Literature type: Scientific
Journal: Wildfowl
Volume: 74 , Pages: 53-68
Language:
English
Full reference: Solovyeva, D., Rozenfeld, s., Barykina, D., Kirtaev, G., Danilova, V., Meng, F., Cao, L., Lei, G. & Zeng, Q. 2024. Estimated size of the Eastern population of the Lesser White-fronted Goose Anser erythropus revealed from aerial surveys of key moulting sites. Wildfowl 74: 53-68
Keywords: aerial survey, moulting period, newly-discovered site, population estimate, eastern populatio, China
Abstract:
The Eastern population of the Lesser White-fronted Goose Anser erythropus (EPLWFG) breeds and moults in Russia and the majority winter in China. Intensive surveys of lakes in the Yangtze River floodplain and in Japan estimated the EPLWFG at 6,600 individuals in 2020 compared to 14,000–19,000 in 2016. Waterfowl are easier to count when concentrated in relatively small areas at key times of the year, and the non-breeding and failed breeding elements of the EPLWFG (an estimated 87% of the population) concentrate at remote moulting sites from early July to mid-August during remigial moult. Locations of GPS-tagged EPLWFG (non-breeding birds and failed breeders), which moulted between 25 June and 17 August, recorded during an earlier study, were plotted on maps of the key moulting region, along the San-Yuryakh and Kyuanekhtyakh Rivers which flow into Omulyakhskaya Bay. An aerial survey undertaken in July 2021 aimed to cover as many locations of the tracked individuals as possible, together with Svyatoy Nos Cape and the New Siberian Islands (where the species was also thought to moult), to count the numbers of geese moulting in these areas. Moulting sites on the delta of the Lena River were also surveyed from the air during the EPLWFG moulting periods in 2019 and 2020. Goose groups were photographed and digitally tagged to GPS coordinates, generating a database which included a date/time stamp to the nearest second, coordinates to the nearest 0.000001 degree, and a picture ID. Photographs were processed using Adobe Photoshop V 21.1.3 software. From detection rates in the survey area, we were able to assess the extent of similar habitat elsewhere in the EPLWFG moulting range, to obtain an estimate of the potential total population size. Moulting EPLWFG were found on Bolshoy Lyakhovaskiy Island in the New Siberian Islands, a new site discovered during this study. A total of 9,373 EPLWFG was counted in moulting flocks at all known and newly discovered moulting sites. The extrapolated estimate for the number of non-breeding and failed breeding birds, on taking the expanded area of suitable habitat into account, was of potentially 24,060 geese. Considering that c. 10% of EPLWFG are successful breeders (i.e. remain on their breeding sites and do not join the moulting flocks), we propose that the overall population size could be as high as 26,733 individuals, excluding offspring of the year.
Literature type: Scientific
Journal: Nature Conservation Research
Volume: 4
Language:
English
Full reference: Rozenfeld, S.B., Kirtaev, G.V., Rogova,N.V. & Soloviev, M.Y. 2019. Results of an aerial survey of the western population of Anser erythropus (Anserini) in autumn migration in Russia 2017. Nature Conservation Research 4. https://www.dx.doi.org/10.24189/ncr.2019.003
Keywords: aerial counts, Lesser White-fronted Goose, monitoring, Nenetsky Autonomous Okrug, Yamalo- Nenetsky Autonomous Okrug
Abstract:
The global population of Anser erythropus has rapidly declined since the middle of the 20th century. The decline in numbers has been accompanied by the fragmentation of the breeding range and is considered as «continuing affecting all populations, giving rise to fears that the species may go extinct». Overhunting, poaching and habitat loss are considered to be the main threats. The official estimate of the dimension of the decline is in the range of 30% to 49% between 1998 and 2008. Monitoring and the prospection of new areas are needed for the future conservation of this species. The eastern part of the Nenetsky Autonomous Okrug, the Baydaratskaya Bay and the Lower Ob (Dvuobye) are important territories for the Western main population of Anser erythropus on a flyway scale. Moving along the coast to the east, Anser erythropus can stay for a long time on the Barents Sea Coast, from where they fly over the Baydaratskaya Bay to the Dvuobye. We made aerial surveys and identified key sites and the main threats for Anser erythropus on this part of the flyway. According to our data, the numbers of the Western main population of Anser erythropus amount to 48 580 ± 2820 individuals after the breeding season, i.e. higher than the previous estimates made in autumn in Northern Kazakhstan. The key sites of Anser erythropus in this part of the flyway were identified.
Number of results: 2