Flight Initiation Distance and Starting Distance: Biological Effect or Mathematical Artefact?

In many studies, flight initiation distance (FID, the distance at which a prey starts to flee at the approach of a walker) is positively related to starting distance (SD, the distance at which the walker begins to approach) and alert distance (AD, the distance at which the focal individual becomes alert to the threat). In spite of the fundamental differences between SD, a covariate that may not have any biological effect, and AD, a measure related to the behaviour of the animal, it is common to use SD as a proxy for AD when AD is hard to measure (e.g. in species that do not exhibit distinguishable alert postures). However, the relationship between SD and AD or FID may not have any biological reasons, but may instead simply result from a mathematical artefact because of the constraints SD = AD = FID. Under such constrains, the homoscedasticity assumption is violated, and thus, the classical null hypothesis of linear regression (slope = 0) is invalid. In this study, we first show that using SD as a proxy for AD can strongly affect the results on FID. Using data from FID tests on alpine marmots (Marmota marmota), a linear mixed model with AD as a covariate, suggested that the interaction between previous activity and AD had an effect on FID, while this effect was not detected when SD replaced AD as the covariate in the analysis. We then propose that the actual statistical test of the relationship between SD, AD and FID should be based on a null hypothesis that incorporates the constraint SD = AD = FID = 0 and generate 95% CI of simulated slopes obtained from random values under this constraint. This null hypothesis can be rejected if the observed slope of the relationship between two of these variables is outside the 95% CI. We demonstrated that, for alpine marmots, the observed slope of the relationship between AD and SD was within the 95% CI of the simulated slopes. The absence of a statistically significant biological effect in the relationship between SD and AD raises important questions on the outcome of relationship between SD and FID. In Alpine marmot flight, decision should be studied separating the effect of SD on AD and the effect of AD on FID

Extrinsic and intrinsic factors affecting the activity budget of alpine marmots ( Marmota marmota )

From Springer Nature via Jisc Publications RouterHistory: received 2021-05-24, accepted 2022-02-07, registration 2022-02-08, pub-electronic 2022-03-15, online 2022-03-15, pub-print 2022-07Publication status: PublishedAbstract: Extrinsic and intrinsic factors may influence the activity budget of wild animals, resulting in a variation in the time spent in different activities among populations or individuals of the same species. In this study, we examined how extrinsic and intrinsic factors affect the behaviour of the alpine marmot (Marmota marmota), a hibernating social rodent inhabiting high-elevation prairies in the European Alps. We collected behavioural observations during scan sampling sessions on marked individuals at two study sites with different environmental characteristics. We used Bayesian hierarchical multinomial regression models to analyse the influence of both intrinsic (sex and age-dominance status) and extrinsic (environmental and climatic variables) factors on the above-ground activity budget. Marmots spent most of their time above ground foraging, and were more likely to forage when it was cloudy. Extrinsic factors such as the site, period of the season (June, July–August, and August–September), and time of the day were all related to the probability of engaging in vigilance behaviour, which reaches its peak in early morning and late afternoon and during July, the second period included in the study. Social behaviours, such as affiliative and agonistic behaviours, were associated mostly with sex and age-dominance status, and yearlings were the more affiliative individuals compared to other status. Overall, our results suggest that in alpine marmots, intrinsic factors mostly regulate agonistic and affiliative behaviours, while extrinsic factors, with the unexpected exception of temperature, affect the probabilities of engaging in all types of behavioural categories

Helpers influence on territory use and maintenance in Alpine marmot groups

In social mammals, territory size and shape vary according to the number and strength of neighbour individuals competing for resources. Two main theories have been proposed to explain this variability: the Group Augmentation (GA) and the realized Resource Holding Potential (rRHP) hypotheses. The first states that the outcome of the interactions among groups depends on the total number of individuals in the group while the second states that only the number of animals directly involved in intergroup competition determines this outcome. We collected data on space use of individually tagged Alpine marmots ( Marmota marmota), a cooperative breeding species that overlaps part of its territory with neighbouring groups. In accordance with the rRHP hypothesis, we found that groups having higher proportion of helpers, rather than higher total number of individuals, had lower percentage of the territory overlapping with neighbouring groups and a larger area available for individual exclusive use

