Carl,
You have asked a bigger question than you realise. In short, they are
northern hemisphere breeders and they spend the austral summer in the
southern hemisphere. Flying through the East Asian-Australasian Flyway,
they arrive around November and most are gone by sometime in April.
The Sunshine Coast is a hotspot for migratory terns, but as you can see
from the numbers supplied, they have a peak in late summer. We don't
know the answer to the question, "where do they spend the height of the
Australian summer" because I have asked many times, and never received a
satisfactory answer. If they do spend the summer in Australia, there are
no reported concentrations, and the only possibility is that they spread
out into very small, unnoticeable groups in southern Australia. Or, it's
possible that they go to Pacific Islands (but where?). However, they
pass through the Sunshine Coast region on their way north in late summer
early autumn in larger numbers than is the stable summer population.
Because there has been little banding of migratory terns (some Commons
flagged orange in Victoria over the years, but no individual marking) we
don't know exactly where our migratory terns breed. They breed in places
like eastern China, Japan, the Philippines, and I think Mongolia.
However, I'd love to know exactly where they go. We need satellite
trackers and in certain cases, perhaps geolocators.
I think there are possibly numerous breeding locations and timetables
for the East Asian subspecies of Common Tern (Sterna hirundo
longipennis). I have no proof, only questions and hints which lead me to
think so.
Nor do we know where the Australian-breeding Little Terns (Sternula
albifrons sinensis) go during the austral winter. We know they don't
join the breeders in Japan, which breed during the northern summer. We
know this because there has never been a record of an Australian breeder
in Japan amongst their Little Terns. The northmost Australian records of
this group are my own in Maroochydore, Sunshine Coast in early autumn,
and a single record by Clive Minton of a bird seen on Swain Reefs off
Qld (or was it the Cap Bunker?) in July, 2000. So we definitely need
geolocators for Australian-breeding Little Terns. I think geolocators
would be suitable because they tend to return to the same breeding sites.
I should explain for clarity. The subspecies of Little Tern which breeds
in Australia during our summer is the same subspecies of Little Tern
which breeds in the northern hemisphere during the northern summer. They
are different populations, and whilst the two populations mix here in
Australia, their breeding habits are out of kilter with each other.
I haven't gone into it too far, but if anyone wants to ask more
questions, that's OK. It's rather complicated.
Cheers,
Jill
Jill Dening
Sunshine Coast, Queensland, Australia
26° 51' 41"S 152° 56' 00"E
On 15/03/2011 12:38 PM, Carl Weber wrote:
Hi,
Where have the terns migrated from and where are they going to?
Carl Weber
-----Original Message-----
From:
On Behalf Of Jill Dening
Sent: Tuesday, 15 March 2011 8:59 AM
To: birding-aus
Subject: [Birding-Aus] Tern migration peak has passed on the Sunshine Coast,
Qld
Hi Everyone,
Last night we did a count of migratory terns arriving to roost in Noosa,
Qld. The vast majority of these birds are Common Terns, but also
included are Little Terns and White-winged Black Terns. This confirmed
that the migration peak has passed in our area. Unfortunately we only
conduct one count each month, limiting our knowledge of the actual peak,
but below are some figures going back to Nov, 05, with dates. Note that
there was a gap in data collection between January and December 2007,
and that we missed a count in March, 2010.
Birds are normally counted on the wing in blocks of 10, so the figures
are never exact. Occasionally at peak periods they are counted in blocks
of 50s, or even 100s rarely.
Cheers,
Jill
Survey_Date Sum Of Number_Seen
28-Nov-05 2380
14-Jan-06 12560
08-Feb-06 38340
08-Mar-06 14910
12-Mar-06 6020
15-Dec-06 573
15-Jan-07 2050
19-Dec-07 2740
17-Jan-08 2930
21-Feb-08 6650
15-Mar-08 1900
22-Apr-08 765
15-Dec-08 60
12-Jan-09 15030
11-Feb-09 1280
05-Mar-09 7400
09-Apr-09 5150
23-Jul-09 6
21-Aug-09 1
10-Dec-09 1170
18-Jan-10 2454
16-Feb-10 6330
15-Apr-10 3379
20-May-10 369
15-Jun-10 264
12-Jul-10 268
13-Aug-10 385
23-Nov-10 7280
07-Dec-10 11000
27-Jan-11 12830
24-Feb-11 21110
16-Mar-11 7170
===============================
To unsubscribe from this mailing list,
send the message:
unsubscribe
(in the body of the message, with no Subject line)
to:
http://birding-aus.org
===============================
|
