# Bird reproduction question **URL:** \ **Category:** Factual Questions\ **Created:** [October 27, 2004, 5:26pm UTC](https://boards.straightdope.com/t/bird-reproduction-question/271490 "2004-10-27T17:26:30Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Cluricaun](https://avatars.discourse-cdn.com/v4/letter/c/bb73d2/32.png) [@Cluricaun](https://boards.straightdope.com/u/Cluricaun)\ **Post date:** [October 27, 2004, 5:26pm UTC](https://boards.straightdope.com/t/bird-reproduction-question/271490/1 "2004-10-27T17:26:30Z")
This is kind of gross, but I’ve always wondered a point about bird reproduction. When birds reproduce they lay eggs. Ok, no problem so far. What I can’t figure out, nor Google while at work, is at what point does fertilization take place? Do birds, ahem, “do it”, or does the male do his business with the egg after it’s been (for lack of a better term) laid? ---
**Author:** ![Early\_Out](https://avatars.discourse-cdn.com/v4/letter/e/6f9a4e/32.png) [@Early\_Out](https://boards.straightdope.com/u/Early_Out)\ **Post date:** [October 27, 2004, 5:33pm UTC](https://boards.straightdope.com/t/bird-reproduction-question/271490/2 "2004-10-27T17:33:26Z")
Birds copulate much like other creatures: [http://www.stanfordalumni.org/birdsite/text/essays/Copulation.html](http://www.stanfordalumni.org/birdsite/text/essays/Copulation.html) ---
**Author:** ![Mudshark](https://avatars.discourse-cdn.com/v4/letter/m/f04885/32.png) [@Mudshark](https://boards.straightdope.com/u/Mudshark)\ **Post date:** [October 27, 2004, 5:40pm UTC](https://boards.straightdope.com/t/bird-reproduction-question/271490/3 "2004-10-27T17:40:59Z")
There is [bird reproduction](http://www.seps.org/oracle/oracle.archive/Life_Science.Anatomy/2001.05/000989465038.9656.htm) and [more bird reproduction](http://www-biol.paisley.ac.uk/courses/Tatner/biomedia/units/bird9.htm) ---
**Author:** ![Green\_Cymbeline](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/green_cymbeline/32/9244_2.png) [@Green\_Cymbeline](https://boards.straightdope.com/u/Green_Cymbeline)\ **Post date:** [October 27, 2004, 5:44pm UTC](https://boards.straightdope.com/t/bird-reproduction-question/271490/4 "2004-10-27T17:44:12Z")
I always wondered about this myself, until my boyfriend, a wildlife biologist, got a job at a wildlife refuge working with endangered whooping cranes. Part of his job was assisting the birds with reproduction. Basically, both male and female birds have one hole, called a cloaca\*. This is where they get rid of bodily waste. In males, their sperm comes out of this hole too (their testes are inside their body and the sperm is emptied into the hole). In females, this hole leads to their uterus, which is where the egg is dropped from the ovary. When an egg comes down, the shell is not yet hardened. The male and female copulate, which is basically when the male mounts the female, and they rub their cloacas together, and the sperm goes from the male’s cloaca into the female’s cloaca. Here, it fertilizes the egg, the shell hardens and the egg is laid. We’ve seen the cranes mate and it’s pretty neat! Here’s an illustration of their reproductive systems: [http://www.nhm.org/birds/guide/pg016.html](http://www.nhm.org/birds/guide/pg016.html) - definition from this site: [http://www-biol.paisley.ac.uk/courses/Tatner/biomedia/glossary/glossary.htm#cloaca](http://www-biol.paisley.ac.uk/courses/Tatner/biomedia/glossary/glossary.htm#cloaca) **Cloaca:** A common chamber receiving digestive wastes and urogenital products (urine and gametes); common in most vertebrates except mammals. ---
**Author:** ![panache45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/panache45/32/64_2.png) [@panache45](https://boards.straightdope.com/u/panache45)\ **Post date:** [October 27, 2004, 6:50pm UTC](https://boards.straightdope.com/t/bird-reproduction-question/271490/5 "2004-10-27T18:50:27Z")
> [@nyctea scandiaca](#): > > …When an egg comes down, the shell is not yet hardened. The male and female copulate, which is basically when the male mounts the female, and they rub their cloacas together, and the sperm goes from the male’s cloaca into the female’s cloaca. Here, it fertilizes the egg, the shell hardens and the egg is laid… Does this mean that the shell hardens only if it’s been fertilized? Have I been eating fertilized eggs all my life? ---
**Author:** ![Sigene](https://avatars.discourse-cdn.com/v4/letter/s/df788c/32.png) [@Sigene](https://boards.straightdope.com/u/Sigene)\ **Post date:** [October 27, 2004, 7:08pm UTC](https://boards.straightdope.com/t/bird-reproduction-question/271490/6 "2004-10-27T19:08:33Z")
My old comparative anatomy professor described it as a “cloacal kiss.” Its been 20 years and I still remember it. Thanks a lot for the image Dr. Brietenbach :rolleyes: ---
**Author:** ![Yllaria](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yllaria/32/3452_2.png) [@Yllaria](https://boards.straightdope.com/u/Yllaria)\ **Post date:** [October 27, 2004, 8:29pm UTC](https://boards.straightdope.com/t/bird-reproduction-question/271490/7 "2004-10-27T20:29:01Z")
> [@](#): > > Have I been eating fertilized eggs all my life? No. The hardening of the shell happens on it’s own schedule. The fertilization has to happen before the shell hardens, otherwise the shell acts as a barrier. ---
**Author:** ![DocCathode](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/doccathode/32/18773_2.png) [@DocCathode](https://boards.straightdope.com/u/DocCathode)\ **Post date:** [October 27, 2004, 8:47pm UTC](https://boards.straightdope.com/t/bird-reproduction-question/271490/8 "2004-10-27T20:47:13Z")
For more on nonhominid copulation, I recommend [How They Do It](http://www.amazon.com/exec/obidos/ASIN/0688087183/ref%3Dpd%5Fsl%5Fov%5Fovlegacy-1%5Fdetail-book%5F641290%5F1/002-3144205-2696001)