1. Citizen science reveals negative effects of roads and road traffic on amphibians across spatial scales and regions in the eastern US
Tom A. Langen
Dept. of Biology
Clarkson University
Cosentino et al. (2014) Citizen science reveals widespread negative effects of roads on amphibian distributions. Biological Conservation 180:31-38.
Marsh et al. (2016) Effects of roads and land use on frog distributions across spatial scales and regions in the Eastern and Central United States. Diversity and Distributions 23: 158–170.

2. Road Effects on Frogs Road Mortality Habitat Change Barrier Effect
Habitat – barrier, toxicity, cover, access
Road mortality – ethics/welfare, safety, conservation
Barrier – habitat access, population connectivity, genetic connectivity
Barrier Effect

3. Frogs & Roads Slower & less perceptible.
Roadside habitat & roads a greater barrier.
Less data available on road encounters.
Less data available on habitat at appropriate scales.
Lower public concern.

4. Frogs & Roads
Inappropriate behavioral responses to roads and vehicles.
Much more severe exposure to surrounding environment.
Perceptual range more narrow, depth perception poorer.
Anurans are the most frequently encountered vertebrate road-kill.

5. Scaling-Up Matters in Anuran Road Ecology
Behavior on a network scale, local landscape, and local interactions at road

6. Big Questions about Roads & Frogs
Are general anuran declines associated with roads?
If so, is it the road barrier, the road mortality, or habitat change?
At what spatial scale are road effects prevalent?

7. North America Amphibian Monitoring Program NAAMP
Citizen science roadside anuran call survey, at assigned roadside wetlands along route, 3 nights across breeding season, repeatedly over multiple years – discontinued after 2015.
Additional critical data provided: nuisance noise, chorus intensity, weather conditions.
Data needs ‘cleaning up’.
Anurans vary in detectability.
There are geographic trends in anuran species richness
Number of species highest where warm and wet, correlates with Net Primary Productivity

8. 1620 stops
Each stop is within 200 m of a wetland!
Amphibian data from the North American Amphibian Monitoring Program
Compile landscape variables for NAAMP survey locations
Each class characterized landscape data and collated amphibian data for assigned states (13 states: 406 routes)
Each route has 10 stops separated by at least 0.5 km where auditory chorus surveys are conducted for 5 min 3-4 times/year. Also record number of cars and whether or not noise interfered.
Characterized landscape structure within 1-km around each stop. Only stops 1,4, 7, and 10 were used in each route to avoid overlap in buffers.
NAAMP:
Citizen science
Volunteers assigned randomly-chosen routes and select stops based on visual confirmation of aquatic habitat within 200 m of road
10 stops per route, each 0.5 km from previous stop
Routes surveyed 3-4 times per year in spring and summer
Surveyors record species heard calling and weather-related variables
Surveyors record number of cars and presence of noise
13 states
406 routes

10. Traffic causes the greatest loss of species – role for roadkill.
Road density and habitat change also associated with species richness loss – role for barrier effect and habitat alteration.
Patterns hold for individual species occurrences.
Traffic noise effect on detection is not the spurious cause of apparent road effects.

11. What Spatial Scale Matters?
More
Fewer
species
Higher road densities, more developed regions have fewer species at all spatial scales.
Agricultural areas are associated with fewer species only at the largest scale.
Greater wetland coverage is associated with more species at all spatial scales.
Landscape
Local

12. Landscape Patterns Vary Regionally
Northeast
Southeast
Midwest

13. Bigger Roads have a Bigger Impact
Unpaved Roads

14. Take-home Messages:
Roads & road traffic may cause anuran species losses at a continental scale.
Road effects occur at the local and landscape scales.
Road effects interact synergistically with land cover/landuse.
Road & landcover effects on anurans vary geographically.
Citizen science data is invaluable for detecting continental-scale trends.
Collaborative student research across universities can be productive.