I’ve studied Brown Bears (Ursus arctos) and Polar Bears (Ursus maritimus) for many years. Polar bears are thought to have evolved from Brown Bears and still share many physiological similarities. One I’d like to address is the Darwinian concept that the largest and strongest males dominate all other suitors and mate with the female. This, in theory, will pass on the males large and strong genes to the next generation. While this is a great theory and in line with much of what we know to be true, I’d like to throw a ‘spanner in the works’. First posited by Carmen and Conrad Field, permit me to introduce, the Sneaky Copulator.
The Sneaky Copulator is usually a recently mature male, that may not be large or strong enough to compete with more mature males for the right to mate with a particular female. The Sneaky Copulator bides his time, and when the larger male is distracted, rushes in and copulates with the female. These trysts don’t last long, but can be successful, and could play a factor in the evolution of the species.
I have seen this scenario play out numerous times in Brown Bears. When a male sets his eyes on a receptive female he begins a series of displays that serve to impress the female, and to show any other males around that they better think twice about perusing the same female. There are several displays they utilize, and some are dependent on terrain. The most common is where a large male stands with his back against a tree, raises his arms up as high as they can go, scratches the tree, and urinates all at the same time. This impressive display ensures other bears see how large he is. Another favorite is the ‘Cowboy walk” which is where the male splays his legs out a bit and high steps (picture a cowboy in a full mosey). This is sometimes accompanied by the sideways stance which is where two males will stand sideways to each other and puff up as much as they can to make themselves look as large as possible. Neither one looks at the other directly, which allows each bear to size the other up without direct confrontation. If both are equal in size and motivated, the bears will sometimes come to blows. Fights, while vicious, are not always deadly. The bears must be careful, for any injury that might inhibit their ability to find food, could be fatal.
On numerous occasions, I have seen two males so engrosed in their displays, that a Sneaky Copulator has walked right around the two displaying bears and taken the waiting female off to mate. This begs the question: When does the size of your brain factor into Darwin’s equation?
While these smaller and smarter bears cannot fight off larger males, they do manage to successfully mate with females. Their success rate is probably not as high as a larger male, but perhaps their small contributions help to diversify and preserve the species.
Interestingly, I have also observed this same behavior in Elephant Seals. The dynamics of an Elephant seal colony are very different given the limited breeding space, fertility timing, mobility and social issues, but the concept is the same. In an Elephant seal colony, there is usually one dominant male, the Beach Master, that rules the beach, and essentially, all of the females on the beach belong to him. Other males challenge him by showing off their size and bellowing. Confrontations are common during the height of the season, and while the dominant male is off chasing away another seal, a sneaky copulator can sneak in an have his way with a receptive female. These couplings are usually short with fairly low success rates, but they occur with some regularity and could factor into the gene pool.
Speed, agility, goal oriented, and excellent at problem solving; the Sneaky Copulator has it all.