Effects of anthropogenic noise on songbirds and how mitigation may differ in high and low-income countries

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Cyr, Marie-Eve
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The negative effects of anthropogenic noise on wildlife, particularly birds, have been widely studied but major gaps in scientific knowledge remain. The inequality of information available and studies conducted between the high-income countries of the Global North, and middle- and low-income countries of the Global South is limiting the applicability and implementation of conservation projects. I investigated the effects of noise in two different contexts: effects of noise from oil extraction in the North American grasslands on chestnut-collared longspurs (Calcarius ornatus) and effects of noise from urban activity in the Caribbean island of Grenada on house wrens (Troglodytes aedon). I tested whether distance from oil development, distance from infrastructure noise, brood size, and parent size and weight affected nestling sex ratio allocation in chestnut-collared longspurs. Large broods were skewed towards male nestlings, and bigger females and older social males reared more male nestlings, indicating that competitiveness and experience may be valuable traits for successful breeding and greater fitness in adults. Male nestlings were also more likely to be produced further from screwpump and silent playback treatments, suggesting that habitat farthest from anthropogenic development favours production of male nestlings. My results suggest that both biological and environmental characteristics interact to regulate sex ratio allocation in my study population. Conservation managers should focus on improved planning to limit landscape fragmentation and reduce the acoustic footprint of oil development. In contrast, I tested whether Grenadian house wrens living in urban and rural areas sing differently. I found that Grenadian house wrens in urban habitats sang shorter introductions, faster trills, and increased the low frequencies of their introductions and whole songs. My result demonstrated that Grenadian house wrens adjusted their song to counteract acoustic masking from anthropogenic noise using some strategies that are unlike their mainland cousins and adapted for urban environments in Small Island Developing States. Additional research is needed to understand the challenges faced by wildlife in the Global South, including in Small Island Developing States. Conservation efforts in the Global South should focus on education and public outreach that include local and Indigenous communities to create community-based conservation programs and research.
Conservation, Songbird, Anthropogenic disturbance, Grassland, Neotropics, Oil development, Sex ratio, Song plasticity
M.-È. Cyr, K. Wetten, M. H. Warrington, and N. Koper. 2020. Variation in song structure of house wrens living in urban and rural areas in a Caribbean small island developing state. Bioacoustics, DOI: 10.1080/09524622.2020.1835538.