Gurney’s Pitta (Hydrornis gurneyi): revise global status?

Gurney’s Pitta has a restricted distribution in extreme southern Myanmar (southern Tanintharyi Region, formerly Tenasserim) and perhaps adjacent Thailand; it also formerly occurred in the far south of Thailand in Khao Nor Chuchi (Krabi Province).

It is currently listed as Endangered under criterion A3c+4c, as a very rapid population reduction (50-79% in three generations) is anticipated to be occurring now and in the near future as a result of land clearance.

After its rediscovery in 1986 in Thailand, intensive surveys found it in at least five localities, although it disappeared from all but one of these, Khao Nor Chuchi. This population declined from 44-45 pairs in 1986 to just nine pairs in 1997. Detailed work in 2003-2007 recorded birds at 27 sites in Khao Nor Chuchi, and a further survey of the area in 2009 found 12 individuals responding to tape playback. Intensive surveys of the site in 2015 and 2016 recorded no individuals, until a single female was recorded in April 2016. It is now considered extinct (or at least functionally extinct) in the country.

Following its rediscovery in Myanmar, the population there was proposed to number 5,152-8,586 pairs (Eames et al. 2005), equating to c10,300-17,100 mature individuals, in 2000. This was based on densities of 3.6-6 pairs per km2 of suitable habitat extrapolated across the five largest remaining suitable forest patches, which covered a total area of 1,431 km2 in 2000.

Since then, the extent of suitable intact forest in Tanintharyi (between 7°N-12°N latitude, below 150 m above sea level and <10° slope), was found to have declined by 81%, from 3,395 to 656 km2, between 1999-2016 (Shwe et al. submitted).  During January-October 2016 Shwe et al. revisited 142 point locations out of 147 where the species was detected between 2003 to 2012 (Donald et al. 2014), and found it remaining in only in 41 of those locations (29%).

Assuming that a reduction in population has taken place in line with the reduction of total suitable habitat from 3,395 km2 in 2000 to 656 km2 in 2016, a revised 2016 population estimate could be in the order of 1,990-3,304 mature individuals, rounded to 2,000-3,300, if using the same methods as Eames et al. (2005). However, based on surveys in 2010-2016 it has been suggested that the population size may be considerably lower than this, at c.800-1,000 (T. D. Aung in litt. 2016).

This rapid loss of habitat and associated population reduction have led several species experts to raise the prospect that the species may once more qualify as Critically Endangered. At the very least, an update to the information in the Red List assessment and factsheet is now overdue. Here we attempt to gather the latest information and request further input as to whether a status change may be warranted.

 

Assessment against Red List Criteria

Criterion A – based on the estimates presented by Shwe et al. (submitted), the rate of habitat loss during three generations between 2003-2016 equated to 38.7%, with the rate of loss having slowed since initial extremely rapid loss between 1999-2003. Indeed, whilst forest loss continues, some major oil palm concessions in the region have recently been cancelled or postponed (P. Insua-Cao in litt. 2018). Nevertheless, the political change and social reform which has been ongoing since 2010 carries environmental risks including the potential for increased commercial access to previously restricted areas (Donald et al. 2015)

Note that Shwe et al. do not find any evidence that the species is being targeted by collectors or hunters, so this is not thought likely to be increasing the rate of decline above that driven by habitat loss.

Nevertheless, the index of population derived from the surveys in Shwe et al.  is worrying. That 142/147 previous confirmed locations were checked, and 101 had been cleared while the 41 that remained forest retained the species (i.e. where habitat remained the surveys detected the species) does indicate within this sample (which is pretty significant) that the population decline exceeded 70% during the three generation period between 2003-2016. This suggests that despite the apparent reduction in the rate of habitat loss, the rate of population decline still exceeds the threshold for listing as Endangered under criterion A. On this evidence however, it does not meet the threshold for listing as Critically Endangered under this criterion (which requires declines of 80% or more in three generations).

Criterion B – extent of occurrence, as measured according to IUCN guidelines based on a minimum convex polygon around the known range, is measured at 24,700 km2 and is therefore too large for the species to qualify for a threatened category based on this measure of range. However, the area of remaining suitable habitat was estimated at 656 km2 in 2016, suggesting that the area of occupancy is likely to be small. The potential category under this criterion depends how much of the remaining suitable habitat is occupied (and a resulting calculation of area of occupancy), and also on the degree of fragmentation and number of locations. Nevertheless, the highest possible category is Endangered since the area of occupancy is certainly greater than 10 km2.

Note that the difference between the BirdLife estimate of 24,700 km2 and Shwe et al.’s figure of 656 km2 is not a question of different modelling methods – we are measuring two different things. The first is the extent of occurrence (24,700 km2, based on a minimum convex polygon), while the latter is an estimate of extent of suitable habitat (which could approximate to a maximum possible area of occupancy).

