acta ethologica最新文献

The preference for colours has profound impacts on the fitness of visually oriented species, influencing the search for food resources and mates of better quality while also modulating various physiological and behavioural features. Such processes may be more important to sexually dimorphic species, especially coloured ones since visual signals play an important role in intra- and intersexual communication. Amazon small streams vary widely regarding the amount of dissolved organic carbon resulting in black (red-biased) and clear (mostly transparent) water types. The sailfin tetra Crenuchus spilurus is a small sexually dimorphic species composed of two main genetic lineages that live in black and clear water types. Recently, we have shown that the female sexual preference for male ornaments colouration differs between individuals inhabiting black and clear water types. Females from black waters do not choose males primarily based on colouration under strongly red-biased lighting, but females from clear waters do, which suggests that the importance of red colours for sexual behaviour differs between lineages of the sailfin tetra. Here, we evaluated the sailfin tetra female environmental colour preference through the choice between a red and a full spectrum illuminated environments. Females from black waters and clear waters preferred red-lightened environments. Such results suggest that the females are attracted to the red colouration outside the context of mating, irrespective of the prevailing lighting condition of their native environment. This preference for red illuminated environments may be important for several processes, including physiological and behavioural features.

Parasites inhabit practically all environments of the planet, representing an important selective pressure on different traits, including behavior. However, there is limited knowledge on the relationship between haemosporidian infection and the behavior of birds. In this study, we recorded risk-taking behaviors exhibited during three behavioral tests: struggle in the hand, open-field, and simulated territorial intrusion, in a resident population of thorn-tailed Rayadito (Aphrastura spinicauda) located on Navarino Island (55°S), southern Chile. This population shows a high prevalence of the haemosporidian Leucocytozoon spp., providing us with an opportunity to explore the connection between this parasite and the risk-taking behaviors of a Neotropical bird species. Our results indicate that birds infected by Leucocytozoon spp. exhibit higher activity scores in the behavioral tests, suggesting that individuals infected may be more propensity for risky behaviors. These findings raise intriguing questions about whether behavior precedes infection or results from it.

One of the commonest pesticides used in agriculture is the fungicide carbendazim, which can cause deleterious effects on the physiology and behaviour of acutely and chronically exposed animals. However, few studies have evaluated the effects of carbendazim on fish behaviour and our main objective was to evaluate behavioural changes on adult zebrafish (Danio rerio) exposed to this fungicide. We studied 177 fishes, divided into control groups (not exposed) and treatment groups, exposed to a concentration of 120 µg/L for 7, 14, 21 and 28. Behavioural data were collected using the scan sampling, with instantaneous recording every 30 s. We evaluated and compared fish behaviours and aquarium occupancy between treatments and controls using Generalized Linear Mixed Models. The results indicate that carbendazim initially elicited slow swimming and later fast swimming, decreased aggressiveness, and caused behavioural changes indicative of distress, like abnormal swimming and the gulping of air in water surface. In the wild, this behavioural change can result in an increased predation risk and consequent decrease or extinction of populations, revealing important ecological issues for animal communities living in polluted water bodies.

Behavioural observations were used to investigate the temporal dynamics events and associated variation in the daily activities of a sedentary population of mallard duck (Anas platyrhynchos) inhabiting an urban park in northern Portugal. Data was collected at Porto City Park from December to April, during the species’ courtship and early nesting periods. The most frequent activities for this population were locomotion, resting and feeding. Statistical analysis revealed that male and female behaviours differed significantly throughout the courtship period, as males exhibited more displays and aggressive behaviour while females were more prone to feed in order to meet their increased nutritional and energetic needs. Temporal analyses showed that courtship reached a peak in intensity in February, since it was in this month that the highest values for mating, aggressive behaviour in males and defensive behaviour in females were observed. Behavioural differences were found for this population, with higher feeding rates compared to those of wild populations as well as lower defensive behaviour rates. This paper sheds light on how synanthropized populations, as well as those from Southwestern Europe, show different behavioural responses from other populations. Additional extensive monitoring of population dynamics and factors such as latitudinal differences, habituation to humans and climate change will help to predict future growth and expansion rates.

