|HAWAIIAN HONEYCREEPERS Drepanidini
a traditional bird family but now a lineage embedded within the Fringillidae
- 17 species extant in Hawaiian islands
- DR personal total: 14 species (82%), 10 photo'd
scientists developed molecular techniques to study genetic evolution,
there were just theories about how the Hawaiian honeycreepers came to
the Hawaiian islands and evolved into one of the most spectacular
radiations of birds in the world. Most everyone agreed they were so
unique that they warranted their own family, the Drepanididae [an
example was the relatively common 'I'iwi, above].
Drepanids were in the colorful big book that I enjoyed as a child
(Austin 1961), which surveyed the 155 bird families then recognized. It
explained that they probably arrived 5 million years ago and "prospered
and diversified so rapidly that it hardly seems possible for such
variation to have developed from a single ancestral type in so short a
time)." Even then the book said that 9 of the 22 known species was
already extinct, and "another 8 or 10 survive precariously in small,
local populations." One of those is the remarkable Maui Parrotbill (left, in a equally remarkable photo by Michael Walther); only about 500 remain.
Today we know from genetic analysis that these
special birds are a small lineage deeply embedded with the Fringillidae
— see a separate page on the rest of this huge family:
and extinction of Hawaiian honeycreepers has continued. Although new
methods have "split" some taxa into multiple species — the list of
known species back 200 years is now 39 species (several recent splits
occurred in just 2015, per AOU Check-list) — only 17 are known to
currently be extant. Since Austin's book, eight more additional
Hawaiian honeycreepers have gone extinct, including Kauai 'Akialoa Hemignathus stejnegeri (not seen since 1969), 'O'u Psittirostra psittacea (lost about 1987), and Po'o-uli Melamprosops phaeosoma
(the last one died in captivity in Nov 2004; see Powell 2008). Only 17
honeycreepers remain alive today — or just 43% of species that are know
from the last 200 years — and about half of them are in decline. There
are multiple causes, including loss of habitat, avian malaria carried
by mosquitoes that have reached the top of all island except Maui and
Hawaii, introduced pigs and other exotics, hurricanes, and genetic
bottlenecks. The remote cloud forest in which rare drepanids still
exist are beautiful but forbidding places, such as Waikamoi Preserve on the slopes of Haleakala, Maui (below), access is by permit only with approved guides.
spent five days, scattered over 3 trips spanning 26 years, on hikes
deep inside prime habitat in Waikamoi Preserve, in search of its
rarities, particularly 'Akohekohe (formerly "Crested Honeycreeper") and
Maui Parrotbill. I've been drenched to the skin by pouring rain,
slipped in the mood, sprained my knee on steep slopes— and finally came
up with success in Mar 2015 with a vocalizing 'Akohekohe (left) and a Maui Parrotbill (right: missed my photo but got a nice view... so I bought the puppet! )
One learns interesting things when spending quality time in prime habitat. For example, young 'I'iwi
are orange-headed and pale-bellied, but the scarlet that will cover its
body starts to appear in the lesser wing coverts (above).
We've had the good fortune to visit the highlands of the Big Island of Hawaii with Jack Jeffrey,
the premier photographer of the Hawaiian honeycreepers (right, a 1989
photo of him showing us a flowering 'ohi'a tree). Jeffrey's research on
the 'Akiapola'au (below) revealed multiple strategies.
'Akiapola'au uses its heavy, straight lower mandible to hammer holes in
dead wood invested with beetle larvae, and then uses its longer, hooked
upper mandible to extract the grub. Another strategy is to drill a deep
hole into the cambium layer of an 'ohi'a tree, much as sapsuckers (a
woodpecker in the New World) do. Each 'well' drilled produces a few
drops of sap and attracts insects. The 'Akiapola'au, like sapsuckers,
feeds on both the sap and the insects when it revisits the 'wells'
was long a mystery how any landbirds could have reached Hawaii, out in
the middle of the Pacific Ocean. The islands themselves are volcanic
and did not emerge from the sea until 5.7 million years ago (mya), when
Kauai and Nihau formed. It was about then that the islands were
colonized by ancestors of today's Hawaiian honeyeaters. Before the most
recent genetic evidence, it had been hypothesized that Hawaiian
honeycreepers reached Hawaii from the New World. Initial theories
revolved around ancient nectar-feeders, like Bananaquit, but
osteological studies did not support that theory, and by the turn of
the new century Pratt (2005) wrote that "the close relationship of
Hawaiian honeycreepers and cardueline finches can no longer be
reasonably questioned." Pratt (2010) hypothesized that a siskin, or
Pine Grosbeak, or even a crossbill could be the ancestral colonizer.
