# Do all bird species lay unfertilized eggs? Some? A few? Just one? **URL:** \ **Category:** Factual Questions\ **Created:** [August 18, 2012, 12:09pm UTC](https://boards.straightdope.com/t/do-all-bird-species-lay-unfertilized-eggs-some-a-few-just-one/631865 "2012-08-18T12:09:49Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [August 18, 2012, 12:09pm UTC](https://boards.straightdope.com/t/do-all-bird-species-lay-unfertilized-eggs-some-a-few-just-one/631865/1 "2012-08-18T12:09:49Z")
Domestic chickens lay eggs, if I understand correctly, every day, fertilized or not. Is this true of birds generally? Or is it something particular just to domestic chickens? Or is it something some birds do but not others? ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [August 18, 2012, 12:22pm UTC](https://boards.straightdope.com/t/do-all-bird-species-lay-unfertilized-eggs-some-a-few-just-one/631865/2 "2012-08-18T12:22:31Z")
Well, don’t know about _all_ birds, but I can confirm that parrots can and do lay infertile eggs. Well, at least the female ones do. ---
**Author:** ![Gatopescado](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gatopescado/32/5711_2.png) [@Gatopescado](https://boards.straightdope.com/u/Gatopescado)\ **Post date:** [August 18, 2012, 5:35pm UTC](https://boards.straightdope.com/t/do-all-bird-species-lay-unfertilized-eggs-some-a-few-just-one/631865/3 "2012-08-18T17:35:38Z")
Not all hens lay every day. They can suddenly quite for a while, and start again without notice. Depends on the season, the feed, weather. Pretty undependable creatures around here. I can tell you there is nothing more depressing than buying chicken feed _and_ eggs during the same trip to town. Its my wife’s gig. ---
**Author:** ![FluffyBob](https://avatars.discourse-cdn.com/v4/letter/f/ecb155/32.png) [@FluffyBob](https://boards.straightdope.com/u/FluffyBob)\ **Post date:** [August 18, 2012, 9:22pm UTC](https://boards.straightdope.com/t/do-all-bird-species-lay-unfertilized-eggs-some-a-few-just-one/631865/4 "2012-08-18T21:22:35Z")
Damn chickens. The hens we had were prolific, pretty much an egg a day per bird for several years. Always amazed me. Those girls kept up a good appetite and went through a fair amount of crushed oyster shells on the side. You would think it would be a very inefficient process to be favoured by natural selection. I am surprised parrots do it also. ---
**Author:** ![Enola\_Gay](https://avatars.discourse-cdn.com/v4/letter/e/3ab097/32.png) [@Enola\_Gay](https://boards.straightdope.com/u/Enola_Gay)\ **Post date:** [August 18, 2012, 9:41pm UTC](https://boards.straightdope.com/t/do-all-bird-species-lay-unfertilized-eggs-some-a-few-just-one/631865/5 "2012-08-18T21:41:18Z")
My brother’s pet cockatiel lays eggs, though only seasonally (in spring/summer). And my hens lay every day, as long as I remove the eggs and don’t let them accumulate. If 8 or so eggs pile up, she’ll stop laying and sit on them. I know that hens in climates that get cold stop laying in the winters. I think it has to do with temperature or hours of daylight or maybe both. And FluffyBob, I don’t think it’s an inefficient process at all. In the wild, there is a male in the picture, so the hens are laying fertilized eggs that become the next generation. ---
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [August 18, 2012, 9:46pm UTC](https://boards.straightdope.com/t/do-all-bird-species-lay-unfertilized-eggs-some-a-few-just-one/631865/6 "2012-08-18T21:46:17Z")
> [@Enola\_Gay](#): > > My brother’s pet cockatiel lays eggs, though only seasonally (in spring/summer). > > And my hens lay every day, as long as I remove the eggs and don’t let them accumulate. If 8 or so eggs pile up, she’ll stop laying and sit on them. I know that hens in climates that get cold stop laying in the winters. I think it has to do with temperature or hours of daylight or maybe both. Hours of daylight. Bright light (sunlight or a 60 watt light bulb) is needed for stimulating the pineal gland, between their birdy little eyes. Before electricity, eggs were a spring equinox beginning treat, which may be why they are a part of so many cultures’ springtime holidays. > **[Hens and Chicks Care and Growing Guide](https://www.thespruce.com/how-to-care-for-hens-and-chicks-plants-2132609)** > > Hens and chicks (Sempervivum tectorum), is a succulent perennial with excellent cold hardiness. Learn how to grow this drought-tolerant plant. ---
