Asities are a small group of tiny specialized arboreal passerines found
only in Madagascar. They have traditionally been considered one of the
five families of birds found only in Madagascar, along with mesites, ground-rollers,
cuckoo-roller, and vangas. Recent biochemical evidence (Prum 1993, Moyle
et al. 2006) shows that they arose from the same lineage as today's broadbills
in Asia and Africa (see below).
There are four species of asity, each quite unique. A most prized and local species is Schlegel's Asity (left; photo of a pair © Lois Goldfrank). As can be seen in the photo, males have colorful blue wattles around the eye.
asities are difficult birds to observe and photograph in their rainforest
habitat. I have taken only a poor and partially blocked shot of a male
Asity (right) in the subcanopy. Perhaps you can make out its long,
thin, decurved bill (recalling sunbirds) and a hint of the bare yellow
wattles around its eye. [For great photos of all four asities, see Morris
& Hawkins (1998)].
Asities build ragged globular nests which are hung from the tips of branches. Nest construction is apparently only by females who first build a hollow sphere and then poke a hole in the side for an entrance. The male photographed in Ranamanfana Reserve was hanging around such a nest in a social group that included another male, a female, and an immature male. Later, in Perinet Reserve, a local guide took us to an old asity nest that was then being used as day-time sleeping quarters for an Eastern Mouse-Lemur Microcebus murinus smithii who sleepily poked its head out at our approach, gave us a quick look, and retreated back inside. Male Velvet Philepitta castanea and Sunbird Asities engage in wing-fluttering and gape-opening displays, but I have not witnessed those.
The two species which I did not see [Schlegel's Asity Philepitta
schlegeli and Yellow-bellied (or Small-billed) Asity Neodrepanis
hypoxantha] are scarce and local. A fine article on the identification
and status of the two species in the genus Neodrepanis is Hawkins
et al. (1997). The two Neodrepanis asities are nectarivorous. Schlegel's
Asity is more of a frugivore but it, like Neodrepanis, has
a brush-tipped tongue.
|Prum (1993) studied the phylogeny and biogeography of the asities and
broadbills and presented evidence that the asities were just a subfamily
of broadbills. Moyle et al. (2006) provided much DNA and other evidence
that sorted out their true relationships. As it turns out, the broadbill
stock arose perhaps 70 million years ago and for some time (perhaps 10
million years) evolved on India when it was still a huge isolated landmass
in the Indian Ocean. When India first crashed into the Eurasian continent
in the Paleocene, broadbills spread east (to southeast Asia) and west (to
Africa) and in that very warm period, likely north as well. As climate
cooled, presumably many species became extinct. Broadbills split into two
main branches about 55 million years ago. One of those branches included
the Eurylaimid Broadbills, the Sapayoa in the New World, and Asities. Sapayoa
became isolated at least 52 million years ago. At some point about 35-45
million years ago, the ancestral asity became isolated in Madagascar, where
the lineage has evolved ever since.
Thus all broadbills, asities, and the Sapayoa, have a common ancestor. One way to look at the evidence is to lump all of them in one huge broadbill assemblage. Another way of handling the exact same evidence is to create four families: the Calyptomenid Broadbills, the Eurylaimid Broadbills, the Asities, and the Sapayoa. To retain Asities as a family, one must make all those splits. Asities have traditionally been considered a family, and the Handbook of the Birds of the World series retained them as a separate family. Making the four-way split, and retaining Asities as a family, is consistent with the way the South American Checklist Committee (and this web site) handled a similar problem with the barbet/toucan assemblage. They either had to be one huge family (including toucans), or five separate families. SACC made the latter choice, and I very much approve. I now handle the broadbill/asity problem in the same way.
|Photos: The pair of Schlegel's Asity
schlegeli was photographed by Lois Goldfrank at Ampijoroa, Madagascar,
on 9 Nov 2006. The Sunbird Asity
Neodrepanis coruscans was photographed in the Ranamanfana
Reserve, eastern Madagascar, in Nov 1992.
In the standard format of recent books in the Pica Press series, color plates are found separately (with facing page captions) from the text, giving the feeling this is meant to be a field guide. The quality of the paintings is good, at least to my eye, given my minimal experience in the wild with these great birds but more experience in handling museum specimens. However, not even well-printed plates can capture the glistening colors of these wonderful birds, and the "field guide" poses are stiff and lifeless. The introductory text appears up-to-date, and the species accounts seemed well-researched. I found no obvious errors in the maps or text, but then I know comparatively little about these families. Despite giving the book high marks for apparent accuracy and attractive paintings within the limits of the genre, how I wish for a more "old-fashioned" book on these special families, with full-page spreads of each species in habitat and evocative detail of each species' discovery to science! The "field guide" approach to the art, and the plodding quality of the scientific text, just does not do justice to these marvelous creatures. Yet for what it is, the book is generally well-done and a welcome addition to the bookshelf.The Handbook of the World volume covering this family (Hawkins 2003) was, as expected, spectacular. But he also did not anticipate the findings about the true relationships in the broader broadbill group.
Other literature cited:
Hawkins, A.F.A. 2003. Family Philepittidae (Asities) in del Hoyo, J., A. Elliott, & D.A. Christie, eds., Handbook of the Birds of the World, Vol. 8, pp. 94-105. Lynx Edicions, Barcelona.TOP