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La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

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Titre :	Testing the Point Count Method to record the avifauna in river ecosystems.
Auteurs :	Miriam M. Hansbauer, Auteur ; Aurelia Munck, Auteur ; Ilse Storch, Auteur
Type de document :	Article
Dans :	Ornithologischer Anzeiger (42(2) Mai 2003)
Article en page(s) :	97-110
Résumé :	The Point Count is a relative method to record bird communities. It is a time and work saving alternative to more costly methods such as territory mapping, and is therefore often used for monitoring. The aim of this work was to examine the influences of external and methodological factors on results of the Point Count Method used in river ecosystems in Bavaria. The birds were counted twice for 3, 5, 10 and 15 minutes between April and June 2001 at 24 points in each of three study sites that varied strongly in habitat structure. At six chosen points per study area birds were counted five times for five minutes. Additionally at one point in Obermenzing and one point in Muehltal birds were counted during the course of a day, three days at each site. Distance to the river (at the banks or 200 m away), periods of observation, temperature and rainfall had significant influence on the counted number of species. During the first 90 min. after sunrise, however, the number of recorded species was not significantly influenced by the time since sunrise. In order to record at least 80% of the species occurring in an area, two counts per season with 10 min. counting intervals per point were required. All-day-surveys showed that in the early morning, around and after sunrise, most bird species were counted; between 10:00 a.m. and 11:30 a.m. the cumulative curve of species numbers started to flatten. The five 5-mill-counts during the season revealed that with only two counts 76% of the species (on average) could be recorded instead of 100% after five counts (not corresponding to the total number of species in the area). The wider the observation radius, the more species were recorded. The results of this work confirmed, that the Point Count is a method that can easily be used in different types of landscapes. External and methodological factors, however, may strongly affect the results. Hence, this method is not useful to obtain absolute quantitative numbers of individuals per area, but if the Point Count Method is applied under standardised conditions over years, trends in bird communities, especially for the more common species can be recorded.

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