The sex life of a bird is no simple thing
Sex is a heck of a thing in the animal kingdom. Species of birds, insects, mammals and fish have developed a whole bunch of strategies to get laid. From mating dances to beautiful plumage to carefully engineered bachelor pads, the birds have come up with all sorts ways to strut their stuff.
Wildlife junior Hannah LeWinter commented on how much effort birds put into reproducing. She remarked on the McGregor bowerbird’s tower—a three-foot-tall structure made of carefully placed twigs, attesting to the bird’s dedication.
“When we think of animals, we assume they do the basic things like mate and get food and make shelter, but they really do have complex [behaviors] too,” LeWinter said. “They make these intricate structures to impress females to say that they are the best suitors but those structures serve no purpose besides attracting a mate.”
Commitment to the craft is just the first step of courtship. The picky female bowerbird inspects her suitor’s structure, carefully judging sturdiness of the construction before joining the male on the forest floor. Then, the show really starts.
The male bowerbird possesses the ability to imitate sounds and begins a showcase of what he’s learned. His voice can emulate everything from birds and animals in the forest to the sounds of human civilization.
Once she’s satisfied with his performance, the male begins his dance. A chaotic shuffle from one side of his tower to the other, darting towards the female while flashing a bright orange haircut at her. Once he’s done with his groove, she submits and they do their thing.
“We like to think we’re the only people or the only species who do that,” LeWinter said. “We think of animalistic sex of doing it only because you need to reproduce, but there are these animals that create these gestures like a pebble or a structure or a dance.”
The McGregor bowerbird works every year to maintain his tower, but there is no expectation in the species to mate with the same female every year. Jeff Black, a wildlife professor at HSU who studies birds, published a collaborative book with 20 other ornithologists titled “Partnerships in Birds: A Study in Monogamy.”
“We asked the question, ‘How special are bird partnerships or pair bond?'” Black said. “We asked, ‘How long do mates stay together?’ ‘Are they really faithful?’ ‘Do the faithful ones fare better than the ones that alternate and are less monogamous?'”
The answer: it depends. Black and his fellow ornithologists quantified bird fidelity on a sliding scale ranging to very faithful to not at all faithful. They also investigated the behaviors between social pairs—pairs who spend their time together raising the young, foraging and nesting together—and genetic, or mating pairs.
“Birds lay their eggs in a basket,” Black said. “When you look at all the 10,000 different types of birds, some birds even though they’re monogamous, when you look at their babies, the genes come from someone else.”
Faithfulness or lack there of may have a couple of purposes, although the hypotheses are not totally fleshed out. One hypothesis is that, if a female searches for a new male mate, she may be looking for a more fit male than her social partner, and engage in what Black called extra-pair copulation.
HSU River Ecologist Alison O’Dowd explained fitness is a measure of the ability for an individual to pass on their genes. Similar to natural selection, sexual selection is when a female looks for certain characteristics in their male partner, ranging from vibrant feathers to well constructed towers to perfectly executed dances.
Black endorsed fidelity in birds. He said in geese and swans for example, more faithful pairs are more likely to successfully reproduce. Their offspring are also more fit for when they’re looking for a mate of their own. There may be a case for faith yet.
“When you look at all the different studies, you can plot out how faithful they are,” Black said. “Swans are 100% faithful, the jays would be about in the middle and other species are just having sex everywhere.”