Population size and trend. Ideally for each biogeographic population the current population estimate as well as historical and recent trends in population size and range (breeding, wintering, migration) should be provided. • National estimates should be provided in a Table.
Population size and trend. Numbers of Red-breasted Geese are believed to have been roughly stable from the 1950s to the late 1980s. Count totals show an increase during the 1990s, followed by a significant decline during the first half of the decade 2001–2010 (figure 4). Whilst this general pattern is widely accepted, the magnitude of the changes is likely to have been less severe than indicated by the numbers. Temporal changes in the number of Red-breasted Geese are difficult to determine with confidence, as a result of the practical limitations involved in undertaking comprehensive surveys. Although count data from the wintering range are available from several years throughout the mid 1950s to late 1980s, most figures are clearly unrepresentative. Efforts to undertake co-ordinated surveys began in the early 1990s, and continue to the present day, particularly in Bulgaria, Romania and Ukraine. Doubts remain over the accuracy of the more recent totals, as counts in the eastern part of the wintering range are less comprehensive, and it is thought that a significant number of birds may winter outside the surveyed area, particularly during mild xxxxxxx which have become more frequent in recent years. Counts of passage and/or wintering birds are made in southwest Russia and Kazakhstan, and support the general picture from co-ordinated winter surveys. The first large estimate of the Red-breasted Goose population is 60,000 birds, made in 1956, when the population was centred on the Caspian region. Between this initial estimate and 1967, the population was believed to vary between 50,000 and 60,000 individuals. Between 1969 and 1990, the maximum number recorded in the non-breeding areas was 25,907. Whilst a population decline is suspected to have occurred, it is impossible to confirm or quantify since counts clearly underestimated the true totals, partly as a result of a lack of adequate surveys in the newly established wintering areas. The more comprehensive coverage subsequently enables a confident estimate of 90,000 individuals at the end of the 1990s: 88,000 were counted in Kazakhstan in autumn 1996; and 88,425 were recorded during a survey of the main wintering areas in 2000. This is thought to represent an increase in population size since the 1970s. Counted totals declined dramatically after 2000 (eg to just 23,000 in 2001/02). Whilst these, and subsequent counts, provide strong evidence for a large decrease following 2000, it is unlikely that the decline was as severe as the numbe...
Population size and trend. Criterion C is designed to identify species with a small population size that is currently declining or may decline in the near future. To meet this criterion for listing the number of mature individuals must be <2,500 for Threatened status or <10,000 for Species of Special Concern status. The BSR estimated that about 785,000 adult gopher tortoises occur in Florida; thus, Criterion C was not met.
