Hi David & Ivor,
This is a very interesting analysis David that makes plenty of good sense to me
- thanks for sharing this with us up here in the Wet Tropics & southwards...
All I wanted to add here is that I can confiirm the "hybrid" birds in the
Halifax-Lucinda area that Kath had reported...
In the very late 90's the birds I always saw at Dungeness looked like apparent
hybrids to me - this locality is at the mouth of the Herbert River at the very
southern end of Hinchinbrook Channel, just to the west of Lucinda. I never saw
any birds there that appeared either pure Varied or Mangrove... However, I
didn't check the birds either side of the Dungeness locality, so I therefore
have no idea from personal observations of what occurs outside the immediate
area of Dungeness.
Sorry but that's about all I can add.
Cheers,
Martin Cachard
Cairns
> Date: Thu, 14 Feb 2013 00:05:41 -0800
> From:
> To:
> Subject: Re: [Birding-Aus] Mangrove and Varied Honeyeater
>
> Hi Ivor,
> I looked into Mangrove and Varied Honeyeaters a bit during
> the 90s and early 00s when I was living in Townsville. To answer your
> question is more complicated
> than you might think. My methods were very simple; I looked at them at as many
> locations as I could in NQ, and recorded some plumage details particularly on
> the
> underparts, throat and head. NO captures, no DNA, not even any photos, just
> plumage
> notes.
> In summary, I found almost exclusively pure Mangrove
> Honeyeaters from the mouth of the Ross River (south side of Townsville)
> southwards
> to Gladstone at many locations. I found almost exclusively pure Varied
> Honeyeaters
> from Rowes Bay (north side of Townsville) north to Cape York and PNG. The
> furthest north I ever found a Mangrove Honeyeater was in the small
> recolonising
> areas of mangroves at South Townsville, near the port. This is about 5 km in a
> straight line from Rowes Bay where Varied were resident, and there is no
> suitable habitat in between, so they effectively abutted at Townsville.
> The exceptions were interesting:
> 1). Julian Ford collected 2 hybrids at “Cleveland Bay” in
> the 1980s. Both Ross River and Rowes Bay are in the huge Cleveland Bay but
> Andrea Griffin was with Julian and she told me they were at the mouth of the
> Ross River. I never saw a single hybrid or anything that made me suspicious,
> anywhere in Cleveland Bay, though of course I might have just missed them.
> 2). 40 km or so South of Townsville at Cape Cleveland and
> Cungulla, there were only Mangrove Honeyeaters, except on a couple of
> occasions I
> saw a single Varied with the Mangroves somewhere in the township of Cungulla.
> I
> suspect it was just the one bird that I saw repeatedly. This was the only
> location where I ever saw the 2 species together.
> 3). In 1989 or 1990 at either Lucinda or Halifax (about 100
> km n of Ross River) Kath Shurcliffe showed me a population of hybrids. Later
> when I was looking into it I couldn’t find this locality again, and only got
> insufficient
> views of honeyeaters in this area, so I was never able to verify the earlier
> sighting for myself.
> My data set doesn’t prove anything, but here is my wild and
> reckless hypothesised explanation:
> Mangrove and Varied Honeyeaters are closely related (sister
> taxa). They evolved from a common answer relatively recently when some
> historical barrier split the
> ancestor’s range into 2. They are now in ‘secondary contact’ after the barrier
> broke down. Since they both have linear distributions tied to coastal
> mangroves
> this is a rare example where the secondary contact effectively occurs at a
> single
> location, rather than across a broad front. They can and do hybridise, but
> mostly they do not. Varied Honeyeater is expanding southwards and displacing
> Mangrove as it goes. The individual Varied I saw at Cungulla living with
> Mangroves was, at that time, leading the charge, an unwitting scout. The 2
> hybrids collected at Ross River were love children of the battle front at that
> time. Varied had not one that battle and had retreated slightly, at least
> temporarily. The hybrid swarms at Lucinda or Hallifax (if they exist) are
> isolated historical
> remnants from a time when Varied swept southwards through there displacing
> Mangrove
> as it went.
> That speculation aside, if someone looked at the genetics I
> wouldn’t be surprised to find either: a) a complex mix of secret hybrids
> throughout, even though they look like one species or the other; or b) there
> is no
> difference between them genetically. My ‘explanation’ would likely prove too
> simple.
> So I would expect that birds north of Townsville are still
> Varied. Your yellow washed birds at Ross River might also be Varied,
> advancing south once more, or they might be hybrids or they might
> even be juvenile Mangroves. Get some photos if you can.
> Thanks Mike Carter for bringing this to my attention.
> Cheers,
> David James
> Sydney
>
>
> ________________________________
>
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