Inbreeding: An Example in San Francisco

I’ve been documenting this family, on the same territory, for over eleven years now.

When this fella turned four, he and his mother (her first mate having been killed by rat poison several years before) produced four pups, three of whom survived to adulthood. By fall of that year, his mother-turned-mate disappeared, possibly killed by a car. So their one daughter then became the fella’s mate the following year: i.e., this mated pair are 1/2 siblings sharing the same mother, and he is her father. Yikes! Of the four litters they have produced over the last four years, only one female has survived to full adulthood. You might want to read about inbreeding depression. The consequences of inbreeding include lower fertility, higher infant mortality, higher susceptibility to diseases and parasites, and generally weakened systems.

Coyotes returned to San Francisco in 2002. There were only a handful of coyotes early on. It is very likely there may have been inbreeding in the population here prior to the time I began documenting this family.

Photos of the evolving inbred family

In 2008 the territorial family consisted of Mom, Dad, and one pup who I simply called “Yearling”. This was the first family unit I ever documented. A year later, this same mated pair had a second litter.

Mom and Dad’s second litter consisted of two males. Within weeks of their birth, Dad was killed by rat poison, leaving Mom single. She and her two male pups, Bruno and Silver, formed a tight-knit family which always did things together, but the male siblings who began as best friends eventually turned into arch-enemies, with the stronger-willed Silver driving his brother out: it appeared they were rivals and jealous for their mother’s attention and affection. If their father had been around, both males would have been driven out, preventing what then happened.


When Silver turned four years of age in 2013, he and Mom produced four offspring: mother and son had become a mated pair. This was the first inbred litter I documented.

One of their pups died as an infant leaving three. Then one male, Acorn was harshly dispersed at 9 months of age. That left two offspring, Chert [female] and Gumnut [male] who remained with their parents until one day in early November in the year of their birth, Mom suddenly vanished, possibly hit by a car. So now these two youngsters, Chert and Gumnut, began living with only their father Silver, (who was also their 1/2 brother), on the territory.

Siblings Chert and Gumnut became BFF — extreme buddies who played together and groomed each other constantly — from all appearances, they were destined to become a pair.

But Chert was the only female around and her father decided she would be his next mate. For months he tried driving off Gumnut who wouldn’t leave. And Chert was definitely bonded to Gumnut, making Silver’s task extremely difficult.

Silver (right) is Chert’s 1/2 brother and her father. Their reproductive success has been very low.

Silver and Chert (who is Silver’s daughter and 1/2 sister) become a pair. When Chert is two years old, she produces a litter: now the close inbreeding has been doubled. There is only one pup, Scout.

In the summer after Scout was born, Silver finally forces Gumnut (his son and 1/2 brother) to leave. [There actually is a chance that Gumnut could have fathered Scout. Scout adored Gumnut and vice-versa, but Silver’s domination and put downs would have been hard to get around — Silver perpetually physically placed himself between Scout and Gumnut to keep them apart. Scat DNA, which is all we have, is only able to identify the maternal lines.]

Litters have been born every year for four years to Silver and Chert, but no pups ever survived except Scout from their first litter. Scout is the only one.

I hope the genealogy is clear here. If you have questions, please send them in a comment (can be kept private). For a couple of short easy-to-read articles about inbreeding see these two articles: and

20 Comments (+add yours?)

  1. Cindie White
    May 10, 2019 @ 19:50:17

    Wow. What an extraordinary and intimate story of genealogy, Janet. Ah, my heart. Thank you once again for your love and dedication to Coyote -and for offering me this deeper connection.


    • yipps:janetkessler
      May 10, 2019 @ 20:11:13

      Thank you, Cindie. Yes, I’m hoping a deeper connection and a deeper understanding will help more people value them and embrace them. Thanks for being part of the process with your own efforts, and for your comments and support! :)) Janet

  2. MelindaH.
    May 10, 2019 @ 19:55:08

    Wow—you have been following these guys for a long time. I read about situations like this, so much of it human-caused, and the saying keeps going through my head, “why can’t we all just get along.” This aspect of coyote life had never occurred to me. Thank you for more education !!


