1,721,037 research outputs found
Dyadic leader-follower dynamics change across situations in captive house sparrows
No full textIndividuals can behave as either leaders or followers in many taxa of collectively moving animals. Leaders initiate movements and may incur predation risks, while followers are thought to be more risk-averse. As a group encounters different challenges and ecological situations, individuals in the group may change their social role. We investigated leader and follower roles using dyads of captive house sparrow (Passer domesticus) during both exploration of a novel environment and a simulation of predator attack. During the exploration of a novel environment, individuals behaved consistently either as leaders or followers. However, in the simulated attack tests, individuals in the dyads switched their roles, with "followers"leading the escape flights and "leaders"following them. Our study provides evidence of 1) consistent differences between individuals in behavior during social escape and 2) a relationship between social roles across different situations. We suggest that such relationship hinges on individual risk-taking tendencies, which manifest through different social roles across different ecological situations. We further speculate that risk-taking individuals might gain benefits by following risk-averse individuals during an escape flight
Familiarity effects on fish behaviour are disrupted in shoals that contain also unfamiliar individuals
No full textResearch on several social fishes has revealed that shoals constituted by familiar individuals behave remarkably differently compared to shoals formed by unfamiliar individuals. However, whether these behavioural changes may arise also in shoals composed by a mixture of familiar and unfamiliar individuals, a situation that may commonly occur in nature, is not clear. Here, we observed the behaviour of Mediterranean killifish (Aphanius fasciatus) shoals that were composed by both familiar and unfamiliar individuals (i.e. individuals were familiar to each other in pairs) and compared it with shoals entirely made by either unfamiliar or familiar individuals. Shoals formed by familiar individuals took longer to emerge from a refuge and swam more cohesively compared to shoals formed by unfamiliar fish. Shoals formed by a mixture of familiar and unfamiliar individuals behaved as shoals formed by unfamiliar individuals. Moreover, mixed shoals did not segregate in pairs according to their familiarity. This study suggests that mixed shoals do not show the behavioural effects of familiarity. Significance statement Laboratory studies have compared the behaviour of shoals formed by familiar fish versus shoals formed by unfamiliar fish, finding notable advantages in the former ones, such as improved antipredator and foraging behaviour. However, comparing these two opposite shoal types may not provide information on the natural situation, because in nature, shoals often change composition. We investigated how shoals formed by a mixture of familiar and unfamiliar fish behaved. We analysed shoals' preference for open environment versus covers and shoals' swimming cohesion. Results showed that shoals formed by both familiar and unfamiliar individuals mostly behave like shoals entirely formed by unfamiliar individuals. This suggests that the advantages of social groups formed by familiar fish might be hardly seen in nature for species in which shoal composition changes frequently
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Nest density, nest-site selection and breeding success of birds in vineyards: management implication for conservation in a highly intensive farming system
No full textInformation about predators varies across an amazonian rain forest as a result of sentinel species distribution
No full textFlock-dependent exploitation of a limited resource in House Sparrow
Full text linkThe performances of different social groups can depend on various characteristics, such as familiarity among their members or the presence of individuals with specific traits. However, it has rarely been investigated how groups perform during an encounter with other conspecifics, even if in the natural environment social groups often run into each other and compete for resources. We investigated whether a certain characteristic of the group (i.e., familiarity) could benefit its members when they are confronted with another group. We designed a novel experimental set-up, creating triads of captive house sparrows (Passer domesticus) and examining whether in a situation of competition for limited resources one triad could gain benefits over the other (consume more mealworms, Tenebrio molitor). While we did not find an effect of previous familiarity among triad members on the triads’ performances, we discovered a group-based difference in the number of mealworms eaten per capita. Group-mates of the very first individual to eat a mealworm (first feeder) ate more mealworms than those in the opposing triad. First feeder individuals also foraged sooner and more than other birds in a subsequent prey consumption assay. Our results suggest that individual performances were influenced by group membership, even when groups were exploiting the same resource simultaneously
Compensatory responses differ between parental tasks in a songbird species
Full text linkIn species with biparental care, the amount of care devoted to offspring is affected by the negotiation rules that the parents adopt. Theoretical models predict that biparental care can be evolutionarily stable if a decrease in parental investment by one parent is only partially compensated by its partner. However, empirical studies have found substantial variability in compensatory behaviour and have mainly used nesting provisioning as a single measure of parental effort. In this study, we investigated parental compensatory behaviour for two parental tasks, offspring provisioning and nest defence. These two tasks are likely characterized by different levels of risk as well as different cost and benefit functions for the parents, which may affect the expected level of compensatory responses. We experimentally widowed (by temporarily removing one parent) male or female Spanish sparrows, Passer hispaniolensis, and measured their compensatory responses to offspring provisioning and nest defence (after predator presentation of green whip snake, Hierophis viridiflavus, models). Parents differed in their compensatory responses in relation to parental task and sex: both sexes partially compensated for offspring provisioning, but females compensated by a larger degree than males. For predator defence, males instead decreased defence behaviour by increasing latency and reducing the number of attacks, while females did not change their behaviour when caring alone. This within-individual comparison indicates that parents adjust their compensatory behaviour according to parental task. We discuss how these differences could arise due to different costs and benefits of extra investments
Parental feeding responses to experimental short-term partner removal in a species with male and female brood desertion
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