Acoustic features involved in the neighbour-stranger vocal recognition process in male Australian fur seals.

Many territorial species have the ability to recognise neighbours from stranger individuals. If the neighbouring individual is assumed to pose less of a threat, the territorial individual responds less and avoids unnecessary confrontations with familiar individuals at established boundaries, thus avoiding the costly energy expenditure associated with fighting. Territorial male Australian fur seals respond more to strangers than to neighbouring males. The present study evaluated which acoustic features were important in the neighbour-stranger recognition process in male Australian fur seals. The results reveal that there was an increase in response strength or intensity from males when they heard more bark units, indicating the importance of repetition to detect a caller. However, lengthening and shortening the inter-unit spaces, (i.e. changing the rhythm of the call) did not appear to significantly affect an animal's response. In addition, the whole frequency spectrum was considered important to recognition with results suggesting that they may vary in their importance. A call containing the dominant and surrounding harmonics was considered important to a male's ability to recognise its neighbour. Furthermore, recognition occurs even with a partial bark, but males need to hear between 25 and 75% of each bark unit from neighbouring seals. Our study highlights which acoustic features induce stronger or weaker responses from territorial males, decoding the important features in neighbour-stranger recognition.

A fatigue questionnaire (QFES) for child athletes: a four-year follow-up study in young skiers.

BACKGROUND: The use of a fatigue monitoring questionnaire is an increasingly widespread practice in sports medicine. OBJECTIVE: To evaluate variations in the QFES fatigue questionnaire score according to periods of rest, training or competition. METHODS: Sixty-six skiers (either alpine or cross-country skiers, aged between 11 and 14 years and training for between 12 and 18 hours per week) filled out a total of 400 fatigue questionnaires over a four-year follow-up period. RESULTS: Our analysis of the QFES fatigue scores showed that only a small proportion of the skiers (5.25%, on average) exceeded the fatigue alert threshold at some point during the longitudinal follow-up; periods of competition correspond to rising fatigue scores, in comparison with the beginning of season and girls always have higher scores than boys (25.32+/-0.90 versus 20.46+/-0.91, respectively; p<0.0002). In contrast, there was no correlation between fatigue levels and the type of skiing discipline practiced. CONCLUSION: Our main results show that the QFES fatigue questionnaire is a sensitive tool for tracking down particular periods of fatigue (competition, intense training). Even though the mechanism of fatigue is still not fully understood (highlighting the complexity of this syndrome), the systematic use of a fatigue questionnaire when monitoring children performing competitive sport and high volumes of training confirms the possible preventive role of this type of tool.

Use of the fatigue questionnaire (QFES) in child athletes for individual follow-up: two cases.

BACKGROUND: Fatigue is one of the multiple components of the life of an athlete. It may have adverse consequences on the health of child athletes in particular in the short or long term. For the trainer or medical staff, detecting fatigue as fast as possible is therefore advisable. OBSERVATIONS: Two young skiers beginning a sports class at age 11 were followed for 3 years within the framework of their practice for sport competition (1 alpine and 1 cross-country skier). At the same time as medical follow-up organized within the sports classes of the school they attended, the children completed at six times a questionnaire about fatigue, the QFES, (in French: Questionnaire de fatigue de l'enfant sportif). At one precise time during this follow-up, the QFES score for each child, both at age 12, clearly increased, by 175% and 133.3%, respectively, from previous scores. A thorough analysis of data gathered by the QFES allowed for revealing particular parameters of the fatigue: decreased sports performance, difficulties in relations and sleep disorders. CONCLUSIONS: Systematic use of the QFES in parallel with medical consultations for children participating in sport may be an efficient tool to detect the early appearance of fatigue and may therefore be integrated in preventive guidance to protect children in sports practice.

Parent-offspring conflict and the coordination of siblings in gulls.

Offspring solicit food from their parents by begging behaviours. Studies on birds suggest that these displays are 'honest signals of need' and adults provide food according to the begging level. However, siblings may compete for parental resources and the begging intensity is expected to change with brood size. Here, we show that in the black-headed gull (Larus ridibundus) an increase of the numbers of siblings can result in a decrease of individual begging cost through nestlings' synchronized signalling. This is in accordance with some mathematical models. As parents respond to the total solicitation emerging from the nest, the probability to get food increases with the number of chicks begging together. The more siblings there are, the more they coordinate their begging while decreasing the number of individual begging bouts. Intra-brood synchronization of begging enables chicks to reduce their effort and hence exerting an important role in parental-offspring negotiation.