Search

This is a manuscript version of an article published as: Haines, J.A., Nason, S.E., Skurdal, A.M.M., Bourchier, T., Boutin, S., Taylor, R.W., McAdam, A.G., Lane, J.E., Kelley, A.D., Humphries, M.M., Gorrell, J.C., Dantzer, B., Coltman, D.W., & Hämäläinen, A. (2020). Sex- and context-specific associations between personality and a measure of fitness but no link with life history traits. Animal Behaviour, 167, 23-29. https://doi.org/10.1016/j.anbehav.2020.06.013 The pace-of-life syndrome hypothesis posits that personality traits (i.e. consistent individual differences in behaviour) are linked to life history and fitness. Specifically, fast-paced individuals are predicted to be proactive (i.e. active and aggressive) with an earlier age at first reproduction, a shorter life span and higher fecundity than slow-paced individuals. Environmental conditions and sex differences may be important in maintaining behavioural and life history variation in populations and may influence the covariance of personality with life history or lifetime fitness. However, these effects are rarely tested together. We investigated whether the occurrence of a resource pulse (called a mast year) during adulthood altered the associations between personality and life history traits or lifetime offspring production in adult North American red squirrels, Tamiasciurus hudsonicus. Despite accounting for environmental context during adulthood, we found no evidence of an overall pace-of-life syndrome in this population as personality was not associated with age at first reproduction or longevity in either sex. Males and females had similar activity levels, but females were more aggressive, potentially due to the fitness benefits of protecting their offspring from predation. In all females, regardless of mast experience, there was no association between activity and lifetime pup production, but there was a positive association between aggression and lifetime pup production. In males that experienced a mast, there was a positive association between lifetime pup production and both activity and aggression. In males that did not experience a mast, there was no association between activity and lifetime pup production, but there was a negative association between aggression and lifetime pup production. Lifetime recruit production (number of adult offspring recruited into the breeding population) in either sex was not influenced by activity or aggression regardless of mast experience. Overall, our results suggest that the infrequent occurrence of mast years may contribute to maintaining variation in personality traits in red squirrels. Pre-print version This is a manuscript version of an article published as: Haines, J.A., Nason, S.E., Skurdal, A.M.M., Bourchier, T., Boutin, S., Taylor, R.W., McAdam, A.G., Lane, J.E., Kelley, A.D., Humphries, M.M., Gorrell, J.C., Dantzer, B., Coltman, D.W., & Hämäläinen, A. (2020). Sex- and context-specific associations between personality and a measure of fitness but no link with life history traits. Animal Behaviour, 167, 23-29. https://doi.org/10.1016/j.anbehav.2020.06.013 https://viurrspace.ca/bitstream/handle/10613/23323/GorrellAB.pdf?sequence=3

Interactions with conspecifics are an important aspect of an individual's environment. Although it is well known that the presence of conspecifics can have important effects on behaviour, in general it is also now acknowledged that the composition of the social environment can vary, and that this variation may have profound effects on individual behaviour and fitness. Using a wild population of North American red squirrels, Tamiasciurus hudsonicus, we investigated the importance of the composition of the social environment in a territorial species by assessing whether the risk of intrusion faced by territory owners varied with the degree of relatedness and familiarity in their social neighbourhoods. To test this, we conducted temporary removals of territory owners and observed the time until intrusion and the identity of intruding individuals. We found that individuals in neighbourhoods with low average familiarity faced a higher risk of intrusion and that unfamiliar neighbours were more likely to intrude. Surprisingly, we found that related neighbours also posed a higher risk of intrusion. The results from our study suggest that familiarity with neighbours may be an ecologically and evolutionarily relevant measure of the social environment, even in a species considered to be ‘asocial’. Future studies should consider the potential importance of the social environment, which has heretofore been mostly overlooked, as a relevant selective pressure in asocial, territorial species.

The ability to discriminate among individuals, or among classes of individuals, can provide animals with important fitness benefits. Although several mechanisms for discrimination are possible, most require animals to show stable phenotypic variation that reflects their identity or their membership in a particular class (e.g. sex, mate, kin). For territorial animals that rarely interact physically, vocalizations could serve as long-distance signals that facilitate discrimination. In this study, we tested whether the territorial rattle vocalizations of North American red squirrels, Tamiasciurus hudsonicus, are repeatable, and whether they could hence provide the basis for multiple types of discrimination. We measured four structural features from two rattles from each of 76 marked squirrels. All four features were repeatable, which is consistent with territorial rattles being individually distinctive. We then conducted a playback experiment to determine whether squirrels use rattles for discrimination. Specifically, we tested whether squirrels discriminate between the rattles of neighbours and non-neighbours, and kin (coefficient of relatedness, r ≥ 0.25) and non-kin (r

Parasites can negatively affect their host’s physiology and morphology and render host individuals less attractive as mating partners. The energetic requirements of defending against parasites have to be traded off against other needs such as feeding activity, territoriality, thermoregulation or reproduction. Parasites can affect mating patterns, with females preferentially mating with parasite-resistant or parasite-free partners. We tested experimentally whether removal of both ectoparasites and endoparasites on free-living, male Columbian ground squirrels, Urocitellus columbianus, affected male mating behaviour, reproductive success and seasonal and posthibernation weight gain compared to control males. We predicted that experimental males would lose less body mass and mate more often than control males. In addition, we predicted experimental males would copulate earlier than control males in the mating sequences of receptive females and sire more offspring, because this species exhibits a strong first-male paternity advantage. Parasite treatment significantly reduced the parasite loads of experimental males. None of these males had ectoparasites at the end of the season, compared to 70% infestation of the control males. However, contrary to our expectations, the experimental treatment did not affect male reproductive behaviour (mating frequency, mating position, consort duration and mate-guarding duration), did not increase male reproductive success, and did not influence male body mass. We conclude that parasite infestation plays a minor role in affecting male reproductive behaviour, maybe because of the overall low infestation rates. Alternatively, males may be able to compensate for any costs associated with moderate loads of parasites.