The extinction-in-progress in the wild of the  Barusan Shama Copsychus (malabaricus) melanurus.

FORKTAIL 35 (2019): 30–37.

Summary:

Unsustainable wildlife trade across South-East Asia has contributed significantly to the extinction threats faced by many songbirds. The Barusan Shama Copsychus (malabaricus) melanurus, a highly-prized songster from the West Sumatran Archipelago,is one of the most threatened taxa in Asia’s songbird trade crisis, yet its predicament is often overlooked because some taxonomists treat it as a mere subspecies of the widespread White-rumped Shama C. malabaricus. Here, we provide the first modern comprehensive assessment of the on-the-ground status of Barusan Shamas across all major islands of the West Sumatran Archipelago based on visual and bioacoustic surveys, mist-netting activity, as well as community interviews covering approximately the last five years. A lack of ornithological field records across many years as well as documented drops in local capture rates indicate that increasing poaching pressure and market value have likely driven the Barusan Shama to extinction in the wild on all islands except Siberut. Even on Siberut, we document a drastic population crash and estimate impending extinction in the wild within perhaps five years in the absence of considerable changes in human behaviour. The decline and presumed extermination of some Barusan Shama island populations was so precipitous that it became evident even within our five-year monitoring period.  Although  our  field  efforts  and  those  of  others  must  continue,  this  bird’s  future  now  likely  hinges  on ex  situ  conservation  efforts. The Barusan Shama occurs in four described subspecies, each endemic to its own island group, further complicating conservation efforts. Although the nominate subspecies melanurus remains relatively common in captivity on Nias and Mentawai, the other three subspecies are currently known from captive populations of a magnitude of about 100 for hypolizus, a handful for opisthochrus and zero for mirabilis, casting doubt on whether ex situ efforts can be initiated fast enough to assure the survival of individual subspecies.

rheindt-biblio

Freigegeben in R

Behavioral evidence for song learning in the suboscine bellbirds (Procnias spp., Cotingidae)

The Wilson Journal of Ornithology 125 (1):1–14.

Abtract:

Why vocal learning has evolved in songbirds, parrots, and hummingbirds but not in other avian groups remains an unanswered question. The difficulty in providing an answer stems not only from the challenge of reconstructing the conditions that favored vocal learning among ancestors of these groups but also from our incomplete knowledge of extant birds. Here we provide multiple lines of evidence for a previously undocumented, evolutionarily independent origin of vocal learning among the suboscine passerines. Working with bellbirds (Procnias spp.), we show that (1) a captive-reared Bare-throated Bellbird (P. nudicollis) deprived of conspecific song not only developed abnormal conspecific songs but also learned the calls of a Chopi Blackbird (Gnorimopsar chopi) near which it was housed; (2) songs of Three-wattled Bellbirds (P. tricarunculata) occur in three geographically distinct dialects (from north to south: Nicaragua, Monteverde, and Talamanca); (3) Three-wattled Bellbirds at Monteverde, Costa Rica, are often bilingual, having learned the complete song repertoire of both the Monteverde and Talamanca dialects; (4) immature bellbirds have an extended period of song development, lasting the 6 years in which they are in subadult plumage; and (5) adult male Three-wattled Bellbirds continually relearn their songs, visiting each others’ song perches and adjusting their songs to track population-wide changes. Perhaps female preferences and strong sexual selection have favored vocal learning among bellbirds, and additional surveys for vocal learning among other lekking cotingas and other suboscines may reveal patterns that help determine the conditions that promote the evolution of vocal learning.

kroodsma-biblio

Freigegeben in K
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