# Birds and live birth **URL:** \ **Category:** Factual Questions\ **Created:** [September 30, 2004, 1:21am UTC](https://boards.straightdope.com/t/birds-and-live-birth/266774 "2004-09-30T01:21:41Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![rippingtons\_fan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rippingtons_fan/32/11767_2.png) [@rippingtons\_fan](https://boards.straightdope.com/u/rippingtons_fan)\ **Post date:** [September 30, 2004, 1:21am UTC](https://boards.straightdope.com/t/birds-and-live-birth/266774/1 "2004-09-30T01:21:41Z")
Are there any types of birds that give live birth (in the way that some types of reptiles and fish do??) ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [September 30, 2004, 2:07am UTC](https://boards.straightdope.com/t/birds-and-live-birth/266774/2 "2004-09-30T02:07:31Z")
No. There are reptiles, amphibians, and even fish that do it, but birds don’t. For the simple reason that birds, as a group, are designed for flight, and eggs are a whole lot of dead weight. They tend to get them out of their body as quickly as possible. I just happened to watch David Attenborough’s “Life of Birds,” and he mentioned that fact. ---
**Author:** ![MrFantsyPants](https://avatars.discourse-cdn.com/v4/letter/m/7ba0ec/32.png) [@MrFantsyPants](https://boards.straightdope.com/u/MrFantsyPants)\ **Post date:** [September 30, 2004, 3:23am UTC](https://boards.straightdope.com/t/birds-and-live-birth/266774/3 "2004-09-30T03:23:17Z")
> [@Smeghead](#): > > No. There are reptiles, amphibians, and even fish that do it, but birds don’t. For the simple reason that birds, as a group, are designed for flight, and eggs are a whole lot of dead weight. They tend to get them out of their body as quickly as possible. > > I just happened to watch David Attenborough’s “Life of Birds,” and he mentioned that fact. That doesn’t make much sense to me. Immediately before the egg is laid, the bird has to carry all nutrients to sustain the embryo until it is ready to hatch. A live birth would me that at its peak, the amount of weight the mother must carry is less (though not significantly). I would suspect that it more a time factor, since an egg can be create in less time than an autonomous creature… ---
**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:** [September 30, 2004, 3:41am UTC](https://boards.straightdope.com/t/birds-and-live-birth/266774/4 "2004-09-30T03:41:11Z")
> [@MrFantsyPants](#): > > That doesn’t make much sense to me. Immediately before the egg is laid, the bird has to carry all nutrients to sustain the embryo until it is ready to hatch. A live birth would me that at its peak, the amount of weight the mother must carry is less (though not significantly). > > I would suspect that it more a time factor, since an egg can be create in less time than an autonomous creature… Also, most birds lay more than one egg, and that has to be taken into account. Birds simply could not carry around several eggs internally and still be able to fly. In contrast, similarly-sized mammals can carry fairly large litters internally. Incidentally, bats have only one or two young at a time, much fewer than most other small mammals. Flightless birds could in theory develop live birth, but none have.