Wednesday, January 22, 2014

Banding results part 2: more old and confused birds


Bird banding in PNG Part 2.  "Old and confused" birds

The longevity of the Chaetorhynchus "drongo" was not that unusual.  Quite a few other species had individuals living over a decade.   The list of species living long is basically just a list of the most commonly caught species-- indicating that with enough captures we'd find lifespans over a decade is probably the norm for most species.

Size doesn't matter.  At 11 years and four months, the miniscule Gray-green Scrub-wren (Sericornis arfakianus) was the third longest-lived recapture.  The mean weight of these guys was 9.2 grams, just over a quarter of an ounce-- less than the weight of two quarters.  The nearly as small Dwarf Honeyeater (Oedistoma iliolophus) weighing in at about two quarters and a penny had the second longest recapture interval-- 11 years and six months.

Like the aforementioned "drongo" that isn't really a drongo, the Dwarf Honeyeater turns out not to be a honeyeater upon examining its DNA.   Ditto for the Long-billed Honeyeater (Toxorhamphus poliopterus): oldest 10 years 9 months.  This is the state of knowledge of birds in New Guinea.  Many species are categorized based on superficial characters that are highly variable and subject to convergence.  These "honeyeaters" have a thin decurved bill like many other honeyeaters, a diverse family centered in Australia-New Guinea.  But look at the DNA and they come out closer to the Berrypeckers.  Anything that feeds on nectar might evolve a thin decurved bill, that doesn't make them related.  Honeyeaters are not related to our nectar-feeding hummingbirds or sunbirds of the Old World.

The Black Berrypecker (Melanocharis nigra) is another common bird at the station, captured 436 times.  The longest-lived was just over 11 years between captures.  These birds have been a bit challenging to ornithologists also.  They've been aligned with several different families depending on the predispositions of ornithologists.  But few ever lumped the berrypeckers, with their short stout-ish bills, with the faux honeyeaters Oedistoma and Toxorhamphus with their long, thin bills.  (Can you see why I like the Latin names better than English Names?  You can place Oedistoma in any family, but when you say a honeyeater is a berrypecker, it gets confusing.)  Now it is beginning to look like Berrypeckers (Melanocharis), and the "honeyeaters" Oedistoma and Toxorhamphus, are all related.  They might best be considered their own family, a family that is endemic to New Guinea, best called the Melanocharitidae.

Slaty-chinned Longbill (Toxorhamphus poliopterus).  The species most commonly banded at the Crater Station.  The oldest recaptured was at least 12 years old.  Superficially similar to honeyeaters and the spiderhunters of SE Asia.  It is neither, and appears to be part of a family unique to New Guinea.

If you are confused, good.  The ornithology of New Guinea is confusing and only a handful of workers are sorting it out.  I'm certainly no expert on the evolutionary relationships of New Guinea's birds.  I'm more of an ecologist and natural historian.  My research doesn't resolve who is related to whom, but I can give a little idea of how long some birds live and what they do in that lifespan.  I think it is exciting to think that a group of birds isolated in New Guinea radiated into different niches-- some eating fruits and evolving a stout bill and others becoming nectar and insect eaters and evolving thin decurved bills.  When I started out the banding project, I did not know I was collecting data on a family of birds endemic to New Guinea.  I'd hazard a guess that there are very few, if any, entire bird families in the world that ornithologists have studied less and know less about. 

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