 Sunbirds
are tiny jewels of the Old World tropics. Most are forest birds, but some,
like the Palestine Sunbird (left) occur in patches of vegetation
in the desert. Many species possess glittering iridescent colors. In this
feature, plus their small size and their nectar feeding behavior, they
recall the hummingbirds. Indeed, I tend to think of them as "Old Word hummers,"
although, of course, they are not related at all. Sunbirds will hover at
flowers, but they don't fly backwards (as do hummingbirds) and in some
respects they seem much simpler than hummingbirds. Ornithologists place
hummingbirds in over 100 genera, many of them monotypic, emphasizing the
wide diversity in bills, plumages and sizes. In contrast, sunbirds are
typically assigned to just three genera (Anthreptes, Nectarinia,
and Aethopyga), plus ten species of spiderhunters in the genus Arachnothera. |
 The
centers of distribution for sunbirds are tropical Africa and the forests
of southeast Asia, including the Greater Sundas and the Philippines. The
Purple-throated Sunbird (right) is just one of 14 species in the
Philippines, and six of them are endemic (Purple-throated is not one of
the endemics as it ranges widely on the Asian mainland). Endemism is high
in sunbirds, and quite a number are restricted to single islands in Lesser
Sundas or the Indian Ocean.
Charles Sibley continued his work on taxonomy until his death. I had the good fortune to assist him in bird distribution as it related to California, but I am most proud of my influence in convincing Sibley to resurrect the monotypic genus Dreptes for the Giant Sunbird of Såo Tomé, a single island endemic in the Gulf of Guinea. Based on personal observation, I found Dreptes thomensis not at all similar to Nectarinia sunbirds with which it had been merged; it actually recalled a woodcreeper of the Neotropics! This same approach (using the monotypic genus for this oddity) is followed by Christy & Clarke (1998), the major new field guide for Såo Tomé & Príncipe. |
 Sunbirds
have another parallel with hummingbirds, and this is that female sunbirds
are often plain in color and lack the male's iridescence. The example to
the left is the Seychelles Sunbird, an island endemic in the middle
of the Indian Ocean. Males possess a glittering blue throat gorget and
yellow pectoral tufts; females are quite plain. Yet, unlike hummingbirds,
sunbirds do not form leks or have other polygamous breeding behaviors.
Both sexes tend the young, while male hummingbirds (in general) do not.
Contrast the female's plain pattern with the glittering green back of this
male White-breasted Sunbird (below), feeding at a flower in South
Africa. |
 All
the sunbird photos so far have been members of the genus Nectarinia,
which often have long decurved bills used to probe open blossoms or to
pierce the bases of deep tubular corollas to reach otherwise inaccessible
nectars. In contrast, members of the genus Anthreptes have relatively
short, straight bills and usually glean foliage for insects, although they
do visit flowers and eat small fruits. Many are canopy species; an example
is a widespread African species, the Collared Sunbird (left). The
14 species of the genus Aethopyga are all in southeast Asia. They,
too, tend to be small and short-billed, and include some of the brightest
species in the world [e.g., Flaming Sunbird A. flagrans of the Philippines].
The ten spiderhunters are also restricted to the Orient; they tend to be
plain green, gray, or brown; possess long and very decurved bills; and
probe in the canopy for spiders and insects. I haven't photographed a spiderhunter
yet (although I've seen six species). Sibley & Monroe (1990) keep then
with the sunbirds, but place them at the end of the listing, next to the
berrypeckers of New Guinea.
|
 Sunbirds
can be at their most bewildering in central Africa, where one deals not
only with sexual dimorphism but regional differences. This Green-headed
Sunbird in Gabon (right) is actually BLUE-headed, not very green at
all, as is typical of the species in this part of its rather wide range
[there is another species, N. alinae, of montane forests of central
Africa which bears the name "Blue-headed Sunbird"].
