Any Ornithologists Out There?

[shanmonster]

Why is it that pretty much any baby animal I can think of spends a fair amount of time playing, but squabs just seem to sit there doing nothing all day? Baby chickens run around and ducklings swim, but baby pigeons just seem to only get excited when it's mealtime. What's with that?

Comments

Life lists

[iagofan.livejournal.com]

birders have a life list of all the species of birds they have seen in their lifetime. pigeons have a statue list. they save their energy for their lifelong quest.

Re: Life lists

[shanmonster.livejournal.com]

Ha!

[miraba.livejournal.com]

If they do anything, it will be reserved to flapping their wings. Flying birds grow quite a bit before they're able to leave the nest.

[ladyiolanthe.livejournal.com]

Pigeons fall into the "altricial" grouping of birds, which are characterised by young that, when they hatch, are almost completely helpless.

Ducks and chickens fall into the "precocial" group, which are characterised by young that, when they hatch, can run about, swim and find food for themselves. For example, common eider ducklings are out on the sea by 24 hours after they hatch, and don't go back to land.

I don't remember all the reasons why there is this strong division among birds, but a lot of it has to do with the amount of energy invested by the mother bird into the eggs. Mother birds have a finite amount of energy that they can invest into reproduction. Thus, there are a couple strategies they can adopt in order to produce offspring that have the greatest chance of surviving.

You'll find that most altricial birds, like pigeons, are cared for by both parent birds, the male and female. Both parents incubate the eggs, and both parents make many, many trips to find food which they bring back to the young birds in the nest. These mothers invest little of their own energy into their eggs, and their offspring hatch almost helpless, but then a lot of energy is invested in them by both parents.

Among precocial birds, the male often just mates with the female and then she is left to do all the incubating and upbringing of the offspring. These mother birds often invest a lot of energy into the forming eggs, the babies hatch out able to feed themselves and run about and swim. Thus, there is a smaller onus on the often single mother to find and provide food for her growing offspring. Common eider hens invest SO much energy into their offspring, actually, that sometimes they die sitting on their eggs, not having left the nest to feed themselves during incubation. Common eiders take this strategy to the extreme: the hens that lay eggs take their ducklings out to sea, where "aunties", which are hens that did not lay eggs that year take over the raising of the babies. Basically, the hens that lay eggs have depleted so much of their energy stores by laying and incubating their eggs that they have no energy left to invest in caring for their young.

It sort of balances out: you can spend a small amount of energy on the developing embryos, with the understanding that you'll have to put a lot of energy into feeding the hatched chicks, or you can put a lot of energy into the developing embryos, with the understanding that you won't have to put as much energy into feeding the hatchlings. (Of course, the birds aren't making conscious decisions about how much energy to invest when; it's just a couple strategies that have evolved over millions of years).

There are exceptions to the rule. In cuckoo birds, which are classified as altricial, the male does NOT stick around to help the female raise the offspring. But then the females have developed the strategy of laying their eggs in other birds' nests, so they end up not having to invest tons of energy into feeding the babies themselves. Maybe this is the exception that proves the rule...

[ladyiolanthe.livejournal.com]

Uh, I should add that these are the THEORIES behind the precocial/altricial division among birds. They aren't written in stone or anything. :)

[shanmonster.livejournal.com]

Thanks! A biologist from Texas send me looking for information on precocial/altricial division, but I couldn't quite determine which of these pigeons are from my observation. I'm not certain how long it was after hatching that I saw them.

Do you think whether or not a bird is a predator has any bearing on its precocial/altricial status?

[ladyiolanthe.livejournal.com]

No, I don't think predation confers precocial or altricial breeding strategies.

Raptors (the "epitome" of predatory birds - eagles, hawks, falcons, owls) are predatory, and they are altricial. Songbirds are all altricial, and within the vast grouping of songbirds, which range from tiny warblers to large ravens, you have birds which eat plant matter (seeds) as well as birds that are predators (insect eaters). You also have altricial scavengers/omnivores - the crows and ravens.

Among the precocial species, you will also find both herbivores and carnivores (predators). For example, Canada geese eat grass, while eider ducks eat molluscs and other little animals that live in rockweed beds. And then I think chickens could be considered omnivores, since they'll happily eat grains and insects, won't they?

So being precocial or being altricial and being an herbivore or being a predator are unrelated.