Data indicates steep drop in the feral cat population
LOS ANGELES, California––Southern California coyotes may be eating 68% fewer feral and free-roaming pet cats in 2018 than they did 20 years ago, indicate comparisons of findings from five major studies of coyote diet.
Since coyotes are opportunistic predators who tend to eat whatever they find, and have had no reason to foreswear cats, the research implies––but not unambiguously––that cats are no longer as accessible to them as they were circa 1998-1999.
That appears to mean that the Southern California feral and free-roaming pet cat population has declined.
But the general trend appears to be contradicted by one outlier set of findings, which showed that as of 2014, coyotes in coastal habitat near San Diego might have been eating 28% more cats than 15 years earlier.
An alternative explanation for the apparent overall drop in coyote consumption of cats shown by the most recent data might be that increasingly coyote-wary Southern California cat keepers are less likely now than 20 years ago to let their cats roam.
72% lower feral cat birth rate
But a variety of surveys done as far back as 1990 showed that from two-thirds to 75% of owned cats were kept strictly indoors even then.
A national survey conducted by VetStreet.com affirmed these findings in 2014, showing no significant changes in cat-keeping behavior.
The most recent data, showing that cats are of steeply reduced importance in the Southern California coyote diet, echoes the 2017 finding by Alley Cat Rescue, in the largest-ever national survey of feral cat colony caretakers, that neuter/return feral cat population control appears to have reduced the feral cat birth rate by 72% since 1992.
Cats are down to 8% of urban coyote diet
The 2014 outlier finding may reflect mainly the unevenness of neuter/return campaigns in covering all types of habitat. Almost entirely conducted by volunteers, using their own and donated resources, neuter/return projects tend to be concentrated near the volunteers’ own homes, and in more accessible areas, which may exclude the steep coastal arroyos that made up much of the 2014 study habitat.
Currently, “Cats seem to make up only about 8% of a local urban coyote’s diet,” California State University at Fullerton graduate researcher Danielle Martinez, 27, told Los Angeles Times reporter Louis Sahagan.
Study takes guts
Martinez, Sahagan wrote, is a participant in “a coyote postmortem on an unprecedented scale — it has so far documented the contents of 104 stomachs and intends to examine 300 by the end of the year.”
The stomachs are collected from coyotes who “perished across Los Angeles and Orange counties under myriad circumstances,” including roadkills and animal damage control trapping.
Continued Sahagan, “The team, led by Niamh Quinn, U.C. Cooperative Extension’s human-wildlife interactions advisor, is already generating a wealth of data,” expected to produce the most accurate portrayal of the coyote menu.
Unlike previous studies, the study by Quinn et al reflects all habitat used by coyotes, not just the urban habitat fragments where previous researchers have searched for coyote scats.
DNA studies started in 1998
The first major study of the diets of Southern California coyotes, completed in 1998 by University of Arizona at Tucson researchers Martha Grinder and Paul Krausman, used DNA analysis of hair and bone found in coyote scats to establish that feral cats were among the coyotes’ primary prey.
However, of the 34 scats that Grinder and Krausman collected for analysis, 10 were found to have actually come from domestic dogs. Thus the study was based on findings from only 24 scats, which might have been produced by even fewer coyotes.
Grinder, who was killed in a July 1999 traffic accident, was unable to participate in follow-up studies.
Krausman, however, with another researcher, Shannon Grubbs, did a somewhat comparable study in Tucson, Arizona, tracking eight radio-collared coyotes from December 2005 until November 2006.
2.5 cats per coyote per year?
During that time, Krausman and Grubbs were able to identify 45 instances of coyotes consuming prey and fruit, including 19 instances of coyotes eating cats, by far the easiest prey the coyotes caught to identify from remains left at the scene. Of 15 observed instances of coyotes eating rodents, by contrast, Krausman and Grubbs were unable to positively identify any by specific species.
