As you begin to see nests full of baby chicks and fledgling birds hopping around in your backyard, you may wonder: how do birds mate? The answer is actually different from what we’ve come to expect as mammals. Did you know that most male birds don’t have phalluses or that the majority of bird species raise their young together?
In this article, we’ll discuss everything there is to know about mating habits in birds, from courtship rituals to raising baby chicks.
How Do Birds Mate?
Unlike most mammals, who have clearly distinguished male and female reproductive parts, most birds have cloacas, also known as avian vents. A cloaca is an opening below a bird’s tail that allows them to pass feces and urine, transfer sperm, and lay eggs. Some species even use it to cool down in the heat, similar to sweating.
As mating season approaches, the cloaca will swell to prepare for reproduction. After mating season, it shrinks back down to make flying easier on the bird.
To mate, a male bird will climb atop a female bird, and they’ll rub their cloacas together. Sperm is released from the male and enters the female. The process is known as a cloacal kiss, and it usually lasts only seconds. However, it may take many of these ‘kisses’ for a female’s eggs to become fertilized, as very little sperm is successfully transferred each time. It’s also possible for a female to hold onto the sperm for months after insemination until she’s found the ideal conditions in which to reproduce. She may wait to be in a safer environment or until she has a great nesting spot.
While the above describes the mating process of most species, there are exceptions, such as in bird species that have penises.
Do Male Birds Have Penises?
Image Credit: Jebakumar Samuel on Pexels
Only 3% of bird species have penises. This includes ducks, geese, ostriches, and emus. However, most male birds do not have penises but cloacas.
This doesn’t mean that male and female genitalia are wholly the same in birds, though it can look that way from the outside. Male birds have interior testicles, while female birds have one ovary each. Usually, it’s easier to sex birds by looking at their feather coloring than their genitals, though it varies by species.
Bird species that have evolved to have penises seem to have more competition amongst males. For instance, ducks have corkscrew shaped phalluses thought to have evolved in part due to their sexual aggression toward females. Research has even found that ducks with more male competition have longer penises than ducks raised in a male-female pair.
Do Birds Mate for Life?
As we discussed above, it can take many tries for a female to mate successfully and lay fertilized eggs. Some birds accomplish this by having sex with the same males repeatedly, while others will have several mates throughout the breeding season. Different eggs may even have different fathers–baby birds in the same brood aren’t necessarily all from the same dad.
The above can all happen even in birds that appear to be monogamous, raising their chicks together year after year–even if they aren’t all biologically related! In fact, some birds will raise chicks that aren’t related to the mother, either. Many species don’t keep all their eggs in one basket, so to speak, but will lay eggs in various nests.
Some species, such as brown-headed cowbirds, lay their eggs in the nests of smaller bird species for them to raise. These chicks tend to hatch before those of the smaller species and grow faster. This often leads to the smothering or starvation of the smaller chicks as they’re outcompeted by the larger ones.
How do Birds Raise their Offspring?
For 90% of bird species, raising offspring is a shared task between males and females. Males may help build the nest, incubate the eggs, feed the baby birds, or protect the nest and offspring.
Most bird species are what is known as “socially monogamous.” These birds may mate with several others but choose one partner to raise their chicks with. They typically remain together for at least one season, though this may extend multiple seasons or even the remainder of their lives.
In around 8% of bird species, only the mother cares for the baby chicks. In 1% of bird species, the father is the sole provider of care.
Lastly, some birds are polyandrous, meaning that they raise chicks with more than one male per season. They may have multiple broods, each born from and cared for by a different male. More rarely, they’ll raise their offspring with multiple males at the same time. In these species, males may be the primary or sole caretakers since the mothers have multiple broods to raise.
Courtship Rituals in Birds
Courtship rituals in birds can be fascinating and complex. They may involve intricate dances, birdsong, preening, or bringing food or other items to their desired companion.
Some birds have extravagant rituals, such as peacocks displaying their colorful feathers or birds of paradise performing a showy song and dance routine. Males that have less to give in other ways, such as helping to raise young, tend to have flashier courtship rituals.
Most species are more down to earth and may simply offer food to their desired mate or perform a more subtle dance to show off their bodies or feathers.
Penguins offer their desired mate a pebble, which, if accepted, is used to help build the nest. Male house wrens lead females to their nest, and after a tour, they decide if they’d like to mate. A female mourning dove will “kiss” a male by inserting their beak into his, and together they bob their heads.
Very rarely, it’s a female bird’s job to woo a male companion. This occurs when there are fewer females competing for males, rather than the opposite. They use similar strategies to capture male attention and also tend to be born with brighter feathers–while in most species, the males are the most colorful.
