Archived 2017 topics: Forest Owlet (Heteroglaux blewetti): downlist from Critically Endangered to Endangered?

Forest Owlet, Heteroglaux blewetti, is currently considered Critically Endangered under criterion C2a(i) on the basis that it has a very small population which is likely declining as a result of habitat loss, and consists of multiple very small subpopulations (BirdLife International 2017). Forest Owlet is endemic to central India and was only known from 7 specimens collected in the 19th Century until its rediscovery in 1997 (G. Jathar in litt. 2012). Surveys since then have found the species in Maharashtra and Madhya Pradesh, and it has been recently reported from Gujarat for the first time (see Kasambe et al. 2015, Patel et al. 2015).

The population size is currently listed as 50-249 mature individuals based on the number of records from known sites. However, as more surveys are conducted more individuals are being found at more sites, e.g. its recent reporting from Gujarat (Patel et al. 2015) and there were 53 sightings from new localities during surveys in Melghat Tiger Reserve, although only 19 were found from known localities there (Kasambe et al. 2015). Given the increasing number of reports of this species it is likely that the global population size is likely to be >250 mature individuals, and so it is suggested that it be placed in the range of 250-999 mature individuals. Melghat Tiger Reserve is considered the main site for this species and the population there has been thought to be c.100 individuals (Kasambe et al. 2005); very roughly equivalent to 67 mature individuals.

The major threat to this species is forest loss and degradation as a result of illegal logging and human encroachment, as well as forest fires and minor irrigation dams (Ishtiaq et al. 2002, Chavan and Rithe 2009). Native raptors may take this species, which can limit productivity, and the species may face competition for limited nesting holes (Jathar 2003, Ishtiaq and Rahmani 2005). In addition to this, the species may be hunted and its eggs collected for use in local customs (Jathar 2003); and pesticides and rodenticides may be having an effect on this species (Jathar 2003). Therefore, the population is likely in decline.

Given that with our expanding knowledge of this species it may be considered that the population size may be >250 mature individuals, and the largest subpopulation is now thought to contain >50 mature individuals, Forest Owlet no longer meets the threshold for Critically Endangered under criterion C2a(i). However, it likely still meets the threshold for listing as Endangered under the same criterion (a continuing decline with a global population size of <2,500 mature individuals, with no subpopulation containing >250 mature individuals). Therefore, it is proposed that this species be downlisted and listed as Endangered under criterion C2a(i).

We welcome any further information, and comments on this proposed downlisting.

 

References

BirdLife International (2017) Species factsheet: Heteroglaux blewitti. Downloaded from http://www.birdlife.org on 05/01/2017.

Chavan, R. A.; Rithe, K. D. 2009. Occurrence and breeding record of the Forest Owlet Heteroglaux blewitti from Yawal Wildlife Sanctuary, Maharashtra, India. Journal of the Bombay Natural History Society 106(2): 207-208.

Ishtiaq, F.; Rahmani, A. R. 2005. The Forest Owlet Heteroglaux blewitti: vocalization, breeding biology and conservation. Ibis 147: 197-205.

Ishtiaq, F.; Rahmani, A. R.; Rasmussen, P. C. 2002. Ecology and behaviour of the Forest Owlet (Athene blewetti). Pp. 80-86 in Newton, I., Kavanagh, R., Olsen, J. and Taylor, I., eds. Ecology and conservation of owls. Collingwood, Australia: CSIRO Publishing.

Jathar, G. 2003. Saving the mysterious Forest Owlet. Mistnet 4(3 & 4): 9-10.

Kasambe, R.; Wadatkar, J.; Bhusum, N.S.; Kasdekar, F. 2005. Forest Owlets Heteroglaux blewitti in Melghat Tiger Reserve, Distt. Amravati, Maharashtra. Newsletter for Birdwatchers 45: 38-40.

Kasambe, R.; Wadatkar, J. S.; Wagh, G. A.; Dudhe, N.S. 2015. Status survey and conservation of the critically endangered Forest Owlet (Heteroglaux blewitti) in the Satpudas. BNHS. Report submitted to BirdLife International.

