Sunday, February 24, 2008

The Sex Lives of Birds

Boy sees girl, girl sees boy. Boy and girl meet, date, and become a pair. They may eventually go on a honeymoon and raise a family.

As it is with people, birds also go through similar steps to ultimately produce offspring. Some species of birds remain together after copulation (sex), sharing in the incubation of the eggs, feeding and raising of the young birds, as well as staying together after the breeding season. Other types of birds are briefly attracted to each other only for the purposes of fertilizing the eggs, with the female incubating and rearing her family by herself.

During breeding season, it is usually the female birds who are wooed and courted by the males. These males have established their territories and work hard to attract a mate.

The male Mockingbird will sing his verses to all who can hear, sometimes into the night, advertising that he is certainly available as a husband. American Robins are another bird that will sing love songs to woo the females.

Male peacockMale Peacocks strut about, fanning their gorgeous multicolored tail feathers. As gorgeous as peacocks are, the male Bird of Paradise is even more spectacular! They grow long iridescent tails that look as though they would impede his flight. When a female comes closer to hear his song better, he will clutch his perch tightly and hang upside down so his prospective mate can better see his tail.

The male Bowerbird builds his lady a room of sticks and leaves, furnishing it with objects that he feels a female will love, such as a pretty stone, flower petals, shells, pods, and other love items.

During breeding season, the male Magnificent Frigatebird's throat turns bright red. When a female comes near, he puffs it up, showing her his very sexy throat which she may find very alluring!

The Great Egret grows long wispy feathers that he fans and displays to any female who saunters by. Male hummingbirds perform swooping aerial dances for the females watching. Northern Harrier males will perform dances in the sky consisting of huge U-shaped swoops.

The male Prairie Chickens meet in a clearing, called a lek, where they raise the feathers on their neck and head to resemble ears, fan their tails, drop their wings to the ground and parade around. They fill air sacs located on either side of their head, then force out the air, producing booming love songs, while they strut around for the ladies' benefit and approval.

Once a female bird has shown that she is interested, the male may do a bit of courting to further entice her.

Just as a human male may take his girlfriend out to dinner, quite a few male birds, including the Northern Cardinals and Blue Jays, feed tender morsels of food to their ladies. Sometimes the females will assume a fledgling begging posture while being fed. Other birds, such as the Roadrunner, may bring food to the female just before mating. Species of birds that feed their girlfriends usually are the guys who stick around to help feed and raise the young chicks.

After dinner, what about going dancing?? Whooping Cranes and Sandhill Crane pairs perform dances together, bowing, jumping, turning and perhaps even presenting a twig to the other. Other pairs of cranes may join in this contagious and joyful dance. Roseate Spoonbills may grasp each other's bill in an amorous clench. And don't forget the Western Grebes who dance across the water, side-by-side, with their wings outstretched.

Pairs of Red-winged Blackbirds fly through the air together, with the male singing, raising his red epaulet feathers, and chasing the female in this courtship ritual. He may even grasp her rump and cause both to crash to the ground, hopefully unhurt, all in the name of love.

Many species of birds, once bonded as a pair, will perch close together, preen each other, and rarely leave each other's side. Ah, love is in the air!

The Honeymoon

Mr. Bird has found his season's love, and she loves him back. What causes these birds to form these bonds in the spring and summer, not when it is cold and snowy, nor while they are migrating?

Hormones from the pituitary gland are the answer. During breeding season in response to the hormones, the male's testes become several hundred times larger than normal to produce sperm, with the left testis usually larger. The female bird's ovaries also enlarge during breeding season to produce the ovum. Female birds usually only have one functional ovary, the left one.

In birds, an ovum is fertilized in the female bird's oviduct by a sperm cell from the male bird. Once fertilized, the ovum becomes the nucleus of the egg. The egg, that has its own food source, the yolk, will be laid by the female into her nest, incubated, and then the baby bird will hatch.

