Babax

Abstract: Obligate brood parasites only account for 1% of birds in the world, but utilize a great variety of avian species as hosts. Host switch theory predicts that parasites should shift from one host to another during the long-term arms race with hosts whenever such a shift would be facilitated by similarity in ecology and distribution. However, few studies have been conducted to address this puzzle because it is extremely difficult for humans to witness such host shifts during the long-lasting process of evolution. Here we adopted an alternative way to understand host switch behaviour of brood parasites by comparing egg colour variation, cuckoo egg mimicry and egg recognition capacity between two sympatric hosts, the Chinese babax (Babax lanceolatus) and the white-browed laughing thrush (Garrulax sannio), which are both parasitized by the large hawk-cuckoo (Cuculus sparverioides). The babax lays dark blue eggs whilst the laughing thrush lays white to pale blue eggs, and the large hawk-cuckoo parasitizes them by laying eggs that optimally match laughing thrush eggs according to avian vision. The laughing thrush possesses a greater capacity of egg recognition than the babax because it rejected all non-mimetic eggs while the babax is an intermediate rejecter. Furthermore, all the nest characteristics measured were similar in these two host species with no statistical significant differences. These results are consistent with the hypothesis that the white-browed laughing thrush is the original and main host species that has a longer coevolutionary interaction with the large hawk-cuckoo than the Chinese babax, which is a recent host acquired through a host switch by the hawk-cuckoo. We discuss the possible outcome of the interaction between the large hawk-cuckoo and these two host species, and emphasize that host switch behaviour in brood parasites is more likely an adaptation to expand the range of host species rather than a change in host species favoring an increase in reproductive output. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, ●●, ●●–●●.

Abstract: Department of Biology, Norwegian University of Scienceand Technology (NTNU), NO-7491 Trondheim, NorwayWe documented brood parasitism by the poorly studiedLarge Hawk-Cuckoo on a previously unknown host spe-cies, the Chinese Babax. Furthermore, we describe anew egg colour for the Large Hawk-Cuckoo. The parasit-ism rate of Chinese Babax nests over 4 years was 6.9%(11 of 159 nests), with significant temporal variation.The Large Hawk-Cuckoo laid immaculate white eggsthat appeared non-mimetic to the blue Babax eggs, animpression that was confirmed by avian visual modelling.Nevertheless, most Cuckoo eggs were accepted by thehost, suggesting that this host–parasite system may beevolutionarily recent.

Abstract: The Lower Risk/near threatened giant babax Babax waddelli is endemic to southern Tibet. The babaxes, living in groups of 3–8 individuals year-round, favoured edge habitats in forest regions where the group encounter rate during the breeding period was 0.35 groups h−1 and population density 0.04 birds ha−1, and in scrub regions they depended on the patches covered with higher bushes in which the group encounter rate and population density were 0.32 groups h−1 and 0.03 birds ha−1 respectively. The global population of the babaxes was estimated to be 120,000 birds. Reproductive and behavioural data were collected from scrub environments in a valley. Egg laying occurred between early May and early June, and clutch size ranged from 2 to 4 eggs, 2.9 on average. Incubation and fledging lasted 16–18 days respectively. Nesting success, measured as the proportion of clutches from which at least one young survives to fledging, was 75%. Some of the babax's nests were cooperatively attended by group members and the others only by both parents. The most preferable nesting areas were in dense bushes more than 1.8 m in height (mainly Rosa sericea, Berberis hemleyana, Cotoneaster divaricatus, Sibiraca angustata and Salix sclerophylla). Such strong dependence on high bushes leaves babaxes more susceptible to vegetation degradation. As a result, the increasing clearance of scrub habitats for firewood is a major current threat to the birds around the mid-Yalong Zangbo River, a region with the densest human population and most rapidly developing economy in Tibet. Their naturally low population density and strongly social grouping behaviour present extra risk factors that have to be taken into account. The importance of vegetation protection for long-term survival of this endemic species is highlighted.

Abstract: If it had not happened so many times in the last two and a half centuries, we would be embarrassed to admit that we created a new homonym, but such is the case. We (Hedges, Duellman & Heinicke 2008:108) proposed the generic name Isodactylus with the type species Eleutherodactylus elassodiscus Lynch (Anura: Strabomantidae) and included in the genus 13 species: Isodactylus adercus (Lynch), I. araiodactylus (Duellman & Pramuk), I. babax (Lynch), I. brunneus (Lynch), I. dolops (Lynch & Duellman), I. elassodiscus (Lynch), I. fallaciosus (Duellman), I. latens (Lynch), I. lucida (Cannatella), I. lundbergi (Lehr), I. mantipus (Boulenger), I. nigrovittatus (Andersson), and I. peraccai (Lynch).