Patel, J.R.; Patel, S. B.; Rathor, S.C.; Patel, J. A.; Patel, P. B.; Vasava, A.G. 2015. New distribution record of the Forest Owlet Heteroglaux blewitti (Aves: Strigiformes: Stigidae) in Purna Wildlife Sanctuary, Gujarat, India. J. Threatened Taxa 7(12): 7940-7944.

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9 Responses to Archived 2017 topics: Forest Owlet (Heteroglaux blewetti): downlist from Critically Endangered to Endangered?

  1. The additional findings from Maharashtra and Gujarat in India were indeed exciting, however there has been no downscaling of any of the threats noted for this species. The major threats to this species which are:
    >>forest loss and degradation as a result of illegal logging and human encroachment
    >>forest fires
    >>minor irrigation dams
    >>pesticides and rodenticides
    all continue to exist.
    Further the good numbers observed in Melghat Tiger Reserve is a good finding, but existence of Tiger Reserves in the distribution area for this species are not many. ‘Tiger Reserves’ are perhaps most stringently protected habitats in the country today, however with increasing human populations both inside and outside them will surely impact upon the biodiversity in the future. Tadoba and surrounding areas, once again a ‘Tiger Reserve’, has revealed this species. Today we have considerations on possible submergence of certain parts of the Panna Tiger Reserve and certain development projects which are likely to impact on the habitat of this species, for example the widening of state/national highways for better connectivity in Central India (Kanha-Pench Corridor), severe drought conditions being experienced in this part of the country which will in all probability make a more pronounced anthropogenic pressures, etc. Distribution of the Forest Owlet (Heteroglaux blewetti) outside protected areas may not have a sustaining future in view of growing loss of biodiversity, in fact at quite a rapid pace, from them. Western and South Western Odisha, which was also a known distribution, has continued failed to reveal any presence of the Forest Owlet.
    So accordingly in our view the status for this species needs to be retained as ‘Critically Endangered’ for some years more, till we are able to understand and analyse the various adversarial impacts being experienced/likely to be experienced in the coming years.

    • Prachi Mehta says:

      Recent reports of Forest Owlet from newer locations may indicate its presence over a larger landscape and therefore its proposed eligibility for downlisting to the endangered status. However, this assessment will benefot from reliable information on the habitat and population size of Forest Owlet from all the known sites.

      We have been studying the ecology of Forest Owlet in the Reserved Forests of Madhya Pradesh (MP) since 2012. We have completed the field work and are in the process of analyzing the data so at this point of time may not be able to provide specifics , but would like to state that the Forest Owlet population in our study site is under considerable pressure from tree cutting and this may be impacting its breeding success. Also, recently we have completed a survey of Forest Owlet in North-western Maharashtra. The findings of this survey is under review for publication. The populations in the surveyed sites are small and the habitat is also under pressure due to tree cutting and encroachment on forest land. It is with this concern we suggest that the proposed downlisting should seek fresh inputs on habitat conditions from working groups in different areas. Some time field data may take time to process so till then downlisting can be deferred.

  2. Praveen J says:

    Reposting – as my previous comment did not appear.
    More additional sites in Gujarat & Maharashtra
    http://indianbirds.in/pdfs/IB_13_3_PatelETAL_ForestOwlet.pdf
    http://indianbirds.in/pdfs/IB_13_3_RahaETAL_ForestOwlet.pdf

  3. Girish Jathar says:

    Background:
    Forest Owlet, Heteroglaux blewetti, is currently considered Critically Endangered under criterion C2a(i) on the basis that it has a very small population which is likely declining as a result of habitat loss, and consists of multiple very small subpopulations (BirdLife International 2017). Forest Owlet is endemic to India and was only known from 7 specimens collected in the 19th Century until its rediscovery in 1997 (Rasmussen and Collar 1998). Surveys since then have found the species in Northern Western Ghats in Maharashtra (Laad and Dhagale 2014,Patel et al. 2017) and Madhya Pradesh (Mehta el al. 2007, 2013-14,), and it has been recently reported from Gujarat for the first time (Patel et al. 2017). So far the Forest Owlet is reported from 13 different locations in Gujarat, Maharashtra and Madhya Pradesh. However, the areas of Chattisgarh, Odisha and Telangana are yet to be surveyed systematically.
    Spatial distribution of the Forest Owlet
    The spatial distribution of the Forest Owlet is approximately 3. 48,971.8 km2 which is based on the historical and present occurrence locations (Map 1.)

