The different environmental conditions in which people live might challenge memory in different ways. Moreover, the frequency of usage can be a source of improvement of both short- and long-term memory. The aim of our study was to investigate the effects of environmental differences on short- and long-term memory in a traditional versus a contemporary population (Dani of Papua, n = 62; Polish, n = 134). We found that both short- and long-term memory varied in the two populations, living in totally distinct surroundings. However, there were no age differences between Polish and Dani participants in either short- or long-term memory tasks, indicating that culture was not a significant moderator of the memory differences between populations. The differences in short- and long-term memory between the two populations are consistent with the argument that short-term memory plays a more significant role in contemporary societies because of technical developments, the electronic revolution, and reading ability. The lack of an age difference appears to support the assumption that it is age, not culture, that plays a crucial role in the memory performance.

Animal contests are energetically costly, but injuries are said to be rare. In gladiator frogs, the males possess a spine beneath their pollex (i.e., prepollex) that can be used as weapons and frequently leave scars during contests over spawning areas. Knowing how scars are made, and how scars are distributed among individuals, might prove valuable to address the costs and benefits of fighting. Here, we studied the gladiator frog Boana curupi in a Neotropical stream to (1) assess the rarity of the contested resource, (2) assess how spines are used during contests, and (3) test how the quantity of scars on males’ backs correlate to their morphology. We found only four spawning areas in ~ 1 km of stream. And when males engaged in physical fights, they stroke the rival on their backs with the prepollex. Scars on males’ back are thus caused by the prepollex. Both results explain the high frequency of injuries: 90.7% (29 of 32 males) presented scars. Furthermore, the amount of injuries on a male’s back increased with the weight of the male, but not its body size. Therefore, heavier individuals are sustaining more injuries than lighter individuals, hinting that heavier individuals fight more frequently and value reproduction more than lighter individuals.

Consistent inter-individual differences in behavior have been shown in several animal groups, ranging from vertebrates to invertebrates. One of the most studied personality traits in animals is boldness, which is the tendency to expose to risky situations. Theory proposes that individuals’ state (e.g., body energy) would influence the expression of personality traits. In this study, we tested if boldness levels of the harvestman Mischonyx cuspidatus (measured as duration of death feigning/freezing after simulated predator attack) differ between two different states, namely sated and food deprived. We also tested if the degree of repeatability in boldness is affected by the individual state. We found no differences in the levels of boldness expressed by M. cuspidatus when comparing between different conditions (sated and food deprived) at a population level. However, we found that individuals showed more consistency in boldness when sated relative to a food-deprived condition. Finally, we suggest new avenues for future studies addressing personality in harvestmen.

Using information acquired from other individuals (social information use) is ubiquitous in animals and not restricted to within-species context. Some of the textbook examples of interspecific information use in the wild has been provided using apparent novel niche experiment approach, with migratory flycatcher species (Ficedula spp.) cueing on apparent nest site preferences (geometric symbols) and clutch sizes of resident great tits (Parus major) and blue tits (Cyanistes caeruleus) to choose their own nest site. However, the interpretation of these results has recently been challenged. It has been argued that there is no evidence that flycatchers visit tit nests to collect information about clutch size or that flycatchers are capable of “counting” tit eggs. Instead, it has been proposed that the decision-making patterns of flycatchers found in earlier studies resulted from aggressive interactions, not information use, between tits and flycatchers (termed owner aggression hypothesis). Here, I contribute to the debate around both hypotheses and specifically explore the remaining points of disagreement, related to the timing of flycatchers prospecting and the cognitive abilities needed to assess tit clutch size. I argue how interannual variation in phenology can explain the apparent discrepancy between the observed and predicted timing of flycatchers prospecting. I also argue why assessing tit clutch size neither requires “counting” eggs nor any sophisticated cognitive capacities. Finally, I propose experimental designs to test the hypotheses on the underlying mechanisms explaining the observed patterns, which will allow taking further leaps in resolving the selective interspecific information use vs. owner aggression hypothesis dilemma.

A lunar phobia is a behavioral trait in which the individual alters or ceases its nocturnal activity during periods of strong lunar illumination found throughout the animal kingdom. Current evidence indicates the changes reflect predator/prey detectability due to increased visibility. The study hypothesizes whether bat activity is more negatively influenced by a discrete threshold of high lunar illumination (nights with ≥ 90% of moon exposure) rather than a continuous linear response to variation in moon exposure. A 1202 mist net bat captures dataset from a preserved area in Northeast Brazil was used to test this hypothesis. A stepwise model was built, using Bayesian information criterion, to determine the effect of lunar luminosity (either as continuous moon exposure or discrete threshold parameter), environment (open vegetation vs canopy-covered), and season (dry/wet). The final model selected showed a significant negative threshold effect of nights above 90% of moon luminosity compared to a weaker non-significant effect of continuous moon exposure variation. The selected model also found a positive effect of forested environments and the wet season in the total number of bat captures. The model was able to detect a significant decrease in captures for the most abundant species, Artibeus planirostris. Our findings support the hypothesis that bats (especially frugivorous) present lunar phobia, which respond in a negative nonlinear fashion to high luminosity, possibly to avoid predation.

