Behaviour

Novčić, Ivana; Vidović, Zoran; Hauber, Mark E.

doi: 10.1163/1568539x-bja10167pmid: N/A

AbstractClassic models of vigilance assume instantaneous and sequential randomness in the scanning process, implying negative exponential distribution of interscan durations and no interdependence among successive interscans. We examined whether vigilance pattern by preening black-headed gulls, Chroicocephalus ridibundus, meets these assumptions. Out of 54 behavioural sequences, 50 departed from the expected negative exponential distribution, whereas the focal interscan duration was significantly affected by the interaction of the preceding scan and the interscan interval. These results reveal departures from randomness in the scanning process by gulls, which may be a consequence of the hunting strategies of their predators or due to the trade-off between the needs for feather maintenance and antipredator vigilance.

da Rocha, Sulamita M.C.; Magnusson, William E.; Rojas, Diana; Lima, Albertina P.

doi: 10.1163/1568539x-bja10168pmid: N/A

AbstractMany dendrobatid frogs are known to be aposematic: brightly coloured and unpalatable to predators. To deceive predators, frog models used to test for predatory colour bias must be similar in size, colour, shape, and movement to frogs. We carried out an experiment with moving models of the species Adelphobates galactonotus, in two localities. A. galactonotus is a polytypic frog and each population of the species has a distinct colour. Birds and mammals were the vertebrates responsible for the marks on the models, but there was no difference in frequency of attacks on local-, non-local- and cryptic-colour models. Only invertebrates avoided cryptic models. Different populations of the species seem to be under different predation pressure, but colour differentiation in this species is probably related to other mechanisms, such as sexual selection.

Dittrich, Carolin; Tietje, Melanie; Rödel, Mark-Oliver

doi: 10.1163/1568539x-bja10169pmid: N/A

AbstractIn explosive breeding frogs, high intrasexual competition between males leads to a sexual coercion ruled mating system, where males presumably evolved preferences for specific female traits. We tested these preferences in the European Common Frog by excluding intrasexual competition. We hypothesized that all males show preferences towards larger female body size, due to higher fecundity. Our results did not show any preference considering female body size, neither in the attempt to amplex a female nor during the formation of pairs. Additionally, we witnessed a high failure rate of male mating attempts, which hints at high mating costs and offers an explanation for the lack of preferences in males. Nonetheless, we observed a non-random mating pattern in successfully formed pairs, where in the absence of size dimorphism females were on average larger than males. This indicates a different mechanism for selection which is independent from male mating preference or scramble competition.

Velasco, Adara C.; Ferrer, Esperanza S.; Sanz, Juan José

doi: 10.1163/1568539x-bja10171pmid: N/A

AbstractBreeding performance and survival are mechanisms through which animal personality affects fitness. Exploration behaviour (EB) is an easily obtainable personality trait that correlates to multiple life-history traits, thus it has been widely used in animal personality studies. Through in situ Novel Environment exploration tests, we assessed the exploration behaviour of blue tits (Cyanistes caeruleus) during two breeding seasons. A principal component analysis revealed two behavioural axes regarding the exploration behaviour: slow-fast and timid-daring. We found that male blue tits are significantly slower explorers than female blue tits, suggesting that evolutionary processes act unequally across sexes in our study area. To investigate these processes, we assessed the relationship between exploration behaviour and two fitness aspects: reproduction and survival. Slower-exploring males bred in nests with significantly shorter incubation periods, and timid males had higher local return ratios. Interactions between male and female EB revealed that disassortative pairs were more successful breeders than assortative ones. Further research should explore potential evolutionary implications of intersexual EB differences.

Havercamp, Kristin; Brindle, Matilda; Sommer, Volker; Hirata, Satoshi

doi: 10.1163/1568539x-bja10166pmid: N/A

AbstractNocturnal penile tumescence (NPT) has been reported for males of only a few mammalian species, including humans, albeit this scarcity might be an artefact of the difficulty of documenting it. We investigated NPT in 12 adult male chimpanzees living in an all-male group at Kumamoto Sanctuary, Japan. Recorded non-invasively with infrared video cameras across 72 nights (6 per individual), we observed NPT in two thirds of the individuals (8/12), with N=46 events in total. More than three quarters occurred during a transition from sleep to wakefulness, suggesting NPT may be associated with rapid eye movement sleep, similar to humans. Masturbation occurred in conjunction with NPT, including the likely consumption of ejaculate, in 4–6 individuals. While detailing nocturnal erections in chimpanzees may help us to better understand this robust physiological phenomenon in humans, further comparative research is necessary to reconstruct its phylogenetic history. At present, our findings support hypothetical functional explanations such as the facilitation of nocturnal emissions in order to increase ejaculate quality or an increase in tissue oxygenation to prevent erectile dysfunction.

Repnik, Anja; Skok, Janko

doi: 10.1163/1568539x-bja10170pmid: N/A

AbstractMale infanticide is a widespread phenomenon in mammals and is usually directed against non-filial infants. In cervids, reports on male infanticide remain very rare. This article reports a case of male filicide (filial infanticide) in farmed European fallow deer (Dama dama). The conflict between the buck and his male offspring took place at the feeding station during the rut and was recorded on camera. Several times (about 7) a fawn entered the feeding station but was repeatedly chased away by the buck. On the last occasion, the buck struck/stabbed the fawn with his antlers. Post-mortem examination revealed penetrating abdominal trauma with gastrointestinal perforation. This is the first record of male infanticide in fallow deer, although it differs from other cases in cervids where the attacks were clearly intentional. Therefore, we cannot provide a firm explanation, although it was likely a non-adaptive/pathological behaviour under the specific (unnatural) circumstances.