acta ethologica最新文献

Urban noise can potentially disturb the acoustic signals of animals inhabiting urban areas. Although a wide variety of noises from different sources is common in cities, the impact of non-engine noise on animal calls is less studied. In a natural experiment, we evaluated the effect of different urban noises on the advertisement calls of urban frogs (Eleutherodactylus nitidus) in the metropolitan area of Puebla, Mexico. We recorded and analyzed 672 advertisement calls from 28 male frogs and the corresponding environmental noises from three distinct localities. Our analysis focused on four acoustic properties of the calls: inter-call interval, call duration, dominant frequency, and call amplitude. To standardize the amplitude measurements of sound pressure levels produced by noise and frog calls, we employed a practical approach using a reference signal for calibration. We treated the longitudinal data of different noises occurring before, during, and after advertisement calls as repeated measures within the urban locations. During our samplings, frogs called amidst spontaneous urban noises, including dog barking, fireworks, and vehicle engine sounds. Our results indicate that vehicle engine sounds and dog barking do not cause significant distortions in the calls of these urban frogs. However, we observed slight variations in the dominant frequency of calls, decreasing by 11 Hz, during and after fireworks. Given the observed plasticity of E. nitidus in response to noise, urban noises may not pose a severe problem for this urban frog.

The degree of prey sociality reflects trade-offs between predation risk, and competition for mates and resources. Consequently, the degree of sociality is predicted to differ spatiotemporally. Variations in nychthemeral sociality are, however, understudied. We assessed the activity of solitary, territorial black wildebeest bulls (Connochaetes gnou) over rutting and non-rutting seasons. We predicted that solitary bulls would reduce their nocturnal use of territorial stands and join herds to reduce predation risk from nocturnally hunting lions (Panthera leo), but that these responses would differ across rutting and non-rutting seasons. We used camera trap data and modelled solitary bull and herd activity over 24-hour daily cycles, across rutting and non-rutting seasons. We calculated the proportion of images with solitary bulls and herds across nocturnal and diurnal periods, across both seasons. We show that solitary bulls are predominantly diurnal across both seasons, but the probability of nocturnal detection is higher in the rutting than in the non-rutting season. Furthermore, we recorded a lower proportion of solitary bulls to herds at night in the non-rutting relative to the rutting season. Thus, wildebeest bulls may trade-off predation risk for mate acquisition during the rutting season but reduce risky solitary behaviour during the non-rutting season.

The blue-winged parrot Forpus xanthopterygius is widely distributed in South America, where it lives in groups in different types of environments and feeds on fruits, seeds, flowers and nectar. In 2023 we observed a group of these birds moving from a forested area to an area of aquatic vegetation on the bank of a water reservoir in Southeast Brazil. The birds landed among the leaves of a cluster of Polygonum ferrugineum, approximately 45 cm above the water surface, and consumed flower buds and flowers — a plant species not yet reported for their diet. This behavior occurred during the driest period of the year (April), and may represent an alternative diet due to the scarcity of the preferred resources of this bird species during this period. The species is known to use habitats associated with water and to feed at low heights or even on the ground. However, this behavior of searching for resources on aquatic vegetation at the water surface in the middle of an urban reservoir has not been described and shows the adaptability of these birds to human environments and their high capacity to find food in the most varied types of habitats.

We documented alloparenting and social group behavior within a leopard (Panthera pardus fusca) population in the Jhalana Reserve Forest (JRF), northwest India. Our observations revealed subadult offspring assisting their mothers in raising their newborn litters, exhibiting previously undocumented alloparenting behaviors. We propose that the familial intra-specific interactions and inter-specific competition collectively influence the social structure of the leopard population. Specifically we suggest that the inter-specific competition and predation, particularly with striped hyenas (Hyaena hyaena), may encourage alloparenting in leopards. Aditionally, we hypothesize that alloparenting, combined with natal philopatry, serves as an alternative strategy for leopards to enhance the survival chances of their progeny.

The ladybird beetles Cheilomenes sexmaculata and Propylea dissecta serve as effective bio-control agents, preying upon aphid populations and thereby mitigating plant damage. These beetles coexist together and show different reproductive strategies. Previous studies have found prevalent heterospecific mating between C. sexmaculata male and P. dissecta female, documenting the effects of heterospecific male C. sexmaculata on the reproductive output of P. dissecta female. In light of these observations, we conducted an experiment examining the influence of heterospecific male age on the reproductive output of P. dissecta. This study involved three age groups of male: (a) young (10–20 days), (b) middle (30–40 days), and (c) old (50–60 days). These males were introduced into Petri dishes with conspecific mates of P. dissecta. Across all experimental treatments, we examined the impact of three different age cohorts of C. sexmaculata males on the mating and reproductive attributes of P. dissecta. Our findings unveiled that older heterospecific males, which displayed reduced choosiness and heightened activity, engaged in reproductive interference to a greater degree than younger C. sexmaculata males during conspecific P. dissecta mating. Further, post-mating encounters with young heterospecific males led to a reduction in the reproductive output of female P. dissecta. The insights gained from this study hold significant implications for comprehending the feasibility of releasing multiple species of ladybird beetles within the same agricultural field. Such understanding of interspecies interactions and their consequences is vital for optimizing integrated pest management strategies.

