Proportion of forest surrounding breeding habitat predicts newt condition and fluctuating asymmetry

We need urgent conservation efforts to curb global amphibian declines. Individual indicators provide valuable insights into how amphibian populations respond to different management practices. We compared body condition and fluctuating asymmetry of individual alpine newts (Ichthyosaura alpestris) from ten populations across a gradient of both terrestrial and aquatic structural habitat complexity. Newt body condition was better in ponds surrounded by a greater proportion of forest (P < 0.001, estimate ± SE = 0.46 ± 0.11). Moreover, newts in such ponds were more symmetrical than conspecifics in ponds surrounded by less forest (P < 0.01, estimate ± SE = -0.25 ± 0.09). Neither structural complexity of ponds nor the complexity of the terrestrial environment had a significant impact on alpine newt body condition and fluctuating asymmetry. Our findings suggest a sufficient proportion of forest adjacent to the breeding habitat is important in sustaining adult condition of a common semi-aquatic amphibian.