Predicting effects of future development on a territorial forest songbird: methodology matters

Abstract

Context Projected increases in human population size are expected to increase forest loss and fragmentation in the next century at the expense of forestdwelling species. Objectives We estimated landscape carrying capacity (N k ) for Ovenbirds in urban, suburban, exurban, and rural areas for the years 2000 and 2050, and compared changes in N k with changes in occupancy probability.Methods Maximum clique analysis, a branch of mathematical graph theory, was used to estimate landscape carrying capacity, the maximum potential number of territories a given landscape is capable of supporting (N k ). We used occupancy probability maps as inputs for calculating Ovenbird N k in the northeastern USA and a spatially explicit growth model to forecast future development patterns in 2050. We compared occupancy probability with estimates of N k for urban, suburban, exurban, and rural areas for the years 2000 and 2050.Results In response to human population growth and development, Ovenbird N k was predicted to decrease 123Landscape Ecol (2018Ecol ( ) 33:93-108 https://doi.org/10.1007 23% in urban landscapes, 28% in suburban landscapes, 43% in exurban landscapes, and 20% in rural landscapes. These decreases far exceeded decreases in mean occupancy probabilities that ranged between 2 and 5% across the same development categories. Thus, small decreases in occupancy probability between 2000 and 2050 translated to much larger decreases in N k . Conclusions For the first time, our study compares occupancy probability with a species population metric, N k , to assess the impact of future development. Maximum clique analysis is a tool that can be used to estimate N k and inform landscape management and communication with stakeholders.

Drivers and Consequences of Alternative Landscape Futures on Wildlife Distributions in New England, United States

“…While current conditions appear to facilitate range expansion for gray fox, changes to New England's climate and land use may decrease gray fox occurrence in the future. Brown et al (2018) also showed that small declines in regional occurrence probability of bird species in New England can result in large declines in the actual number of territories that a region can support. This is an important consideration, as seemingly small changes in occurrence probability may translate to much larger shifts in a species actual abundance.…”