Testing the effectiveness of a novel approach to measure a large roosting congregation in a wetland ecosystem.

Data support the research carried out at Rotopiko's pest proof fance site. Since the completion of the pest proof fence, the number of roosting birds has increased dramatically. By removing mammalian pests, an unexpected sanctuary has been created for communal roosting birds such as starlings and sparrows. There is growing concern about the large amounts of bird faeces produced each day and the associated nutrient load particularly as the pest fence encircles a low nutrient peat lake. In this study two methods were developed for estimating the relative abundance of the large roosting congregation, based on (1) gridded plates for gathering guano and (2) the acoustic energy of the roost cacophony.  The findings of this study are site specific; however, the guano plates and sound recorders could be implemented to estimate large bird numbers at other sites facing a roosting bird problem.