Running head: Variation in nest characteristics and fitness Substrate and structure of ground nests have fitness consequences for an alpine songbird DEVIN R. DE ZWAAN 1 * & KATHY MARTIN 1 1 Department of Forest and Conservation Sciences, 2424 Main Mall, University of British Columbia, BC, V6T1Z4, Canada * Corresponding author. E-mail: drdezwaan@gmail.com, Telephone: (1)778-879-5429 This is the accepted version of the following article: de Zwaan, D. R., & Martin, K. (2018). Substrate and structure of ground nests have fitness consequences for an alpine songbird. Ibis. Accepted Author Manuscript. doi:10.1111/ibi.12582, which has been published in final form at [http://onlinelibrary.wiley.com/doi/10.1111/ibi.12582/full]. This article may be used for non- commercial purposes in accordance with the Wiley Self-Archiving Policy [ https://authorservices.wiley.com/author-resources/Journal-Authors/licensing-open-access/open- access/self-archiving.html ].