Den Sharing Case in San Francisco

I’ve put together a simple map of our coyote territories here in San Francisco — we have just about 20 such territories covering most of the 49 square mile city. In addition, there are a fair number of temporary holding spots, including a few backyards, which over the years have been used off-and-on very sporadically by numerous coyotes, and even families, for very short periods of time as they disperse. The important point is that I’ve achieved this without the use of radio-collars or tags. I’ve been able to do so, working alone, through my own recognition and knowledge of individual coyotes and their families. And we’re on track for all of it to be confirmed using DNA from scat for which I have collected almost 500 samples here in San Francisco over the past 12 years. A couple of graduate students at UC Davis are now collaborating with scat finds and the DNA analysis for their own dissertations. I will post the map shortly and then continue to refine it if needed.

Each of these territories, I’ve determined from my visual observations, runs from 1.5 to 2.5 square miles, and is occupied by just one family. Each of these families, families which I’ve gotten to know, consists of an alpha mated pair (Mom and Dad), their pups born this year, if there are any, and sometimes a lingering yearling or two born the previous year who will soon disperse. There are occasionally variations of this arrangement, consisting of just a portion of the standard family — i.e., any one of these elements might be missing for awhile. The alphas keep other coyotes out, except for the rarely-seen “dispersing” few who might pass through inconspicuously and quickly, or may even more rarely remain several weeks before moving on. Coyote population is controlled naturally through their territoriality, as just explained above, and also through their biology, as will be explained below. Limited resources are also a factor in their population numbers, but this appears not to be a limiting factor here in San Francisco with all the feeding by humans occurring here.

Biologically, as documented by F.F. Knowlton in 1972, only the alphas on any particular territory reproduce — the terms “alpha” and “parent” are synonymous when talking about coyotes — and this is what I’ve seen in almost every instance here in San Francisco over the last 14 years. However, according to Knowlton, when coyote alphas get removed (i.e., killed by humans), it creates social chaos, and then the younger females — who are usually “behaviorally sterile” in normally very stable and well organized family situations — produce litters. This means more litters, which means more coyotes. I can only imagine that this is the extenuating circumstance that happened in the family I will describe here  — although in the case here, the removal of the alpha male was an act of nature and not caused by a human. This posting points to the important point that there always are variations and exceptions to the defining generalities.

So, last winter, the long-time resident elderly alpha male in one of the territories passed away at almost 12 years of age: he had been the alpha there his whole life. Vacancies in coyote families are usually filled pretty quickly. It seemed logical to me that one of the remaining yearling males — two males and a female youngster remained from the litter born in 2019 — would take Dad’s place. That has occurred in the past on this territory. But two years old is a a bit young for becoming an alpha male: I myself have only seen it happen at the age of 3 or older.

Instead, an older newcomer male — I say “older” based on the wear and tear in his appearance and the way he carries himself — who no doubt sensed the situation, came into the territory. At the same time, there was no alpha male to fight him off — the yearlings were probably not up to the task. Initially the newcomer was not welcomed: lengthy and repeated distressed vocalizations by the territorial family could be heard for several weeks after his arrival. But he was the only viable male around and he stayed and now he is part of the family, the alpha male.

To the left is the lactating 8-year-old mother; to the right is her daughter, the 2-year-old mother who also is lactating on the same property at the same denning site.

First video is of 8-year-old mother with her new litter; then her 2-year old daughter with two pups (one pup is far in the back and is hard to see).

So, the result is that we now have TWO moms in this territory: 1) the eight-year-old “widowed” mother AND 2) her two-year-old daughter (daughters, as opposed to sons, appear ready to reproduce at 2 years of age). Both of these females have been lactating over the past couple of months. I’ve seen both of them with pups in the exact same denning area and on the exact same paths around that denning area. I’m calling it den-sharing. However, I don’t venture close to any active dens, so I don’t know if the actual den itself has been shared, nor do I know if each set of pups sticks with only its own mother. Whatever that exact situation is, there are two mothers in one small area on one territory which I have not seen before here in San Francisco. Of the nearly twenty territories I’ve delineated covering the whole of San Francisco, this is the only such case up to now, and I’m pretty sure — this is my opinion and a likely explanation — that it is related to the extenuating circumstance of the older alpha male’s death. Another possible simpler explanation might be that most youngsters disperse before the age of two which is when they become reproductively viable, but this younger mother remained on the territory past that point. The trigger, here again, would have been the instability caused by her father’s death.

I’ll post more about the behaviors I saw leading up to and during this development next time.


© All information and photos in my postings come from my own original and first-hand documentation work which I am happy to share, with permission and with properly displayed credit:©janetkessler/

2 Comments (+add yours?)

  1. James B. Mense
    Jul 02, 2021 @ 21:54:35

    Remember Occam’s razor!


    • yipps:janetkessler
      Jul 03, 2021 @ 00:01:05

      The first explanation has been well documented by science, which is why I mention it. The second one is mine — it’s logical and simpler, and you are right, probably the better explanation!

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