The applicability of biodiversity indicators strongly increases if accompanied by proper measures of uncertainty. A confidence intervals for the trends in an indicator enables trend testing and classification and statistical comparison with other indicators. However, in multi-species indicators like the European Wild Bird Indicators, the inclusion of the sampling error of species indices has shown to be hard to realize. Missing values and time series of different lengths disable the use of analytical approaches, whereas bootstrapping across sites requires the raw abundance data on the site level, which may not always be available. We developed a practical and conceptually elegant method to account for sampling error in the calculation of multi-species indicators based on Monte Carlo simulation of annual species indices. The construction of confidence intervals is elaborated to allow various trend assessments, like testing for linear or smooth trends, testing for changes between two time points, testing the significance of a supposed change-point and testing for differences between two multi-species indicators. In the workshop the method will be explained and demonstrated. An R-script with the Monte-Carlo method can be obtained during the workshop and participants equipped with a laptop with R installed will be assisted in applying the method on test databases.

Across Europe, data collection for the European Breeding Bird Atlas EBBA2 is advancing rapidly. There are regions, however, where gaps remain, which should be covered as well as possible in 2017. A big effort by the ornithological community is needed to support national coordinators in several countries. The workshop will present the current situation and discuss the possibilities.

In addition to data collected at the level of the 50x50 km grid, which will allow comparison with the first atlas, "timed visits" provide standardised data that will allow modelling the probability of occurrence at a smaller resolution. In 2015, a pilot data provision was launched. National coordinators from almost all European countries provided nearly 100’000 species lists from timed surveys carried out during atlas or breeding bird monitoring projects. These data are a basis to explore the modelling possibilities. The pilot data provision also allowed to test data transmission and data quality. After two provisions of preliminary data at the level of 50x50 km grid (the last one ongoing) and one for "timed visits", the real data provision for EBBA2 is approaching and their characteristics and timings will be discussed at the workshop.