**Author:** ![RealityChuck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/realitychuck/32/195_2.png) [@RealityChuck](https://boards.straightdope.com/u/RealityChuck)\ **Post date:** [August 18, 2012, 10:33pm UTC](https://boards.straightdope.com/t/do-all-bird-species-lay-unfertilized-eggs-some-a-few-just-one/631865/7 "2012-08-18T22:33:30Z")
> [@FluffyBob](#): > > Damn chickens. The hens we had were prolific, pretty much an egg a day per bird for several years. Always amazed me. Those girls kept up a good appetite and went through a fair amount of crushed oyster shells on the side. > > You would think it would be a very inefficient process to be favoured by natural selection. I am surprised parrots do it also. It evidently worked out very well for the species: chickens are extremely successful. It’s the same for navel oranges: both developed a trait that seems on first glance to be counterproductive, but which, due to interaction with humans, worked out by well. ---
**Author:** ![Filbert](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/filbert/32/3433_2.png) [@Filbert](https://boards.straightdope.com/u/Filbert)\ **Post date:** [August 18, 2012, 10:47pm UTC](https://boards.straightdope.com/t/do-all-bird-species-lay-unfertilized-eggs-some-a-few-just-one/631865/8 "2012-08-18T22:47:32Z")
All birds _can_ lay infertile eggs, though in most species they don’t do it very often, at least in the wild. Normally, there’s a series of environmental triggers (which can include stuff like nest building and pairing, as well as day length and temperature) that stimulate the release of eggs in wild birds, but this can misfire sometimes, or fertilisation can be unsuccessful, despite mating. Pet birds of several species are known to lay even when kept singly, others will sometimes form a pair with another female, fulfilling the environmental triggers needed, and both will lay in a shared nest (and they keep sitting for _ages_, it’s both funny and depressing to watch). No other species lays as many eggs as domestic chickens though- that is, after all, what they were selected for- even the wild ancestors of chickens, Jungle fowl, won’t lay more than about 20 eggs a year tops, during the breeding season, and normally will only lay about 6 eggs- one normal sized clutch- in the year. Other domesticated species kept for eggs, such as quail, and some ducks, can also produce pretty impressive numbers of infertile eggs, but chickens have a much longer history of selection, and are still the most productive. ---
**Author:** ![Pyper](https://avatars.discourse-cdn.com/v4/letter/p/5f9b8f/32.png) [@Pyper](https://boards.straightdope.com/u/Pyper)\ **Post date:** [August 19, 2012, 4:04am UTC](https://boards.straightdope.com/t/do-all-bird-species-lay-unfertilized-eggs-some-a-few-just-one/631865/9 "2012-08-19T04:04:36Z")
Anecdotally: Turtles also lay unfertilized eggs. Our pet box turtles got together and produced some baby turtles. The male was subsequently packed off to live in spoiled bachelorhood with family friends, but the female continues to lay eggs every year. ---
**Author:** ![Kobal2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kobal2/32/20_2.png) [@Kobal2](https://boards.straightdope.com/u/Kobal2)\ **Post date:** [August 19, 2012, 7:42am UTC](https://boards.straightdope.com/t/do-all-bird-species-lay-unfertilized-eggs-some-a-few-just-one/631865/10 "2012-08-19T07:42:43Z")
> [@FluffyBob](#): > > You would think it would be a very inefficient process to be favoured by natural selection. I very much doubt natural selection had much to do with it ;). Domesticated species have been quite thoroughly re-engineered by man on just about every level. ---
**Author:** ![Bozuit](https://avatars.discourse-cdn.com/v4/letter/b/edb3f5/32.png) [@Bozuit](https://boards.straightdope.com/u/Bozuit)\ **Post date:** [August 19, 2012, 10:56am UTC](https://boards.straightdope.com/t/do-all-bird-species-lay-unfertilized-eggs-some-a-few-just-one/631865/11 "2012-08-19T10:56:53Z")
I’m not sure how one can look at a chicken and think of natural selection. ---
**Author:** ![Max\_Torque](https://avatars.discourse-cdn.com/v4/letter/m/e9bcb4/32.png) [@Max\_Torque](https://boards.straightdope.com/u/Max_Torque)\ **Post date:** [August 20, 2012, 2:07pm UTC](https://boards.straightdope.com/t/do-all-bird-species-lay-unfertilized-eggs-some-a-few-just-one/631865/12 "2012-08-20T14:07:56Z")
> [@Kobal2](#): > > I very much doubt natural selection had much to do with it ;). Domesticated species have been quite thoroughly re-engineered by man on just about every level. No doubt. Chickens are yummiest when they’re young, so it’s to the farmer’s advantage to weed out the poor layers early. If one chicken only produces half the eggs of another chicken for the same amount of feed, that poor performer is slated to become a “young broiler/fryer”. The good layer gets to grow old, breed, and eventually become a “stew chicken” when she’s old and tough. So, by weeding out the poor performers, farmers will 1) save the money it would cost to feed an inefficient chicken, and 2) send a desirable young chicken to market. With the top performers as the only ones left to reproduce, the next generation gets a little more efficient at laying. ---
