Abstract
Similarity or dissimilarity between 2 individuals that have formed a pair to breed can occur in morphology, behaviour and diet. Such patterns influence partners’ cooperation when rearing their offspring, consequently influencing reproductive success. They may confer different benefits, depending on species and contexts. However, the extent to which breeding partners are more similar in morphology, behaviour, and diet is poorly documented. Furthermore, the relationship between behavioural consistency and mate choice is particularly poorly understood. To investigate these issues, Kerguelen shags Phalacrocorax verrucosus, which are monogamous with high mate fidelity across years, were studied. Partners were equipped with GPS and diving behaviour loggers. Feather and blood samples were analysed for stable isotopes (δ13C, a proxy of foraging habitat, and δ15N, a proxy of diet/trophic position). Generalized linear mixed effects models and permutation tests were used to investigate pair similarity in morphology, foraging behaviour, behavioural consistency, overlap in foraging areas, and diets/foraging habitats. Mates were found not to exhibit size-assortative mating, but were more similar in foraging behaviour. They did not show assortative or disassortative mating based on foraging behavioural consistency. Furthermore, they followed more similar bearings and overlapped more in foraging areas. In accordance with this, partners were more similar in δ15N. Given the lack of assortative mating by morphology, the similarity in behaviour could be due to individuals selecting mates with similar foraging abilities, linked with individual quality, and/or subsequently using information gained from their partners’ foraging strategies (e.g. local enhancement). This could help breeding pairs increase their foraging efficiency and reproductive success.
Highlights
Similarity in behavioural traits within breeding pairs can have important, long-lasting effects on reproductive success and fitness in species with biparental care, probably because of reduced sexual conflictPublisher: Inter-Research · www.int-res.comMar Ecol Prog Ser 578: 183–196, 2017 formance, including offspring growth and survival (Spoon et al 2006, Schuett et al 2010, 2011, Rangassamy et al 2015)
Our aim was to determine whether (1) individuals exhibit size-assortative or -disassortative mating; (2) the foraging behaviour of partners was more or less similar compared to non-mated birds; (3) the consistency in foraging behaviour of partners was more or less similar compared to non-mated birds; (4) partners overlapped more or less than non-mated birds in foraging locations; and (5) partners exhibited more similar or dissimilar diets/foraging habitats compared to non-mated birds
A total of 20 Kerguelen shag Phalacrocorax verrucosus individuals were equipped with GPS data loggers (I-gotU GT120, Mobile Action; 44.5 × 28.5 × 13 mm, 12 g in air corresponding to ca. 0.5% of mean body mass) for 3 to 6 d at the end of the incubation/early chick-rearing period (26 November to 10 December, hereafter ‘incubation/early chickrearing’), when chicks were no older than 1 wk
Summary
Similarity in behavioural traits within breeding pairs can have important, long-lasting effects on reproductive success and fitness in species with biparental care, probably because of reduced sexual conflictPublisher: Inter-Research · www.int-res.comMar Ecol Prog Ser 578: 183–196, 2017 formance, including offspring growth and survival (Spoon et al 2006, Schuett et al 2010, 2011, Rangassamy et al 2015). Similarity in behavioural traits within breeding pairs can have important, long-lasting effects on reproductive success and fitness in species with biparental care, probably because of reduced sexual conflict. Disassortative mating with respect to the partners’ recognition cues may, lead to reduced inbreeding (Holman et al 2013). Disassortative mating can lead to the production of offspring of intermediate personality, associated with lower variance in survival in the long-term and higher life expectancy (Dingemanse et al 2004, Schuett et al 2010). Combinations of dissimilar behavioural traits within pairs could result in unstable and disharmonious conditions, generating high stress levels that have the potential to negatively influence reproduction (Von Holst 1998, Rangassamy et al 2015). The extent of mate similarity in behaviour is poorly investigated (Schuett et al 2010)
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