How are unwitnessed behaviours (such as an adult bird building a nest the chick never saw the construction of) passed onto the next generation?

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How are unwitnessed behaviours (such as an adult bird building a nest the chick never saw the construction of) passed onto the next generation?

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Nest building is a species-specific innate behavior, birds don’t learn how to build a nest, they’re born with an instinctual drive that lies in their genetics. It’s also why different species make different types of nests which be radically different in construction.

For a contrast, brown bears are NOT born knowing how to fish, they have to both learn from their mother by watching her, and also they develop their own unique style. Each bear fishes in slightly different ways, some like to wait under the water, others prefer to wait at the top of a fall for a fish to practically leap into their mouths, others wait behind the boil of the fall to pick up fish that failed the jump, some use jaws first and others use paws.

A lot of animal behaviors are instinctual. For example beavers have an instinct to build dams if they hear the sound of fast flowing water. It works out for them, but they’ll also start to build a dam if there is a loudspeaker playing water sounds. It’s an example of relatively simple fundamental behaviors building up to a big complex thing.

Other behaviors are learned. Either by the bird remaining with their parents and helping out the next years hatching before flying off on their own, or by watching adult birds do it and then practicing (weaver birds building nests is not an inborn instinct. Males will watch, try, fail and retry until they build a nest that a female accepts).

I don’t think this question has been answered yet. Yeah, it’s “instinct” but how exactly does that work? My go to example is spider webs. Those are deliberately built in a specific way with no instruction from the elders.

This is a very good question. There are a whole pile of answers to this thread that basically say “instinct.” But that doesn’t really mean anything. What do we mean when we say instinct? Is it some sort of neurological pathway that forms during embryogenesis? Or maybe it’s something that develops at different lifestages. Can it be hormone mediated? If so, can we manipulate instinct? Perhaps it is actually a learned behavior based on based on a mother’s stereotyped dance that we have not yet developed the ability to observe. There could be any number of answers to this question. Is instinct the same thing from one species to another? Is the instict for nest building, bird migration, butterfly migration, etc all explained by the same mechanism?

You’ve asked one of the big questions of natural history/ethology/neurology/developmental biology…

Top-voted comment over-simplifies the case. In all vertebrates, at least, it’s fair to say that some behaviors are entirely instinctual but most are a mix of instinctual and learned. Birds comprise a whole order of vertebrates and a very wide range of behaviors and genetics. Highly social species such as parrots have young that accompany the parents for several years. IDK if they help build the nest of subsequent generations [but they do help rear the young](https://phys.org/news/2012-07-family-key-social-birds.html), and it’s very likely that they learn some things by watching. I’m not an ornithologist, but I’d love to hear from one about this.