The decision to escalate aggression in a contest is based on the assessment of oneself and the opponent's capabilities, previous experiences and the asymmetries between contenders. Interestingly, there is increasing evidence that color polymorphism may also influence the result in a contest during agonistic encounters. Therefore, this research aimed to analyze, for the first time, the intra-sexual competition of adult males of the Mexican Rivulus Millerichthys robustus, testing the influence of color polymorphic variations during agonistic contests. The results of this study suggest that the aggressiveness between morphotypes is of orange and red over yellow. The orange morph was related to winning the greatest number of encounters, whereas yellow lost the most. The red morpho registered the greatest number of ties. Interestingly, in contests between more aggressive morphs (orange and red), fish tended to modulate and lower aggressiveness levels, possibly to avoid injuries. In contrast, the least aggressive morphotype (yellow) tended to raise its aggressiveness against the most successful morphotype and lower it in matches against its own color, changing to a scheme between contenders with symmetrical aggression levels. These results suggest that differential aggression between morphotypes can influence the evolution of color polymorphism in M. robustus, differentially influencing the fitness of the individuals.

The Southern Lapwing (Vanellus chilensis) is a widespread bird across Southern America and commonly found in any large open areas, including agriculture and urban. Despite being a conspicuous species, little is known about its copulatory behaviour. In this research, we studied the copulation behaviour of Southern Lapwings and identified specific behaviours that preceded copulation events. Focal observations were made during one year on two pairs of lapwings that inhabit an urban area in the southeastern Pampas region, Argentina. A total of 110 intra-pair copulations were recorded (pair 1 = 64 and pair 2 = 46). Frequent copulations began 97 and 64 days before the first egg-laying, respectively, although the highest frequency occurred before the onset of the first nesting attempt. The Southern Lapwing copulated during all daylight hours, with a peak in the morning. Copulation occurred for up to five consecutive days, and the maximum number of copulations observed in a single day was four. Courtship and territory defence were the most common behaviours preceding copulation. Among the multiple hypotheses that have been proposed to explain frequent intra-pair copulation, our results seem to support two of them: the territory signalling hypothesis and the social bond hypothesis. The high population density coupled with the low availability of territories and a strong social bond based on cooperation and coordination could support both hypotheses, respectively. Given that the social environment can modify the behaviour of plovers, future research should evaluate the copulation behaviour at different population densities and the adaptive functional significance of this behaviour.

We report the first record of mutual allogrooming in free-ranging wild northern red muntjac (Muntiacus vaginalis) from dense tropical forests of Similipal Tiger Reserve, Odisha, India. This observation is similar to reciprocal allogrooming behaviour between social partners, reported only in Impala (Aepyceros melampus) in free-ranging conditions. We video-recorded cooperative allogrooming between two female (one adult and another juvenile) northern red muntjacs. Behavioural quantification suggests that although both individuals exchanged equal numbers of grooming bouts, the adult female received a greater share of grooming time and episodes, respectively. The time spent on grooming as well as the number of tongue strokes delivered were found to be negatively correlated between the two individuals. The grooming pattern could possibly be attributed to kin selection and detailed work is required to understand this behaviour in this poorly-studied primitive deer. Our record indicates the possible existence of cooperative allogrooming in other ungulates of the Order Artiodactyla.

Parental age plays a major role in determining the life history attributes of an organism. Variation in parental age can have a big impact on offspring development, body mass and structure of population. To test the hypothesis that the increase in parental age has negative effects on offspring development of next generation, we observed the effect of parental age on the selected population of developmental variants (slow and fast developers) in a ladybird beetle, Propylea dissecta Mulsant (Coleoptera: Coccinellidae). The newly emerged adults were divided into two lines: Slow and Fast developers on the basis of their total developmental durations. Adult body mass, slow-fast emergence, sex-ratio, percentage of immature survival of newly emerged adults was recorded. Total developmental duration increased with the increase in age across generation and more fast developers were found in the offspring of young age groups; however, only slow developers were produced by old age groups. Offspring of older age showed higher immature mortality which supports slow-growth-higher mortality hypothesis. Thus, it can be concluded that young age beetles show better performance in terms of growth and developmental duration in P. dissecta in comparison to middle age and old age groups.