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Finn's Weaver Ploceus megarhynchus



Justification

Justification of Red List Category

This species is thought now to occur in just two small subpopulations and to be suffering a continuing decline, with a very rapid reduction suspected for the western population as a result of the loss and degradation of terai grasslands, principally through conversion to agriculture and overgrazing. While the eastern population is thought to be stable or only slowly declining, it is also suspected to be very small. As a result, the species is listed as Endangered.

Population justification
Based on surveys conducted by Bhargava (2017) maximum numbers were fewer than 200 in Uttarakhand and Uttar Pradesh together, and fewer than 300 in north-east India. However, the study also reported rapid declines in Uttarakhand and Uttar Pradesh, suggesting this number may be even lower today. The population in the Nepalese stronghold has been most recently counted as 254 individuals, following an expanded survey effort (Bird Conservation Nepal 2020), but nesting surveys in 2020 showed a continuing decline in the number of active nests and breeding birds, with 66 nests in 2020 down from 115 in 2019, and 133 birds down from 177 (Poudyal et al. 2020). Overall, the number of mature individuals is considered most likely to be 210–300 mature individuals in the western population and 200–250 in the eastern population. There may be a small number remaining in the disjunct West Bengal population, however there are few recent records from this area (Bhargava et al. 2017). The population is therefore suspected to fall in the band of 410–600 mature individuals, and estimated to lie within a wider band of 250–999 mature individuals, with no subpopulation larger than 250 mature individuals.

Trend justification
The population is inferred to be declining owing to the conversion of terai habitats for agriculture and industrial development as well as the effects of trapping for the cage-bird trade (Bhargava 2017). 

The rate of this decline is suspected to be severe. The most well-studied area, Udham Singh Nagar in Uttarakhan, showed a reduction from 220 to 35 individuals between 2002-2017. This decline of 84% over 15 years is equivalent to a rate of decline of 72% over three generations (10.5 years [Bird et al. 2020]). Declines have also been noted in the species's Nepalese stronghold, Shuklaphanta National Park, where the population was previously increasing. The population is estimated to have decreased from 300 individuals in 2017 to 254 individuals in 2021 (Bird Conservation Nepal 2020).

The trend of the southern population (West Bengal) is not clear due to the very small number of recent sightings: In 2008 and 2009, the species had been seen in some locations, but while there appears to be suitable habitat in the area, there has not been a confirmed sighting of this species since 2009 (Bhargava 2017).

Due to the rapid declines in Udham Singh Nagar, and Shuklaphanta National Park, and the reports of its disappearance from other former locations, it is suspected that overall this species is experiencing rapid declines in excess of 50% but most likely below 80% over three generations. Based on the threats, there is no reason to suspect that these rates of reduction will not continue.

Distribution and population

This species is endemic to the Terai of the northern Indian subcontinent, where it is known from three disjunct populations: The western population occurs in Delhi, northern Uttar Pradesh and Uttarakhand states, India, and adjacent extreme western Nepal where it is a rare breeding resident and summer visitor. The eastern population occurs from eastern Nepal to Assam in India (BirdLife International 2001), and the southern population in West-Bengal. Throughout the range in India, the species was known from 17 discrete sites up to the year 2000. Extensive survey effort increased this to 47, but by 2017 only nine were still known to be occupied (Bhargava 2017). Notably, three of the locations where the species is currently recorded are new locations identified during 2016-2017 (Bhargava 2017). Surveys in north and north-east India also indicate that the species is very uncommon, even in protected areas where there has been little apparent habitat change (A. Rahmani in litt. 2016, 2021, A. Choudhury in litt. 2021).

Ecology

It inhabits Terai marshes and extensive stands of Imperata, Narenga, Phragmites and Saccharum grassland, particularly those that are seasonally inundated, with well-scattered trees, and occasionally interspersed with patchy rice and sugarcane cultivation. It is gregarious, foraging in flocks and breeding (May-September) in colonies. Nests are built in trees, reedbeds, or extensive stands of tall grass. Whilst its movements are poorly understood, populations appear to wander erratically.

Threats

During the last 60 years, the Terai region has been almost totally converted to human-dominated landscape with agriculture, orchards, factories, canals, roads, expanding villages and cities, and very rapid human population growth. The rising population of crows (Corvus splendens and Corvus macrorhynchos), related to garbage and human habitations, threatens nesting colonies (Bhargava 2000, 2017). These threats are compounded by capture for the live bird trade (Bhargava 2017).


 

Conservation actions

Conservation Actions Underway
It is considered Critically Endangered in Nepal (Inskipp et al. 2016). It is protected in India, where trapping and trade of the species has been banned since 1991. It has been recorded in very small numbers from Kaziranga, Orang, Dibru-Saikhowa and Manas National Parks (Assam), Jaldapara Wildlife Sanctuary and Buxa Tiger Reserve (West Bengal), Corbett National Park (Uttar Pradesh), and Suklaphanta National Park and Koshi Tappu Wildlife Reserves (Nepal) (H. Baral and C. Inskipp in litt. 2016).

Conservation Actions Proposed
Conduct widespread interviews with bird-trappers to identify population centres, followed by field surveys in remaining habitat to establish its distribution and status. Conduct surveys outside protected areas to establish whether the species is found in significant numbers outside the protected area network. Conduct a detailed survey of the Brahmaputra Valley for this species (A. Rahmani in litt. 2016). Extend, upgrade, link (where possible) existing protected areas and establish new ones in order to conserve remaining tracts of natural grassland across its range. Control livestock-grazing in protected areas to reduce rates of habitat loss and degradation. Promote conservation awareness initiatives focusing on sustainable management of grassland to maximise both thatch productivity for local people and available habitat for threatened grassland birds. Upgrade its legal protection status to Schedule I of the Indian Wildlife (Protection) Act.

Identification

17 cm. Large weaver with yellow rump, uppertail-coverts, head and underparts and dark ear-coverts. Heavily streaked mantle, back and scapulars. Female is duller with paler, more buff-tinged yellow parts, particularly crown and nape. Similar spp. Female/non-breeding male Baya Weaver P. philippinus is smaller with shorter, narrower bill and lacks dark lateral breast-patch. Voice Song is subdued twit-twit-tit-t-t-t-t-t-trrrrr wheeze whee wee we. Calls a harsh twit-twit etc.

Acknowledgements

Text account compilers
Martin, R., Clark, J.

Contributors
Ashpole, J, Baral, H.S., Benstead, P., Bhargava, R., Choudhury, A., Gilroy, J., Hermes, C., Inskipp, C., Jain, A., Laad, P.M., Martin, R., Rahman, A., Rahmani, A., Taylor, J. & Westrip, J.R.S.


Recommended citation
BirdLife International (2022) Species factsheet: Ploceus megarhynchus. Downloaded from http://www.birdlife.org on 08/12/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 08/12/2022.