Data from: Division of labor as a bipartite network

Bipartite ecological networks are increasingly used to described and model relationships between interacting species (e.g. plant-pollinator or host parasite). Here, we apply network methods developed in community ecology to quantify division of labor in insect societies. We consider two quantitative indices (H2' and d') derived from information theory that inform on how much the actual patterns of task performance deviates from the null expectation that workers perform tasks randomly. In addition, we computed network modularity to identify clusters of specialized individuals that are preferentially engaged in the completion of subset of available tasks. We analyzed both simple synthetic networks, varying in size and degree of specialization, and published datasets to introduce the metrics and to show that a bipartite approach provides useful insights into task allocation. Considering division of labor as a bipartite network offers a conceptual framework that could substantially increase our understanding of division of labor in animal societies

Data from: Division of labor as a bipartite network

Bipartite ecological networks are increasingly used to described and model relationships between interacting species (e.g. plant-pollinator or host parasite). Here, we apply network methods developed in community ecology to quantify division of labor in insect societies. We consider two quantitative indices (H2' and d') derived from information theory that inform on how much the actual patterns of task performance deviates from the null expectation that workers perform tasks randomly. In addition, we computed network modularity to identify clusters of specialized individuals that are preferentially engaged in the completion of subset of available tasks. We analyzed both simple synthetic networks, varying in size and degree of specialization, and published datasets to introduce the metrics and to show that a bipartite approach provides useful insights into task allocation. Considering division of labor as a bipartite network offers a conceptual framework that could substantially increase our understanding of division of labor in animal societies

Commentary: Do Bees Play the Producer-Scrounger Game?

A commentaryon:Foraging Bumble Bees Weigh the Reliability of Personal and Social Informationby Dunlap,A.S.,Nielsen,M.E.,Dornhaus,A.,andPapaj,D.R.(2016).Curr.Biol.26,1195–1199.doi: 10.1016/j.cub.2016.03.009Copy-when-uncertain:bumble bees rely on socia information when rewards are highly variableby Smolla,M.,Alem,S.,Chittka,L.,andShultz,S.(2016).Biol.Lett.12:20160188.doi:10.1098/rsbl.2016.0188International audienceGroup-living animals often use social information, in addition to personal sampling, to learn about foraging opportunities. Small-brained insects are no exception (Grüter and Leadbeater, 2014). For instance, inexperienced bumblebees learn to identify profitable flower species by observing conspecifics (Leadbeater and Chittka, 2005). Bumblebees are especially suitable to study insect social learning as they can be easily tested in the lab, allowing for precise control of food resources, individual experience and social cues (Avarguès-Weber et al., 2015). Here we comment on two recent studies showing how bumblebees use personal and social information discriminately to make adaptive foraging decisions, thus setting the scene for complex social foraging dynamics among bees exploiting variable ressources in the field. Writing in Current Biology, Dunlap et al. (2016) report that foragers of the common eastern bumblebee (Bombus impatiens) rely more on social information than on personal information if the former predicts a reward. The authors trained bumblebees to collect sucrose solution in arrays of 12 artificial flowers in which they manipulated personal information (by using yellow or orange flowers) and social information (by marking some flowers with a pinned dried conspecific). During training, each type of information was either fully reliable (100% of flowers rewarded), moderately reliable (83% of flowers rewarded), or unreliable (50% of flowers rewarded) in a full factorial design of nine treatments. Bumblebees were equally successful at associating personal and social information to a reward. However during the test, in which only unrewarded flowers of all four types were used, most bumblebees preferred flowers with a conspecific. For treatments in which social information was moderately or highly reliable, bumblebees always preferred flowers with a conspecific, even if personal information was more reliable. When both information were unreliable, bumblebees did not show any preference. Only, when social information was unreliable and personal information moderately or highly reliable, bumblebees preferred flowers without a conspecific. In another study published in Biology Letters, Smolla et al. (2016) show that buff-tailed bumblebees (Bombus terrestris) rely on social information when personal information is unreliable

Traveling Salesman

International audienceThe traveling salesman problem is the task of determining an optimal path through several points and return to the starting point