**Author:** ![Ulfreida](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ulfreida/32/8014_2.png) [@Ulfreida](https://boards.straightdope.com/u/Ulfreida)\ **Post date:** [August 20, 2012, 6:18pm UTC](https://boards.straightdope.com/t/do-all-bird-species-lay-unfertilized-eggs-some-a-few-just-one/631865/13 "2012-08-20T18:18:57Z")
> [@Max\_Torque](#): > > No doubt. Chickens are yummiest when they’re young, so it’s to the farmer’s advantage to weed out the poor layers early. If one chicken only produces half the eggs of another chicken for the same amount of feed, that poor performer is slated to become a “young broiler/fryer”. The good layer gets to grow old, breed, and eventually become a “stew chicken” when she’s old and tough. So, by weeding out the poor performers, farmers will 1) save the money it would cost to feed an inefficient chicken, and 2) send a desirable young chicken to market. With the top performers as the only ones left to reproduce, the next generation gets a little more efficient at laying. Maybe it worked this way long before the industrialization of chicken meat and egg production. The chicken you buy wrapped in plastic at the grocery store has been bred for meat and meat only, and is weeks, not years, old. It never got anywhere near old enough to lay an egg. The eggs you buy in styrofoam cartons are produced by hens who have been bred solely for maximum egg production for hundreds of generations. They have almost no meat on them. They lay nonstop under lights for a year and then are ground up into chicken meal. Homestead, family-flock chickens are usually ‘dual purpose’ breeds (lay eggs pretty well and have some meat on them too). The cockerels are killed at a couple months of age while the hens typically lay for two to five years before they are stewed. ---
**Author:** ![Nadnerb](https://avatars.discourse-cdn.com/v4/letter/n/ee7513/32.png) [@Nadnerb](https://boards.straightdope.com/u/Nadnerb)\ **Post date:** [March 7, 2018, 1:40am UTC](https://boards.straightdope.com/t/do-all-bird-species-lay-unfertilized-eggs-some-a-few-just-one/631865/14 "2018-03-07T01:40:57Z")
I would like to point that not all birds lay eggs. Now it may sound like blasphemy, but it is objectively true. So if anyone says that all birds lay eggs, then they are sorely mistaken. I can name at least one kind of bird that doesn’t lay eggs and that is a rooster. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [March 7, 2018, 2:00am UTC](https://boards.straightdope.com/t/do-all-bird-species-lay-unfertilized-eggs-some-a-few-just-one/631865/15 "2018-03-07T02:00:47Z")
> [@Nadnerb](#): > > I would like to point that not all birds lay eggs. Now it may sound like blasphemy, but it is objectively true. So if anyone says that all birds lay eggs, then they are sorely mistaken. I can name at least one kind of bird that doesn’t lay eggs and that is a rooster. yes, and human men can’t conceive and bear children. Did you think this was some genius insight you were laying down on us? ---
**Author:** ![PoppaSan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/poppasan/32/189_2.png) [@PoppaSan](https://boards.straightdope.com/u/PoppaSan)\ **Post date:** [March 7, 2018, 2:47am UTC](https://boards.straightdope.com/t/do-all-bird-species-lay-unfertilized-eggs-some-a-few-just-one/631865/16 "2018-03-07T02:47:05Z")
> [@Nadnerb](#): > > I would like to point that not all birds lay eggs. Now it may sound like blasphemy, but it is objectively true. So if anyone says that all birds lay eggs, then they are sorely mistaken. I can name at least one kind of bird that doesn’t lay eggs and that is a rooster. This was alluded to in post #2. Albeit with other bird species. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [March 7, 2018, 2:50am UTC](https://boards.straightdope.com/t/do-all-bird-species-lay-unfertilized-eggs-some-a-few-just-one/631865/17 "2018-03-07T02:50:26Z")
> [@Nadnerb](#): > > I would like to point that not all birds lay eggs. Now it may sound like blasphemy, but it is objectively true. So if anyone says that all birds lay eggs, then they are sorely mistaken. I can name at least one kind of bird that doesn’t lay eggs and that is a rooster. **Nadnerb** , we prefer that old threads be bumped in General Questions only for good reason. Since this isn’t one, I’m closing this. Colibri General Questions Moderator ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 7, 2018, 2:59am UTC](https://boards.straightdope.com/t/do-all-bird-species-lay-unfertilized-eggs-some-a-few-just-one/631865/18 "2018-03-07T02:59:39Z")
But the OP didn’t ask about “all birds”. He asked about “all bird species”. And the rooster’s species does lay eggs. Besides which, roosters do too lay eggs. Where do you think cockatrices come from?