Online trade as a serious additional threat to the Critically Endangered silvery pigeon Columba argentina in Indonesia

The elusive and Critically Endangered silvery pigeon Columba argentina is only found on small offshore islands in western Indonesia and Malaysia. Historically, trade records have suggested that, in addition to habitat degradation and invasive predators, commercial exploitation could be a threat to the species. The current study confirms this to be the case, with a relatively high volume of silvery pigeons found offered for sale on social media platforms in Indonesia between October and December 2021. The trade numbers (at least 10 individuals) observed within this short period exceeded 20% of the global silvery pigeon population according to the latest Red List assessment, suggesting that actual population numbers may be larger than previously thought but also confirming that trade poses a considerable threat. Some of the recorded posts were in new areas within the species’ presumed range, further suggesting that the population may be slightly larger than hitherto assessed. The reported trade observations are reason for grave concern, particularly given the potential interest of international collectors which could further drive demand and increase prices. Due to the locations of the observed online trade we recommend timely field surveys to confirm the species’ presence and current status, particularly in the Riau-Lingga island group, as well as the development of a species conservation action plan to catalyse local and regional efforts to tackle the current illegal trade and work towards the regulation of international trade.


Distribution and status
The silvery pigeon Columba argentina is found in western Indonesia and Malaysia, exclusively on coastal islands and small archipelagos off Sumatra, Kalimantan, Peninsular Malaysia and Sarawak. The proximity of the species' suggested range to Singapore and Brunei makes occurrence in either country plausible but no current or historical records could be found (Collar et al. 2001;Yong 2009;BirdLife International 2019). Recent records of the species are only from islands off the west coast of Sumatra, including Simeulue, Nias and the Mentawai islands (Yong 2009;Eaton and Rossouw 2011;Svensson and Yong 2016;Rheindt et al. 2020;M. Iqbal pers. comm. 2021). There are no recent reports of sightings in other parts of the species' range, including the Riau-Lingga island group between Singapore and the south-east coast of Sumatra, and Natuna off West Kalimantan.
The silvery pigeon has been assessed as Critically Endangered by the IUCN Red List of Threatened Species (hereafter Red List) since 2000 (BirdLife International 2019). Until the late 2000s, the species was speculated to be extinct following a 70-year absence of definite records (Svensson and Yong 2016). The entire silvery pigeon population is currently estimated to consist of 1-49 individuals (BirdLife International 2019). However, considering possible misidentification of silvery pigeons during past population surveys in which the species may have been mistaken for the sympatric and superficially similar pied imperial pigeon Ducula bicolor, actual population numbers may be higher than previously thought. Recent surveys have already identified further remnant populations and made suggestions to revise the population estimates upwards (Rheindt et al. 2020). These surveys have mostly focused on islands off the west coast of Sumatra (Rheindt et al. 2020;M. Iqbal pers. comm. 2021) and future research on other islands may uncover more birds of the species. The total population is nevertheless anticipated to be small and at risk (BirdLife International 2019). Considering this and the fact that the population is distributed over a relatively large disjunct area, any threats, which include habitat degradation, trade, and the introduction of invasive predators, are a cause for high concern.
Legislation In 2018, the species received full protection in Indonesia under the Regulation of the Minister of Environment and Forestry No. P.20/MENLHK/SETJEN/KUM.1/6/2018, which it continues to have under the current No. P.106/MENLHK/SETJEN/KUM1.1/12/2018. Any harvest, trade, transportation (including export) or possession of wild-caught silvery pigeons is therefore punishable by law, with penalties of up to IDR100,000,000 (USD6,922 in December 2021) and/or up to five years imprisonment under the Act of the Republic of Indonesia (No.5) of 1990 concerning Conservation of Living Resources and their Ecosystems. Silvery pigeons are also nationally protected in Malaysia but are not known to be protected in other countries. The species is not listed in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), meaning that international trade is unregulated from a conservation perspective.

Historic trade
While trade and trapping records are scarce, the species has been previously reported in three instances. Nash (1993) recorded an unspecified number of silvery pigeons for sale in Indonesia and Singapore during surveys of bird markets across Southeast Asia between 1991 and 1993. Lee et al. (2009) reported on a photograph of two captive silvery pigeons in a Hong Kong SAR aviary (Lam 2000), but efforts to investigate the fate of these birds or track their origin proved futile (N. Collar pers. comm. 2021). In June 2016, two birds were reportedly trapped in Nias Selatan (South Nias Regency), constituting the first record of the species on Nias island (Svensson and Yong 2016). These two individuals were subsequently placed in an aviary in the Museum Pusaka Nias (Nias Heritage Museum) in Gunungsitoli. In 2019, SB witnessed another case of trapping, reportedly from the West Nias Regency, involving two injured birds which were also placed in the Museum Pusaka Nias by oversight of local authorities.

