Assessing spatial learning and working memory in plateau zokors in comparison with plateau pikas and laboratory rats Abstract Spatial learning and memory skills are imperative for the survival and fitness of subterranean rodents because of the harsh underground niche in which they live that necessitates the avoidance of higher energy expenditures or probable conflicts with conspecifics or predators. Our study aims to assess the spatial learning and working memory performance of a subterranean rodent species, plateau zokors (Eospalax baileyi), compared to that of the surface-dwelling plateau pikas (Ochotona curzoniae) and laboratory rats (Rattus norvegicus) which spend a considerable time of their lives above ground. Animals were tested with a spatial delayed alternation task in a T-maze for six consecutive days. Plateau zokors showed less efficient learning and working memory capacity in the T-maze compared to plateau pikas and laboratory rats, which maintained accurate and consistent increased spatial learning rates and working memory performances. The three species did not show bias towards a certain arm of the maze. Additionally, clear sex-specific differences were observed in the laboratory rats regarding spatial learning and working memory functions, while in pikas and zokors, no sex-specific variations were detected. The latency to accomplish the task was significantly lower in rats than in pikas and zokors, but no sex-specific differences were detected in all the species. The inferior performance of plateau zokors, compared to pikas and rats, in the T-maze might imply that although the functional significance of working memory may overlap in diverse taxonomic groups, the adaptive value thereof may differ considerably across taxa on account of the divergence in environmental stability, domestication, habitat structure, behavioural needs and the available sensory cues between species.

Individual variation in advertisement calls of the pale-shouldered horned toad ( Xenophrys boettgeri ) Abstract The characteristics of male anurans’ calls play an important role in mating success during the breeding season. In this study, we analyzed intra- and inter-individual variability of the advertisement calls of the pale-shouldered horned toad (Xenophrys boettgeri) in the field during its breeding season in Lishui, Zhejiang Province, China. The results showed that some acoustic parameters were significantly correlated with morphological features and air temperature. Most acoustic parameters including note numbers, call duration, and dominant frequency were static, whereas the call interval was intermediate. The CVb/CVw ratio was greater than 1.0 for all acoustic parameters analyzed, with between-individual variation being higher than within-individual variation. Furthermore, the acoustic parameter results of principle component analysis and discriminant function analysis indicated that note numbers and call interval are potentially useful for individual discrimination of X. boettgeri.

Male performance and associated costs in successive sexual encounters in a polygynous web wolf spider Abstract Polygynous males increase their reproductive success by fertilizing as many females as possible. However, this strategy can lead to costs for the males. This study focused on an atypical wolf spider that lives in webs, Aglaoctenus lagotis. Previous studies report polyandrous females, but little is known about the mating strategy of males and its potential associated costs. Our goals were to determine the potential polygyny and the changes in sexual behaviour, body condition and physiology of males throughout successive matings. Males were expected to mate with multiple females; males’ body condition was expected to decrease and male mating performance, including sperm transfer, was expected to decrease over successive matings. Males were exposed to successive virgin females every 3 days until the male did not court, was cannibalized or died of natural causes. Agreeing with our predictions, males were capable of multiple matings, showing an average of 5 ± 2 matings (range 3–11). Their mating performance decreased in successive matings and, although no changes were found in the behavioural patterns during the courtship over successive matings, the number of palpal insertions decreased. Unexpectedly, overall body condition did not decrease and males did not deplete their sperm supply. We found that 44% of the males were victims of sexual cannibalism after their third mating. The females that attacked or cannibalized males had less sperm stored in their spermathecae than those that did not. We discuss hypotheses that may clarify this scenario and the role of the cryptic female choice mechanism.