    The recent publication by Jathar et al. (2015) proposes 3 models which suggest possible ecological niche of the species. The first model (5 layer) identifies 70,697 km2 as suitable habitat for the species. The second model (10 layers) identifies 5,625 km2 and third model (21 layer) identifies 4,315 km2 as suitable habitat. Therefore, the suggested extent of occurrence i.e. 550 km2 (Birdlife 2017) requires a revision.
    Similarly, based on Jathar et. al. (2015) analysis of the occurrence data, Minimum Convex Polygon (MCP) was calculated for 3 clusters. The analysis suggests that the total area of three clusters sums to 5763 km2. The clusters are as follows Melghat-Burhanpur Cluster (MCP) – 3,323 km2, Toranmal-Taloda Cluster (MCP) – 85.5 km2 and Tansa-Purna Cluster (MCP) – 2,355 km2. This suggests that the actual area occupied by the species is much more than what it was assumed previously.
    The most important aspect which requires attention is occurrence of species in Chattisgarh and Odisha states (type locality and areas near Valenitine Ball’s specimen). Only two surveys have been carried out in these areas which did not yield any results (Mehta et. al. 2007). These surveys were confined to 204 point locations across 102 km in Chattisgarh and 60 point locations across 30 km in Orissa. However, new surveys in the area following results of Jathar et al. (2015) may result in locations of unknown populations of the Forest Owlet in these two states.

    Estimate of numbers:
    So far the highest numbers of birds were known from Melghat Tiger Reserve (Jathar and Rahmani 2004, Kasambe et al. 2015). However, recent publication by Patel (2016) suggests 184 individuals in Purna Widlife Sanctuary and 42 individuals from Tansa Wildlife Sanctuary (Laad et al. 2016). This indicates that the criteria ‘C’ – (Small population size and decline) suits more for the Endangered rather than Critically Endangered. The Table 1 indicates number of Forest Owlets at one location since 2000. The Forest Owlet is now known from 13 locations across central and western India. The number of mature individuals according to the published literature since 2000 is certainly more than 150. Areas of eastern Madhya Pradesh, Chattisgarh and Northern Odisha are yet to be surveyed systematically. Surveys in these areas may result in addition into the number of mature Forest Owlets.

    Conclusion:
    The new insights into the spatial distribution and number of mature individuals suggests for revision of the status of the Forest Owlet. The number of mature individuals have seen decline in Toranmal and Taloda Reserve Forests. However, there is no indication of decline in numbers in Melghat Tiger Reserve, Burhanpur and Khandawa region. This indicates that the population is more or less stable in these region over last one decade.
    New populations in Western Ghats and Gujarat indicates, 36 mature individuals in Tansa Wildlife Sanctuary and 184 in and around Purna Widlife Sanctuary. Similarly, a new population has been observed near Tansa Wildlife Sanctuary (Raha et al. 2017). However, exact number of the birds cannot be assumed at this moment. This evidence is rather encouraging in terms of conservation of the species.
    These evidences justify down listing of the Forest Owlet from Critically Endangered to Endangered.

    References
    BirdLife International (2017) Species factsheet: Heteroglaux blewitti. Downloaded from http://www.birdlife.org on 18/07/2017.

    Jathar, G., Patil, D., Kalra, M., De Silva, T., Peterson, A., Irfan-Ullah, M., Rahmani, A., Mehta, P. and Kulkarni, J. (2015) Mapping The Potential Distribution of the Critically Endangered Forest Owlet Heteroglaux blewitti in India. Journal of the Bombay Natural History Society, 112(2): 55-64.

    Laad, S., Dagale, R and Jathar, G. (2016) Northern Western Ghats: Forest Owlet’s new abode. MISTNET Vol.17 ( 2 & 3): 2-6.

    Mehta, P., J. Kulkarni, D.N. Patil, P. Kolte & P. Khatavkar (2007): A Survey of Critically Endangered Forest Owlet (Heteroglaux blewitti) in Central India: Final Report Envirosearch, Pune. Pp. 60.

    Mehta, P., Kulkarni, J. and Sajan, S. (2013) A study on Population, Demography and Ecology of Critically Endangered Forest Owlet Heteroglaux blewitti in Madhya Pradesh. Progress Report. Pp- 9.

