Individual consistency in exploration and shyness but not activity in smooth newts (Lissotriton vulgaris): the effect of habituation?

Abstract

Behavioural consistency (i.e. personality) is an important aspect of behavioural ecology that has yet to be thoroughly examined in amphibians. Currently published studies often address only one or two aspects of personality, using many different methods for evaluating behavioural consistency. This is the first study focusing on all relevant behavioural traits and their relationships in urodele amphibians. Based on three trials within the experiment, we examined the consistency of activity (time spent moving), the boldness (latency of the first movement and time spent escaping) and the exploration (number of visited segments of the test arena) of 42 smooth newts (Lissotriton vulgaris). Individual consistency, calculated through the intraclass correlation coefficient (ICC), was low in newt activity (ICC = 0.192) and was moderate in boldness (0.476) and in exploration (0.403). Activity was moderately consistent for each trial (0.425), indicating possible habituation, supported by a decrease in mean activity throughout the trials. Newt activity, shyness and exploration were correlated throughout the experiment, suggesting the possible existence of a common selective pressure. With a summary of existing studies and their effect sizes, we aim to highlight the inconsistencies in the methods and in the results of these studies, to emphasize the need for a complex approach to the study of amphibian personality and the need for a standardized methodology, which would solve the current difficulties in comparing published results.

The relationships between toad behaviour, antipredator defences, and spatial and sexual variation in predation pressure

“…The cylinder was built with a metal mesh (5 mm light), which allowed acclimation to the experimental setting. After 2 min, the cylinder was gently removed in the vertical plane, and the toad’s activity was recorded for 10 min ( Chajma, Kopecký & Vojar, 2020 ).…”

“…I measured several variables as surrogates of different traits of alleged relevance in the behaviour of animals in general ( Réale et al, 2007 ) and of amphibians in particular ( Kelleher, Silla & Byrne, 2018 ). Activity time was the amount of time (s) the toad spent moving ( Chajma, Kopecký & Vojar, 2020 ). Exploration behaviour was estimated as the number of squares visited (excluding squares that had been visited before; Chajma, Kopecký & Vojar, 2020 ) and the number of square visits (counting the number of times any square was visited, including repeated visits; Carlson & Langkilde, 2013 ).…”

“…Activity time was the amount of time (s) the toad spent moving ( Chajma, Kopecký & Vojar, 2020 ). Exploration behaviour was estimated as the number of squares visited (excluding squares that had been visited before; Chajma, Kopecký & Vojar, 2020 ) and the number of square visits (counting the number of times any square was visited, including repeated visits; Carlson & Langkilde, 2013 ). These measures differ in the fact that the former assumes that the individual distinguishes and keeps track of the areas that have already been visited, whereas the latter assumes the opposite ( Carlson & Langkilde, 2013 ).…”

“…These measures differ in the fact that the former assumes that the individual distinguishes and keeps track of the areas that have already been visited, whereas the latter assumes the opposite ( Carlson & Langkilde, 2013 ). Time until the first move ( i.e ., latency) was also recorded, as a surrogate of the shyness/boldness gradient, as bolder individuals are expected to start moving sooner ( Chajma, Kopecký & Vojar, 2020 ). The use of space is also widely considered a surrogate of the shyness/boldness gradient, in amphibians ( Réale et al, 2007 ; Carlson & Langkilde, 2013 ; Chajma, Kopecký & Vojar, 2020 ) and other taxa ( Burns, 2008 ; Harris, D’Eath & Healy, 2009 ).…”

“…Time until the first move ( i.e ., latency) was also recorded, as a surrogate of the shyness/boldness gradient, as bolder individuals are expected to start moving sooner ( Chajma, Kopecký & Vojar, 2020 ). The use of space is also widely considered a surrogate of the shyness/boldness gradient, in amphibians ( Réale et al, 2007 ; Carlson & Langkilde, 2013 ; Chajma, Kopecký & Vojar, 2020 ) and other taxa ( Burns, 2008 ; Harris, D’Eath & Healy, 2009 ). Specifically, thigmotaxis, the tendency for some individuals to remain in the periphery of their enclosures next to the walls rather than in the open areas, has been regarded as an anxiety-like, predator-avoidance behaviour as opposed to the boldness subjacent to the use of open areas ( Harris, D’Eath & Healy, 2009 ; Carlson & Langkilde, 2013 ; Chajma, Kopecký & Vojar, 2020 ).…”