Species have developed several defensive strategies for survival in response to predation pressures, including chemical, acoustic, visual, and behavioral mechanisms. Anurans serve as prey for numerous species, leading to the evolution of a diverse array of antipredator strategies. Among these strategies, acoustic emission defenses are categorized into distress calls, alarm calls, and warning calls. Although distress calls in frogs have been recognized to occur within the audible spectrum, the occurrence of ultrasound calls has been suggested for one species, but not yet confirmed. Based on our observations, we confirmed the presence of ultrasound distress calls emitted by an adult Haddadus binotatus. The distress call exhibited a high-pitched tone with decreasing frequency modulation and ultrasonic harmonics extending up to approximately 44 kHz. The presence of ultrasound frequencies in distress calls may confer advantages in deterring a broader range of predators. The use of broad-band screams synchronously with other behaviors, as raising the front of the body while arching the back and extreme mouth-gaping, intensified the defensive display, likely being more efficient in deterring predation. We observed similar behavioral repertoire for an adult Ischnocnema cf. henselii. Therefore, it could be widespread across individuals of other Brachycephaloidea genera as well.

Traffic noise is a pervasive pollutant that affects wildlife at individual and group levels through mechanisms such as disrupting communication, affecting antipredator strategy, and/or changing how they use space within a habitat. Urbanization is expanding rapidly—few places remain untouched by anthropogenic noise disturbance—so understanding the implications of noise on wildlife behavior is paramount to conservation efforts. We asked whether traffic noise could change space use and social network metrics in flocks of captive birds. Specifically, we quantified the effects of playbacks of traffic noise on individual sociality (weighted degree, number of social partners weighted by the frequency of interactions with those social partners) and flock clustering (global clustering coefficient, connectivity of neighbors). In this study, we recorded social interactions and space use of flocks of captive zebra finches (Taeniopygia guttata) before, during, and after an experimental traffic noise introduction in two treatments: high- and lower-amplitude noise. Our results demonstrated that individual sociality and flock clustering increased in response to the noise introduction in both high-amplitude and low-amplitude treatments. Additionally, birds in the high-amplitude treatment spent more time in the room with active playback during noise playback whereas birds in the lower-amplitude treatment decreased time spent in the room closest to the high-amplitude treatment. Increased social behavior in response to traffic noise could influence disease transmission, social learning, and mating dynamics. We suggest future studies explore the mechanisms driving increased social behavior in traffic noise, such as perceived predation risk, vigilance, and cross-sensory interference.

Squirrels and some corvids have successfully adapted to urban conditions. Their populations are often more abundant in city parks than in rural areas. These species may compete, especially in terms of food resources. We studied interactions between corvids (hooded crows and rooks) and red squirrels inhabiting urban park, mostly in relation to supplementary food utilisation in Poland. The study included the following: (a) feeding trials, when squirrels were offered hazelnuts and all stealing attempts by other animals were noted; (b) direct observations of groups of animals (at least one squirrel and one corvid species) with all behaviours being recorded. During the feeding trial, and with constant corvid presence, corvids tried to steal almost every third nut cached by squirrels. Regardless of the season, the share of nuts that corvids tried to steal was similar. When the feeding trial proceeded, more squirrels joined in order to obtain food. On the contrary, the presence of corvids seemed to refrain other corvids from joining the trial. The presence of a bird/squirrel audience did not result in more deceptive caches. During direct observations, squirrels interacted mostly with corvids, and less often with people or other squirrels. The most frequent interaction of squirrels with other animals was flight and chasing away; for corvids, it was chasing and following or attempting to steal food. Overall, we showed that corvids can be food competitors and kleptoparasites for red squirrels. Red squirrels, with whom people often have affinity relationships, benefited from direct supplementary feeding. Corvids, in turn, learnt to follow red squirrels to steal human-delivered nuts.

