Hi Jeff,
Yeah, Audubons or 'Tropical' Shearwater (although I saw no darker leading edge)
are the ones that immediately comes to mind with the characteristics I saw but
they would be a long way out of range. One bird maybe? 7 or 8 I would doubt
unless there is a closer breeding location than currently known. As I was
seeing so many Little Shearwaters I reckon going with the commoner species is
much more likely but this is exactly why I was mentioning these birds to see if
others have seen similar things. It seems as if there is still a lot to learn
about the whole Little/Audobons Shearwater groups.
Cheers Dan
> From: > To: > Subject: RE:
> [Birding-Aus] Seabirds off WA and Christmas Island - incl.GREAT SHEARWATER>
> Date: Fri, 5 Dec 2008 00:03:44 +1100> CC: > > G'day
> Daniel,> > Thanks for your report, I enjoyed reading it and congratulations
> on the> Great Shearwater, I hope you will submit it to BARC.> Your
> description for odd Little Shearwaters could actually describe> Audubon's
> Shearwater, a species unknown to those waters thus far. Did you> consider
> that species when you were observing them, or were you able to> eliminate
> them as a possible ID.> > Cheers Jeff.> > > -----Original Message-----> From:
> >
> On Behalf Of Daniel Mantle> Sent: Thursday, 4 December 2008 11:16 PM> To:
> > Cc: > Subject: RE:
> [Birding-Aus] Seabirds off WA and Christmas Island - incl.GREAT> SHEARWATER>
> > > Hi Evan, Birding-aus> > I am sure the birds have no clue how deep the
> water is but there is no> doubting they will congregate in areas of richer
> feeding and are adept at> reading the oceans to this end - whether this is
> through smell, temperature,> sight or a combination of these thinbs. The
> density of birds is often much> higher along the shelf edge and continental
> slope than up on the shelf or> out in the open ocean. Commonly this is
> associated with areas of cold> upwelling along the shelf edges that brings
> with it nutrients and thus an> increase in planktics for seabirds to feed
> upon. It is not this simple off> the WA coast, as there are several currents
> running at different depths,> different directions, and at different
> distances from the coast. The most> important or well known of these is
> probably the warm Leeuwin Current that> runs south along much of the west and
> northwest coast of Australia. It is no> doubt this warm current that
> influences the rather subtropical/tropical mix> of seabirds off the west
> Australian coast - many Bridled and Sooty terns,> noddies, and Wedge-tailed
> and Little Shearwaters.> > So why the increased density in the canyon systems
> off the WA coast (eg> Murchison Canyon off the Abrolhos and Perth Canyon off
> Perth)? Probably the> increase I observed in the Murchison Canyon also
> reflects the proximity to> nesting sites in the Abrolhos Islands but there
> was also a very noticeable> drop off in numbers as we transited to the next
> canyon systems north and> south everytime we movednalong this stretch of
> coastline. So there must be> something causing better feeding in these areas.
> There may be some limited> cooler, nutrient rich upwelling in these areas, or
> maybe the transfer of> sediment through these systems provides the nutrients
> for an increase in> planktonic species in these areas (although just how much
> sediment transfer> there is going on at present would be very debatable or
> even doubtful).> Sorry, I can't give a more definitive answer than this but I
> would have to> find out a lot more about the rather complex current patterns
> and influences> along this coastline.> > Any other thoughts?> > I would still
> be particularly keen to hear if anyone else has observed> 'Little'
> Shearwaters with dark trailing edges off the WA coast? Have any of> the Perth
> seabirders any thoughts on Little Shearwater plumage wear to add?> > Cheers
> Dan> Date: Thu, 4 Dec 2008 11:34:56 +1100> From: >> To:
> > Subject: Re: [Birding-Aus] Seabirds off WA and>
> Christmas Island - incl. GREAT SHEARWATER> CC: > >>
> Fascinating report indeed Dan.> > A question: How do the birds know how deep>
> the water is?> "By far the best areas for seabirds were in moderate to deep>
> waters> (800-4000m) within the canyon systems that run perpendicular to the>>
> shelf edge."> > My understanding was that pelagic species (fish and>
> invertebrate> marine) were pretty constant in the top of the water column...>
> so what> changes that causes the birds to pick the deeper water?> > EB> > On>
> 12/3/08, Daniel Mantle <> wrote:> >> > I have just>
> returned from the 1st Leg of Geoscience Australia's current marine surveys>
> off the West Australian coast and thought I would write up a brief(ish) note>
> on some of the seabird observations during the trip.> >> Evan Beaver>>
> Lapstone, Blue Mountains, NSW> lat=-33.77, lon=150.64>
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