    • yipps:janetkessler
      May 10, 2019 @ 20:12:49

      Hi Melinda: We have to remember that they are leading their own lives. This is what interests and absorbs their activities and thinking. Humans often forget that these animals actually have lives. Thanks for following! :))

  3. ole possum
    Jun 07, 2019 @ 18:29:20

    Curious? Why do you say that coyotes ‘returned” to San Francisco in 2002? When did they leave? Why did they leave?


    • yipps:janetkessler
      Jun 07, 2019 @ 20:06:11

      Hi Ole — Coyotes were exterminated from the city in the last century. Remember that they, as Wolves, were considered vermin: no-good critters who stole chickens and eggs and sometimes killed sheep. This is why we didn’t have them for a while. Here’s the history of their return, which occurred at about the same time as coyotes were turning up in many urban areas throughout the US: For The Record: How Coyotes Returned to San Francisco.

    • ole possum
      Sep 15, 2019 @ 03:15:56

      But I thought it was impossible for coyotes to ever be eliminated from anywhere. Is that no longer true? What was different about a century ago that they could eliminate them but now everyone swears that is impossible?

    • yipps:janetkessler
      Sep 15, 2019 @ 03:43:59

      Hi Ole — There were no reportings of sightings during many years. Then suddenly there WERE sightings by more and more people. Possibly it’s because SF is a very small peninsula — almost an island — with water on three sides? I don’t think anyone has suggested a “reason”.

    • ole possum
      Sep 15, 2019 @ 17:13:51

      I find it interesting that everyone always insists it’s impossible to get rid of them, yet ity seems it was a hundred years ago???? What did they know then that we don’t know now?

    • yipps:janetkessler
      Sep 15, 2019 @ 18:24:48

      It’s impossible to get rid of them: in San Francisco we have a near-island situation which is different from elsewhere. Every single coyote was eliminated (we are only 47 square miles) which is almost an impossible task. Even so, they have returned.

    • ole possum
      Sep 15, 2019 @ 17:26:16

      So,,, it IS possible to eliminate coyotes from an area? Really? Truly?

    • yipps:janetkessler
      Sep 15, 2019 @ 18:24:25

      No, it’s not. They’re back here in SF. Again: in San Francisco we have a near-island situation which is different from elsewhere. Every single coyote was eliminated (we are only 47 square miles) which is almost an impossible task. Even so, they have returned.

    • ole possum
      Sep 15, 2019 @ 19:11:04

      So they were “exterminated” for roughly a hundred years, but never eliminated? Is that the difference? I find it a little confusing, considering what I’ve been told.

    • yipps:janetkessler
      Sep 15, 2019 @ 19:32:14

      There were sightings mid-century, maybe a little later. Yes, apparently they were wiped out, but not for long. This is the point. Janet

  4. ole possum
    Jun 07, 2019 @ 18:30:17

    Why were they able to “return” now, and not before now? I wonder…


    • yipps:janetkessler
      Jun 07, 2019 @ 20:12:13

      Hi Ole — See my response to your last query. Also, most people, have become more liberal and accepting, and with the environmental crisis, more people realize that coyotes are PART of that environment. We’ve also learned how easy it is to coexist with them. Here are the guidelines I put together to help people get over their fears, accept them, and know how to live with them: How to Handle A Coyote Encounter: A Primer. I always hand this information out along with information about coyote family life: Inside A Coyote Family. Janet

  5. ole possum
    Jun 07, 2019 @ 20:08:53

    Were you able to have an autopsy done to be certain of the cause of death was pesticide poisoning? Is every case of mange caused by this?


  6. ole possum
    Sep 15, 2019 @ 03:21:32

    You mentioned Dad died due to rat poisoning. How were you able to tell the cause? Did you have an autopsy done on him?


    • yipps:janetkessler
      Sep 15, 2019 @ 03:59:09

      Hi Ole — No there was no autopsy done on that coyote, so I can’t be 100% sure, but the emaciated carcass was found close to where a small dog slipped his leash. It took the owner a considerable amount of time to retrieve her dog who was eating stuff. Within days — during the same time period when the coyote carcass was found — that dog was acting strange, so it was taken to the vet where it died of rat-poisoning according to the veterinarian. We never saw the Dad coyote again, so it had to have been him.

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