Evolution Question: Bird Nests (birds, eagle, pet, look)

[Eeyore1954]

There are many things about evolution that to my mind seem to not make sense.
We have been looking out an upstairs window and watching a birds nest first being built and then sitting on the eggs all the way to hatching. We never saw the babies leave.

Anyway I started wondering how the behavior of building the nest fits into evolution.
Was there a mutation once that caused birds to fly around and collect sticks and twigs but they didn't do anything with them? Then later they made some sort of structure but their instinct did not tell them to lay eggs in it. So they built a nice nest and left it and laid their eggs in the grass somewhere. How would any of these fit into natural selection?

I did take a few basic college couses in biology, adaption and evolution some 35 years ago and I know this is a simplistic view of a complicated subject.
But I am interested in healthy discussion on things like this.

[timberline742]

Well nests didn't start with twigs/grass/etc, by almost all reasoning. Lots of birds to this day don't use these items for nest building. Some still don't build nests at all. But there are a number of papers on this topic out there, especially regarding passerine birds which is what I think you're mostly thinking of. And of course, the use of nests predates this existence of birds, and birds evolved from other species.

A lexus nexus search, heck, even a google one, will lead you to some journal citations.

[leebeemi]

Birds aren't the only animals to build nests, either. Dinosaur nests have been discovered. Mammals build nests. Many fish build nests. The nest is simply a protective abode for eggs/young. The better the protection, the greater the chance of survival for the young. Those birds with superior nest-building skills were the ones that prospered (of those species that build nests--that's not the only key to survival). The behavior didn't come after the bird, rather right along with it.

[Kracer]

Interesting observation during bear 'nest survey' in Nj. NJ bear will pile brush and grass on a dry high spot in a thick swamp and use it for a winter bed or 'den' of sorts.

Acrually as they get up and move arounf on the pile, the center gets crushed and eventually the pile looks exactly like anyone's version of a birds nest, a giant one.

The young cubs are then confined in the nest given its higher side walls.

Birds now weave strands of plastic tarp into their nests. Seen more oriole nests with with blue plastic. Have some pics.

Wrens tend to pile broken sticks into any open cavity in what appears as a early evolution nest.

Flycatches attach their nests to vertical rock walls. Their spit might serve as a reference for a new super glue. Another one for, 'how do that do that!!!???"

Watched eagles build a nest beginning in January and by late April there were two chicks in the nest. Nest was built on a high tension tower. I would have loved to see how they placed the first thee sticks.

Then in the same area as the eagles we have hummingbirds, whose nest will fit in your shirt pocket. Amazing adaptation showcasing either end of the spectrum coexisting in the same habitat.

See article in winterbearrising.wordpress.com
search on, "how many ounces in a ton?"

[Cleonidas]

Originally Posted by Eeyore1954

There are many things about evolution that to my mind seem to not make sense.
We have been looking out an upstairs window and watching a birds nest first being built and then sitting on the eggs all the way to hatching. We never saw the babies leave.

Anyway I started wondering how the behavior of building the nest fits into evolution.
Was there a mutation once that caused birds to fly around and collect sticks and twigs but they didn't do anything with them? Then later they made some sort of structure but their instinct did not tell them to lay eggs in it. So they built a nice nest and left it and laid their eggs in the grass somewhere. How would any of these fit into natural selection?

I did take a few basic college couses in biology, adaption and evolution some 35 years ago and I know this is a simplistic view of a complicated subject.
But I am interested in healthy discussion on things like this.

Behaviors evolve just like physical traits do and birds have had quite a long time to hardwire some very complex nesting behaviors.

If you're asking about intermediary behaviors that would lead certain birds to the complex behaviors of, for example, weaving an intricate hanging nest of precise dimensions and exact tolerances, well, that's probably a mystery, but the fact that we can't easily and intuitively explain how you go from a ground nesting theropod to a baya weaver doesn't mean that the birds didn't figure it out. As an aside, the driving force behind the complexity of the baya weaver nest is probably PICKY FEMALES. Picky females are the most potent and most powerful agent in natural selection, full stop.

To the bolded portion, the roots of complex nesting behaviors go much farther back than feathered birds, of course. Archosaurs like modern crocodilians bury their eggs for thermal stability and protection and many fish have very exact standards for spawning sites, so I think that egg care in general is a very, very ancient competency. Animals that live off of the ground all have some mechanism of dealing with the ever present risk associated with offspring and potential falls; it just doesn't seem that confounding to me that as birds left the ground they would simultaneously develop behaviors to suit the new altitudes.