    Mehta, P., Kulkarni, J. and Sajan, S. (2014) A study on Population, Demography and Ecology of Critically Endangered Forest Owlet Heteroglaux blewitti in Madhya Pradesh. Progress Report. Pp- 10.

    Mehta, P., Prasanna N. S., Nagar, A. K., & Kulkarni, J., 2015. Occurrence of Forest Owlet Heteroglaux blewitti in Betul Distrist, and the importance of its conservation in the Satpura landscape. Indian BIRDS. 10 (6): 157–159.

    Patel, J (2016) Assessment of the status, distribution and conservation issue of Forest owlet (Heteroglauxblewitti) in Gujarat, India. Final Report. Submitted to Rufford Foundation (http://www.rufford.org/files/17923-1%20%20Final%20Report.pdf).

    Patel, J., Vasava, A., & Patel, N., 2017. Occurrence of the Forest Owlet Heteroglaux blewitti in Navsari and Valsad Districts of Gujarat, India. Indian BIRDS. 13 (3): 78–79.

    Raha, B., Gadgil, R., & Bhoye, S., 2017. Sighting of the Forest Owlet Heteroglaux blewitti in Harsul, Nashik District, Maharashtra. Indian BIRDS. 13 (3): 80–81.

    Rasmussen, P.C. & N.J. Collar (1998): Identification, distribution and status of Forest Owlet Athene (Heteroglaux) blewitti. Forktail 14: 41–49.

  4. Dharmaraj Patil says:

    I wonder the basic note doesn’t refer to all the publications on Forest Owlet. It mainly has focused on BNHS publications alone. Girish has later added the remaining ones in his comment. Kindly refer to all those.

    Yes, It is time that we can think on downlisting the bird to Endangered category BUT not before understanding the following points.

    1. The downlisting should by no means spread a message that the number has increased. As we all know it is nothing to do with the conservation measures for the species. Its pure resultant of added base of serious birdwatchers nationwide leading to discovery of newer and newer sites. The figure of 250 that we are talking here also has no scientific base. It just is a sum of numbers seen randomly. No demographic study has been done on the species so far. Yet, the owlets are surely more than that in number but we don’t have exact estimate. Some ongoing longterm projects have never been led to any publications that might have helped our understanding on actual conservation of the species.

    2. Although there are known stronghold sites like Melghat, Burhanpur-Khandwa, Purna, even Tansa, we should not miss out on serious decline of the species from sites like Toranmal in Maharashtra (The rediscovery site, 1997) , Basna (the type locality from Chhattisgarh, 1872), Khariar (Vallentine Ball’s specimen from Orissa, 1877). These are not natural declines ofcourse but human induced. Out of these, only Toranmal site is well studied and the decline is well evident [ Jathar, G. A. and D.N. Patil (2011) Reassessment of the status of Forest Owlet in its known distribution and evaluation of conservation issues. Final Report]. I myself have visited all these sites and habitat loss there is rampant. Yet, no detailed study is done in the vicinity of these sites where the owlet could be still surviving. The Khaknar site from Madhya Pradesh, which was discovered in 2000, is also under serious threat. These all are the sites which need urgent attention of conservation instead we focus entire research/discussion on the stronghold sites where the bird is anyway going to survive irrespective of our intervention.

    3. All these sites referred in point no. 2 are significant as these are disconnected sites from stronghold sites and so important in conservation of the owlets’ entire genepool.

    Other details I suppose are covered in earlier comments by other people. Regards,

  5. Andy Symes (BirdLife) says:

    Preliminary proposals

    Based on available information, our preliminary proposal for the 2017 Red List would be to list:

    Forest Owlet as Endangered under criterion C2a(i).

    There is now a period for further comments until the final deadline of 4 August, 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 2017 Red List categories will be published on the BirdLife and IUCN websites in early December, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  6. Praveen J says:

    Additional Reference on FO distribution

    Mehta, P., Kulkarni, J., Mukherjee, S., Chavan, S., Anand, A. V., 2017. A distribution survey of the Forest Owlet Heteroglaux blewitii in north-western Maharashtra. Indian BIRDS 13 (4): 103–108.

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