I’ve written several postings with information about mange. One on how the malady has just recently exploded here in San Francisco, and another on how weakened immune systems allowing the mange mite to proliferate on a coyote host have been linked to the use of rat poisons. But there are other stressors which raise cortisol which in turn weaken immune systems, allowing the mite to take over. An interesting correlation (maybe related) is that San Francisco’s coyote population might have reached an over-saturation point, as indicated by territories being divided up and shared at the same time that mange has spread wildly through the city. It’s this correlation that I’m attempting to point out.
2024 marked the breakup of one of San Francisco’s long-term stable coyote territories: This territory had been stable since 2007. The shift began when Scowl, the alpha male, left his older mother-turned-mate, Chert, after two years of fathering and raising a family of pups with her. Whether age played a role, I don’t know — but he soon turned up with a younger female, Bonus, on her much smaller territory, where they had pups that year.
Left behind was Chert, aging, along with three yearlings. Several new males passed through, but appear to have been rejected. the one who remained for several weeks had mange. Within months Chert and her offspring had mange. In addition, this is when a mangy “squatter” pair of coyotes moved into a portion of her territory, maintaining their separation from Chert’s family. Their pups did not survive, and the pair left by early summer — but the area had effectively become shared space.
2024 was also the year mange appeared to take hold across the city.
After Chert died towards the end of the year, 2024, two of her offspring remained and claimed the southern portion of what had once been her and Scowl’s shared domain. This kind of territorial inheritance — offspring retaining natal land — has characterized this lineage since 2007. In fact, it characterises a number of San Francisco’s territories, but not all of them.
Meanwhile, Scowl eventually led Bonus back to his former territory, reclaiming the northern section. By 2025, what had once been a single large territory was permanently divided in two. The families are closely related — both are offspring of Chert’s from different years — but they never interact, maintaining a firm boundary.
Another divided territory: Scout’s story
Scout originally acquired her territory after it was vacated — a rare and lucky find. Yet in 2022 she denned about a mile away, possibly because of her mate Scooter’s family ties there. Even so, during this time, she continued returning to her original territory, where earlier offspring remained, almost as if holding it for her.
In 2023 she returned to her original old territory full-time with a new mate, Skipper, and they stayed for two seasons. But in 2025, one of Scout’s daughters resisted dispersal. So it was Scout and Skipper then who abruptly left, returning to the territory she had denned in a mile away, where they squeezed the other claiming family into a less desirable portion of the park.
That displaced family developed severe mange; Scout and Skipper had milder cases but recovered. Once again, the territory appears permanently divided, with mange disproportionately affecting the weaker group.
Shared space and shifting use
In 2025, two families shared the Sunset area, using the same passageways at different times of day or evening. Both alpha pairs had serious mange.
A similar pattern is now emerging in a denning area of West Portal. After Mouse — the territorial female — was killed by a car in 2022, the area became something of a no-man’s-land. Coyotes came and went: loners, then pairs. But by 2024-25, three mangy pairs were using this small area regularly.
An open question
Across these examples, territorial divisions and shared-use areas appear to coincide with mange outbreaks beginning in 2024. Population pressure appears to be driving these divisions. Does crowding and social stress increase vulnerability to disease and accelerate its spread? I don’t know whether these patterns are causal or coincidental.
I’ve simply observed the overlap. Determining whether one feeds the other is a question best left to someone with an infectious-disease background — but the pattern itself is becoming hard to ignore.
Feb 10, 2026 @ 08:31:50
Hi Janet,
Here we go again… I had heard and read that the government introduced mange to the United States to control, you guessed it, wolves, coyotes, and foxes; however, it has spread through the years to wildlife the government would not like infected – no surprises here, except disgust and sick of the manipulation, control and despicable experiments on wildlife and more. I found one article this evening,
https://www.thewildlifenews.com/2007/03/02/1905-montana-legislatures-action-spread-mange-throughout-montana-and-wyoming/
Though with this lead perhaps others can lend a hand at the research regarding the government introducing it to wildlife.