From Krausman and Grubbs data, one might extrapolate that urban coyotes in Tucson at that time ate on average fewer than 2.5 cats per year. However, one could not extrapolate how that coyote rate of predation on cats may have changed over time, nor how much or how little coyote predation habits in Tucson may resemble what coyotes do in Southern California.
Cat remains in 21% of coyote scats
Meanwhile, Kevin R. Crooks, of the Department of Biology at the University of California in Santa Cruz, and Michael E. Soule of the Wildlands Project in Hotchkiss, Colorado, completed a more comprehensive study of Southern California coyote diets and predation published in the August 1999 edition of the prestigious peer-reviewed journal Nature.
Crooks, widely recognized as a pioneer in doing DNA analysis of wildlife scats, affirmed the Grinder and Krausman findings by discovering cat remains in 21% of 219 coyote scats found in arroyos near San Diego, apparently the same locations later searched for scat in the outlier 2014 study.
The Crooks study areas are located just south of Los Angeles and Orange counties, the two counties from which coyote stomachs have been collected for the Quinn study. All of the study areas are potentially within the wandering radius of the same coyote families. However, the area is densely enough populated with coyotes that actual overlap of habitat use by some of the same coyotes is unlikely.
Crooks and Soule found from surveying 636 cat owners near their study areas––an exercise not repeated in connection with the other Southern California studies of coyote diet and predation––that 77% allowed their cats to go outdoors.
However, Crooks and Soule failed to establish what percentage of the cats in the habitat those owners kept. Other studies have fairly consistently documented that cat owners who keep their cats indoors tend to have two to three times as many cats as those whose cats roam, chiefly because of the much greater longevity of indoor cats.
Thus, even in the 1980s and early 1990s, when several national surveys found more than 70% of cat owners allowed their cats to roam, unlike today, two-thirds or more of the cat population were kept strictly indoors.
Cats, coyotes, foxes & bobcats
Crooks in 2014 joined Rachel N. Larson, Dana J. Morin, and Izabela A. Wierzbowska in producing the outlier study, “Food Habits of Coyotes, Gray Foxes, and Bobcats in a Coastal Southern California Urban Landscape,” published a year later by Western North American Naturalist.
This study found that among a sampling of 119 coyote scats, “domestic cats occurred in 29%,” markedly more than Cooks and Soule found in their 1999 research.
Gray foxes and bobcats, by contrast, did not appear to prey heavily on cats––but also tended to live farther away from humans than coyotes.
The 2014 study by Crooks et al, compared to the 1999 study by Crooks and Soule, might have indicated that neuter/return was failing to reduce the numbers of cats at large and available as coyote prey. But the findings from both of Crooks’ studies might also be indicative only of what is occurring in habitat that is relatively inaccessible to neuter/return practitioners, or where there simply are none.
Meanwhile, the 2014 study is still the only such research to indicate that coyote predation on cats might have increased.
Combining the 2014 study data from Crooks et al with the data from the first 100 coyotes whose stomach contents have been investigated by the Quinn team indicates that cat remains were found in 42 of 219 samples, a finding almost the same as the discovery of cat remains in 45 of 219 samples by Quinn and Soule in 1999.
That would suggest that the number of cats at large in the study habitat may not have changed much––but what change there has been has been in the direction of fewer cats.
Truth emerges from a lot of poop
In 2016, two years after publication of “Food Habits of Coyotes, Gray Foxes, and Bobcats in a Coastal Southern California Urban Landscape,” the Urban Coyote Project enlisted more than two dozen volunteers citizen scientists to help collect and process coyote scat from around Los Angeles.
Preliminary findings from the Urban Coyote Project, compared to the studies by Crooks et al, indicated that coyotes overall are not eating cats in great number.
The Urban Coyote Project is modeled after the Cook County Coyote Project, begun by Stan Gehrt, Ph.D, in the Chicago Forest Preserve greenbelt in 2000.
Analyzing more than 1,400 scats, four times more than were evaluated in both Crooks studies plus the earlier Grinder/Krausman study, the Cook County Coyote Project reported that “the most common food items were small rodents (42%), fruit (23%), deer (22%), and rabbit (18%).” Only 2% of the scats collected in Cook County contained identifiable human garbage and cat remains were found in just 1.3%.
