Wednesday, 13 September 2017

Myna miracle needed for Indonesia’s threatened starlings

Posted by Tom Squires

Trade-driven extinction threatens a growing number of Indonesia’s songbirds, as unsustainable trapping to supply the cagebird trade continues seemingly unabated (Eaton et al. 2015). In 2016, 19 of Indonesia’s bird species, all bar one songbirds, were uplisted to a higher extinction risk category on the IUCN’s Red List for birds. Indonesia is home to ten Critically Endangered species on the brink of extinction, primarily because of trapping. All except the helmeted hornbill Rhinoplax vigil, a species long-exploited for its ‘ivory’ casque, are traded as songbirds. In response to the significant and growing threat of extinction facing Southeast Asia’s songbirds, the first Asian Songbird Trade Crisis Summit convened in 2015 to devise a conservation strategy to tackle the issue.
 

Manchester Metropolitan University (MMU) and Chester Zoo developed two research projects that will focus on Indonesia’s cagebird trade (see Stu’s previous post). Tom’s PhD aims to understand the ecology and management needs of some of Indonesia’s most endangered birds that are affected by trade on the Indonesian islands of Java and Bali. Here, he introduces his research project and outlines its objectives.

Bratang bird market, Surabaya, East Java - not only can you buy songbirds, parrots and owls, but also reptiles, amphibians and mammals. (Photo: Tom Squires)

Unsustainable trapping to supply Indonesia’s domestic cagebird trade involves millions of wild birds annually and threatens an ever-increasing number of species with extinction (Eaton et al. 2015). Seven of Indonesia’s Critically Endangered songbirds affected by trade are endemic to Java and Bali. Java, the most populous of the Indonesian islands (145 million inhabitants in 2015), lies at the heart of Indonesia’s cagebird trade, due to its deep-rooted songbird-keeping culture and the rising popularity of songbird competitions.

Black-winged myna populations have plummeted in response to increased trade demand. They are a next best replacement for the coveted, but hard to obtain, Bali myna. (Photo: Jonathan Beilby)

My project will include ecological studies of two of Indonesia’s most endangered birds, the black-winged myna Acridotheres melanopterus and Bali myna Leucopsar rothschildi, both members of the starling family. The black-winged myna was formerly quite common in the lowlands of Java and northwest Bali, but in recent decades has become almost impossible to find, except in local bird markets (see Nijman et al. 2017). Nevertheless, small populations persist at up to ten locations, and current actions – including a reintroduction at Taman Safari in West Java and a captive breeding programme to enable further releases – provide hope of a species recovery. I will carry out fieldwork at one of the most important remaining sites for the species, Baluran National Park in East Java, to estimate population size and study aspects of black-winged myna ecology. Fieldwork will also be replicated at other sites where black-winged myna are known to be present. The information gleaned will help guide in situ conservation efforts for the species.

Bekol savannah at Baluran National Park supports one of the largest remaining populations of black-winged myna. (Photo: Tom Squires)
Bali myna: king of cagebirds, this species may have been trapped to extinction in 2006  (Photo: Jonathan Beilby)

The iconic Bali myna, Bali’s faunal emblem and its only endemic bird, is highly coveted as a cagebird for its song, pristine white plumage that has symbolic associations with peace, and rarity. Consequently, the Bali myna has suffered a steady population decline since the 1960s and 70s, when its popularity as a cagebird reached its pinnacle, with hundreds being exported overseas annually. Habitat conversion, from monsoon forest to agricultural land, has certainly contributed to this decline, but in part only because it made birds more accessible to poachers. Despite being listed on Appendix 1 of CITES (prohibiting international trade) and protected under Indonesian law since 1970, numbers in the wild continued to diminish until a possible extinction in 2006 (Jepson 2015). Since then, conservation efforts and releases of Bali myna at various locations on Bali and its neighbouring island of Nusa Penida mean that they can still be seen in the wild, albeit in small numbers.
A released Bali Myna seen using one of the artificial nest-boxes provided (Photo: Tom Squires)

The number of released Bali myna in the wild probably remains at around 100, suggesting that conservation efforts have been hampered. It is unclear what the outcome of all releases of birds has been, but is highly probable that birds have suffered continued illegal poaching for the cagebird trade, and birds may have also failed to reproduce. I plan to initiate a radio tracking study to follow the fortunes of reintroduced Bali myna closely at release sites. Daily monitoring of released birds, for the lifetime of the radio tags, will be carried out to collect data on post-release dispersal, mortality, feeding behaviour and habitat-use. Additionally, birds will be colour ringed to facilitate a long-term monitoring project of the releases, hopefully with collaboration from Indonesian partners. This post-release study is urgently required to establish patterns of behaviour following release and ultimately optimise conditions for future releases.

