Justification of Red List Category
This recently-split species qualifies as Critically Endangered because it is thought to have an extremely small and fragmented population, which is suspected to be in rapid to very rapid decline owing to on-going trapping pressure and the continued loss and degradation of suitable habitat. Research and informed conservation actions are now urgently needed to increase the chances of this species's survival.
The species appears to have an extremely small population, which is likely to number fewer than 250 mature individuals, with each subpopulation probably containing 50 mature individuals or fewer (van Balen et al. 2011). It has also been suggested that the total population probably does not exceed 100 individuals, but could number fewer than 50 individuals, as there may be only one or two dozen birds at each site where the species may still be extant (van Balen et al. 2013); however, surveys should be conducted to confirm whether this is the case.
The species underwent an extremely rapid decline during the late 1990s and first part of the 2000s as a result of the cagebird trade (van Balen et al. 2013). Prior to 1990, Javan Green Magpies were observed erratically and in small numbers in trade: none were recorded among 150,000 birds in a market in Jakarta in 1989 (Basuni and Setiyani 1989). By 1992, 25 of 39 market surveys recorded the species and 320 individuals were authorised for export between August and December 1992 (Nash 1993). Many individuals were reported trapped from Halimun in the 1990s, with bird trappers specialising in the species (van Balen et al. 2013). By 2011, numbers in the markets had crashed and prices had rocketed, suggesting that the stock had already depleted.
The rate of decline for the period between 1990 and 2010 is believed to have exceeded 80%, a decline driven almost exclusively by trapping (van Balen et al. 2013, Eaton et al. 2015). Since this point, actual rates of decline are likely lower than at the peak of exploitation, as the population is at such a low base. However, there is no disincentive for trappers not to catch this species should they be fortunate and find some. Trapping pressure remains high on Java, hence declines are believed to be ongoing at a rapid rate. On this basis, the population is suspected to have undergone a decline of 50-79% over the past three generations, and is expected to decline by 30-49% over the next three generations, owing primarily to trapping wherever it does remain.
Cissa thalassina is endemic to western Java, Indonesia, where there are few recent records and the species now appears to be very rare and localised (van Balen et al. 2013). Since 2001, the species has been recorded in only four protected areas: the National Parks of Mt Merapi, Mts Halimun-Salak and Mts Gede-Pangrango/Megamendung, and the South Parahyangan Protection Forest/Nature Reserve. In the 1990s, it was also recorded at Pembarisan Mts Protection Forest and Dieng Mts Protection Forest, with records earlier in the 20th century from Jampang Kulon (not protected), Mt Slamat Protection Forest and North Parahyangan Protection Forest/Nature Reserve (van Balen et al. 2013). The paucity of recent records implies that there are probably fewer than 250 mature individuals remaining, and the population is suspected to be in on-going decline.
The species inhabits mainly foothill and montane forest at 500-2,000 m, occasionally ranging into lowland areas, and may be seen in adjacent cultivated areas and at the edge of forests (van Balen et al. 2013 and references therein). Its diet compromises mostly invertebrates and small vertebrate prey. Breeding appears to take place throughout the year, with a preference for the months with highest rainfall (October-April). Clutch size is one or two (van Balen et al. 2013 and references therein).
Trapping for the songbird trade is the primary reason for the rapid declines observed in the species (van Balen et al. 2013, Eaton et al. 2015). Bird-catchers tend to specialise in particular species, suggesting that remnant populations are at increased risk of local extirpation through targeted trapping pressure (van Balen et al. 2013). This is supported by the sporadic, unpredictable appearance of occasional wild-caught individuals for sale in urban markets or roadside cages (Eaton et al. 2015).
Habitat loss likely caused a considerable decline over the course of the previous century and its results have enabled trappers to access the majority of the population. On Java, most forest below 1,000 m, and in some areas up to 1,500 m, has been cleared, which is suspected to have caused serious declines in this species’s population (van Balen et al. 2013). Habitat and loss and degradation is driven primarily by agricultural expansion, logging and mining.
Conservation and Research Actions Underway
The species may still persist in some or all of the four protected areas in which it has been seen since 2001, including three national parks. However, despite their designations, at least two of these national parks (Halimun-Salak NP and Mts Gede-Pangrango NP) suffer encroachment along their borders, resulting in habitat loss and degradation and trapping pressure, whilst Mt Merapi National Park has lost habitat to volcanic eruptions (van Balen et al. 2013). Eight surviving birds found in trade in 2011 were acquired and taken to the Cikananga Wildlife Centre, where breeding has been achieved regularly since the first success in 2013 (Richter 2013). With additional supplementation from further confiscations, the total captive population was 32 individuals in January 2016, divided between five organisations (Eaton et al. 2015). A breeding programme may be established; although experience of successful captive breeding of Cissa species is limited (Collar et al. 2012), the first chick ever bred in captivity hatched in March 2013.
Conservation and Research Actions Proposed
Conduct range-wide surveys in order to generate an improved population estimate. Closely monitor rates of habitat loss and degradation within the species's range. Protect the species by law, but manage awareness to avoid encouraging trapping (van Balen et al. 2013). Protect any remaining substantial fragments of suitable habitat not already covered by a designation. Increase and improve enforcement measures in protected areas within the species's range (see van Balen et al. 2013). Intensify awareness-raising activities within and around protected areas to reduce trapping pressure and encroachment, and amongst the wider public to discourage trade in the species (see van Balen et al. 2013). List the species in international trade management agreements.
31-33 cm. Distinctive and striking green magpie, with black mask, red bill and chestnut remiges and wing coverts; iris dark brown. The Bornean Green Magpie Cissa jefferyi is darker green with a pale iris.
Text account compilers
Wright, L, Martin, R., Taylor, J., Symes, A.
BirdLife International (2021) Species factsheet: Cissa thalassina. Downloaded from http://www.birdlife.org on 22/01/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 22/01/2021.