Effects of trap confinement on personality measurements in two terrestrial rodents

Abstract

In recent years, consistent individual differences in behavior, or personalities, have been a topic of increasing interest as researchers strive to understand and predict the responses of individuals and populations to anthropogenic changes. Behavioral studies in wild populations often require that animals are live trapped before behavioral observation can occur, and this is especially true in studies investigating animal personalities. However, it is unknown whether the amount of time confined to a live trap may regulate the behavior of trapped individuals. Specifically, if the duration of trap confinement directly influences behavior, then by obtaining wild animals through live trapping we may be confounding the very measurements of greatest interest. To investigate whether the duration of trap confinement influences the behavior of trapped individuals, we performed a study on two small mammal species, focusing specifically on personality traits. We positioned high-definition trail cameras facing Longworth small mammal traps in the field to observe capture events and record the time of capture. We then measured personality in captured deer mice (Peromyscus maniculatus) and southern red-backed voles (Myodes gapperi) using three standardized tests, and through linear and generalized linear models we found that the time an animal had spent confined to a trap before testing did not affect 86% of behaviors exhibited. Our results showed two weak behavioral effects of confinement duration on boldness and docility resulting from an interaction between the duration of confinement and whether or not an individual was naïve to trapping. Our results suggest that behavioral measurements of wild, trapped small mammals are not determined by the time spent confined to a trap. However, researchers should use caution and consider whether an animal is naïve to trapping during analysis since habituation to the live trap may play a role in the effects of confinement duration on behavior. OPEN ACCESSCitation: Brehm AM, Tironi S, Mortelliti A (2020) Effects of trap confinement on personality measurements in two terrestrial rodents. PLoS ONE 15(1): e0221136. https://doi.org/10. Observations 43� Only results from the top model (based on AICc scores) are shown. We have omitted occasions where the null model was the top model. See materials and methods for more information.

Measuring personality traits in Eurasian red squirrels: A critical comparison of different methods

“…Significant results (0 not included in the 95% CIs) personality traits for red squirrels, in both alpine and plain sites (Brehm & Mortelliti, 2018;Carter et al, 2013). This is similar to other studies on the same species, where repeatabilities for activity and immobility were also moderate (Mazzamuto et al, 2019;Santicchia, Wauters, Piscitelli, et al, 2020;Wauters et al, 2019), and on other studies on rodents where repeatability of activity measured in the OFT were from moderate to high (Tamiasciurus hudsonicus: Boon et al, 2008;Tamias striatus: Montiglio et al, 2012;Sciurus carolinensis: Mazzamuto et al, 2019, Santicchia, Wauters, Dantzer, et al, 2020Marmota flaviventer: Petelle et al, 2019;Peromyscus maniculatus, Myodes gapperi, Blarina brevicauda: Brehm et al, 2019, Brehm et al, 2020. Previous studies on the same species and on a different squirrel species also found low repeatability values for exploration measured in the OFT (Sciurus vulgaris: Santicchia, Wauters, Piscitelli, et al, 2020;Wauters et al, 2019;Sciurus carolinensis: Santicchia, Wauters, Dantzer, et al, 2020) and among-individual variation in the duration of exploration behaviours in the OFT was low, compared to other behavioural measures taken during the same tests (see Table S2; Santicchia, Wauters, Dantzer, et al, 2020; Table 1; Santicchia, Wauters, Piscitelli, et al, 2020; (Boon et al, 2008;Boyer et al, 2010;Martin & Réale, 2008;Patterson & Shulte-Hostedde, 2011).…”

Environmental heterogeneity and population density affect the functional diversity of personality traits in small mammal populations

“…The test is conducted prior to marking animals and once per session (to avoid test habituation) on new and recaptured individuals (minimum interval between tests is one month). In our previous work [26,36] we showed that trap confinement does not affect our behavioural measurements and that personality does not affect trappability, thus demonstrating that our sample is not biased towards certain personality types.…”

“…The area covered by each trapping grid (0.81 ha) was, at a minimum, less than 10% the area covered by each treatment and large enough to encompass multiple home-ranges of individual small mammals. Further details on methods are available in [9,26,35,36].…”

Land‐use change alters associations between personality and microhabitat selection

“…2018, Brehm et al. 2020) and microhabitat selection (Dueser and Shugart 1978, Longland and Price 1991, Mortelliti and Boitani 2007, Kellner and Swihart 2014).…”