on genetic studies, it is now known that all the Hawaiian honeycreepers
emerged from just that single colonization of Eurasian rosefinches (Carpodacus),
presumably from Asia (Lerner et al. 2009, Zuccon et al. 2012). All the
major lineages — the nectar feeders (like 'I'iwi), the 'warbler-like'
predators (like 'Amakihi), and the seed-eaters (including today's
Palila on Hawaii) — had diverged after Oahu emerged (4.0–3.7 mya) but
before the formation of Maui and adjacent islands (2.4–1.9 mya; Lerner
et al. 2009). This is illustrated above, using some of my photos.
evolved just 5 mya, Hawaiian honeycreepers are much too young a lineage
to be consider a "Family" among the many ancient lineages that are
currently supportable at that status. Almost all of today's bird
Families diverged 20 mya or more. The traditional "family" Drepanididae
was down-graded to a subfamily [Drepanidinae] but the early 21st
century (e.g., Pratt 2005). However, the Handbook of the Birds of the
World series — whose format is planned years in advance — did permit
Pratt (2010) to write and illustrate an entire account of the Hawaiian
Honeycreepers as if it were a full bird Family. With the most recent
genetics (Lerner et al. 2009, Zuccon et al. 2012) might be better
reduced to a "tribe" [Drepanidini]. I list it that way in the title
(above), but the AOU does not formally designate the honeycreepers as a
tribe. Currently (2015) the AOU simply lists the genera among this
radiation as members of a much broader Carduelinae subfamily, along
with rosefinches, Purple & House finches, crossbills, siskins, and
various types of Hawaiian honeycreepers evolved in a "single line"
evolution — as is usual in isolated radiations — with one exception.
The emergence of the "creepers" is an example of convergent evolution.
The "creepers" are the Hawaii Creeper (right) on the Big Island, 'Akikiki (or 'Kauai Creeper') Oreomystis bairdi, and Maui Alauahio (or "Maui Creeper") Paroreomyza montana.
These arose through two separate divergences from the main evolutionary
line near the base of the lineage, and then they evolved to resemble
each other in their barking-hunting habits through convergent
evolution; Reding et al. (2009), Lerner et al. (2011).
species that are doing the best in lowland forests — and are thus the
ones must likely to be seen by tourists — are a contrast in red and
green. The bright red male 'Apapane (below left) is
the most widespread species, occurring on all the major islands
(Hawaii, Maui, Oahu, Kauai) plus Lanai and Molokai. It has an amazing
vocal range and is the 'symphony' of native birdsong in good habitat.
The widespread native green bird is the traditional 'Amakihi — which is now split into three species: Hawaii 'Amakihi [below right — on Hawaii (this photo) and on Maui], and then two single-island endemics, Kauai 'Amakihi Chlorodrepanis stejnegeri and Oahu 'Amakihi Chlorodrepanis flava. Like 'Apapane, the Hawaii 'Amakihi frequents a wide range of elevations, from lowland forest to cloud forest.
have enjoyed efforts over 3 decades to search for most of the
still-living Hawaiian honeycreepers. I'm now missing only the two
northwest island species [Laysan Finch Telespiza cantans and Nihoa Finch T. ultima — these may resemble the original Carpodacus-like
ancestor most closely] and the 'Akikiki on Kauai. But it is very sad to
realize that a half-dozen have become extinct in my lifetime and that
others, like Hawaii 'Akepa (male right, taking
flight;), continue to decline. The 'Akepa is now restricted to small
areas of protected forest high on Mauna Kea, Hawaii.
threats to the survival of Hawaiian honeycreepers are many. Those
endemic to Kauai have collapsed as exotic mosquitoes reached the top of
the island, bringing avian malaria and other diseases to the entire
island population. Exotics such as pigs create wallows in which
mosquitoes thrive. Non-native ungulates eat favored plants. An
introduced snake (like the Brown Tree Snake that wiped out the avifauna
of Guam) could be deadly. Hurricanes could devastate protected areas —
all these threats discussed in detail in Pratt (2005). The scarcity and
specialization of some species can lead to genetic bottlenecks or
worse. The Po'o-uli on Maui might have been the most specialized of all
honeycreepers — specializing on native land snails in rain forest — and
its recent extinction may well be linked to the introduction of
non-native garlic snails that replaced native snails in prime areas,
leaving the bird without adequate prey. Hawaii (and Guam) may seem like
paradise to tourists, but it is surely "Paradise Lost" from an avian
Doug Pratt wrote (2005) that in his
lifetime he had "seen the Alaka'i [swamp on Kauai] go from a dawn
greeted exuberantly by songs of 'O'o'a'a, Kama'o, Puaiohi, Kauai
'Elepaio, 'O'u, 'Akeke'e, 'Akikiki, Kauai 'Amakihi, 'Anianiau, 'I'iwi
and 'Apapane to mornings nearly silent except for the alien voices of
shama, Hwamei, and bush-warbler in just [25 years]. With a little bit
of luck and few strategic research breakthroughs, most of the remaining
honeycreepers can probably hang on for decades. But if any one of the
potential disasters [discussed in his book] were to render today's high
elevation refugia inoperative, we can bid them all of wistful 'aloha'."
