Machael Price wrote -

> Jerry Tangren writes, re Marbled Murrelets fledging directly to ocean from
> nests often far inland :
>
> >Just a wild guess, but the ocean reflects a different color off the sky
> >than land does. I've heard that South Sea Islanders can navigate their
> >boats from island to island by observing the color of the sky.
>
> But Janet Hardin writes:
>
> >Chicks usually fledge at dusk.
>
> Interesting! In trying to resolve these two points in my mind, at first, I
> thought they'd simply be orienting to the light and heading to it, but the
> place where the last glow of twilight--so a differently-colored stretch of
> sky--would be at that time of year could be as much as another 45 degrees to
> the NW of the direction they'd need to take to arrive as they do at the
> stretch of ocean directly opposite the nest. Maybe Jerry's right, that they
> look for light indicators--which would imply they'd not fledge in dull
> overcast, or maybe would, but earlier in the day--but they then subtract
> 30-45 degrees for Kentucky windage. Given their bullet flight, even those
> nesting far inland are still only an hour or two at most from the ocean, and
> if they head even vaguely west they'll still hit ocean.

This would all be elementary if it were possible for Marbled Murrelets to hear in
the infrasonic frequencies (as do elephants). The crashing of the surf onto the
coast can be sensed for many miles inland with the proper equipment, and it would
provide an easy mechanism for young murrelets to orient seaward. Of course, there
will be the argument that the infrasonically adept should make infrasonic noises
of their own if they really were able to hear the low notes. I don't see any real
casual reason here, though. Perhaps most maritime animals have some ability to
sense infrasound given the ability of seawater to transmit the low frequencies
with great efficiency.

It has also been posited that this is how some soaring bird species find the best
mountain waves to glide on - they home in on the "best sounding" ridges. We
humans are missing a lot with our restricted hearing range, I think.

- Jack



Jack Bowling
Prince George, BC
jbowling at direct.ca