Behaviour (2019) DOI:10.1163/1568539X-00003535 brill.com/beh Are nest defense behaviours and fitness components linked in white-rumped swallows (Tachycineta leucorrhoa)? Uschi Wischhoff a,∗ , Fernando Marques-Santos a , Giselle Bonetti b , Lilian T. Manica c , James J. Roper b and Marcos Rodrigues d a Pós-graduação em Ecologia, Conservação e Manejo de Vida Silvestre, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil b Pós-graduação em Ecologia e Conservação, Universidade Federal do Paraná, Curitiba, Brazil c Departamento de Zoologia, Universidade Federal do Paraná, Curitiba, Brazil d Departamento de Zoologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil * Corresponding author’s e-mail address: uschiw@gmail.com Received 8 July 2018; initial decision 27 August 2018; revised 7 October 2018; accepted 7 December 2018 Abstract How are personalities maintained in wild animal populations? A possible mechanism is the ex- istence of trade-offs between fitness components (survival and reproductive success) among be- havioural types. We investigated this trade-off in white-rumped swallows (Tachycineta leucorrhoa) by capturing adults and monitoring their reproduction over time. We focused on the personality trait of nest defence against a human. We found that swallows with different levels of nest defence had similar probability to return from migration between two years (a proxy for survival). In one year, swallows that defended their nests more boldly were also more likely to succeed. However, nest defence was not linked to nestling weight or number of fledglings. Thus, we found no evidence of a trade-off between fitness components. It is possible that the investigated relationships become relevant only in extreme years that severely alter the costs and benefits of this behaviour. Keywords boldness, capture-mark-recapture, life-history trade-off, MARK, pace-of-life, personality, nestling size, nest success.  Koninklijke Brill NV, Leiden, 2019 DOI 10.1163/1568539X-00003535