Effects of oil infrastructure and associated noise on the stress physiology, growth and development of an altricial grassland songbird nestling

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Heathcote, Alexandra L.
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In recent decades, oil and gas development has increased in central North America, fragmenting grassland ecosystems and introducing anthropogenic noise to the soundscape. Chronic exposure to anthropogenic noise on the landscape may increase corticosterone levels in altricial songbird nestlings, potentially influencing growth rate, fledgling success, and adult behaviour. To determine how anthropogenic disturbance and chronic noise impacts the development of Chestnut-collared Longspur (Calcarius ornatus) nestlings, I isolated noise from the associated infrastructure by broadcasting generator-powered screwpump recordings on the short- and mixed- grass prairies of southeastern Alberta, and compared these impacts with those of real wells and controls. I measured basal corticosterone and stress response in nestlings and mothers as well as mass and outer primary length in nestlings as a metric for fitness. Surprisingly, I found nestlings closer to anthropogenic noise exhibited down-regulated HPA-axis activity as well as evidence to suggest that maternal stress mediated the relationship between noise and basal corticosterone. Mothers that responded strongly to novel stressors produced nestlings with longer primaries. In addition, across all sites nestlings with lower corticosterone were heavier. These results suggest that nestlings may benefit from living in noisy environments and that mothers may prepare their offspring for living in sub-optimal environments or growing up with sub-optimal care.
Nestlings, Grasslands, Corticosterone, Songbirds, Stress, Disturbance, Oil and Gas