Trends in abundance and changes in the distribution of the Northeast Europe/ Northwest Europe Bewick’s Swan Cygnus columbianus bewickii population have been studied in detail since the second half of the 20th century, but much less is known about the Northwestern Siberia/Caspian population which was estimated at 1,000–1,500 individuals at the turn of the century. Here, we describe the results of the first species-specific mid-winter International Bewick’s Swan Census (IBSC) covering the East Mediterranean to Central Asia, made in January 2020. We also use longer-term data collated by Wetlands International through the annual International Waterbird Census (IWC) programme to construct trends in wintering numbers in the region. Results from the IBSC and IWC both showed a marked increase in population size for the Northwestern Siberia/Caspian Bewick’s Swans over the past two decades. A total of 6,819 was recorded during the IBSC and there was a five-year mean of 9,111 ± 4,300 swans reported to the IWC (for the years 2018–2022) with a peak count of 13,775 in 2019. An aerial survey of the Volga Delta in the northern Caspian Sea in 2020, rarely covered because of the logistical difficulties of carrying out mid-winter counts in the region, found an estimated 551 Bewick’s Swans wintering at the site. There was marked annual variation in the IWC counts recorded from 2017 onwards, although the reasons for these fluctuations remain unknown. Trends analysis suggested a slow increase over time from 2000–2015, followed by a period of rapid increase during 2015–2017, then a weak decline in 2017–2022. Given that the IBSC and the IWC have provided totals of > 6,000 Bewick’s Swans in five of the last six years, however, we propose that the new population estimate should be increased to 6,000–13,000 birds, pending further comprehensive surveys of the whole region.
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RBINS Staff Publications 2024
Association for Tropical Biology and Conservation annual meeting https://www.atbc2024.org Large old tropical trees as keystone biodiversity structures: the Life on Trees program Leponce Maurice1, Basset Yves2, Aristizábal-Botero Ángela1, Albán Castillo Joaquina3, Aguilar Rengifo Guillermo4, Barbut Jérôme5, Buyck Bart5, Butterill Phil6, Calders Kim7, Carrias Jean-François8, Catchpole Damien9, D’hont Barbara7, Delabie Jacques10, Drescher Jochen11, Ertz Damien12, Heughebaert André13, Hofstetter Valérie14, Leroy Céline15, Leveque Antoine16, Macedo Cuenca Victor4, Melki Frédéric17, Michaux Johan18, Ocupa Horna Luis19, Pillaca Huacre Luis3, Poirier Eddy20, Ramage Thibault21, Rougerie Rodolphe5, Rouhan Germinal5, Rufray Vincent17, Salas Guererro Marcos4, Scheu Stefan11, Schmidl Jürgen22, Silva Dávila Diana3, Valenzuela Gamarra Luis23, Vanderpoorten Alain18, Villemant Claire5, Youdjou Nabil1, Pascal Olivier17 1 Royal Belgian Institute of Natural Sciences, Vautier st. 29, Brussels, 1000, Belgium; 2 Smithsonian Tropical Research Institute, Panama; 3 Museo de Historia Natural, Universidad Nacional Mayor de San Marcos, Lima, Peru; 4 Servicio Nacional de Áreas Naturales Protegidas por el Estado, Ministerio del Ambiente, Peru; 5 Muséum national d'Histoire naturelle, Paris, France; 6 Biology Centre, Czech Academy of Sciences, České Budějovice,Czech Republic; 7 Ghent University, Belgium; 8 Université Clermont-Auvergne, Clermont-Ferrand, France; 9 Independent Consultant, Lima, Peru; 10 Centro de Pesquisas do Cacau – CEPEC, Itabuna, Brasil; 11 Göttingen University, Germany; 12 Meise Botanic Garden, Belgium; 13 Belgian Biodiversity Platform, Brussels, Belgium; 14 AGROSCOPE, Nyon, Switzerland; 15 AMAP (Univ. Montpellier, CIRAD, CNRS, INRAE, IRD), Montpellier, France; 16 PatriNat (OFB-CNRS-MNHN), Paris, France; 17 Fonds de Dotation Biotope Pour La Nature, Mèze, France; 18 Université de Liège, Belgique; 19 Centro de Investigación en Biología Tropical y Conservación, Piura, Perú ; 20 Independent entomologist, Cayenne, Guyane ; 21 Independent entomologist, Concarneau, France ; 22 Universität Erlangen-Nürnberg, Germany. ; 22 Jardín Botánico de Missouri, Peru E-mail: (presenting author): mleponce@naturalsciences.be The aim of the Life on Trees (LOT, www.lifeontrees.org) program is to generate baseline knowledge about the number of eukaryotic species that a single large mature tropical tree can host and to understand how these communities of organisms are assembled. The program is being undertaken in the Andean Amazon biodiversity hotspot. Our first project, LOT01 in the Andean foothills in 2022, located at 400m a.s.l., involved the study of a spectacular Dussia tessmannii tree (Fabaceae), towering at 50 meters in height and 45m wide. Our second project, LOT02 in the Andes in 2023, at 2450m a.s.l., focused on a 32-meter-tall Ficus americana subsp. andicola. Surveys were carried out by professional climbers, guided by experts of the different eukaryotic groups studied (plants, fungi, animals, protists). To better understand the contribution of different tree components (bark, leaves, fruits, flowers, living and dead wood) to overall tree biodiversity, we partitioned observations into communities based on vertical strata or microhabitat and will examine similarities and nestedness in the composition of these communities. Initial findings indicate that significant diversity is harbored by the individual tree at both locations (e.g., LOT01 vs LOT02: 42 vs 114 orchid species, 28 vs 28 fern species, 200+ vs 300+ bryophyte species, and 180 vs 100+ lichen species identified). These figures set world records for their respective elevations. This confirms that large old tropical trees are important pools of biodiversity, probably related to the variety of local microhabitats and tree age.
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RBINS Staff Publications 2023
