Hi,
And here are the answers
Cheers
Carol de Bruin
Johannesburg
-----Original Message-----
From: Les Underhill <>
To: HAROLD RESNIK. <>
Cc: <>
Date: 22 July 2000 11:56
Subject: Re: thinking of penguins
Harold and others
> Why were the penguins specifically released in Port Elizabeth
The shortest time for a penguin to swim from Cape Town back to PE was
known to be 11 days. At the time the decision was taken, it seemed
fairly certain that the Robben Island landing areas would be clean by
then, and that it was likely that the Treausre would be largely oil
free. Places to the north were considered (eg Luderitz), but
dismissed for a variety of valid and sensible reasons. East London
was considered too far, because it is beyond the normal range of the
species. Mossel Bay or Plet were too close because the birds would
be likely to return too soon.
> What is the longest recorded distance covered by a member of this family =
> of penguins
SAFRING has many records of penguins moving from the Western Cape to
Namibia, and rather fewer of penguins moving from the Western Cape to
Algoa Bay.
> How did the penguins know which way to go and where to go
As far as I am aware, no specific research has been done on penguin
navigation (as opposed to the navigation of flying birds).
> What made them swim west and not east
We are not sure why, but would have been surprised if they didn't!
> Is the homing instinct common in these birds
Young penguins after they "fledge" are extensive wanderers in their
adolescent years. They do NOT go to sea with their parents; they
have to find their own food, never having seen what they eat in its
natural habitat. Many penguins will therefore have experienced long
outwards and return journeys involving long distances. Penguins
almost invariably ultimately return at age three to five years to the
island where they hatched to breed (but the exceptions to this led to
the establishment of the Stony Point, Boulders and Robben Island
colonies, and we have recently found a few birds that have bred at
more than one colony).
> Do they "sleep" when swimming continuously
Swifts "sleep" on the wing. We need to be careful of tending towards
the anthropomorphic.
> When nearing the predator danger areas, what made them swim out way from =
> the coast, was this "instinct"
There is no evidence that they particularly evaded predator danger
areas.
> How were the satellite transmitters fixed to their bodies
With velcro. The details of this are on the ADU web page. At the
bottom of the SAPmap there is a link to a page of technical details
written by Rob Crawford at MCM. The glue that sticks the bottom
layer of velcro to the feathers will deteriorate after about 40 days
in and out of seawater and fall off.
> If one of them (with a transmitter) were eaten, could the signal, in the =
> predator, be followed by the satellite
No. The transmitter is programmed not to transmit if the penguin is
under water.
> What is the life of such a transmitter
The battery packs up after about 30-50 days, depending on the pattern
of switching on and off to save battery life.
> And finally, what is the possibility of finding the 3 penguins with the =
> transmitters
Quite good. What is needed is a bit of patience while Phil
Whittington, my PhD student, and others do the necessary detective
work. Sooner or later, we will get enough high quality fixes for one
part of the island that we can have a good idea which "highway" down
to the shore they use. Then it is a matter of waiting. All three are
also flipper banded, so even if we don't find them before they lose
their satellite tags, there is a good chance that they will sooner or
later cross paths with a researcher.
Best wishes
Les
****************************
Professor Les Underhill
Director: Avian Demography Unit
Department of Statistical Sciences
University of Cape Town
Rondebosch 7701 South Africa
Phone +27 21 650 3227 Fax +27 21 650 3434
Web http://www.uct.ac.za/depts/stats/adu/
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