Two cyprinodontids, Garmanella pulchra and Cyprinodon artifrons, coexist in a small mangrove floodplain on the Yucatan Peninsula, enabling comparison of male territoriality in two species with similar social structure and resource needs. There were two contrasting situations, one where territorial males of G. pulchra were several times more abundant than those of C. artifrons and one where the reverse was true. In both situations, the roughly circular breeding territories were non-overlapping intraspecifically and showed complete overlap interspecifically. Territories of both species were several times smaller in the situation where they were numerically dominant. In that situation, the territories of G. pulchra were about twice as large as those of C. artifrons and males of both species showed higher conspecific aggression, lower heterospecific aggression, more reproductive activity, lower feeding rates, and lower percentages of body fat. In both situations of relative density, the percentage fat content was orders of magnitude greater in C. artifrons than in G. pulchra, potentially reflecting higher rates of territorial male turnover in the latter. Social behavior in the wild, described for the first time for both species, generally conforms to typical cyprinodontid themes for territorial and reproductive behavior. There was no evidence, in G. pulchra, of the courtship dance, nor the overt, male parental care described for Jordanella floridae, a species once considered a congener.

Understanding how heatwaves impact on different aspects of mating behaviour and fertility is getting increasingly important. In this context, laboratory fertility and mating experiments involving manipulation and exposure of insects to different thermal conditions are common procedures. To conduct such experiments practical methods such as dyes are needed for an easy, non-invasive discrimination of individuals. We report here a study measuring the effect of an extended heat stress applied to males on several parameters of mating behaviour and fertility of laboratory populations of Drosophila subobscura derived from two distinct European locations. We found highly detrimental effects of heatwave on mating behaviour—with longer (courtship and copulation) latencies and lower mating occurrence but no changes in mating duration—and fertility, with reduced fecundity and reproductive success. Furthermore, we also tested the efficacy of food dye as a marker for individual discrimination and mating occurrence. While food dye did not allow to infer the occurrence of a mating based on a transfer of coloration from male to female, it did not affect mating and fertility, attesting its utility has a method for discriminating individuals within mating experiments in the context of thermal studies. Importantly, despite the fact that the heatwave was only applied in males, we observed an impact on behaviour of females that mated with stressed males, by often refusing their nuptial feeding. This opens possibilities for further integrated research on the changes of female and male mating behaviour and fertility under different thermal scenarios.

Increased group size is predicted to dilute predation risk for individuals and increase predator detection at the group level. Individual vigilance tends to decrease with group size for many species. However, this pattern varies across species, context, space, and time. We explored the effects of group size on vigilance behaviors of white-tailed deer (Odocoileus virginianus) in relation to season, sex-age status, group composition, diminishing food returns, and intraspecific competition. We used classical behavioral observation methods and camera traps to study deer behavior. Sex-age class, season, intraspecific competition, and diminishing food returns interacted with group size to shape vigilance behaviors in deer. During spring, the effect of group size was essentially non-existent, and during winter, vigilance patterns exhibited a non-linear relationship with group size. Subadult deer benefited most in terms of increased foraging and decreased vigilance from the presence of 1–2 conspecifics, likely a maternal family group. This effect diminished in the presence of additional conspecifics (≥3), apparently as a function of contest competition. Individual deer spent less time at a site in areas with greater intraspecific abundance; however, in the presence of conspecifics, the relationship was reversed. Our research suggests that maternal family groups play an important seasonal role in vigilance behaviors of deer. Our study demonstrates the complex effects of group size in white-tailed deer. Group size effects are generally considered to be in response to changes in predation risk; however, our work supports a growing body of evidence that group size effects may also be influenced by intraspecific interactions.