Choice of conflict resolution strategy is linked to sociability in dog puppies

Abstract

Measures that are likely to increase sociability in dog puppies, such as appropriate socialisation, are considered important in preventing future fear or aggression related problems. However, the interplay between sociability and conflict behaviour has rarely been investigated. Moreover, while many studies have addressed aggression in domestic dogs, alternative, non-aggressive conflict resolution strategies have received less scientific attention. Here we tested 134 Border collie puppies, aged 40–50 days, in a personality test which included friendly interactions with an unfamiliar person, exposure to a novel object, and three brief restraint tests. Considering the latter to be mild ‘conflict’ situations, we analysed whether the puppies’ behaviour in the restraint tests was related to their sociability or to their boldness towards the novel object. Strategies employed by the puppies during restraint tests included trying to interact socially with the experimenter, remaining passive, and attempting to move away. In line with findings from humans and goats, puppies scoring high on sociability were more likely to adopt an interactive conflict resolution strategy, while those with low sociability scores tended to react passively. In contrast, avoidance behaviours were unrelated to sociability, possibly reflecting inconsistency in the flight strategy in dogs. Boldness towards a novel object was not related to sociability or to puppies’ reactions in restraint tests. This is one of the first studies to demonstrate a link between sociability and conflict resolution strategies in non-human animals.

Introduction

Group-living confers many advantages to animals such as increased foraging or prey-capture efficiency, defence of kills and territory, vigilance and defence against predators, and rearing of young (Krause and Ruxton, 2002). However, there are costs associated with sociality such as increased competition, incompatible goals, or clashes of interest regarding the coordination of activities or travel decisions, which may lead to inter-individual conflicts (Aureli and de Waal, 2000, Preuschoft and van Schaik, 2000, Aureli et al., 2002, Bergmüller and Taborsky, 2010). To maintain the benefits of group living and avoid the costs of aggressive interactions, behavioural conventions such as greeting gestures, reconciliation (affiliative post-conflict behaviours between former adversaries), and the establishment of dominance relationships are common in group living animals (Aureli and de Waal, 2000, Preuschoft and van Schaik, 2000, Aureli et al., 2002).

Conflict management strategies such as appeasement, submission, or avoidance serve to increase tolerance within the group, control aggression and reduce conflicts (reviewed in Aureli and de Waal, 2000, Aureli et al., 2002, Miranda-de la Lama et al., 2011). In the behavioural context, a strategy can be defined as a behaviour or collection of behaviour patterns which an individual uses to achieve a goal, whereby different behavioural solutions to the same problem may be equally successful (Mendl and Deag, 1995). It has been suggested that personality represents an important underlying factor for individuals’ choices of strategy (Miranda-de la Lama et al., 2011). Work primarily on rodents and some birds has shown that responses to challenge – referred to as ‘coping styles’ – are often related to a suite of other behavioural tendencies, as well as physiological responses: Proactive individuals are bolder, more explorative, and tend to react to stressful events with a fight-or-flight response, whereas reactive individuals show lower aggressiveness, tend to freeze in aversive situations, and are more flexible to environmental changes (Benus et al., 1991, Koolhaas et al., 1999, Carere et al., 2010).

In humans, personality factors, especially those related to social interactions – extraversion and agreeableness – are suggested to be helpful predictors of individual preferences of conflict resolution strategies (Wood and Bell, 2008). Similarly, it has been suggested that behaviour, such as use of aggression, in non-human animals can be predicted and manipulated based on a knowledge of individual coping strategies (Mendl and Deag, 1995). However, there is a lack of studies on conflict behaviour other than aggression and post-conflict reconciliation (reviewed in Aureli and de Waal, 2000, Aureli et al., 2002) in non-human animals, particularly in non-primate species (Judge, 2000, Aureli et al., 2002; but see Miranda-de la Lama et al., 2011). Moreover, apart from the coping styles model, where the presence or absence of a fight/flight response or freezing in a challenging situation is inherent in the definition of two behavioural extremes (proactive and reactive coping styles, Koolhaas et al., 1999), links between personality and behaviour in social conflict situations in non-human animals have received little scientific attention (but see Thierry, 2000, Cote and Clobert, 2007, Miranda-de la Lama et al., 2011).

Domestic dogs (Canis familiaris) constitute a suitable model species to investigate the proposed link between personality and conflict resolution for various reasons. Over the course of domestication, they appear to have evolved specialised and flexible social skills for reading human social and communicative behaviour (Hare and Tomasello, 2005), and the human environment and social setting has become their natural ecological niche (Miklósi et al., 2004). Thus, it is possible to test dogs’ personality and conflict behaviours outside of the laboratory environment but in a standardised way by using a human test person. Many studies have described different personality traits in domestic dogs including reactivity, fearfulness, trainability, aggressiveness and sociability (reviewed in Jones and Gosling, 2005). Surprisingly, not much scientific information is available on conflict resolution strategies in dogs (but see Cools et al., 2008, for reconciliation following intraspecific conflict). A few papers report dogs’ differential responses in inter-group conflicts (Bonanni et al., 2010) or to a threatening human (Vas et al., 2005, Vas et al., 2008, Horváth et al., 2007, De Meester et al., 2008, Győri et al., 2010). Walker et al. (1997) classified dogs’ strategies in relation to fear behaviour, adapting the model by Marks (1987 as cited by Walker et al., 1997) – freeze (immobility), flight (withdrawal, escape, avoidance), flirt (deflection of attack and appeasement/submission), and fight (aggressive defence). Lindsay (2005) similarly suggested the following five behavioural reactions in conflict situations in dogs: fight, flight, flirt, freeze (wait for the situation to change), and forbear (tolerate or accept the situation).

Relating personality and conflict resolution in dogs has been addressed only to the extent that behavioural assessments have aimed at identifying dogs’ tendency to react aggressively, typically by threatening or manipulating the dog or by removing resources from the dog (e.g. Netto and Planta, 1997, Bollen and Horowitz, 2008, De Meester et al., 2008, van der Borg et al., 2010, Bennett et al., 2012). There is currently a lack of scientific data on dogs’ use of alternative, non-aggressive, conflict resolution strategies. Our aim was therefore to determine alternative conflict resolution strategies in dogs and to investigate whether dogs’ reactions to a perceived conflict situation are related to their personality, particularly their sociability and boldness.

We compared the behaviour of 134 Border collie puppies in a friendly greeting situation with an unfamiliar person to that in three restraint tests (a back test, a simulated veterinary examination and staring into the puppies’ eyes), which could be perceived as conflicts by the dogs. We predicted that the puppies’ sociability is positively correlated with active but nonaggressive ways of conflict resolution (interaction, c.f. flirt strategy), and negatively with aggressive (fight strategy) or avoidant (flight strategy) strategies (c.f. Walker et al. (1997), Lindsay, 2005). Passivity could either indicate high tolerance (forbearing) or constitute a freeze strategy (c.f. Lindsay, 2005). While highly sociable puppies might potentially be more tolerant of handling, less sociable puppies might be more likely to freeze during handling; therefore no a priori prediction was made. Given a suggested association between boldness and reactions in the back test (e.g. Hessing et al., 1994– but see Forkman et al., 1995), we furthermore analysed whether boldness towards a novel object was related to behaviour in the restraint tests.