Explore the vast range of titles available.

Beaver (Castor canadensis) activity creates wetland habitats with varying hydroperiods important in maintaining habitat diversity for pond-breeding amphibians with significantly different breeding habitat requirements. We documented pond-breeding amphibian assemblages in 71 freshwater wetlands in Acadia National Park, Maine, USA. Using 15 variables describing local pond conditions and wetland landscape characteristics, we developed a priori models to predict sites with high amphibian species richness and used model selection with Akaike's Information Criterion to judge the strength of evidence supporting each model. We developed single-species models to predict wood frog (Rana sylvatica), bullfrog (R. catesbeiana), and pickerel frog (R. palustris) breeding site selection. Sites with high species richness were best predicted by 1) connectivity of wetlands in the landscape through stream corridors and 2) wetland modification by beaver. Wood frog breeding habitat was best predicted by temporary hydroperiod, lack of fish, and absence of current beaver activity. Wood frog breeding was present in abandoned beaver wetlands nearly as often as in nonbeaver wetlands. Bullfrog breeding was limited to active beaver wetlands with fish and permanent water. Pickerel frog breeding sites were best predicted by connectivity through stream corridors within the landscape. As beavers have recolonized areas of their former range in North America, they have increased the number and diversity of available breeding sites in the landscape for pond-breeding amphibians. The resulting mosaic of active and abandoned beaver wetlands both supports rich amphibian assemblages and provides suitable breeding habitat for species with differing habitat requirements. Land managers should consider the potential benefits of minimal management of beavers in promoting and conserving amphibian and wetland diversity at a landscape scale.

The return of Castor canadensis (beaver) to areas of their former range has restored a natural disturbance regime to wetland landscapes in North America. We used aerial photographs to study wetland creation and modification by beaver in Acadia National Park, ME, during a period of beaver population expansion (1944–1997). We quantified the change in the number of available ponded wetlands in the landscape during the study period and documented an 89% increase in ponded wetlands between 1944 and 1997. Spatial and temporal patterns of beaver colonization and changes in wetland vegetation and hydrology were recorded at six time periods (1944, 1953, 1970, 1979, 1985, and 1997) for 33 beaver-created wetlands for which we had current amphibian assemblage data. Beaver colonization generally converted forested wetlands and riparian areas to open water and emergent wetlands, resulting in significant increases in the percentage of open water and emergent wetland habitat and a decrease in the percentage of forested wetland area at the study sites. Temporal colonization of beaver wetlands initially favored large sites occurring lower in the watersheds; sites that were impounded later were generally smaller, higher in the watershed, and more likely to be abandoned by the end of our study. Our results suggest that beaver have not only increased the number of available breeding sites in the landscape for pond-breeding amphibians, but also the resulting mosaic of active and abandoned beaver wetlands is likely to provide suitable breeding habitat for a diversity of species.

STATEMENT SHOWING THE CONDITION OF THE MANUFACTURES AND BUILDERS' FIRE INSURANCE COMPANY OF NEW YORK, N. Y., DEC. 31, 1881.