Population estimates

One of the main objectives of the present atlas was to generate reliable population estimates for the different bird species breeding in Catalonia and thus take an important step towards knowing the conservation status of these species. Generally, due to their scarcity some species have been the target of greater conservation efforts and research institutes, governments and individuals have devoted an important amount of time to trying to estimate their populations. This is the case of a number of raptors, wetland and steppe birds, all of which are birds of special conservation concern in our country. The total populations of these species are often known very accurately and are re-evaluated regularly often on a yearly basis. From complex triangulations for Dupont's Lark, to the direct counting of the Glossy Ibis, a great range of techniques have been used in order to determine the total number of birds in the Catalan population of these species. This atlas is an attempt to unify all the work carried out in these specific monitoring schemes by different research groups. In spite of this, specific procedures to evaluate population size only exist for a few Catalan breeding species. Thus, new methodologies have had to be designed to address this issue and either consist of data collected by atlas contributors or the combining of data from other monitoring projects such as the Common Bird Survey in Catalonia (SOCC).

Species conservation status

The data in this atlas (above all, that concerning distribution, trends and population estimates) provides a standardised and objective assessment of the conservation status of the bird species that breed in Catalonia. We decided to follow the IUCN (International Union for Conservation of Nature) criteria that are applied worldwide (UICN 2001), as well as the regional correctors proposed by Gardenfors et al. (2001) and other correctors for species such as raptors whose Catalan densities and population are very small (for the whole procedure, see Estrada et al. 2004). The status of each bird species were further discussed with 43 Catalan ornithologists, all experts in different groups of birds and with historical visions of the changes in bird populations that are occurring in Catalonia. The categories considered are: Not Evaluated (NE), Data Deficient (DD), Least Concern (LC), Near Threatened (NT), Vulnerable (VU), Endangered (EN), Critically Endangered (CR) and Extinct (EX).