Effects of highways on bird distribution and soundscape diversity around Aldo Leopold’s shack in Baraboo, Wisconsin, USA

Abstract

In the 1940s, Aldo Leopold took extensive notes on birds and their sounds near his iconic shack in Baraboo, Wisconsin, USA. His observations, along with his land management techniques, helped frame his seminal book, A Sand County Almanac. After his death, two interstate highways were built near his property and subjected this historically significant area to traffic noise. While highways currently represent vital transportation corridors, their observed and potential impacts on biodiversity and ecosystem services are cause for concern. As the area including Leopold's shack is now an Important Bird Area, we sought to evaluate the impact of these highways on the bird community and its related acoustic diversity. In 2011, 150 avian point counts were conducted in the three main habitats composing the landscape-upland deciduous forest, floodplain forest, and herbaceous wetland. In 2012, soundscape recordings were collected in seven floodplain forest sites using automated passive acoustic recorders. We described the local bird communities and measured their acoustic diversity. Linear models accounting for additional factors including land cover and vegetation structure characteristics showed that as the distance from highways increased, bird community descriptors (overall abundance and species richness) and acoustic diversity increased (when relationships were significant). On the species level, forest interior specialists were negatively affected by the presence of the highways, contrary to edge specialists. In addition to the direct effects of the edges produced by the highway structure, this difference might be due to the masking effect of traffic noise on interior specialists' low-frequency vocalizations and their reliance on acoustic, as opposed to visual, communication. We conclude that while habitat structure is a principle driver of bird diversity on a broader scale, highway-induced changes in both habitat structure and soundscapes may affect bird communities.

Advancing avian road ecology research through systematic review

“…This coincided strongly with the sound average, equivalent sound level (LeQ 30 ), produced by the highway over 30 minutes (Rashidi et al, 2019). Khanaposhtani et al (2019) observed increased richness and abundance of forest interior species with distance from two major highways in Canada. This was attributed partly to the intrusion of traffic noise pollution into the surrounding landscape (Khanaposhtani et al, 2019).…”

“…Khanaposhtani et al (2019) observed increased richness and abundance of forest interior species with distance from two major highways in Canada. This was attributed partly to the intrusion of traffic noise pollution into the surrounding landscape (Khanaposhtani et al, 2019). Bird richness and abundance have also declined significantly through traffic noise playbacks in quiet (i.e., non-road) environments (McClure et al, 2013;Ware et al, 2015;Senzaki et al, 2020).…”

Disentangling LiDAR Contribution in Modelling Species–Habitat Structure Relationships in Terrestrial Ecosystems Worldwide. A Systematic Review and Future Directions

“…Canopy cover: Number of first returns above a height/total number of first returns [42]; Intensity sum of all non-ground points divided by intensity sum of all points [43]; Canopy gaps and ruggedness [44]; Fractional cover [45]; LiDAR penetration ratio (LPI), as the ratio between terrain points and total points [22].…”

“…Gini coefficient [48]; Simpson index [39]; Vertical gap index, measured as the total distance between individual canopy strata divided by maximum canopy height [43].…”

Soundscape dynamics of a cold protected forest: dominance of aircraft noise

“…If the negative effects of anthropogenic noise have been thoroughly studied at the individual level through animal behavior and animal physiology studies (Slabbekoorn and Ripmeester 2008 ; Barber et al 2009 ; Brumm 2013 ; Shannon et al 2015 ), less research has been conducted at larger ecological scales. Anthropophony has been shown to be a prevalent part of preserved soundscapes (Francis et al 2011a , b ; Mullet et al 2015 ), and to have a role in the structure of soundscapes, in relation to massive noise generators, such as industrial sites (Duarte et al 2015 ; Deichmann et al 2017 ) or highways (Munro et al 2018 ; Khanaposhtani et al 2019 ). Anthropogenic noise can alter the benefits that humans may experience from natural soundscapes (Francis et al 2017 ).…”