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Re: Altitude effects on hummingbird flight?

> The question really isn't why hummers from other
> parts of the world may have 
> become extinct; perhaps the more interesting
> question is why such highly 
> specialised species have managed to survive (and
> even thrive) in the 
> Americas for so long. Specialists generally don't do
> so well during 
> extinction events. 

They had no major extinction event in their way yet
(they do fairly well until now) and they are hardy.
Not versatile, but tough.

What would kill them off entirely is a large enough
bolide impact: no flowers, no hummers. But they are
resilient against tectonic and climate shifts (or
rather the consequences of these).

It can be safely assumed that hummingbirds have been a
major ecological factor for the last 20 million years.
>From the point of a flower waiting to be pollinated,
they're just some weird smart insect that likes red.
For all the flower-pollinator coevolution that has
been going on, and considering that most sphinx
moth-pollinated flowers are theoretically at least
accessible for hummingbirds, I think for the time
being it's safe to say that a) they won't be
outcompeted in the Americas* and b) if global warming
is gonna be anything like the nametag implies, they're
probably gonna spread to Asia and possibly Europe in
the next 100s of years, at least with ephemeral
populations. We have resident parakeets already; the
warmer parts of Central Europe provide the occasional
marginal hummer habitat already all-year round (due to
decorative plants, and much to the benefit of our
Hummingbird Hawkmoth).

The important factor is: how deeply is their migration
genetically engrained? Do they have some "map" of
sorts that is hardwired, or do they just check where
is south and then swim with the flocks?



* As opposed to other regions with nectarivorous
birds,  the Americas do not have significant plants
with flowers that are adapted to pollination by more
conventional birds. It is, for a plant, not a very
good strategy to assist some bird in evolving into
something that could even seriously try hummers on
their home turf.


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