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 I want to thank my advisor, Nicola Koper. Nicky has let me progress and find my way through the difficulties of graduate school without judgment and helped make my experience a positive one. She believed in me as a researcher and I could not have asked more from an advisor.For their time, support, and positive attitudes, I want to thank my committee members Rachel Vallender, Margaret Docker, and Kevin Ellison. Countless people have helped me and were vital to the completion of this project. I would have no results if it wasn't for Chelsea Enslow, Erin Wieler and Arfa Khan's assistance in the lab. Thank you to all my predecessors and fellow graduate students for all the knowledge and skills you have shared with me, as well as for your friendships: Patricia Rosa,