No benchmark data
The low incidence of cats in the Chicago study might indicate the success of neuter/return feral cat control, also practiced in Chicago for more than 20 years, but there were no earlier studies of coyote diet in and around Chicago with which to compare the findings.
The Cook County Coyote Project became the pilot for a much larger Urban Coyote Research Program now also including ongoing studies in Denver and New York City.
Both Denver and New York City are also longtime hubs of neuter/return activity, but as in Chicago, no benchmark studies were done in either location to establish what coyotes were eating there 20 years ago or longer.
Indeed, coyotes have only known to be living in New York City since 2006, and were only confirmed to have reached Long Island in 2013.
Feral cats avoid coyote habitat
Gehrt believes that coyote predation on cats tends to be low because, as he explained in 2012 to Science Daily, “Free-roaming cats are basically partitioning their use of the urban landscape. They’re not using the natural areas in cities very much because of the coyote presence there.
“It reduces the cats’ vulnerability to coyotes,” Gehrt said, “but at the same time, it means the coyotes are essentially protecting these natural areas from cat predation.”
Gehrt confirmed this hypothesis in a 2013 study that tracked 39 radio-collared feral cats. This established that while the cats made extensive use of alleys, yards, parking lots, and other areas that coyotes avoid, the cats tended to stay away from the greenbelt habitat favored by coyotes.
North Carolina Museum of Natural Sciences zoologist Roland Kays and collaborators in 2014- 2015 “used motion-activated cameras to take snapshots of domestic cats and coyotes in backyards, small urban forests, and protected areas such as parks and nature preserves in Raleigh and other parts of the eastern United States,” reported Rose Rimler for the Raleigh News & Observer. “The cameras captured almost no cats in the natural areas the coyotes preferred. In half the protected areas, no cats were photographed at all; most of other sites captured images of just one cat apiece.”
This too may hint at the success of neuter/return projects, but no research was done to find out what had been done to control feral cat populations in and around the study areas.
More cats fixed in past five years than in 20 years preceding
Also of note relative to the recent findings pertaining to coyote predation on feral cats, the 2017 Alley Cat Rescue survey of neuter/return practitioners found that more than half of all the cats who have ever been sterilized by neuter/return programs were sterilized in the 2012-2017 time frame: more in just the past five years than in the preceding 20.
What this meant to any of the coyote-and-cat study areas is unclear, but the national surge in feral cat sterilization came after Los Angeles Superior Court Judge Thomas McKnew ruled in December 2009 that California municipal governments may not assist or promote neuter/return of feral cats without first completing an environmental impact report.
Birders sought to kill neuter/return
McKnew held that the Los Angeles Department of Animal Services was in violation of the California Environmental Quality Act for issuing $30 sterilization vouchers to neuter/return practitioners and for referring people who call to complain about feral cats to charities that do neuter/return.
The McKnew verdict, issued on behalf of The Urban Wildlands Group, the American Bird Conservancy, the Endangered Habitats League, the Los Angeles Audubon Society, the Palos Verdes/South Bay Audubon Society, and the Santa Monica Bay Audubon Society, was expected to markedly inhibit neuter/return projects.
Some nonprofit neuter/return programs had already been underway in the Los Angeles, San Diego, and San Francisco Bay areas for more than 20 years, but little had been done to document what net effect they were having.
More research is needed
Post-McKnew, no governmental agency has coordinated neuter/return work in California, and therefore no data is readily available even pertaining to such basic questions as the numbers of feral cats trapped, sterilized, and released into monitored colonies in any given city or county.
The coyote diet studies appear to confirm, however, that the national trend found by Alley Cat Rescue has continued in Southern California as well as elsewhere.
As published peer-reviewed studies often conclude, more research is needed, especially to establish not only how many cats coyotes are eating, but also how many cats––both owned and feral––are actually still at large in urban habitats.