Chemical pollution of aquatic environments has been increasing in recent times, causing great damage to the ecosystems and to the fishery sector. Pollutants can negatively alter an animals’ life, and in this investigation, we verify if a neutral household detergent, one of the most common aquatic pollutants, causes changes in the behaviour and personality of guppy (Poecilia reticulata). Thirty milligrams per litre of detergent was added to the water of two aquariums and the behaviour of eight adult guppies were recorded using focal method with instantaneous recording of behaviours every 15 s, for 30 min daily. Results showed that the detergent modified the behaviour and the personality of guppies, making them shier and more inactive. Thus, more efficient disposal techniques should be applied or developed to avoid the pollution of aquatic environments.

Rabbits can successfully avoid their enemies by evaluating the risk of predation. They have various defensive strategies, such as morphological adaptations and behaviours patterns, which enable them to perceive their predators and thus reduce the risk of predation. It is well documented that rabbits recognise the scats of terrestrial predators and avoid those areas in which they are present. However, few studies show whether the prey species can recognise the presence of congeners in carnivores’ scats, which would allow them to identify their predators in a more efficient manner. We have carried out a comparative analysis of the use of space made by rabbits on plots on which a neutral odour (water) or the odours of the ferrets’ scats that had consumed either rabbit or another mammal (beef) were applied. Our results showed a lower number of rabbit pellets on those plots containing predator odours than on the control plots. During the first 6 days after applying the first odour, the number of rabbit pellets was lower on plots on which rabbit had been included in the diet when compared with scats obtained from a beef diet. However, no differences between the two experimental plots were recorded during the third visit (9 days after applying the first odour). Our results suggest that rabbits may be able to detect congeners in their predators’ scats, thus leading them to, in the short term, avoid areas in which their terrestrial predators’ diet is based on conspecifics, probably as the result of them perceiving a higher risk of predation.

An extended period of parental care is fundamental for survival of cetacean offspring. Although qualitative descriptions of parental care and mother-calf spatial relationships are available for several species, studies using a quantitative approach throughout development of offspring are scarce. Here, we analyzed how strategies of parental care occur during the ontogeny of the Guiana dolphin, Sotalia guianensis, in the Cananeia estuarine system, Sao Paulo, Brazil. We tested the hypothesis that both the strategy and frequency of parental care vary according to the development of the offspring and assessed whether such changes are associated with the life stage of the calves. The frequency of parental care did not decrease according to the age of the calves. However, parental care strategies directed at infants were more diversified than those directed at neonates and juveniles. Increasing maternal-calf separation can expose older calves to new and risky situations and may demand different strategies of care. We conclude that there is a shift in the strategy adopted by the S. guianensis mothers according to the requirements of each age class, with parental care being dispensed until calves become fully independent.

European rabbit translocation is an extended practice in Spain, France, and Portugal, for both conservation and hunting purposes. Some of these translocations are carried out with the aim of reinforcing existing rabbit populations. In these cases, some of the new rabbits are released into warrens already occupied by resident conspecifics. This could have a negative impact upon both the released and the resident individuals owing to the “dear enemy” effect and the territoriality of the resident rabbits. In this study, we evaluated the effect of rabbit release into occupied warrens, in small areas populated by low-density resident rabbit populations. We observed negative effects at two different levels: the number of active entrances per recipient warren and the number of active warrens per reinforced plot, in addition to a general lack of increase in rabbit abundance in the area and, therefore, the failure of the reinforcement actions. Our results strongly suggest that the release of European rabbits into warrens occupied by resident rabbits is contraindicated if the objective is to recover rabbit populations in the area.

Understanding the adaptive function of the unique morphology of the human eye, in particular its overexposed white sclera, may have profound implications for the fields of evolutionary behavioural science, and specifically the areas of human interaction and social cognition. Existing hypotheses, such as the cooperative eye hypothesis, have attracted a lot of attention but remain untested. Here, we: (i) analysed variation in the visible sclera size in humans from different ethnic backgrounds and (ii) examined whether intraspecific variation of exposed sclera size is related to trust. We used 596 facial photographs of men and women, assessed for perceived trustworthiness, from four different self-declared racial backgrounds. The size of the exposed sclera was measured as the ratio between the width of the exposed eyeball and the diameter of the iris (sclera size index, SSI). The SSI did not differ in the four examined races and was sexually monomorphic except for Whites, where males had a larger SSI than females. In general, the association between the SSI and trustworthiness was statistically insignificant. An inverted U-shaped link was found only in White women, yet the strength of the effect of interaction between sex and race was very small. Our results did not provide evidence for the link between exposed sclera size and trustworthiness. We conclude that further investigation is necessary in order to properly assess the hypotheses relating to the socially relevant functions of overexposed sclera.