The drivers and functions of rock juggling in otters

This is the final version. Available on open access from the Royal Society via the DOI in this recordData accessibility: Data and code for rock juggling frequency, hunger and food puzzles can be accessed through the Dryad Digital Repository: https://doi.org/10.5061/dryad.rn8pk0p64. Tables of post hoc test results for puzzle order have been uploaded as part of the electronic supplementary material.Object play refers to the seemingly non-functional manipulation of inanimate items when in a relaxed state. In juveniles, object play may help develop skills to aid survival. However, why adults show object play remains poorly understood. We studied potential drivers and functions of the well-known object play behaviour of rock juggling in Asian small-clawed (Aonyx cinereus) and smooth-coated (Lutrogale perspicillata) otters. These are closely related species, but Asian small-clawed otters perform extractive foraging movements to exploit crabs and shellfish while smooth-coated otters forage on fish. We thus predicted that frequent rock jugglers might be better at solving extractive foraging puzzles in the first species, but not the latter. We also assessed whether species, age, sex and hunger correlated with rock juggling frequency. We found that juvenile and senior otters juggled more than adults. However, rock juggling frequency did not differ between species or sexes. Otters juggled more when ‘hungry’, but frequent jugglers did not solve food puzzles faster. Our results suggest that rock juggling may be a misdirected behaviour when hungry and may facilitate juveniles’ motor development, but it appears unrelated to foraging skills. We suggest future studies to reveal the ontogeny, evolution and welfare implications of this object play behaviour.Royal Societ

Aggressivity and social balance in a captive tursiops truncatus community

Social systems in which animals are arranged according to ranks, such as the bottlenose dolphin ones, usually find in aggressive interactions a means for determining social balance and hierarchies. The aim of this study was to quantitatively investigate, according to the age and sex of the animals, intra-communal agonistic behaviours, in particular pointing out: a) quality and distribution of the displays, b) features of the agonistic sessions and c) dominance relationships among individuals. Five subjects (adults: 1,1; young: 2,1) were focally observed at the Rimini Delfinario (Italy) from April to October 2005, through a total of 780 systematic observations lasting 15 minutes each (total 195 hours, i.e. 39 hours/animal). A specific behavioural catalogue and Observer (Noldus) were applied to measure the frequency and duration of seven conflictual behaviours, a priori chosen for the study. As for active assaults, beside a general low intensity level of aggressiveness and a frequency range included within 2.01 and 13.98 events/hour (respectively registered in adults and young), the results showed that male aggressions were usually twice as frequent as female ones, while the young surpass adults up to seven times. In all classes, "chasing" (always > 30%) was the preferred action, but similar values were reached by females also in "tail hitting". Moreover, aggressive behaviours seemed to occur in distinctive agonistic sessions, lasting between 57.0 (in adults) and 149.8 (in young) seconds and including up to 4 displays each. Again, from the observation of winner/looser diadic interactions, a predominance of the pair composed by the adult female and her still unweaned calf emerged over all the rest of the group. In the end, even in the typically cooperative bottlenose dolphin societies, intra-communal aggressiveness reveals to a certain level to be absolutely functional for group relationships and coordination, as well as, from an evolutionistic point of view, crucial for species conservation

Route to non-Gaussian statistics in convective turbulence

Motived by the work of Li and Meneveau (Phys. Rev. Lett. 95, 164502 (2005)), we propose and solve a model for the Lagrangian evolution of both longitudinal and transverse velocity and temperature increments for Boussinesq convection. From this model, the short-time evolution of an initially imposed Gaussian joint probability density function (PDF) of both velocity and temperature increments is computed analytically and the trend to non-Gaussian statistics shown in a quantitative way. Predictions for moments of the joint PDF are obtained and their behavior analyzed with respect to known experimental and numerical results. The obtained results do not depend on the model free parameters, a fact in favor of their robustness

Non-invasive Multidisciplinary Approach to the Study of Reproduction and Calf Development in Bottlenose Dolphin (Tursiops truncatus): The Rimini Delfinario Experience

Reproduction is a fundamental biological process that occurs only when all other vital needs are satisfied. In cetaceans reproduction takes place completely in water. From courtship and mating to calf weaning, every step of the reproductive process occurs under the water\u2019s surface. This complicates data acquisition in wild populations, making captive observations a useful complement to wild studies. By allowing close examination of phenomena, studies in captive environments are able to collect long-term data on known subjects, and sample, in detail, complete behavioural sequences while monitoring physiological or acoustic patterns. Studies of reproduction in bottlenose dolphins (Tursiops truncatus) were initiated at Rimini Delfinario (Italy) in 1995. Four bottlenose dolphin births (in 1995, 1997, 2003 and 2007) have occurred since the start of this research. Due to evidence suggesting that mother and calf associations are closest in the first year of the calf\u2019s life, mothers and calves were studied from birth to the end of the first year. Beginning in 1997, studies encompassed the behaviour and physiology of dolphin mothers during gestation. Here, we report results of interdisciplinary studies of reproductive processes in bottlenose dolphins, including aspects of behaviour, physiology, endocrinology, and acoustics. In an effort to reduce the potential for bias brought about by invasive sampling, we investigated methods of sampling expired air from the dolphin\u2019s blowhole as a means of monitoring steroid hormone levels. In summary, our research combines an interdisciplinary network with specialized professional alliances and offers a potentially crucial approach to the biological aspects of reproduction. At the same time, research findings presented here aim to help bridge the gap existing between captive and wild studies in favor of a common aim of conservation biology