How Do Birds Mate?

Birds are among some of the most intriguing animal species in the world. The way that they live and interact with one another and the larger environment is incredibly interesting and we know so much, yet so very little about them.

One of the questions that often gets asked though is how birds actually reproduce – and therefore, how do they mate in order to do so. In short, they mate by a process known as a cloacal kiss, which differs wildly from the mating technique than anyother animal species. 

However, there’s a lot more to know than just this, so we’ve written this handy guide which looks to help explain all of the questions and misconceptions you may have about birds and how they mate. 

Ready to learn more about it? Then read on! 

Photo by Pixabay

The Basics 

To answer this question, we must first understand the sexual design of birds.

Male birds actually do not have a penis – and this can make it difficult to know the difference, at least objectively speaking, between a male and a female bird.

Both male and female birds have what is known as an avian cloaca or vent and during the mating process, both birds will touch these briefly together which allows the passing of sperm from the male to the female. These vents are located just below the tail and it is this area that allows for genetic material and waste products to leave the body of the birds. 

Inside of the bird’s body, the sexual equipment necessary for reproduction can be found. The males have testicles and the females have one ovary. However, throughout the year – birds’ sexual organs adapt to seasonal change. This is usually to accommodate for the change in temperature, food availability and the levels of light they are exposed to.

It is during this change that the signals for the mating season become obvious and the birds’ cloaca swells up and then expands. After mating has completed, the cloaca and other internal reproductive organs begin to shrink to allow for the bird to lose weight. This then makes it easier for the birds to fly when they migrate.

It’s important that we note at this point though that this isn’t the case for all birds. Some, like most waterbirds (swans and ducks for example) have penises and they perform sexual penetration to mate. 

The Cloacal Kiss 

While the attracting process of birds to find a mating partner can be something very impressive to behold with their mating calls, dancing and plumage, the actual act of mating is nothing especially spectacular. 

The cloacal kiss, the act of mating, is when the male will mount the female from behind whilst balancing on her back. This allows for the two cloacas to become much closer together, both underneath the tail.

However, due to the difficult nature of the male balancing on the female’s back – this process may be repeated a few times. In fact, it’s suggested that only around two percent of the male’s sperm makes it to the female, so the pair must increase the chances of reproduction by repeating this mating process as much as possible.

This process can be seen in the video below where 2 Australian Fairy Terns are mating. Note the display of affection as they touch bills.

After mating, the female may begin to produce eggs within either a few days or a few months, which varies from bird to bird. Many female birds can actually hold onto the male’s sperm until they are in better conditions for nesting.

The family unit of birds varies depending on what type of bird we’re speaking about, but a large proportion of male birds will leave and the female must raise her young. However, there are exceptions like the songbird, that stays to raise their young as part of a family unit.

Are bird relationships exclusive?

As we said, generally males will leave the female after the mating process aside from some exceptions. However, when we look at how birds behave in terms of their reproductive cycles, it might be much clearer as to why.

Some birds may stay together for a year as part of the mating season – but a large number of these birds will have multiple mating partners throughout this time. In fact, as females can hold onto sperm until conditions are better, it’s common for females to lay eggs belonging to multiple different fathers.

Some experts have suggested that this mating behavior could be described as social bonding, rather than romantic or sexual.

What about waterbirds?

Yes, as we mentioned earlier, most water birds have penises which allows them to perform penetrative mating. The process occurs on water and much like other birds, the male will mount the female from top at the back. 

Briefly, the female’s head will go underwater and insemination will occur. This method of mating could be seen as far more practical than other birds and the act will only occur once at a time – unlike multiple times we see with other birds. However, it can seem a little brutal, especially if multiple males try to mount the female.

Photo by Imogen Warren

The importance of bird privacy 

It’s vital that if you happen upon birds during the mating process, you leave them be and do not disturb them. Some birds are endangered and must be allowed to mate in order to increase their population.

Aside from this, mating may occur in nesting areas, meaning potential danger to you from other birds, or the two mates may abandon their safe spot and fail to successfully mate – meaning less chance of seeing more of their species in the area! 

Photo by Imogen Warren

Final Thoughts 

The majority of birds will mate through a method known as a cloacal kiss whereas some birds like water birds mate in a more traditionally understood sense.

We hope this guide has helped answer your questions!


Which birds do not have a cloaca?

Some water birds like ducks , geese and swans mate with a phallus rather than a cloaca. Other species that also do a cloaca are some Australasian flightless birds like Cassowary and Kiwi.

Can birds reproduce without mating?

While it is known in some species of reptiles and fish, it was not known in birds until a condor successfully hatched eggs with no fertilization. Tests showed that the chicks were related to the mother but had no male relation. The condor is the only known bird to be able to do this.

How does a male bird fertilize eggs?

The egg is fertilized by the sperm once the birds have mated and before the eggs are laid.

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