The Effects of Vegetative Disturbance on Winter Riparian Bird Populations: A Multinomial Analysis

Abstract

Two rural stream sites intended for enhancement were evaluated pre-construction to collect baseline data on riparian bird populations and vegetative characteristics. The fixed-radius point count method was used to survey the winter avian community, and vegetative attributes (DBH, percent tree canopy cover, volume of downed woody debris) were collected within each of the radius plots. Using a multinomial regression, the probability of detecting each bird species was calculated for each survey plot and subsequently related to the characteristics of the vegetation to create a model that describes the winter bird-habitat relationship. The model predicted that major vegetative disturbances would be highly detrimental to the diversity of the winter bird community, and demonstrated that mature bottomland hardwood forests are ideal for the numerous habitat preferences of different wintering birds. These data provide the basis for multiple suggestions for stream restoration practices on sites where the riparian buffer is already composed of mature bottomland hardwood forests, the most important of which is conserving and improving the established vegetation by considering stream mitigation practices that are less disruptive than restoration.