JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.

SummaryIn order to determine whether Aratinga erythrogenys and Brotogeris pyrrhopterus can be formally classified as globally threatened species, their distribution, population sizes and ecological requirements are reviewed, together with national and international trade data from the last decade. The study concludes that, on current data, it is not possible to classify the two species formally, but there are strong indications that, at least locally, the populations of the two species are in decline. The causal factors appear to be a combination of high trade levels and habitat loss. It is essential that trade moratoria are implemented, pending the outcome of further research into the species' population sizes, ecology and breeding success, and further work to determine the extent of trade. Interim recommendations are given and it is proposed that future exploitation of the species should continue only when it has been determined that it has a sustainable basis.

summaryTropical forests are disappearing very rapidly, so there is often not time for thorough quantitative studies. It therefore becomes increasingly important to use rapid, reliable and informative methods which are also adjusted to tropical logistic constraints. In this paper we use data from seven dry and semi-humid temperate forest patches in Bolivia and three humid, temperate forests in Ecuador to estimate the efficiency, potential biases and the amount of information obtained by the 20-species list method, which we applied in a rapid assessment of avian species richness. Even when used without any standardizations, 20-species lists produce more data than simple species lists, particularly on the amount of survey effort, the order of species richness, the relative abundances of species and the α-diversity index. This approach precludes comparisons with lists from other sites. However, when applied with standardization of area, altitude and effort, the method is neither easier to use nor superior to point counts (based upon vocalizations) in combination with dawn chorus tape-recordings. In species-poor habitats, it is more appropriate to use lists of fewer species. The method is recommended due to its simplicity and the increased quantity of information produced, but it requires a reasonable amount of observer competence and is therefore unfit for use by people ignorant of local avifaunas.

No abstract

Megascops screech-owls are endemic to the New World and range from southern Canada to the southern cone of South America. The 22 currently recognized Megascops species occupy a wide range of habitats and elevations, from desert to humid montane forest, and from sea level to the Andean tree line. Species and subspecies diagnoses of Megascops are notoriously difficult due to subtle plumage differences among taxa with frequent plumage polymorphism. Using three mitochondrial and three nuclear genes we estimated a phylogeny for all but one Megascops species. Phylogenies were estimated with Maximum Likelihood and Bayesian Inference, and a Bayesian chronogram was reconstructed to assess the spatio-temporal context of Megascops diversification. Megascops was paraphyletic in the recovered tree topologies if the Puerto Rican endemic M. nudipes is included in the genus. However, the remaining taxa are monophyletic and form three major clades: (1) M. choliba, M. koepckeae, M. albogularis, M. clarkii, and M. trichopsis; (2) M. petersoni, M. marshalli, M. hoyi, M. ingens, and M. colombianus; and (3) M. asio, M. kennicottii, M. cooperi, M. barbarus, M. sanctaecatarinae, M. roboratus, M. watsonii, M. atricapilla, M. guatemalae, and M. vermiculatus. Megascops watsonii is paraphyletic with some individuals more closely related to M. atricapilla than to other members in that polytypic species. Also, allopatric populations of some other Megascops species were highly divergent, with levels of genetic differentiation greater than between some recognized species-pairs. Diversification within the genus is hypothesized to have taken place during the last 8 million years, with a likely origin in Central America. The genus later expanded over much of the Americas and then diversified via multiple dispersal events from the Andes into the Neotropical lowlands.