Although locomotor performance and behaviour are closely linked to survival in many wild animals, our understanding of the potentially important co-adaptations between locomotor performance and behaviour is still limited. Our objective was to quantify the among-individual correlation (rind) and within-individual correlation (re) between locomotor performance and personality traits in wild eastern chipmunks (Tamias striatus). We repeatedly measured sprint speed, docility, and exploration behaviour and found that all traits were significantly repeatable. Sprint speed was not correlated with docility and time spent in the centre of the open field. However, sprint speed was significantly and negatively correlated with distance moved in the open field at both the among-individual (rind = − 0.59) and the within-individual (re = − 0.54) levels. Thus, individuals with high locomotor performance are less explorative in a novel environment, which is somewhat counter-intuitive and opposite to the predictions generated by the pace-of-life syndrome and the “phenotypic compensation” hypotheses. Our results suggest that sprint speed and exploratory behaviour are co-specialised traits as they can reinforce each other’s effects in reducing predation risk. In refuging species such as chipmunks (i.e. individuals have to leave a refuge to forage), low exploration levels may reduce exposure to predators and high sprint speed may further reduce the probability of capture given an encounter with a predator. Thus, looking at how locomotor performance and behaviour interact and contribute to fitness is key to understanding the multivariate architecture of—and co-adaptations among—ecologically relevant complex phenotypes.
Study site and animal capture
From May to August 2016, we monitored a free-ranging population of eastern chipmunks (Tamias striatus) at the Queens University Biological Station (44° 33′ N, 76° 19′ W). Various grids and trap lines around the property were rotated weekly, with an average of 15 Longworth traps set per day between 09:00 and 17:00. The traps were baited with peanut butter and visited at least every 2 h. Upon first capture, chipmunks were individually tagged on each ear using metal ear tags (National Band and Tag Company 1005-1) to allow future identification. For every capture, individuals were weighed using a 300-g Pesola scale (± 2 g) and checked for sex, parasites (ticks and botflies were the only parasites noted), and reproductive status. As this was the first year of data collection at this site, we could not age individuals; however, if individuals were less than 80 g upon first capture and appeared to be non-reproductive, they were identified as juvenile (Careau et al. 2010b). For all individuals greater than 80 g, males were identified as either scrotal (by the presence of an enlarged and darkened scrotum) or non-reproductive and females were categorised as pregnant (swollen abdomen and increased mass; excluded from this study), lactating (visible and swollen mammae; excluded from this study), receptive (swollen vulvae), or non-reproductive (Bennett 1972).
Docility was measured on every capture, directly at the capture site before any manipulations were done on the chipmunk (see below). After standard manipulations (see above), chipmunks were placed back into their trap for transport to the laboratory where we conducted the open-field tests (see below). After the open-field test, chipmunks were placed back into their trap for transport to a grass field for the sprint speed test (see below). Since chipmunks can quickly become habituated to the open-field test (Montiglio et al. 2010), we waited at least one week between successive open-field tests on a given individual. Therefore, chipmunks recaptured within one week of their open-field testing were transported directly to the grass field for sprint speed measurements. Chipmunks were regularly caught multiple times on a given day, in which case they were released onsite after docility measurements and standard manipulations.