Archived 2012-2013 topics: Silver Oriole (Oriolus mellianus): uplist to Endangered?

BirdLife species factsheet for Silver Oriole Silver Oriole Oriolus mellianus is found in China, Cambodia and Thailand. It is currently listed as Vulnerable under criterion C2a(ii), because it has a small population (<10,000 mature individuals), which is declining as a result of the loss and fragmentation of forest habitat in its breeding and wintering ranges. However, recent records of this species are rare and there is evidence of potential declines at historically important sites. It is recorded in summer from south-central Sichuan, southern Guizhou, northern Guangxi and northern Guangdong, China. Despite a massive increase in coverage of forest sites in these and adjacent areas and much higher levels of reporting than in the 1990s, no new populations have been found and populations at known sites have all declined since about 2001, such that a serious decline is apparent (R. Lewthwaite in litt. 2012). Whereas surveys in 1988 found it to be locally common in south-central  Sichuan, with a notable record of a flock of 40 birds, the highest count  there subsequently is 10 in June 2006 (COS 2007). One at Maolan, southern Guizhou in May 1984 remains the only summer record for the province. In Guangxi, there are no records since August 1998 when four individuals were found at Maoershan (Kadoorie Farm and Botanic Garden); the absence of records at Dayao Shan, a historically important site, is also striking. In Guangdong, peak day counts at Ba Bao Shan/Nanling NNR were 20 in 1998 and 10 (including nine males) in 2001; but the highest count since then is four in May 2007 (COS 2008, R. Lewthwaite in litt. 2012). There are also records in China of single birds on passage at Nankun Shan, southern Guangdong in August 1995, Weining, west Guizhou in September 1984 and Ningming, southwest Guanxi in October 1958; one at Ximeng, southern Yunnan on an unknown date was presumably also on passage (R. Lewthwaite in litt. 2012). Records of wintering birds in Thailand have also declined through the 1990s, although survey effort in the far north of the country has been limited. An increase in ornithological surveys in Cambodia has yielded recent records from the Cardamom Mountains and Bokor (Pilgrim and Pierce 2006) but, given the limited area of remaining habitat, it is likely to have a small and declining population here too. The global population of this species was previously estimated to number 2,500–9,999 mature individuals, but this has since been described as optimistic (R. Lewthwaite in litt. 2012). If the population is now estimated to be <2,500 mature individuals, is continuing to decline and ≥95% mature individuals are in one subpopulation, this species would warrant uplisting to Endangered under criterion C2a(ii) of the IUCN Red List. Further information is required on population size, trends and distribution of this species. References: China Ornithological Society (2007) China bird report 2006. China Ornithological Society: Beijing. China Ornithological Society (2008) China bird report 2007. China Ornithological Society: Beijing. Pilgrim, J. D. and Pierce, A. J. (2006) Some significant bird records from the Cardamom Mountains, Cambodia, including the first recent record of Silver Oriole Oriolus mellianus. Forktail 22: 125-127.

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5 Responses to Archived 2012-2013 topics: Silver Oriole (Oriolus mellianus): uplist to Endangered?

  1. What is th evidence for:

    “Cambodia … given the limited area of remaining habitat, it is likely to have a small and declining population here too”,

    with its implication that declines would be reflecting habitat change in Cambodia. Isn’t this a close relative of Maroon Oriole? Is there evidence or credible suggestion that wintering birds use habitat much more selectively than do Maroons? Looking at Maroon in Lao there must be abundant suitable habitat for Silver oriole in its wintering range, if the winter habitat use of the two are at all similar.

  2. Simon Mahood says:

    The data from the breeding areas suggest that uplisting is appropriate.

    I doubt that this decline has much to do with “…the limited area of remaining habitat” in Cambodia – the Cardamoms are subject to logging and clearance, but still represent one of the largest evergreen forest blocks in SE Asia. By this reasoning every forest dependent bird in SE Asia should be Threatened/Near Threatened. Like other frugivores, most of the very few records of Silver Orioles are from fruiting figs, which are not targeted by loggers.

  3. John Pilgrim says:

    Agreed with WD and SM that the text on wintering grounds is misleading – Pilgrim & Pierce detail very few records, and certainly nothing meaningful for interpretation on trends. Certainly, too little is known about wintering grounds of this species to draw conclusions… but there seem to be enough data about breeding grounds to uplist?

  4. Simon Dowell says:

    I haven’t recorded this species for several years in Sichuan, despite making annual visits over the last 10 years, usually in spring/summer. However, I believe there is still a small population in forests north of the Xining valley in Leibo county, Sichuan province where I recorded it in 1997 and subsequently in the early 2000s. Anecdotally I would say this species has declined, but have no data on rate of decline.

  5. Frederic Goes says:

    I fully agree with Simon in seeing a vast suitable wintering habitat for the species in the Cardamom Mountains of Cambodia.

    Silver Oriole
    A very rare winter visitor in semi-evergreen and hill evergreen forest, from 400m to 1,000m. Only known from one historical and four recent records in the southwest, from 12 December to 24 February. (details of records available on request)

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