ABSTRACT The water bird species to be protected in the Ruzizi Delta in Burundi and in the Democratic Republic of Congo (DRC) was investigated from April 2019 until August 2021 in five sites in the Rusizi Burundian Delta (RBD) and five sites in the Ruzizi Congolese Delta (RCD). Each site was visited three times a year during the years 2019, 2020 and 2021. The investigation was conducted by direct observation on transects, counting points and on bird species recognition routes using binoculars and two telescopes. Displacements were done by the motorized fiberglass boat and the double cabin field vehicle of the Centre for Research in Hydrobiology (CRH) of Uvira, DRC. At the end of our investigations, we drew up the list of 490 species divided into 84 families and 18 orders. 176 (36%) species were water bird species. Of them, 140 (80%) meet the Ramsar A4i criterion for bird conservation, and 36 species do not meet this criterion. Of these 36 species, we recognized 9 species (5%) of waterbirds specializing in aquatic environments (WBS), and 27 species (15%) of Water Bird species Generalists or visitors to aqueous environments. 26 species of aquatic birds (15%) were recorded in the unprotected Ruzizi Congolese Delta (RCD), 49 (28%) in the protected Rusizi Burundian Delta (RBD), and 101 species of aquatic birds (57%) were recorded both in the Ruzizi Congolese Delta and in the Rusizi Burundian delta. The difference in the distributions of aquatic birds between the Ruzizi Congolese Delta and the Rusizi Burundian Delta is significant. Waterbirds are not affected by the boundaries between RCD and RBD. Their sustainability in the Ruzizi Delta requires the protection of the Ruzizi Congolese wetlands as is the case for the Rusizi Burundian Delta. Keywords: Aquatic bird species; Conservation of water bird species; Bird species specialized in aquatic environments; Water Bird Species Generalists of aquatic environments; Water Bird species visitors of aquatic environments. REFERENCES Bashonga, A. B., Sande, E., Kahindo, C., & Ntakimazi, G. (2023). Checklist of the Bird Species from the Ruzizi Delta, Northern End of lake Tanganyika, in Burundi and the Democratic Republic of Congo. Biolife 11 (2);115-129. ISSN (online):2320-4257. Burke, K. A., Rodwell, L., Steinacker, M., & Seal, U. S. (2001). Population and Habitat Assessment for the Wattled Crane in South Africa Final Workshop Report. IUCN/SSC Conservation Breeding Specialist Group, Apple Valley, MN, USA, 169 pages. Butchart, S., Stattersfield, A., & Collar, N. (2006). How many bird extinctions have we prevented? . Oryx, vol. 40, no 3,‎, 266-279. Chapman, A. D. (2005). Numbers of Species Living in Australia and in the Word. Report for the Department of the Environment and Heritage Canberra, Australia. Canberra Australia: Australian Biodiversity Information Services Toowoomba Australia. Pp 64. Chapman, A. D. (2009). Numbers of Living Species in Australia and the World. Canberra: Australian Biological Resources Study. pp. 1–80. ISBN 978-0-642-56861-8. Deanna, W. M., Brunner, J., Nige, l. S., Karr, C. J., & Nielsen, D. (1998). Forests and the Democratic Republic of Congo Opportunity in a Time Crisis: A Contribution to the Forest Frontiers Initiative. New York: World Resources Institute, pp 30. Demey, R., & Louette, M. (2001). Democratic Republic of Congo. In Fishpool L.D.C.& Evans M.I eds Important Bird Areas in Africa:Priority Sites for Conservation. Pisces Publications and Bird Life International, 199-218. Dowset, & Dowset-Lemaire. (1993). A contribution to the Distribution and Taxonomy of Afrotropical and Malagasy birds Tauraco Research Report . Liège, Belgium.: Tauraco Press, Jupille No. 5 pp195-204. Fishpool, L., & Evans, M. (2001). Important Bird Areas in Africa and Associated Islands, Priority Sites for Conservation. Newbury and Cambridge, UK: BirdLife International, 1144 pages. Gaugris, Y. (1979). Les oiseaux aquatiques de la plaine de la basse Rusizi (Burundi) (1973-1978). Belgium: l’Oiseau et la Revue française d’ornithologie, volume 49 n° 21:33-153. Gujjeti RP, Mamidala E. Anti-HIV Activity and Cytotoxic Effects of Aerva lanata Root Extracts. American Journalof Phyto medicine and Clinical Therapeutics 2014; 2(7):894-900. Guggisberg, C. (1986). Birds of East Africa. Supra Safari Guide No 6 Volume II. Nairobi: Mount Kenya Sundries, 196 pages. Guggisberg, C. (1988). Birds of East Africa. Supra Safari Guide No 6 Volum I. Nairobi: Mount Kenya Sundries, 198 pages . MEEATU, Ramsar, C., & WWF. (2014). Atlas of Burundi's four Ramsar sites: Location and Resources. Bujumbura, Burundi: Ministry of Water, Environment, Land Use Planning and Town Planning (MEEATU), 44p. Mubalama, K. L. (2010). Monitoring Law Enforcement Effort and Illegal Activity in Selected Protected Areas: Implication for Management and Conservation, Democratic Republic of Congo. Ghent, Belgium: Ghent, Belgium, 375 pages. http://www.catsg.org 12/01/2022. Nkezabahizi, L., & Bizimana, D. (2008). Burundi’s Important Bird Areas, Status and Trends. Bujumbura-Burundi: Association Burundaise pour la protection des Oiseaux, 58 pages. Nkezabahizi, L., & Manirambona, A. (2011). Burundi’s Important Bird Areas Status and Trend 2010. London: BirdLife International & RSPB (Royal Society for the Protection of Birds (UK), 36 pages. Ntakimazi, G., Nzigidahera, B., Nicayenzi, F., & West, K. (2000). Étude Spéciale Biodiversité (ESBio) Rapport: État de la diversité biologique dans les milieux aquatiques et terrestres du Delta de La Rusizi. New York: LBP/PBLT/UNDP/GEF/UNOPS, 70 pages. Ntakiyica, A. (2008). State of knowledge on the distribution sites of ornithological fauna in Burundi. Bujumbura Burundi: Departement of Biology, Faculty of Sciences, University of Burundi, 76 pages. PERSGA, & GEF. (2003). Status of Breeding Seabirds in the Red Sea and Gulf of Aden, PERSGA Technical Series No. 8. Jeddah, Aden Gulf: . PERSGA (Regional Convention for the Conservation of the Red Sea and Gulf of Aden Environment), 78 pages. Stevenson, T., & Fanshawe, J. (2002). Field Guiede to the Birds of East Africa: Kenya, Tanzania, Uganda, Rwanda and Burundi. London: T. & A. D. Poyser, 606 pages. Vijayagiri, R. C., & Mamidala, E. (2012). Ethnobotanical investigations among traditional healers in Warangal district of Andhra Pradesh, India. Pharmacognosy Journal, 4(34), 13–17. Wetlands, & International. (2012). Waterbird Population Estimates Fifth Edition - Summary Report. Antananarivo, Australia: Wetlands International, 28 pages. ISBN: 978-90-5882-000-6. www.wpe.wetlands.org 21/01/2022. Williams, J., & Arlott, N. (1988). A Field Guide to the Birds of East Africa. London: Collins, Grafton Street, 415 pages. ISBN 0 00 219179 2. Zimmerman, D., Turner, D., & Pearson, D. (1999). Hem Field Guides Birds of Kenya & Northern Tanzania. . London UK: Christopher Helm A & C Black (Publishers) ltd, 35 Bedford Row, WC1R 4JH 0-7136-5079-6, 578 pages.