It will basically allow drawing the distribution maps. The UTM 10x10 square will remain as work unit, as done with the two breeding bird atlases previously published in Catalonia to date. Likewise the last breeding bird atlas, and especially because of time constraints, exclusively the Catalan administrative territory will be surveyed in the boundary squares.
Surveying all these 386 units, nevertheless, will involve significant modifications in relation to the breeding atlases, basically to improve the standardization of the field data collection which will facilitate comparisons among squares.
The essential objective of the extensive sampling is detecting as many specis as possible, both land and sea birds, in each 10x10 UTM square. The sampling will be divided in two periods (A: November 15th - December 31st, and B: January 1st - February 15th). It should be emphasized that both periods are independent; therefore the species detected in the first survey won't count for the second. For this reason, the observer will try to cover all the habitats present in the square seeking for the maximum number of species in each of the two periods, regardless of whther a certain species was detected or not during the previous period. The "journeys" do not need to be the same for both periods. Only especial areas of restricted distribution will have to be surveyed in both periods. Importantly, the sampling effort will be time controlled. Indeed, squares with 100% of land surface totally located in Catalonia will require 8 hours of effort in each period. The pilot tests conducted in the winter 2005-2006 show that, on average, 70-80% of the species present in a square are detected in 8 hours (more information: extensive method, estimation of the sampling effort; PDF file, 126Kb). These 8 hours of standardized censusing are subdivided into 8 1-hour units. The collaborators themselves must select the areas where they will carry out these censuses. They must give priority to detecting the maximum number of species. These areas are not necessarily distributed homogeneously throughout the 10x10 UTM square. The species detected in each census have to be listed separately. The 1-hour censuses can be conducted in different days, although bearing in mind that the last one of the first period and the first one of the second must be, at least, 10 days apart. The 1-hour censuses always have to be conducted on foot; time spent between censused areas is not computed. If necessary The observer can visit more than one area during the 1-hour censuses, although he or she will have to neutralize the time invested between areas and the species observed meanwhile will not be computed.
Surveys can be conducted anytime during day light hours. However, one 1-hour census has to coincide with the twilight (approximately 30 minutes before sunset until 30 minutes after it) in order to cover the peak of activity of the nocturnal species. 40-60% of Catalan surface: 6 hours; 20-40%: 4 hours; <20%: 2 hours. Anyway, one of these hours will have to coincide with the twilight.
Whether for including a sea portion and/or an extra Catalan territory, those squares that do not reach a 60% of surface will require fewer timed censuses per period:
In all cases, those species detected between censuses, neutralized periods or in additional surveys will be recorded in the out of cens column of the field sheet.
With regard to the location of the species, data should be double-checked in order to verify that they belong to the right UTM 10x10 square surveyed on a regular basis. The 1x1 UTM coordinates will be required for some scarce species. This atsk will be facilitated by the presence of the 1x1 grid superimposed on the topographic maps to be delivered to each collaborator. These coordinates are independent for each sampling period (A or B), and they will aid drawing high resolution maps for those species with insufficient SOCC data.
Collaborators of the extensive sampling have to make a qualitative population estimate for scarce species and also for those species for which specific censuses are not available. These estimates just refer to the surveyed square, and must be given for each one of the periods. The estimates do not have to take a roost into account, if it is thought that part of its elements have an extra square origin. The intervals for these intuitive estimates would be: A: 1-5 ind., B: 6-10 ind., C: 11-50 ind., D: 51-100 ind., E: 101-500 ind., F: 501-1,000 ind., G: 1,001-5,000 ind., H: 5,001-10,000 ind., I: 10,001-50,000 ind., J>50,001 ind. This classification has more intervals than the one used for the latest breeding bird atlas because we learnt that, at a log scale, they sometimes defined too rough ranges when estimating population sizes.
Collaborators will have to be aware of possible roosters inside their squares. In case of finding one, they will have to count the birds (at the rooster itself or by counting the evening pre-roosting flocks) independently of the aforementioned square estimates. For species such as Chough, Alpine Chough, Raven or Red Kite, roosts are very obvious and concentrate many individuals that scatter over areas comprising several squares during the daytime. Several data are required for the species that roost (marked in the sheet) : number of individuals, 1x1 UTM square where they are found and date of observation.
Dates of last observation in the first period and first observation in the second are required for those species that are basically in transit or that are summer visitors in Catalonia. These particular cases are adequately marked in the field sheet.
For more information you can read this article (PDF file):
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