The blue-winged leafbird Chloropsis moluccensis may grow in popularity similar to its cousin, the greater green leafbird C.sonnerati, whilst the Javan nominate of crested jay (or jay shrike) Platylophus galericulatus is already being substituted by the Sumatran and Bornean subspecies coronatus (in photo; Photos: Jonathan Beilby)

Indonesia’s cagebird markets are dynamic and trends of popularity in groups of species can change quickly. Some species, such as the greater green leafbird Chloropsis sonnerati, are beginning to exhibit worrying population trajectories that could go on to replicate historic declines of Critically Endangered species like the Bali myna (Eaton et al. 2015). Thus, an objective of this project is to investigate broad patterns of change in the range of species affected by trade. To achieve this, I will build species distribution models (SDMs) for a suite of traded species. Locations of species occurrence, obtained from citizen science datasets such as eBird, will be related to environmental (e.g. land-use and climate) and trade-pressure related variables (e.g. human population density and distance to bird markets), to determine which factors best predict species distribution. It is hoped that results will indicate where species are exposed to high levels of trapping pressure, as well as areas where trapping pressure is relatively low; these could be the best areas within which to search for ‘sanctuaries’ for future species reintroductions. This will serve as a predictive tool to pre-empt areas of concern for species that begin to emerge in large numbers at bird markets.

Living rent-free: the endemic Java sparrow is clinging on in unlikely places, like at this hotel in Yogyakarta city centre, Java. (Photo: Tom Squires)


An interesting feature of the distribution of some species threatened by trade is that they appear to thrive in some unusual locations, either because they have so many visitors that trappers cannot covertly take birds, or security arrangements exist which indirectly protect birds. A couple of examples include the Java sparrow Lonchura oryzivora that I saw in Yogyakarta, roosting under the eaves of an exclusive hotel, and the Bali myna that were out in the open near a temple and very conspicuous to visitors of the site. I will review as many of these sites as possible to understand why species persist in these locations but are missing from others, and discover what is happening in terms of population dynamics. I will carry out bird surveys and collect environmental and socio-economic data in and around the sites supporting target species including Java sparrow, Javan myna Acridotheres javanicus and ruby-throated bulbul Pycnonotus dispar. Assessing these sites and searching for sites with similar attributes could help find locations for future species reintroductions, and possibly even new populations of threatened species. This work will certainly help document the biodiversity value of such sites and may highlight a need to formalise their protection wherever possible.

This project is joint-funded by MMU and Chester Zoo and is a collaboration between these organisations, Burung Indonesia (Indonesia’s BirdLife partner), and Universitas Indonesia. Tom’s supervisors are Stu, Nigel Collar (BirdLife International), Andrew Owen (Chester Zoo), Christian Devenish (MMU), Simon Tollington (Chester Zoo), Huw Lloyd (MMU) and Nurul Winarni (Universitas Indonesia).


References

Collar, N.J. & Butchart, H.M. (2014) Conservation breeding and avian diversity: chances and challenges. International Zoo Yearbook 48: 7-28

Eaton, J.A., Shepherd, C.R., Rheindt, F.E., Harris, J.B.C., van Balen, S. (B.), Wilcove, D.S. and Collar, N.J. (2015) Trade-driven extinctions and near-extinctions of avian taxa in Sundaic Indonesia. Forktail 31: 1-12

Jepson, P.R. (2016) Saving a species threatened by trade: a network study of Bali starling Leucopsar rothschildi conservation. Oryx 50: 480-488

Lee, J.G.H., Chng, S.C.L. and Eaton, J.A. (eds.) (2016) Conservation strategy for Southeast Asian songbirds in trade. Recommendations from the first Asian Songbird Trade Crisis Summit 2015 held in Jurong Bird Park, Singapore, 27-29 September 2015

Nijman, V., Sari, S.L., Siriwat, P., Sigaud, M. & Nekaris, K.A-I. (2017) Records of four Critically Endangered songbirds in the markets of Java suggest domestic trade is a major impediment to their conservation. BirdingASIA 27: 20-25.

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