Hi all
Can anyone tell me how many subspecies of little tern there are in Australia?
HANZAB suggest there is only one, however del Hoyo et al (1996) Handbook of
Birds of the World suggest two subspecies.
As we all know there is an endemic population that breeds in southern (and
northern?) Australia during the austral summer. At the same time there is a
large non-breeding population that is presumably a trans-equatorial migrant
(at least some go to Japan).
So is there one or two subspecies, and if there is only one, how do we explain
the evolutinary mechanism that would have allowed the same subspecies to have
populations that migrate short distances and breed on the the same continent,
while another part of the population breeds in one hemisphere and migrates to
the other in the non-breeding season.
Has anyone conducted DNA or enzyme analysis of the two populations.
Most importantly, the Little Tern is an endangered species. Is the whole
(Aust) population endangered, or only that part of the population that breeds
in southern Aust?
I ask these questions because proponents of an estuarine remodelling progam at
the entrance to Lake Illawarra (NSW), have pointed out that because the bulk
of the tern population that frequents this site (300+ Chafer & Barndis 1992)
are non-breeding birds. Thus their breeding population is not threatened!
Cheers
Chris Chafer
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