Re: Cormorants, anhingas & soaked feathers (resend)

[don ohmes <d_ohmes@yahoo.com>]

Resending...
--- don ohmes <d_ohmes@yahoo.com> wrote:
> Add to the "conclusions": insulation may affect
> locomotion, and the lack of insulation make them
> more
> effective predators (as well as harder to catch).
> --- don ohmes <d_ohmes@yahoo.com> wrote:
> > 
> > Knowing very little about comorants/anhingas--
> > 
> > 1. The default hypothesis is that
> > flight-ability-immediately-post-dive, and thermal
> > insulation "in-dive" are not a significant
> > advantages
> > for these birds.
> > 2. A sub-hypothesis is that predation risk is NOT
> > such
> > that flight is a necessary escape mechanism.
> > 
> > Conclusions-to-be-tested -- 
> > Predation-- Body size protects them from aerial
> > predators, water protects them from terrestrial
> > predators, and aquatic predators are only a factor
> > during resource aquisition (i.e., diving).
> > Thermal relations-- Body size and water temps are
> > such
> > that insulation is not a significant selection
> > pressure in their habitat range.
> > 
> > --- Brian Lauret <zthemanvirus@hotmail.com> wrote:
> > > As we all know (I presume), cormorants and
> > anhingas
> > > lack water-repellent 
> > > plumage. That is, diving means they'll get
> soaked
> > to
> > > the skin and will have 
> > > to dry their feathers afterwards.
> > > 
> > > The latter thing takes time while the succes of
> > the
> > > dive isn't even assured. 
> > > In my logic, this puts cormorants and anhingas
> at
> > a
> > > considerable 
> > > disadvantage compared to their waterproof
> > > competitors.
> > > The diving itself doesn't seem like the reason
> for
> > > the strange strategy 
> > > employed by these birds. After all,
> > > loons,grebes,auks and mergansers all 
> > > dive succesfully with their waterrepellent
> > plumage.
> > > 
> > > So I wonder, what could be the use of getting
> > soaked
> > > to the skin and having 
> > > to dry up, what makes it such a succesful
> strategy
> > > and why could it have 
> > > evolved in the first place (or: why didn't
> > > waterproof plumage evolve in 
> > > cormorants and anhingas?
> > > 
> > > Brian
> > > 
> > >
> >
> _