Disturbance by Large Scale Gold Mining: Effects on Long Distance Migration in the Ruby Mountains of Eastern Nevada
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Authors
Blum, Marcus E.
Issue Date
2014
Type
Thesis
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Keywords
anthropogenic disturbances , migration , mining , mule deer , Nevada , resource selection
Alternative Title
Abstract
Loss of migratory corridors has been identified as an important ecological issue among species that exhibit long-distance migration worldwide. Increased mineral exploration and development has raised the level of concern over the protection of terrestrial migration routes for ungulates. Mineral exploration and other types of development may adversely affect migratory corridors for large herbivores, but little is known about functional impacts on energetics, resource selection, or fitness. To address these important questions we examined movement patterns and resource selection to understand the effects of an operating gold mine on a migratory pathway of mule deer (Odocoileus hemionus). We captured and applied radio collars to female mule deer on the migratory pathway and in the proximity of an active mine in the Ruby Mountains of eastern Nevada. We used Brownian Bridge Movement Models (BBMM) to delineate stopover sites for each individual during both the autumn and spring migrations. We calculated efficiency of movement and movement rate between stopover locations and throughout the mining area to determine the effects of the mine on movement patterns. We also used resource selection functions to determine if mule deer avoided areas with extensive excavation and disturbance of the land surface when navigating through the mine complex. Our results indicated a 4.7% greater efficiency of movement and 0.20 kph movement rate between stopover locations outside the mine when compared with movement through the mine complex. Additionally, mule deer migrating through the mine complex avoided the highest disturbance levels by spending the majority of their time in undisturbed habitat patches within the mine complex. These results suggest an increase in energy expenditures of mule deer navigating the highly disturbed areas, which may negatively affect migratory movements. Such increases in energy expenditure during migration may decrease survival or productivity of migratory populations of large terrestrial mammals.
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In Copyright(All Rights Reserved)