Comparing detectability patterns of bird species using multi-method occupancy modelling.

A robust knowledge of biodiversity distribution is essential for designing and developing effective conservation actions. The choice of a suitable sampling method is key to obtaining sufficiently accurate information of species distribution and consequently to improve biodiversity conservation. This study applies multi-method occupancy models to 36 common bird species associated with small ponds in the province of Murcia (south-eastern Spain), one of the most arid regions of Europe, in order to compare their effectiveness for detecting different bird species: direct observation, combined observation and video monitoring and mist netting captures. The results showed that the combined method and direct observation were similar and most effective than mist netting for detecting species occupancy, although detection rates ranged widely among bird groups, while some large species were poorly detected by all the methods used. Average detectability did not increase during the breeding period. The chosen approach is particularly applicable to both single- and multi-species bird monitoring programmes. However, we recommend evaluating the cost-effectiveness of all the available methods in order to reduce costs and improve the success of sampling designs.