SUGARBIRDS & ALLIES Promeropidae
- 5 species in Africa
- DR personal total: 1 species (20%), 1 photo'd
The Sugarbirds are a small family of African passerines. Traditionally there were just two species of sugarbirds (genus Promerops)
endemic to southern Africa, but molecular research suggests that three
more drab 'thrush-like' birds are closely related, so for now, they are
tentatively assigned here. It is possible that the three 'extra'
species currently assigned to Promeropidae should be in their own
family [Arcanatoridae]; more on that below.
Turning to the traditional two species of sugarbirds, perhaps the best known is Cape Sugarbird
(male [left] and female [below]). Males have dramatically long tails
that blow in the breeze; females also have long tails but nothing like
the very long tails of males. They have brush-tipped tongues to consume
nectar, and overall they resemble a very large and long-tailed sunbird.
Sugarbird is a resident endemic in the Fynbos biome, centered on the
Western Cape Province of South Africa, extending eastward into the
Eastern Cape Province. The range of the other sugarbird — Gurney's
Sugarbird Promerops gurneyi — extends from the mountains of the Eastern Cape Province, South Africa, to eastern Zimbabwe and adjacent Mozambique.
sugarbirds "live in close association with protea scrub, where they are
dependent on nectar for food. The genus Protea belongs in the
Protaeceae, a plant family virtually confined to the Southern
Hemisphere. Africa is home to well over 100 species of protea, 91 of
which grow naturally in southern Africa" (de Swardt 2008). The close
association of these sugarbird species to specific plants recalls the
close association of various hummingbirds with New World flowering
In the distant past, sugarbirds were thought
to be related to Australasian honeyeaters because they both fed on
nectar. Anatomical studies suggested a relationship to thrushes. Early
egg-white protein studies — the forerunner to the DNA-DNA hybridization
studies of Sibley & Ahlquist (1990) — found potential links to
either specialized starlings or to sunbirds. It is now known (e.g.,
Beresford et al. 2005) that sugarbirds are an ancient basal lineage
among the Passeroidae, with no close ties to any other major lineage in
research (Beresford et al. 2005, Johansson et al. 2008) found that
three disparate 'thrush-like' birds might be the sister group to the
traditional Sugarbirds. These species are
- Spot-throat Modulatrix stictigula of montane forests in the eastern arc mountains in north Malawi, north Mozambique, and eastern Tanzania.
- Dapple-throat Arcanator orostruthus, also of the eastern arc mountains from eastern Tanzania to north Mozambique [Usambara Mts., et al.]
- Gray-chested Kakamega [aka "Gray-chested Babbler"] Kakamega poliothorax of montane forests from Cameroon to western Uganda
three birds from sub-saharan Africa had been considered babblers, but
they aren't. At various times in the past, Spot-throat was thought to
be a thrush or a bulbul, Dapplethroat had been placed with chats or
bulbuls, and Kakamega had been considered a thrush. The apparently
belong in Passerida, next to the sugarbirds (Beresford et al. 2005).
the "Spot-throat" set should be placed in the Sugarbird family or in
their own family [Arcanatoridae] is a more difficult question. All the
primary research is now 8-10 years old and there has been no published
follow-up so far. It is not clearly known when this "Spot-throat" group
split from the Sugarbirds. Beresford et al. (2005) estimated the split
at between 28 and 39 million years ago [mean 28 mya]. In another
radiation within the Passerida, Fjeldså et al. (2010) estimated
that the Cinnamon Ibon Hypocryptadius cinnamomeus of montane
Mindanao, Philippines, split from the other Old World Sparrows about 31
mya. Yet, among all the global checklists, I am the only one to split
the Ibon as a family [Hypocryptadiidae]. Why is
this? Why, for example, does the IOC split Arcanatoridae as a family,
at around 28 mya divergence, and not Hypocryptadiidae, at around 31 mya
One problem may be that the methodology
used ten years ago to estimate age of divergence among related clades
is not as accurate as more recent methodologies. We need newer and
better evidence on the time of divergence on both the Spot-throat set
and on Cinnamon Ibon. Until that is accomplished, I remaining
conservative and just following Beresford et al. (2005), who place the
Spot-throat set among the Promeropidae. There is some doubt, though,
that they are even sister clades. Depending on which Bayesian consensus
tree one cites among the options set out in Johansson et al. (2008),
one can argue either side of that issue.
In short, we
need more certainty about the age of divergence of the proposed
"Arcanatoridae" and we need to better understand the full set of
species that might belong to that clade. Gray-chested Kakamega [aka
Gray-chested "Babbler"] was added to the clade in 2008. Are there more
species to be included?
Photos: The photos of Cape Sugarbird Promerops cafer come from vicinity of Walker Bay, South Africa, in March 2005.
All photos © Don Roberson; all rights reserved.
There is no "family book" but a nice introduction to the traditional
two species of sugarbirds, with some good photos, is in de Swardt
Literature cited:Family book:
Robert A. Cheke, Clive F. Mann, and Richard Allen. 2001.
Sunbirds: a Guide to the Sunbirds, Flowerpeckers, Spiderhunters, and Sugarbirds of the World. Christopher Helm, London.
is a very nicely done "family book" — actually, a three-family book —
in the Helm Identification Series. In standard format, the first half
of the book is color plates with facing text on plumage characters and
i.d. points, plus a good showing of subspecific variation. The second
half is the main text with range maps, detailed descriptions, full
discussion of subspecies, habitat, food, and breeding biology. All
these topics are given in short summary fashion, but provide a fine
overview. The two sugarbirds are a very small part of this book, and
they did not anticipate that the spot-throat et al. might be related,
but this was before molecular evidence was available. Overall the
paintings are crisp, clear, and useful, and the text a good summary on
P., F.K. Barker, P.G. Ryan, and T.M. Crowe. 2005. African endemics span
the tree of songbirds (Passeri): Molecular systematics of several
evolutionary `enigmas'. Proc. Royal Soc. B 272: 849–858.
R.A., C.F. Mann, and R. Allen. 2001. Sunbirds: a Guide to the Sunbirds,
Flowerpeckers, Spiderhunters, and Sugarbirds of the World. Helm
Identification Guide. C. Helm, London.
de Swardt, D.H. 2008. Family Promeropidae (Sugarbirds), pp. 486–497 in
Handbook of the Birds of the World (del Hoyo, J., A. Elliott & D.A.
Christie, eds). Vol. 13. Lynx Edicions, Barcelona, Spain.
Fjeldså, J., M. Irestedt, P.G.P. Ericson, and D. Zuccon. 2010. The Cinnamon Ibon Hypocryptadius cinnamomeus is a forest canopy sparrow. Ibis 152: 747–760.
U.S., J. Fjeldså, and C.K. Bowie. 2008. Phylogenetic
relationships within Passerida (Aves: Passeriformes): A review and a
new molecular phylogeny based on three nuclear intron markers. Mol.
Phylog. Evol. 48: 858–876.
Sibley, C.G., and J.E.
Ahlquist. 1990. Phylogeny and Classification of Birds: a Study of
Molecular Evolution. Yale Univ. Press, New Haven, CT.