Percorrer por autor "Latruffe, Claire"
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- Functions of mudballing behaviour in the european fiddler crab Uca tangeriPublication . Oliveira, Rui Filipe; McGregor, Peter K.; Burford, Fiona R. L.; Custódio, Maria do Rosário Viegas dos Santos; Latruffe, ClaireEuropean fiddler crabs place mudballs around their burrow openings. Both males and females placed mudballs, but there were major differences between the sexes in mudballing behaviour, suggesting that the female’s mudballs were a by-product of digging out the burrow whereas the male’s may have additional functions. When the male’s mudballs were removed experimentally, the number and intensity of male–male agonistic interactions increased significantly. Experimentally visually isolated males spent longer making mudballs and less time waving. In a binary choice test, females were more likely to approach dummy males with mudballs, spent longer near these males and were more likely to enter their burrows than dummy males without mudballs. The same pattern was apparent for males with 30 rather than 20 mudballs. These results are consistent with a dual function for mudballs in U. tangeri: to reduce the number and intensity of aggressive interactions between neighbouring males and to attract females.
- Human exploitation of male fiddler crab claws: Behavioural consequences and implications for conservationPublication . Oliveira, Rui Filipe; Machado, José Luis Gorjão H. C.; Jordão, Joana; Burford, Fiona R. L.; Latruffe, Claire; McGregor, Peter K.Male fiddler crabs have one of their feeding claws greatly enlarged, which may comprise up to 40% of their weight. In southern Portugal (Ria Formosa) the major claw of the fiddler crab Uca tangeri is a local delicacy. Fishermen break off the male major claw and throw the crab back into the mudflat to regenerate a new one. Approximately 38 % of the males sampled had a missing or a regenerating claw. Although individuals are not removed from the population the operational sex ratio is biased towards females since other males and females behave towards clawless males as if they were females. Moreover, removing the major claw from males prevents them from signalling (waving display) to females to attract them to their breeding burrows and it also places them at a disadvantage if they have to defend their burrows from males with intact claws. Thus, the harvesting of male fiddler crab claws has potential consequences at the population level. In this paper we investigated these potential consequences by comparing an exploited population of fiddler crabs at Ria Formosa with a remote population at the Mira estuary that is not under human exploitation. The unexploited population has significantly larger males and a significantly higher density of burrows. The operational sex ratio is also significantly different between the two populations with a female-biased sex ratio in the exploited population. These preliminary results suggest that claw harvesting in fiddler crabs has a measurable effect at the population level. The consequences of this type of fishery in which the individuals are not removed from the population but the population structure is potentially affected need further investigation.
- Visual signalling and sexual selection in male fiddler crabs Uca tangeriPublication . Latruffe, Claire; McGregor, Peter K.; Oliveira, Rui FilipeSimilar to many other species of fiddler crabs, the interactions of Uca tangeri are influenced by 2 characteristic visual signals: the waving display performed by males with their enlarged claw, and the building of structures (mudballs) around the burrow entrance. This study focused on male signalling, male-male competition and female mate choice Female choice and male mating success were investigated by looking at male quality, male visual signals (waving activity and mudballs) and male interactions and their outcome. Fieldwork was carrled out In June and July 1997 at the Ria Formosa Natural Park, Algarve, Portugal, on a sandy beach with an average population density of 2.06 burrows m-2. Behavioural observations of focal males were made at low tide, 1 h before and after the peak of low tide, that is during the mudballing phase or interaction phase. This was also when measurements of male characteristics, mudballs and burrow charactelistics were taken. The results show that the quality of a male's burrow IS related to its depth, and depth is correlated with 4 features: claw size, waving rate, mean dlstance to mudballs and number of mudballs. Therefore, females could use these features as Indicators of gallery depth, eliminating the need to enter the burrow for sampling. Males compete for the possession of burrows that are more vlslted by females, thus taking over burrows is an alternative strategy to burrow digging Male waving activity, mudball distance and claw size can be considered as multiple visual signals available to females for mate choice. Females' first choice cntenon would seem to be burrow quality.