Building for the future: Abandoned beaver ponds promote bird diversity

Abstract

We examined beaver (Castor canadensis) pond dynamics and associated riparian bird communities, based on call- response surveys. Following water disappearance, abandoned beaver ponds were invaded by grassy areas and alder shrubs and supported higher bird species numbers than nearby riparian areas. We detected a total of 49 species. At abandoned beaver ponds, the mean number of species was 6.4, whereas it ranged between 2.4 and 3.1 species for active beaver ponds, rivers, and lakes. Density of deciduous shrubs and graminoid cover, higher in abandoned beaver ponds, was positively associated to the number of species of birds. However, riparian avian diversity was lower near clearcuts and large water areas. Beaver population control or geographic confinement may suppress both spatial and temporal dynamics of beaver pond creation and abandonment, and could impact riparian vegetation and birds.