Criterion C – The subpopulation structure is unclear, but there are almost certainly still >250 mature individuals in total and therefore the highest category the species could qualify for under this criterion is Endangered.

Criterion D – If we accept a population estimate of 800-1,000 individuals the species would qualify as Vulnerable under criterion D1.

Criterion E – To the best of our knowledge, no quantitative analysis of extinction risk has been conducted for this species, and so it cannot be assessed against this criterion.

In the absence of any further information Gurney’s Pitta appears to continue to warrant listing as Endangered, under criterion A2+3+4, as the population index suggests that declines likely fall within the range 50-79% in three generations. However we recognie that the species is certainly close to the threshold for listing as Critically Endangered and we welcome any further information to help refine population and trend estimates, as well as discussion of future threats and the likely future trend in the rate of loss of suitable habitat for the species.

Please note that this topic is not designed to be a general discussion about the ecology of the species, rather a discussion of the species’ Red List status. Therefore, please make sure your comments are relevant to the information that is sought, or about the species’ Red List status.

References

Donald, P. F.; Aratrakorn, S.; Thura Win Htun; Eames, J. C.; Htin Hla; Thunhikorn, S.; Sribua-Rod, K.; Pinyo Tinun; Sein Myo Aung; Sa Myo Zaw; Buchanan, G. M. 2009. Population, distribution, habitat use and breeding of Gurney’s Pitta Pitta gurneyi in Myanmar and Thailand. Bird Conservation International 19: 353-366.

Donald, P. F.; Hla, H.; Win, L.; Aung, T. D.; Moses, S.; Zaw, S. M.; Ag, T. T.; Oo, K. N.; Eames, J. C. 2014. The distribution and conservation of Gurney’s Pitta Pitta gurneyi in Myanmar. Bird Conservation International 24: 354-363.

Donald, P. F.; Round, P. D.; Aung, T. D. W.; Grindley, M.; Steinmetz, R.; Shwe, N. M.; Buchanan, G. M. 2015. Social reform and a growing crisis for southern Myanmar’s unique forests. Conservation Biology 29(5): 1485-1488.

Eames, J.C., Htin Hla, Leimgruber, P., Kelly, D.S., Sein Myo Aung, Moses, S. & U Saw Nyunt Tin. 2005. The rediscovery of Gurney’s Pitta Pitta gurneyi in Myanmar and an estimate of its population size based on remaining forest cover. Bird Conservation International 15: 3–26.

Erritzoe, J. & de Juana, E. (2018). Gurney’s Pitta (Hydrornis gurneyi). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/57560 on 15 February 2018).

Gurney’s Pitta Working Group. 2017. Gurney’s Pitta Strategic Plan and 2018 Annual Workplan: Goals and Actions to Protect the Tanintharyi Endemic Gurney’s Pitta and Its Habitat. Report 59 of the Tanintharyi Conservation Programme, a collaboration between the Myanmar Forest Department and Fauna & Flora International, FFI: Yangon.

Round, P. D. 2014. Gurney’s Pittas in Thailand – from rediscovery to extinction in just 28 years. Nat. Hist. Bull. Siam Soc. 60(1): 3–8.

Shwe, Nay Myo, Sukumal, N., Grindley, M., & Savini, T. submitted. Gurney’s Pitta on the brink of extinction!

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3 Responses to Gurney’s Pitta (Hydrornis gurneyi): revise global status?

  1. Rob Martin (BirdLife International) says:

    Preliminary proposals

    Based on available information, our preliminary proposal for the 2018 Red List would be to close this topic and retain the species as Endangered under criteria A2c + A3c +A4c for now, pending any further information regarding current trends.

    There is now a period for further comments until the final deadline in mid-July, after which the recommended categorisations will be put forward to IUCN.

    Please note that we will then only post final recommended categorisations on forum discussions where these differ from the initial proposal.

    The final 2018 Red List categories will be published on the BirdLife and IUCN websites in November, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  2. Christoph Zockler says:

    Gurney’s Pitta is continuing to decline rapidly and deserve to be uplisted to CR!
    The species is now effectively endemic to Myanmar after the last stronghold in Thailand is lost or almost lost (Round 2014). The remaining territory of occurrence is in the south Taninthary region of Myanmar only. Previously (2003) ranging from Taninthary NP south to Lenya and outside it is today virtually restricted to Lenya and Lenya Extension (Nga Wun). Although the remaining habitats are mainly located in the proposed Protected Areas Lenya and Nga Wun these sites are by no means securing the remaining population and are subject to constant internal political infighting, insurgency and power struggle preventing the establishment of a PA in the region. Slash burning, palm oil extension and rubber plantations continue to destroy habitats. Small scale burning is wide spread even in the Lenya NP and logging continue to poses additional threats to the remaining habitat in Lenya NP.

