Spatio-temporal patterns in beaver pond complexes as habitat for Eastern spotted newts (Notophthalmus viridescens) in a hemlock-northern-hardwood zone in Western New York State

Abstract

Amphibians are among the most threatened of animal groups, so understanding the nature and dynamics of their habitats is essential to their conservation. The Eastern Spotted Newt (Notophthalmus viridescens) prefers shallow quiescent soft-bottomed habitat, generally in small streams and pools. An increasingly important source of such habitat in the Northeast has been beaver ponds, which are abundant within the 27K ha Allegany State Park, NY, studied during this thesis. The main objective was to determine the influence of landscape-scale (size, age, and stability of ponds) and local habitat conditions (flow regime, sedimentary environment, submerged/emergent vegetation) on the use of beaver ponds as spotted newt habitat. Georeferenced satellite imagery between 1995 and present-day of five multi-pond complexes and one artificial impoundment were used to assess spatio-temporal stability of ponds and pond complexes, while proximate habitat characteristics were catalogued at individual survey points. Newts were visually surveyed in shallow water within 1 m of shoreline on multiple dates during April -- June 2015. Both a factorial ANOVA (pond complex X habitat type) and multivariate Principle Components Analysis (PCA) ordination of landscape and habitat variables were used to assess patterns in habitat use by spotted newts. Newts were consistently abundant at pond complexes that were the most stable and predictable over time, which was a reflection of smaller watershed areas and lower potential for flood damage and breaching of dams. In contrast, less stable ponds yielded lower newt abundances. Some evidence suggested mud-bottomed pond margins, back-flooded connecting channels, and former pond remnants might be preferred habitat within ponds, but the overarching pattern was driven by landscape-scale variables.