Why do coyote females have larger litters in heavily hunted areas?

coyote pupps.jpg

I have a lot of quibbles with Dan Flores’s book, Coyote America. Among them is a contention that coyotes howl because it allows them to “take a census.”  If no other coyotes howl back, the females wind up releasing more ova and having larger litters. This description, which Flores calls an “autogenic trait,” cannot be found anywhere in the coyote literature. His account is not described in the book, but it is mentioned in his interview with National Geographic and on The Joe Rogan Experience.

I have no idea where Flores got this idea, but it’s not really what happens. The literature on why coyotes have larger litters in areas where they have been heavily hunted says that the larger litter sizes are associated with better access to food resources. The best-known paper on this issue comes from Eric Gese, a researcher with the USDA, who studied coyote population dynamics in an area of Colorado.

Gese contends that what happens with coyotes in pressured areas is that the surviving females are healthier, simply because they have access to more food resources. This greater health causes them to release more ova during the estrus cycle, and this increase in ova results in greater litter sizes.

It is not because the coyotes are taking census and can somehow magically figure out that they should produce more young.  It is simply that the coyote females’ own bodies respond to greater food resources by becoming more fertile.

What has possibly evolved in coyotes is that they have a tendency to become significantly more fertile when the females are at their most healthy. This is a great trait for a mesopredator to have.

After all, coyotes evolved in North America with dire wolves and a host of large cats breathing down their necks. Natural selection favored those that could reproduce quickly if populations were dropped dramatically.

But it’s not because of some “autogenic trait.” It is simply how coyote populations expand as mesopredators with increased or decreased access to prey.

So yeah, my take on Coyote America is that it is mostly a science fiction book. Not only does he mess up the exact genetic difference between a wolf and a coyote, which is not equivalent to the genetic difference between a human and an orangutan (as he claims),  he also messes up that coyotes really do hunt down and kill cats and eat them. They are not just killing a competitor. They are using cats as a food resource.

This was a book I was so looking forward to reading. It got good press, but the actual science in it was so lacking.

 

Natural History

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