Photos: Michael Walther photographed Maui Parrotbill Pseudonestor xanthophrys in Waikamoi Preserve, Maui, on 8 June 2008. The uppermost photo of 'I'iwi Vestiaria coccinea, 'Akiapola'au Hemignathus wilsoni, Hawaii Creeper Loxops mana, and Hawaii Akepa Loxops coccineus
were taken on 2 Jan 2012 in Hakalau Forest NWR on the slopes of Mauna
Kea, Hawaii; the photo of Jack Jeffrey was taken there in August 1989.
Photos of Palila Loxioides bailleui and Hawaii 'Amakihi Chlorodrepanis virens were taken high on the slopes of Mauna Loa, Hawaii, in Aug 1989 and Jan 2012, respectively. The 'Akohekohe Palmeria dolei, the young 'I'iwi, and the habitat shot were taken at Waikamoi Preserve, on the slopes of Haleakala, Maui, in March 2015.
Photos © Michael Walther, as credited and used with permission, and © Don Roberson; all rights reserved.
Family book: Rating
Pratt, H. Douglas. 2005. The Hawaiian Honeycreepers (Drepanidinae). Oxford Univ. Press, New York, N. Y.
is quite a wonderful book, reasonably up-to-date and well written, and
lavishly illustrated with Doug Pratt's own meticulous paintings of each
species, both those that currently exists and those that are now
extinct. There are also a profusion of great Jack Jeffrey photographs
illustrating behaviors, plants, and associations — alas, these are
published in comparatively small size and in black-and-white. Pratt is
the world's authority on this set of amazing birds, so the text is
authoritative. The entire first half of the book (184 page) is
introductory material on almost any aspect of the group that might be
discussed, including their amazing evolutionary radiation. This Oxford
Press publication considered the honeycreeper radiation to be at
subfamily level. Pratt considers that the radiation "far exceeds the
degree of variation in any other bird group of equivalent taxonomic
rank," in part because the real contenders for that title – the vangas
of Madagascar and the birds-of-paradise of New Guinea – are
"continental rather than an archipelago situation."
My only quibbles now (in 2015) is the lapse of a
decade since publication. Obviously, many species accounts need
updating to current numbers and distribution. Po'o-uli is now extinct
(at Pratt's writing, in March 2004, there were 3 left in captivity).
Yet, with the proviso that information on populations needs to be
updated to the present, this remains a model of the modern bird-family
Further, Pratt himself has provided a significant
update in his Family account of the "Drepanididae" in the Handbook of the Birds of the World
series (Pratt 2010). All the species accounts were updated to
then-current populations levels; the Po'o-uli is considered extinct;
and the wonderful Jack Jeffrey photographs are here in full color!
Pratt's classic tome, now added with the HBW account, together form a
very excellent overview of these wonderful birds.
Austin, O.L., Jr. 1961. Birds of the World: a Survey of the 27 Orders and 155 Families. Golden Press, New York.
Collar, N.J., and I. Newton . 2010. Family Fringillidae (Finches), pp. 440 –617 in
Handbook of the Birds of the World (del Hoyo, J., A. Elliott & D.A.
Christie, eds). Vol. 15. Lynx Edicions, Barcelona, Spain.
H.R.L., M. Meyer, H.F. James, M. Hofreiter and R.C. Fleischer. 2011.
Multilocus resolution of phylogeny and timescale in the extant adaptive
radiation of Hawaiian honeycreepers. Current Biol. 21: 1–7.
D.M., Foster J.T., James H.F., Pratt H.D. and Fleischer R.C. 2009.
Convergent evolution of 'creepers' in the Hawaiian honeycreeper
radiation. Biol. Lett. 5: 221–224.
Powell, A. 2008.
The Race to Save the World's Rarest Bird: The Discovery and Death of
the Po'ouli. Stackpole Books, Mechanicsburg, PA.
Pratt, H.D. 2010. Family Drepanididae (Hawaiian Honeycreepers), pp. 618 –659 in
Handbook of the Birds of the World (del Hoyo, J., A. Elliott & D.A.
Christie, eds). Vol. 15. Lynx Edicions, Barcelona, Spain.
D., Prys-Jones, R., P.C. Rasmussen, and P.G.P. Ericson. 2012. The
phylogenetic relationships and generic limits of finches
(Fringillidae). Mol. Phylog. Evol. 62: 581–596.