Nature Notes: More Than One Way

There are many variations on the theme
The female Galapagos hawk is polyandrous; she keeps more than one male on more than one nest at the same time. Dell Cullum

There are many ways of pairing up and raising young, among humans and in the natural world. Monogamy is found in all other vertebrates, but mostly in birds. We defend the foreigner mute swan from exile in part because it is monogamous, at least seasonally. The bald eagle, osprey, and a host of other avian species are also monogamous.

But there are many variations on the theme. The common red-winged blackbird, for example, is serially polygynous, it has several mates among a long strip of reeds. The spotted sandpiper, which is found throughout the United States, is polyandrous, courting several different males at the same time and leaving more than one male incubating and raising young from more than one nest, while she scoots away to migrate south. The female Galapagos hawk is also polyandrous; she keeps more than one male on more than one nest going at the same time. The comb-crested Jacana of Indonesia and nearby countries goes even further. She is the pretty one of the two sexes, with her brilliant red forehead. She has more than one mate and more than one nest on a lily pad or other floating vegetation. She becomes the protector, while the males do all the dirty work.

On the other side of the aisle, many mammalian species are harem keepers, a practice in which one male services several females, until eventually defeated in a scrap with another up-and-coming male. The elephant seal of the Pacific Coast is such a harem keeper; the gorilla of the African jungles, another. 

In addition to the many diseases that are fatal to us, the human animal engages in several acts that reduce the human population. One such act is infanticide, the taking of the life of a baby. Apparently, statistics show that in human culture, there are more babies killed by women than men. Many wild mammals commit infanticide, among them, male lions, mice, and bears. And among birds, the Jacana will kill the young tended by a consort that is not one of hers. In most cases, as among African lions, the infant taken and often eaten is not one of his but the young of another male. Many wild mammals not only commit infanticide, they also eat the infants after killing them.

Infanticide is also practiced by one avian species eating a second avian species’ babies. The pelican will eat the young of gannets and other smaller seabirds. The bald eagle, in a kind of interspecific competition, will rob and eat the young from an osprey nest while the osprey adults are away fishing.

In the bigger scheme of things, where does all this fratricide, infanticide, polygamy, polygyny, polyandry, cannibalism, and other unusual but not so infrequent behavior in the animal world get you? You could opt for the conservative solution: If you are an animal and your population is large and in good shape mentally and health-wise, why take a chance at trying to change your lifestyle? If monogamy is working, and keeps one out of trouble and has a high probability for a species’ survival, don’t fool around. On the other hand, polygyny is still practiced in almost all Islamic countries. One can see the advantage of such practice, say, when there are many more women than men, which is especially true when wars have decimated the male population. Would elephant seals do better if the males shared the group’s sexual responsibilities?

It was recently written in The New York Times that the number of American deaths per 1,000 individuals now exceeds the birth rate. If that trend continues, it bodes for a smaller population in the future. With all of the variations in mating, reproduction, and human behavior worldwide, you can hardly predict the future with any degree of accuracy. The will to succeed and live a long fruitful life has become more questionable than at any point in human history. It’s still my philosophy, but I may be becoming a member of the minority. Yet I’m not about to give in to Watson or any other mechanized brain. What say you?


Larry Penny can be reached via email at