New Female Disperser Evidence Continued

Female dispersers from the Black Hills and Utah are not philopatric after all. They are traveling further than we expected. Females can reach the Great Lakes from South Dakota. That changes how we look at recolonization in Mid-America as well as in the Northeast.

During the last week I came across a series of studies by Thompson that examined dispersal of young mountain lions in South Dakota. To my surprise, I learned that 60% of young Black Hills females dispersed from their natal ranges and traveled beyond the range of tracking devices into adjacent states. Today, I came across another study from Utah that said the same thing. In both locations, more than half the females dispersed, which is the opposite of earlier studies from other parts of the west that had them establishing home ranges near those of their Mother. Researchers have assumed that most females remain near their natal home ranges while nearly all young males depart. That assumption has now been turned on itís head.
What we now know for certain is that females cougars are not philopatric as everyone had assumed. A high percentage of Black Hill cougars are leaving the immediate area where they were born and heading off on all point of the compass in search of a home range and mates. Both males and females were making longer dispersals than pumas in other regions of the country which is of special interest to us. The fact that adjacent states had little to offer in terms of suitable habitat for mountain lions did not act as a barrier to dispersals. Lack of resources and avoidance of conflict were cited as reasons prompting the dispersals of females in SD. Black Hills scientists gave a long list of evidence to support their view that the Black Hills had reached a population saturation point, which included smaller sized home ranges, increased conflict, and skewed kitten sex ratios.
Figures provided Cougar Network executive Director Michelle LaRue indicate that 24% of cougar mortalities recorded in the Mid-West were of females, which, again, supports this notion of long distance female dispersal. Despite this, serial deniers are still claiming we canít have a breeding population in the East because they believe very few females disperse. Many of those that do die along the way. For that reason, they think none have succeeded in making it as far as Michigan. Well, the evidence suggests they are mistaken.
It now is clear from the literature that more than half of young females are dispersing, and the percentage in SD is 60% of all females (14 months and above). Some go less than 50 miles on these dispersals but the numbers from the Black Hills studies show half of those that disperse are making long treks-far enough to arrive at places skeptics say they canít reach. Dispersals of 800 miles by one female is on record so this is not mere speculation. From a SD study that sampled litters of kittens in the Black Hills- but not all of them, the sample of kittens (84) produced 7 long distance dispersers in a single year. Given the limited size of the sample, it is probable that a similar percentage of these young females from litters that were not included in the study also disperse. That increase the odds that more young cougars heading east will reach Michigan and beyond.
Jay Tiscendorf, founder of ReWilding, at one time believed that females rarely made long distance dispersals. Now we know that a high percentage of females make these long walks. From the most recent studies from South Dakota and Utah we can now say that a larger number of long distance dispersing females leave the Black Hills and other puma refuges in the US and Canada and make their way eastward than previously thought. Female cougars in eastern Canada are likely doing the same thing. Immigrants from either source are providing the necessary females for natural reproduction to occur in states like Wisconsin and Michigan, assuming neither place has females present now. Long distance dispersers from Ontario, Quebec and other provinces are capable of traveling south a few hundred miles to reach us. Montreal, for example, is only 225 miles from Boston- not much of a trip for a mountain lion compared to the 2200 mile journey agencies claim the Milford cougar had to make over a period of two years to reach CT.
Tiscendorf acknowledged that it would only take two (dispersing females) to plant a population seed. Confirmations of females and kittens in the Northeast are evidence that this, in all probability, has already happened. Despite the odds, some females from the north must have made it to New England, mated with Toms and gave birth to kittens. Their descendants are among the many cougars we are seeing all across New England from Greenwich to Matunuck... from Spencer,MA to Beacon, NY. And this time, the science is on our side.


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