Habitat provision is a major driver of native bird communities in restored urban forests

Abstract

Urbanization, and the drastic loss of habitat it entails, poses a major threat to global avian biodiversity. Ecological restoration of urban forests is therefore increasingly vital for native bird conservation, but control of invasive predators may also be needed to sustain native bird populations in cities where species invasions have been particularly severe. We evaluated restoration success by investigating changes in native bird communities along a restoration chronosequence of 25 restored urban forests representing 72 years of forest development, which we compared to two target reference systems and a control system. We hypothesized that total species richness and relative abundance of native forest birds would increase with the age of restoration planting. We further hypothesized that relative abundance of rats, possums and cats would negatively impact native birds, while amount of native forest in the surrounding landscape would have a positive effect. We used structural equation modelling (SEM) to investigate the relative influence of forest structure (complexity index, tree height, canopy openness, basal area, species richness and density), landscape attributes (patch area, perimeter length, landscape composition within three buffer zones, distance to the nearest road and water source) and invasive mammalian predator indices of relative abundance on total species richness and relative abundance of native forest birds. Species richness increased with age of restoration planting, with community composition progressing towards that found in target reference systems. SEM revealed that years restored was a direct driver of bird species richness but an indirect driver of abundance, which was directly driven by canopy openness. Contrary to our predictions, invasive mammals had no significant effect on native bird species richness or abundance. Our results demonstrate that provision and improvement of habitat quantity and quality through restoration is the vital first step to re‐establishing native forest bird communities in cities.

Tree functional composition, functional diversity, and aboveground biomass show dissimilar trajectories in a tropical secondary forest restored through assisted natural regeneration

“…The CWM of biotically dispersed species was significantly lower in the secondary than old‐growth forest, which suggests that a full recovery of biotic dispersal might take longer than 22 years, for instance 40–50 years in central Panama (Estrada‐Villegas et al, 2022). Since the ability of animals to colonize restored areas depends on vegetation structure (Elliot Noe et al, 2022), we predict that full recovery of the secondary forest structure (i.e., tree height and aboveground biomass) might facilitate recovery of biotic dispersal.…”

“…depends on vegetation structure (Elliot Noe et al, 2022), we predict that full recovery of the secondary forest structure (i.e., tree height and aboveground biomass) might facilitate recovery of biotic dispersal.…”

Of acoustics and avifauna: An integrative approach to avian ecology across the Southern Hemisphere

“…Given the archipelago's unique biogeographical history (Cooper & Millener 1993), biophonies in urban soundscapes in Aotearoa New Zealand are dominated by bird species. Even more so in urban forested reserves, which provide valuable habitat for native species (Chapter3; Noe et al 2022). This means that variability in these acoustic environments is likely driven by bird vocalisations, but that acoustic index responses could rather be linked to factors such as vocalising behaviour or species abundance Maintaining diverse and well dispersed functional and phylogenetic features of biological communities could benefit ecosystem processes in cities (Steenberg et al 2017), while greater taxonomic richness could have wide-ranging benefits, including improved human wellbeing (Wolf et al 2017;Methorst et al 2021a;Methorst et al 2021b).…”

“…While predation is often highlighted as a primary driver of composition and persistence of bird communities in Aotearoa New Zealand, relatively little is known about how it interacts with urbanisation. Noe et al (2022) recently presented evidence of habitat provision driving native bird species abundance and richness in two other urban centres on the archipelago's North Island. I build on this by exploring functional, phylogenetic, and taxonomic responses to urban forest patch structural features and the presence of introduced mammalian predators.…”

“…I build on this by exploring functional, phylogenetic, and taxonomic responses to urban forest patch structural features and the presence of introduced mammalian predators. In addition, many studies, including in Aotearoa New Zealand, singularly focus on native bird communities (Linck et al 2020;Benitez et al 2021;Noe et al 2022), which often therefore fails to take account of competition and/or co-occurrence of non-native species or their influence on functional and/or phylogenetic community features (Chace & Walsh 2005;González-Oreja et al 2018). I take a broader approach, with the consideration of both non-native species and non-native forests.…”