    Already in 2015 the total population was estimated based on local experts from BANCA and FFI, who have surveyed in the area for almost a decade, to be less than 500 individual. This is also confirmed by other surveyors such as Thet Zaw Naing (WCS), who surveyed the more northern part of the range between 2012 and 2016. These figures were not quoted in the summary above, although the report by Saw et al. (2015) has been made available to BL. The report listed several observations from within the Lenya NP, where the species has declined: ‘Compared to 2011 when 9 birds and 2012 when four birds were recorded near camp 1 just three birds depicts a continued decline, even though not always the same areas have been surveyed again, but survey methodology and effort were similar if not higher than in 2011 and 2012. It was not possible to confirm any of the sightings at locations with GP in 2011 again in 2015. In fact, map 3 in Figure 2 of the report (Saw et al. 2015) shows that one pair in 2011 has fallen victim expanding plantations.’ Meanwhile the situation has not improved and the total population might be even much lower, qualifying for CR on the degree of decline and the threshold of 500 individuals. Shwe (unpubl. ) also referred to a decline of almost 80%. His recent study using radio tagged birds also confirms that the species is much more restricted in habitat use than previously thought. Previous Extrapolations based on the wider habitat range might though have over-estimated the actual population size and range. Even, if there remain some uncertainty about the real figures, its seems that all agree that the decline and range restrictions have reached a critical point and urgent conservation actions are needed and activities so far have to seriously step up to really prevent the species from extinction. So far all efforts to protect the habitats and secure the last remaining sites Lenya and Nga Wun have failed, but new efforts by FFI to engage with village communities are to be applauded and hopefully can make some progress towards protecting these precious habitats that are also home to many other rare and threatened forest species.
    Christoph Zöckler and Nay Myo Shwe on behalf of FFI and BANCA

    add. Ref:
    Saw, M., Lay, W.& Zöckler C. (2015). Avifauna of the Lenya Forests: Report on 2015 Bird Surveys in Southern Tanintharyi Region, Myanmar, and a Compilation of Other Recent Published and Unpublished Records. Report No. 21 of the Tanintharyi Conservation Programme, Fauna & Flora International (FFI), the Myanmar Biodiversity and Nature Conservation Association (BANCA), ArcCona Consulting and the Myanmar Forest Department. FFI, Yangon.

  3. Thiri Dae We Aung says:

    Gurney’s Pitta, Pitta gurneyi, is a globally threatened species listed as Endangered by IUCN, and is the endemic to peninsular Thailand and Myanmar. It is confined to Sundaic lowland forest. The Sundaic lowland forests are one of the most threatened habitats on mainland South-east Asia, having been nearly extirpated from Thailand and the forests of southern Thanintharyi support a rich and notable biodiversity, beyond the presence of the Gurney’s pitta.
    A search for Gurney’s Pitta in Myanmar in 2003 discovered the species at four sites with a maximum of 10-12 pairs per site. This discovery of a population in Myanmar led to reducing its status from “Critically Endangered” to “Endangered” in 2007 (BirdLife International 2008). Surveys in 2007 and 2008 led to the development of a distribution model which estimated a population ranging from 9,300 to 35,000 territories (Donald, P. et al, 2009). Further surveys were carried out in 2010, 2011, 2012 to refine the distribution model through an iterative process, which used previous years’ results to define the following year’s survey sites. Through these surveys the species’ known altitudinal and latitudinal limits were extended to between 250m and 300m and 12.5°N respectively (Donald P. et al 2014). Further surveys were conducted in 2014 to 2016 by BANCA under contract to a landscape conservation project implemented by FFI, which is seeking to designate a substantial area of habitat of the Gurney’s Pitta as protected area. In 2018, BANCA conducted Gurney’s Pitta survey together with Village Conservation Group (VCG) in the area of Lenya forest. There was only one Gurney’s Pitta on 31 May 2018 (N 11.23418, E99.17002 in elevation 25m).

    Alarmingly, the habitat of Gurney’s Pitta has been declining rapidly in Myanmar due to the establishment of commercial plantations, particular for oil palm, but also rubber and other crops. Recent years have been seen a rapid decline in lowland forest cover, especially areas below an altitude of 150 m asl, which are converted to shifting cultivation for agriculture, the main crops being paddy, betel nut, coconut, rubber and dhani. Tapioca, rambutan, durian and mangosteen are also grown on a large scale. The most important source of cash income is betel nut in all villages. Some farmers are very interested in further expanding the betel nut plantations and dependence on one commodity as the primary source of income. Habitat is being lost to betel nut plantations, shifting cultivation and logging.

    Another threat of disturbance to Gurney’s pitta habitat comes from villages relocated into lowland valleys following rivers and trails opened for mining activities, particularly in Ngawun Forest Reserve.

    The Karen National Union (KNU) still controls much of the area, and where they do there is less hunting, following locally enforced laws on wildlife protection. Armed conflict between the KNU and Myanmar government has now ceased and the two sides are negotiating peace terms.
    That is why, Gurney’s Pitta should be up-listed to Critically endangered.

    Thiri Dae We Aung on the behalf of BANCA

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