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The Red-throated Diver in Finland in 2010 This is a short summary of the main results of the nation-wide inventory in 2010, organized by BirdLife Finland and its member societies. The main aim of the inventory was to map present distribution, pair numbers in different parts of Finland, as well as breeding success. Every local ornithological society (their areas of observation cover the whole of Finland) had an expert who organized surveys of previously known and suitable un-known ponds in 2010. The RTD has declined considerably in numbers during the last 100 years but in recent decades trends have varied. The main reasons for long-time decline have been hunting (legal up to 1961) as well as drainage of peatlands and forest ponds due to forestry. In some areas the number of breeding pairs has even increased due to active building of artificial nesting rafts to peaceful ponds, especially in larger forest and peatland areas, the main habitat type in our country. Newer threats during the breeding season are disturbance by people because a dense forest road network goes to or near-by tens of nesting ponds. Researchers have noted tens of cases where fishermen, hikers, photographers, dogs etc. have caused nesting failures. Some birds are still shot. In wintertime on the North Sea oil spills are presumably a major threat, as well as fishing nets, for the Finnish RTD. The total breeding population in Finland has been estimated several times since the 1960s, and the estimates have varied from 600 to 2000 pairs. The total number of recorded pairs (confirmed breeding) was 462. By summing the local estimates one gets 740 pairs as the national estimate for the breeding population. Recent data from BirdLife Finland (occasional bird observation data base) and Metsähallitus ("National Board of Forestry", governmental organization responsible for the nature protection areas) was also checked. The most probable estimate for the Finnish population, based on all available data from recent years, is 600-750 pairs, seemingly nearer to the lower than the upper limit. Although higher estimates have been proposed e.g. based on bird atlases, their data bases have not been as accurate as the 2010 species-specific inventory. According to monitored local populations in several parts of Finland it seems probable that the general level of the population has not changed markedly during the last 20 years. Traditional nesting ponds have been abandoned in many areas but new ones have been inhabited simultaneously. The mean nesting success in the whole of Finland was 1.13 in 2010 which is over 0.9 estimated by Pakarinen and Järvinen (1984, Lintumies 19: 46-54) as the critical limit for a stable population. The population is largest in Kymenlaakso, Päijät-Häme and Etelä-Savo (SE Finland), Uusimaa (southernmost Finland), Kainuu (east of Oulujärvi region), Keski-Suomi (Central Finland), Pirkanmaa (southwestern inland), as well as in Lapland. Although the general level of the national population seems to have remained at the same general level in recent decades, there is a good reason to wait for further declines due to increasing recreation activity, new summer cottages etc. causing disturbance for breeding pairs. Ravens, Hooded Crows, American minks and other predators seem to rob nests fairly frequently. Whooper Swans and Common Cranes are increasing rapidly in Finland, and in many times they have "robbed" nesting rafts of the RTD for their own use (also immature swans staying the whole summer in the same ponds as divers). There are some cases where the Marsh Harrier (an increasing bird species in Finland) has robbed the eggs of RTD. In addition, many networks of artificial rafts are old and in need of reparation, but there is lack of manpower for the field work. Thus, there are good reasons to fear for a slight but long-term RTD population decline in Finland in the near future. Table in the article shows the results from 2010. Alue = region ("county"), Pesinnät = confirmed no. of nesting pairs, Arvio = estimated no. of nesting pairs, Poikastuotto = no. of young per pair.