Picture of the Week—Hawaiian Honeyeaters
Hawaiian Honeyeaters, Credit: John Anderton
I wish I could draw, but I’m really quite hopeless in that arena. It’s sad because I especially enjoy botanical and fauna illustration (I even keep reproductions of 17th-century drawings of tulips here in my cube) but dare not even try something like this drawing of Hawaiian honeyeaters. When I first saw it, I marveled at the birds’ beauty. However, I quickly realized the sad truth: they were drawn because none are now alive to be photographed, according to Smithsonian Institution researchers.
From the Smithsonian press office:
Until the 1980s, when the last species went extinct, five Hawaiian honeyeater species sipped nectar from Hawaii’s flowers. These birds, illustrated lower left (Hawaii `o`o) and upper center (kioea), have always been considered Australasian honeyeaters (family Meliphagidae; two on right branch), and share many similarities in form, behavior and ecology. However, DNA sequence analyses of museum specimens by Smithsonian researchers reveal that the Hawaiian species are distantly related to meliphagids and are instead a new songbird family, the Mohoidae, related to Holarctic waxwings (shown upper left), neotropical silky flycatchers and related families. The mohoids and meliphagids are a remarkable example of convergent evolution, and the only bird family known to go extinct over the past few centuries.
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My first experience of the importance of D.N.A. studies occurred in the 1980s when a friend looking at rookeries discovered that Dad wasn’t always what he appeared to be; sometimes he wasn’t dad at all, but he didn’t know it and neither did science, until there were D.N.A. blood samples. Seeing isn’t necessarily believing and D.N.A. evidence changed the meaning of behavioural studies forever.
In the early 1080s I filmed honeycreepers. The I’iwi (Hawaiian Scarlet Honeycreeper) on Kauai Island. Honey creepers, honeyeater, what’s the difference I thought – they have similar beaks, there similar birds, but of course they are not closely related? When I came to New Zealand and saw tui and bell birds (true honeyeaters), feeding on pohutukawa flowers (they are doing this now in my garden), I thought how similar these flowers looked to the flowers of o’hia that I saw I’iwi feeding on in Hawaii (same plant Genus). Makes sense, until you realise that i’iwi are adapted to trumpet shaped flowers of species of Lobelia now either extinct or on the way out, and it appears that the I’iwi has been adapting to feed more generally – apparently the beak is reducing in length to this end, according to work published around 1996 – (evolution in action, as it were).
At present the main visitor to my Pohutokawa flowers are European wasps (and they shouldn’t be here at all), but the flower has the look of an insect pollinated species, and to be honest, the tuis and bellbirds move onto pohutukawa only after the flax flowers are on the way out – it looks as if these two honeyeaters are best adapted to flax flowers – the beak seems to fit – there is a lot of nectar and the birds really know how to work it. The other N.Z. honeyeater, the stitchbird is a less successful native and it struggles to hang on with a very limited distribution on offshore islands (this bird is now to be reclassifed in anycase). The tui, like the i’iwi seems to be adaptable – they are survivors, both appear to follow the same pattern of feeding, but are quite different and not closely related. There is then, a lot going on and as a behaviourist you really have to have an enormous background to work out what is happening – and even then, it is easy to get things wrong. I wonder if, when more D.N.A. work is undertaken on other Genera and Families, parallel evolution may have quite a few surprises in store. We might expect to see similar behaviours in animals that look similar, but relatedness is quite another thing and this discovery showing us the roots of Hawaiian ‘Honeyeaters’ is going be rather important; it confirms that we can’t rely on appearances. Behavioural studies are drifting off shore; taxonomy is clinging to the dock, but D.N.A. appears to be on firm ground. This isn’t playing at science anymore – it’s the real thing!
Comment by Stephen Bolwell — December 30, 2008 @ 6:11 am
In deference to the source material I ought perhaps to have said convergent rather than parallel evolution, although I am happy with the latter.
Comment by Stephen Bolwell — December 30, 2008 @ 6:30 am