Spatial risk assessment of eastern monarch butterfly road mortality during autumn migration within the southern corridor.

Autor: Kantola, Tuula1 tuula.kantola@helsinki.fi, Tracy, James L.1, Baum, Kristen A.1, Quinn, Michael A.1, Coulson, Robert N.1
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Zdroj: Biological Conservation. Mar2019, Vol. 231, p150-160. 11p.
Abstrakt: Abstract Road mortality may contribute to the population decline of eastern monarch butterflies (Danaus plexippus L.). We estimated autumn monarch roadkill rates within the primary Oklahoma to Mexico southern migration corridor (i.e., Central Funnel). Dead monarchs were surveyed along Texas roadsides during four weeks of autumn migration in 2016 and 2017. Roadkill averaged 3.4 monarchs per 100 m transect, reaching 66 per 100 m in a roadkill hotspot in southwestern Texas. Extrapolations of Central Funnel roadkill based on survey data and road types were 3.6 and 1.1 million in 2016 and 2017, respectively. Spatial distribution of roadkill across the Central Funnel was projected from Texas survey data using 30 m resolution MaxEnt niche models. Highest roadkill probability was linked to arid climate and low human population density. The latter variables may not be directly related to roadkill, but instead represent indirect correlates of increased densities of monarchs where the migration corridor narrows southwards. The higher roadkill projected in southwest Texas and Mexico by MaxEnt models agrees with previously reported monarch roadkill hotspots. MaxEnt-based 2016–2017 projections for annual roadkill rates throughout the Central Funnel averaged 2.1 million. This figure is similar to the result by simple extrapolation, and represents about 3% of the overwintering monarch population for these years. Mitigation at roadkill hotspots in the Central Funnel could reduce monarch roadkill mortality during migration and contribute towards conservation efforts for the monarch butterfly. Graphical abstract Unlabelled Image Highlights • Texas autumn monarch roadkill averages 3.4/100 m, reaching 66/100 m in hotspots. • Central Funnel estimated roadkill ranged from 0.2 to 2 million in 2017 and 2016. • MaxEnt projected 1.3 million overall roadkill, mainly in West Texas and Mexico. • Central Funnel roadkill may represent 2–3% of monarch overwintering population. • MaxEnt models can guide mitigation efforts needed to reduce monarch roadkill. [ABSTRACT FROM AUTHOR]
Databáze: GreenFILE
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