution of California’s 25 bat species. When CDFW’s bat acoustic data are combined with data collected by partners at other state and federal agencies, academic researchers and non-governmental organizations, we should have more accurate knowledge of where various bat species occur, as well as their seasonal movements.
White Nose Syndrome (WNS) is now a real threat to California’s bats. WNS is a fungal disease that is estimated to have killed more than 6 million bats in eastern North America. With the discovery of WNS for the first time on the west coast (in Washington state) last year, California is bracing for potentially devastating impacts to our bat populations. CDFW is working with the US Fish and Wildlife Service and other partners to conduct surveillance for the fungus that causes the disease, as well as develop plans to manage the disease when it arrives in California. So far, all of the samples collected from bats and their roosts in California have been free of the fungus, but increased vigilance is necessary to help ensure the disease is detected immediately when it arrives. Special measures to reduce the impact of WNS on hibernating bats may include closing caves and other roosts to visitors, because people can unwittingly spread the fungus on their clothing, shoes and gear. Ultimately, it is hoped that ongoing research into the disease will provide tools to either eliminate or control the fungus, both in the environment and in infected bats.
To learn more about the exciting world of bats and how you can “Go to Bat for Bats!” check out the Bat Week 2017 website.
Top photo: A California bat in a crevice. ©Dave Feliz, all rights reserved.
Fate has not been kind to the San Joaquin kit fox (Vulpes macrotis mutica).
Shrinking habitat caused by urbanization and agricultural expansion landed this Central Valley native on the federal Endangered Species List decades ago. California’s total population of San Joaquin kit foxes may now be down to a few thousand animals. To make matters worse, its favorite food, the kangaroo rat, is likewise endangered as the desert habitat it prefers continues to disappear.
Wildlife biologists took heart, however, in a population that seemed to be thriving within the city limits of Bakersfield. Unlike San Joaquin kit fox populations in other parts of the Central Valley range, the Bakersfield foxes adapted quite nicely to urban life. Their number – estimated between 200 and 400 animals – has evidently seemed to be holding steady and possibly increasing.
Their cute and cuddly appearance make them popular with city residents. Earlier research showed the population was healthy and genetically robust. Wildlife biologists were counting on those urban foxes to ensure the species’ survival should kit fox populations completely collapse elsewhere.
Today, those Bakersfield kit foxes are under siege, suffering from an outbreak of highly infectious sarcoptic mange. Mange – a skin condition caused by parasitic mites -- leads to hair loss, open wounds from scratching and, ultimately, death. The first case was detected among the kit fox population in March 2013, and since then, more than 200 cases have been documented. The epidemic has grown worse every year.
Given the importance of the Bakersfield population, CDFW, the U.S. Fish and Wildlife Service, the California State University, Stanislaus, the University of California, Davis (UCD), and various nonprofit wildlife groups have all joined forces to combat the mange.
Jaime Rudd, an environmental scientist in CDFW’s Wildlife Investigations Lab in Sacramento, is leading CDFW’s efforts while simultaneously writing her UCD Ph.D. dissertation on the outbreak. Rudd is researching ways to prevent mange from spreading to healthy animals, and assisting Stanislaus State’s Endangered Species Recovery Program with trapping and treating diseased foxes.
Severely diseased kit foxes are trapped and transported to the California Living Museum, a Bakersfield wildlife rehabilitation facility and zoo. There, the kit foxes are hospitalized, given life-saving antibiotics and fluids and treated with a topical pet product that kills the mites. The foxes often need months of treatment before they are healthy enough to release. And although the intervention saves individual lives, the process is costly and time-consuming – and doesn’t prevent the treated fox from getting mange a second or third time.
Rudd is making good use of her undergraduate degree in molecular biology, analyzing the DNA of the mites to see if they might be related to those in dogs and coyotes, which could be spreading the mange to the foxes.
“Essentially, we want to look at their molecular signature to see if these mites are related,” Rudd said.
Rudd is studying a group of wild kit foxes living on the CSU Bakersfield campus, which no doubt are supplementing their diet with burger bits and pizza crusts discarded by college students. Rudd is monitoring the group with trail cameras, outfitting some foxes with radio tracking collars and others with the type of preventative flea and tick collar you might use on a pet dog or cat.
“We want to evaluate the efficacy of these collars,” she said. “If they’re only going to work for two months, the collars won’t help us slow down the spread of mange, so is it really worth the effort of putting them on? But if they’re going to work for five months or more, then it might be worth the effort.”
If there is any hope sustaining Rudd and her colleagues in this important, though often disheartening, work, it’s this: “The fact we are not seeing mange in the outlying populations is cause for optimism,” she said. “If nothing else, we can at least try to keep it from leaving the city.”
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