Current trade
On 2 December 2021, a post advertising two silvery pigeons, including photos and videos (see Fig. 1A), was placed in a closed Indonesian pigeon and dove hobbyist Facebook group. Within a single day, the post had received considerable positive attention with dozens of comments and likes from international users, including from Korea and Qatar, as well as local Indonesian group members. The original post did not mention prices or the location of the birds. After contacting the seller and enquiring about the birds it was found that they were in Padang, Sumatra, with their price being a moderate IDR900,000 (USD63 in December 2021) for the pair including their transport to Java. Padang is a regular port for ships from Siberut island where the species has previously been recorded (Yong 2009). This is not an unusual price asked for rare species sent to collectors in Java, but the asking price does not necessarily suggest a very high current demand (Putri et al. 2021). We also received a video from the seller showing the birds in relatively poor plumage, suggesting a recent capture and/or inappropriate holding conditions (see Fig. 1B).
Following the initial post, other images were posted in the same social media thread showing another captured silvery pigeon in Singkep island in the Riau islands (see Fig. 1D). On further investigation, yet another social media video was discovered that had been posted by a pet shop owner from Bintan island, also in the Riau islands, in October 2021. This video showed a caged group of pied imperial pigeons and green imperial pigeons Ducula aenea. Among these birds were at least seven silvery pigeons which were not mentioned by the seller, perhaps due to misidentification (see Fig. 1C, Suppl. material 1-4). From the two latter sources four videos were secured. These were posted between 6 October and 22 December 2021 and appear to have been recorded in three different locations (see Fig. 1C, E, Suppl. materials 1-4).
These recent observations of at least 10 silvery pigeons advertised for sale on social media platforms by three different Indonesian vendors within a short period of time between October and December 2021 are of grave concern. Considering the species' conservation status and population size, any trapping for trade must be considered a serious threat to the survival of the species (Lee et al. 2009;Eaton et al. 2015). In addition to depleting local populations, commercial illegal exploitation may disrupt the natural connectivity between subpopulations by eliminating individual "stepstone populations" between breeding colonies, which would further threaten these rare birds. If trade interests continue to intensify domestically and/or abroad, the risk trade poses will increase even further.
Although some limited historical trade, including internationally, has been reported (Lee et al. 2009), no successful captive breeding of silvery pigeons has ever been reported and there is currently no indication of captive populations existing outside of Indonesia. This is significant as some regions already have regulations in place that would prevent legal imports of the species, e.g., the US Lacey Act and the EU Import Ban on Wild Birds. However, once birds enter such regions through illegal border crossings, there is no legislation in place to curb commercial exploitation within those regions (Heinrich et al. 2021).

Recommendations
Organisations in Indonesia monitoring and investigating the trade in birds should be aware of silvery pigeons in trade and report observations to the relevant authorities such as the BKSDA Balai Konservasi Sumber Daya Alam (Indonesian Nature Conservation Agency) and other organisations monitoring the bird trade. Coordinated efforts to raise awareness of this issue should be prioritised.
The relevant authorities in Indonesia are encouraged to deter the illegal exploitation of silvery pigeons by taking strong action against anyone found poaching, trading, buying or illegally keeping silvery pigeons.
Given the species has been observed historically in international trade in Singapore and in a private collection in Hong Kong, and knowing that other protected species from Indonesia are smuggled and trafficked into other parts of the world for private collections and for commercial exploitation (Nijman and Stoner 2014;Heinrich et al. 2021), listing the silvery pigeon immediately in Appendix III of CITES, and proposing a listing in Appendix I, would help prevent further international trade in illegally sourced birds. A CITES Appendix III listing can be realised unilaterally by any range country and would allow for better documentation and monitoring of international trade in the period leading up to a possible CITES Appendix I listing which would prohibit any commercial trade in the species. Additionally, pied imperial pigeons should also be considered for a CITES II listing due to their resemblance to silvery pigeons (see Article II, paragraph 2b of the Convention (CITES 1973) and Annex 2b, paragraph A of Resolution Conf. 9.24 (Rev. CoP17) (CITES 2016)). In addition to immediate documentation and legal protection, a CITES listing would bring muchneeded attention to the conservation of the silvery pigeon and may also help promote the enforcement of existing national legislation to protect the species in Indonesia.
The apparently increasing online trade and international attention is a cause of great concern. It is feared that, when trade moves from being localised and opportunistic towards being specialised and targeted, there will be a plausible risk of the trade volume increasing. The illega online trade has proven to be resilient against law enforcement and current COVID-19 restrictions (Morcatty et al. 2021). We anticipate that prices within Indonesia will increase. We also anticipate that subsequent to the new trade activities documented here, silvery pigeons will be entering the international trade spheres imminently and are likely to appear in unregulated trade incidents involving specialised collectors in Asia, Europe, and Middle East. These regions can also make use of national or regional regulations such as Annex B or C listings under the EU Wildlife Trade Regulations to reduce any demand for this Critically Endangered species.
We recommend that plausible sites, particularly within the Riau-Lingga island group, be thoroughly surveyed for the presence of silvery pigeons and urge that a strategy in the form of a species action plan, involving all relevant stakeholders, be developed to support enforcement efforts where illegal trade in silvery pigeons is detected. Additionally, protocols for release or for placement in conservation breeding centres should be created. Organisations monitoring the bird trade should be vigilant and openly share reports on all observations of trade in this species with the relevant authorities, international conservation agencies and the IUCN SSC Pigeon and Dove Specialist Group.