But how does the sperm from the male bird get into the female? How can they have intercourse without any external male organs, such as a penis? The male's sperm, produced in the testes, passes to the cloaca where it is stored until copulation (act of sex). The female also has a cloaca that leads from the ovaries. The female bird unfans her tail, moves it to one side while the male climbs up onto her back or gets close to her. Their cloacas are pressed together and the sperm moves from the male to the female. This act is called a cloacal kiss.

The sperm is stored by the female for at least a week, in some species over a hundred days. Then as each ovum from the ovary moves into the oviduct, it gets fertilized with the stored sperm, producing a clutch of many eggs, all with the sperm from that one cloacal kiss.

There are a few species of birds where the males do possess a retractable penis that can be pulled back into the bird. These birds include ostriches, cassowaries, kiwis, swans, geese, and ducks. Since waterfowl sometimes make love while in the lake or pond, the penis helps ensure that the sperm is not washed away by the water.

Sperm can be transferred from male cloaca to the female in a blink of an eye - less than a second. Some birds seem to want to linger longer though, sometimes having sex for more than an hour! And, although it is not necessary to copulate frequently since the sperm is stored within the female, remember those hormones are still making the birds excited. Many pairs of birds will mate numerous times within a few days.

Gulls mating

Gannets mating

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Mating Variations

Most of the birds you see in your backyard are monogamous, at least for that breeding season. The cardinals, the jays, the robins stay together as a pair, helping with the nest building, the feeding of the young and perhaps even with the incubation of the eggs.

Some birds enjoy having more than one spouse. Polygyny is when a male bird has multiple wives, such as the Northern Harrier and the Eastern Meadowlark. It occurs in species where there is abundant food (male does not need to help the female feed the young.) Polyandry is when the female has multiple husbands, such as the Spotted Sandpiper who may have four husbands. And then there is is polygynandry where both the female and male have multiple spouses.

The Red-winged Blackbird male has an avian harem with up to 15 females in his territory. These females find that nesting close to each other helps deter predators as long there is a sufficient food supply for all of them.

Although two birds may be paired together for the season and may have already produced a clutch of eggs, either spouse could have wandering eyes and commit adultery. Tree Swallows, the Red-winged Blackbird females, some woodpeckers, some buntings, and even Baltimore Orioles are only a few species that have extra-martial flings now and then.

Some males just entice a female for sex, then leave to find another female to mate. In these cases, the female builds the nest, incubates the eggs, and raises the chicks by herself. Species of birds that follow this pattern include the hummingbirds. However, to feed hungry young birds and defend them from predators it usually takes both parents. Therefore, most birds work with their spouse to ensure that the greatest number of their chicks survive.

Hummingbirds usually allow no other hummer within their territory. They will chase off all other hummers, male or female, who try to feed at "their" flowers or feeders. However, female hummingbirds have been observed being allowed to feed within a male's territory before or after having sex with him.

And then there are the Galapagos Hawks who live in threesomes, one female with two attentive males. She mates with both, although one at a time, and both help her with raising the young hawks. Harris' Hawks threesomes have one male with two females. These threesomes find that life is easier and the chick survival rate higher with three parents.

Divorce and Death

Troubles do arise occasionally in bird pairings, and divorce is not unheard of.

A frustrated pair of birds who are unable to produce any eggs, may "divorce" and go in search of new mates, hoping that with their new lover, a nest full of healthy babies can be raised.

Most birds remain with the same mate throughout the breeding season, although they might have a few extra-marital flings.

Some birds such as raptors, swans and geese, live their entire lives with the same spouse. These birds remain together for years, both migrating back to the same territory each year. Even in species that don't migrate, staying with the same spouse, year after year can be beneficial. The territory is familiar and sources of food are known. Each bird knows the other's habits as well they know their mating will produce offspring.

Once a spouse dies or fails to return to the territory, the remaining spouse will eventually attempt to find a new mate. It is an old wives' tale that the remaining spouse will die of a broken heart.

(Article found at Birds)

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