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From: Jeffrey Martz <martz@holly.ColoState.EDU>
> > >Coots, ducks, geese, and swans all feed from the bottoms of water bodies
> > >as
> > well as on dry land. They each have their own niche resulting from the
> > length of the neck, that is, how deep they can reach.
> This sounds like suspiciously tight niche partitioning. You mean the
> ducks dominate the the 12-24 inches from shore niche while the swans
> dominate the 24-48 inches from shore niche?
I believe what he meant would be closer to "12-24 inches below water".
> Can swans dive significantly
> deeper than ducks with thier larger size and longer necks to stake out
> thier own niche?
The niche partitioning mentioned is in reference to the non-diving
ducks. The true diving ducks go deeper yet. Then there are the
dabbling ducks which feed high in the water column, as filter feeders,
not on the bottom. Swans (and water-feeding geese) do not dive, per se,
though they may "stand on their head", like in the song.
Really, partitioning based on water depth is quite reasonable. It is
really no different than partitioning on the basis of height in a tree,
which is well-documented for many groups, from warblers to monkeys.
[P.S. there are many species of geese - geese make up about one
fifth of the water fowl species, most of the rest being ducks].
[There are about four groups of ducks, the dabbling ducks, the "pond"
ducks, the diving ducks, and the wood ducks]
The peace of God be with you.