I’m sick and tired of the shadowy movements of government agencies and what they do!
Feb 10, 2026 @ 11:57:59
Hi Tish — I read this about humans introducing the disease in Coyote America by Dan Flores. Yes, pretty disgusting. But that is not what is causing today’s outbreak. It’s weakened immune systems. The weakened immune systems are caused by rat poisons that humans put out, but also by other stressors that raise cortisol which weaken immune systems. An interesting correlation (maybe related) is that San Francisco’s coyote population might have reached an over-saturation point, as indicated by territories being divided up at the same time that mange has spread wildly through the city. It’s this correlation that I’m attempting to point out.[I’ll add this to my posting]
Feb 10, 2026 @ 15:11:45
In Southern California, it is assumed that Rodentcide ( in prey animals) has a large influence on mange. This can negate treatment as the cause remains.
Feb 10, 2026 @ 17:09:26
Yes, rodenticide has been implicated in weakening their immune systems.It appears that stress in the form of population pressure may be another factor weakening immune systems and leading to mange. No matter what the cause, treatment can still be administered which will alleviate symptoms and allow healing, even if it is a temporary fix. The medication lasts 3 months in killing the mite, and it can be administered again if needed.
Feb 18, 2026 @ 22:05:06
If we see a coyote with mange what is the best treatment? And is it readily available?
Currently, there is a product that has been rolled out to inhibit rodent population, basically a birth control. Because I have lost chickens last year due to their eating poisoned rats and mice, sadly they succumbed. I wondered at first what was killing my young chickens within their coop; wonder no more. It’s a tough spot to be in: you need a deterrent from the rodents getting in your insulation and walls but the loss of my chickens PLUS now realizing it’s the secondary poisoning that is killing the wonderful wildlife and is killing household animals.
I’ve spoken with the local wildlife service that assists injured, sickened and dying wildlife and they recommended ContraPest. Folks can read up on it though I’ll mention it doesn’t kill the rodents only stops or slows their ability to reproduce. Also, it was mentioned the wildlife will not get sick and die if they consume a rodent with ContraPest in their system.
Lastly, I’ve considered having the small gauge fencing installed at the crawl space thereby making it difficult for a rodent to dig underneath the foundation and enter the crawl space. If anyone has remedies for keeping rodents out of the crawl space please let me know. And thanks, Janet, for this space to share ideas, news and information.
Feb 18, 2026 @ 22:25:06
Hi Tish —
There is indeed a readily available medication to treat mange in coyotes IN THE FIELD, which is the best of all possibilities. However, your state laws may be impeding this, as they are here in California. The remedy is “Bravecto” which works for three months and can be administered again. It can be administered in the field without interfering with a coyote’s family life, which is vital. The catch is that it must be ground down and added to one tablespoon of food, such as a raw meatball or liverwurst: in other words, administering the medication would be considered “feeding” a coyote, which is illegal. Your state may not have this law, in which case your are free to proceed!
Poison is poison, including ContraPest: I’ve heard it doesn’t really stop the rats, and it continues to hurt wildlife. Exclusion is the only ecologically responsible alternative: however, it is expensive and time consuming and has to be done right. The fine mesh wire you are talking about has to be put down deep which requires digging a trench. There might be better solutions, but this is what I’ve heard. I myself don’t have a rat problem. Hope this helps!
Feb 11, 2026 @ 22:35:39
Okay, I see the other cause and have heard of this as well. Currently, several states, Washington included, are trying right now to pass legislation to stop using rodenticides because it is also killing wildlife as the wildlife: hawk, eagle, coyote, fox, wolf, etc. eats the dying sickened animal: rat, mice, etc. and they become sick and die. If anyone would like to get involved with the legislature to have this passed in your state, please contact your representatives or senate leaders. If anyone cares to research this devastating outcome on wildlife, any use of these terms:
secondary rodenticide poisoning
Feb 11, 2026 @ 23:04:08
I believe its sale has been stopped for the general public here in SF — but people get it anyway. :(