At La Lopé Reserve in Gabon, I tried to sort out the 14 sunbirds
seen in this vicinity of central Africa. These quotes are taken from my
original field notes. This was my preliminary attempt to sort them out
not only by color patterns, but by habitat and niche within habitat (comments
in brackets were added later): "Male Collared [Anthreptes collaris]
is short-billed" and has "lime green back & head, with blackish band
on chest above yellow belly." [This was the commonest sunbird at forest
edge at La Lopé & M'Passa reserves.] Inside the forest, "Olive
[Nectarinia olivacea] is common in canopy flocks" where it is "large,
dull, long-billed" and "sometimes shows yellow [pectoral] tufts." [Probably
the commonest sunbird inside the forest at La Lopé & M'Passa
reserves.] "Bates' [Nectarinia batesi] is similar [to Olive] but
is smaller & shorter-billed in canopy flocks." [I was only satisfied
with a single bird at La Lopé in a canopy flock, but others had
it daily there.] "Fraser's (Scarlet-tufted) [Anthreptes fraseri]
is yellow below & looks warbler-like in canopy flocks -- fortunately
I did see red tufts on one of them." [This is an interior forest species.]
Blue-throated Brown Sunbird [Nectarinia cyanolaema] "is big &
rangy & long-billed & territorial on flowers in canopy of forest."
[Fairly common inside the forest]. "I've only seen a female Green-throated
[Nectarinia rubescens] (id'd by Patrice Christy) but it was medium
in all aspects, yellowish below with distinct streaks, and thin prominent
supercilium."
|
 Sunbirds
are at their least bewildering in Australia where there is only one species,
the Olive-backed Sunbird (left), restricted to the Aussie northeast.
In Australia and New Guinea, where this bird is common, the local name
is "Yellow-bellied Sunbird". New Guinea has but one other species (Black
Sunbird N. aspasia) but as the range of the Olive-backed moves west
it overlaps with more and more species until it reaches southeast Asia.
There, many other species have yellow bellies but no other males have olive
backs. Thus the name "Olive-backed" seems best from a world view perspective.
Sunbirds grace a wide variety of habitats in the Old World, from lowland
jungle to montane epiphytes, from flowering trees in open savanna or thornscrub
to mangrove specialists. Wherever they are found, they brighten the field
ornithologist's day.
|
| Photos: The male Palestine Sunbird
Nectarinia osea was photographed at Wadi Ammud, Israel, on
26 Oct 1981. The male Purple-throated Sunbird
N. sperata was at Balsahan, Palawan I., Philippines, on 21 Feb 1990.
The female Seychelles Sunbird N.
dussumieri was on Mahé I., Seychelles, in Nov 1992. The male
White-breasted Sunbird N. talatala
(called "White-bellied Sunbird" in many South Africa books) was at Kruger
Nat'l Park, South Africa, in July 1996. The Collared
Sunbird Anthreptes collaris was in the Sokeke forest,
Kenya, on 28 Nov 1981. The Green-headed Sunbird
N. verticalis was at La Lopé Reserve, Gabon, on 7 July 1996.
The male Olive-backed Sunbird N.
jugularis was on Lizard I., off ne. Queensland, Australia, on 8 Oct
1983. All photos © D. Roberson; all rights reserved.
Bibliographic note: There is no "family book" of which I'm aware yet published, but a book entitled "Sunbirds: a Guide to the Sunbirds, Flowerpeckers, Spiderhunters & Sugarbirds of the Word" by B. Cheke, O. Mann, and R. Allen is advertised for "spring 2000." Neither the Birds of Africa series (Brown et al. 1982) nor the Handbook of the Birds of World series has yet reached the Nectariniidae, but I look forward to each. Accordingly, my discussion here is more "thrown together" from bits and pieces I know than it is based upon serious literature. Literature cited: Brown, L. H., E. K. Urban, and K. Newman, eds. 1982. The Birds of Africa. Vol. 1: Ostriches to Birds of Prey. Academic Press, London & New York. |