Egglaying hens...

[Externet]

Hi.

Hens do lay eggs without intervention of males of the species.  That has to be a considerable expense and waste of resources. What is going on ?

Why do eagles, ducks, pelicans... do not ?  Or do they ?

[Genady]

7 minutes ago, Externet said:

Hi.

Hens do lay eggs without intervention of males of the species.  That has to be a considerable expense and waste of resources. What is going on ?

Why do eagles, ducks, pelicans... do not ?  Or do they ?

I don't know about the birds you've mentioned, but I know that other species do. For example, sharks.

PS. Sharks... not laying eggs, of course, but giving birth without a male.

[Peterkin]

24 minutes ago, Externet said:

Hens do lay eggs without intervention of males of the species. 

Domestic fowl have different life patterns from their wild ancestors. A wild bird could lay unfertilized eggs, and sometimes do, in captivity, when they have no mate. However, they only do so in the nesting season of their species. Once the season is over, their ovaries shrink (reducing their weight for flight during the busy time when they have to get food for their chicks. Domestic fowl are sedentary; don't have to fly great distances, or catch their own food, or raise their hatchlings, if they have any. They're bred to be heavier, fatter, and more fecund: domestic chickens ovulate year round (or almost; egg production slows during winter). 

In short, like the size and variety of dogs, it's a man-induced change.    

[Externet]

Genady :  Are you talking about fertile eggs ?

 

Edited March 4, 2022 by Externet

[Genady]

1 minute ago, Externet said:

Genady :  Are you talking about fertile eggs ?

 

No. They give birth to their own genetic clones.

[Peterkin]

Quote

Are you talking about fertile eggs?

Who, me? No. Caged factory chickens never see a rooster at all, so your supermarket eggs are quite sterile. 

Free range chickens may or may not be co-ed. If so, the eggs are 'candled' to sort out any that might have embryos in them.  The rooster (just one, or very few; unwanted males are butchered quite young) is kept separate from the hens, who lay one egg every day or every second day during their productive period (fewer and smaller when they're just maturing, and when they're growing old, as well as in winter), and immediately abandon it, as being no use to them. Hens become 'broody' in the springtime, which was once their natural nesting season. At this time, they are more possessive of the eggs they lay and will sit on them, rather than walk away. If the farmer wants a new batch of chicks to rejuvenate her stock, that's when the rooster is allowed into the hen-house.   

Edited March 4, 2022 by Peterkin

[swansont]

1 hour ago, Genady said:

I don't know about the birds you've mentioned, but I know that other species do. For example, sharks.

PS. Sharks... not laying eggs, of course, but giving birth without a male.

Humans ovulate without the intervention of a male, too.

[Genady]

This is an example of what I've referred to earlier:

Quote

Parthenogenesis is common in some insect species and has been observed in certain species of birds, reptiles, amphibians and bony fishes, but the new finding suggests vertebrates’ ability to reproduce without sex evolved earlier than scientists had thought. Parthenogenesis hasn’t been documented in mammals.

Study: Female sharks can reproduce without males | The Seattle Times

[Peterkin]

5 minutes ago, swansont said:

Humans ovulate without the intervention of a male, too.

That's a little bit wasteful, too, as the unfertilized human egg takes with it the sloughed-off uterine lining that would have been required by an embryo. But as resources go, a non-birth is far cheaper than a birth. The hen would have to spend the next three weeks incubating and four or five more, taking care of the brood. That's about i sixth of the hen's life spent on reproduction - but she would have up to 20 chicks to show for it. In the wild, probably 6-10, of which one or two might reach maturity. 

Live mammalian births are far more costly in terms of parental investment.