Molecular evidence of bird-eating behavior in Nyctalus aviator Abstract Insectivorous bats consume a large variety of food items. Previous observations of feathers found in feces led to the hypothesis that the birdlike noctule (Nyctalus aviator, Vespertilionidae) could prey on birds. To test the hypothesis, we analyzed fecal samples from six species (Barbastella pacifica, Murina hilgendorfi, Myotis frater, N. aviator, Plecotus sacrimontis, and Vespertilio sinensis) collected from central Hokkaido, Japan, via DNA barcoding. We identified the presence of the Middendorff’s grasshopper warbler (Locustella ochotensis) in the diet of a pregnant individual of N. aviator. All the other samples proved negative regarding bird prey DNA. This is the first time that the consumption of a bird by N. aviator is confirmed with molecular evidence. Our findings add invaluable insight into the diet of this bat and its potentially opportunistic foraging behavior.

Prey-predator interactions between two intraguild predators modulate their behavioral decisions Abstract Intraguild predators can have behavioral mechanisms to maximize foraging and/or avoid predation. However, there is a lack of information about the influence of such prey-predator interactions on the daily activity of the species involved. Therefore, we investigated the daily activity of two intraguild predators, Tityus pusillus Pocock, 1893 and Ananteris mauryi Lourenço, 1982, in the presence and absence of each other. Animals were observed in three experimental conditions, containing individuals of T. pusillus (control 1), A. mauryi (control 2), and both species (treatment). In addition, we evaluated the correlation between the number of active individuals with air temperature and humidity. Our results showed that T. pusillus and A. mauryi have similar daily activity between 18:00 and 05:00 h. However, T. pusillus was more active and shifted from a sit-and-wait hunting mode to actively hunting when in the presence of A. mauryi. In contrast, under predation risk, A. mauryi did not change its level of activity but became more vigilant by reducing the frequency of rest, hydration, and mating attempts. Activity of A. mauryi was positively correlated with air humidity whereas activity of T. pusillus was negatively correlated. This work highlights the influence of intraguild predators in the behavioral decisions during daily activities of each other, indicating adaptive behaviors in both prey and predator.

Cue recognition and behavioural responses in the three-spined stickleback ( Gasterosteus aculeatus ) under risk of fish predation Abstract To effectively respond to predation risk, prey must assess the risk associated with different predation cues. Predation cues can stem either from the predator or from conspecifics and indicate different predation risk levels, thus eliciting different anti-predation responses. The three-spined stickleback is a well-studied fish species often found in gregarious formations. Previous studies show that sticklebacks perform a variety of anti-predation behaviours; however, little is known about how they respond to multiple simultaneous predator cues, characteristic of heterogeneous natural habitats. Here, we experimentally compare the relative importance of three types of predation cues (visual predator cue, chemical predator odour cue and chemical alarm cue from injured conspecifics) and their interactions, on anti-predation and foraging behaviour of sticklebacks. Results showed that (1) individual sticklebacks responded most strongly to visual predator cues, which resulted in reduced foraging activity, increased spine erection and increased predator inspection; (2) the presence of chemical cues (predator odour and/or conspecific alarm cues) stimulates freezing behaviour to a minor extent; and (3) anti-predation behaviour manifests as a trade-off with foraging-related activities. Overall, the results indicate that sticklebacks could assess risk and modify their behavioural responses depending on which cues are present in the environment. The experimental approach of using factorial combinations of different predatory cues can increase our understanding of the role of multimodal cues in aquatic ecosystems.

Behavioral and adrenocortical responses of captive white rhino adolescents to the introduction of a new calf Abstract Changes in group composition are not exclusive to zoos and conservation breeding centers. The recent increase in poaching of African rhino species has accelerated the arrival of orphan calves at rehabilitation centers. Introducing new members into an existing group is often stressful for many mammal species. However, when young animals are involved, such responses may be reduced or absent. The goal of the present study was to evaluate the effect of introducing orphan calves on the stress responses of young orphan rhino from existing groups. The behavior and fecal glucocorticoid metabolite (fGCM) concentrations of eight orphan southern white rhinoceros (Ceratotherium simum simum) were assessed 1 month before and after the introduction of a new calf. From the 10 variables measured, only the response to humans and submissive behaviors showed significant changes. Stereotypies were not observed during the course of the study, and adrenocortical activity, monitored by means of fGCM concentrations, did not increase after the introductions, showing values within the range observed in free-ranging white rhino. However, strong individual differences were evident in most variables. Our results suggest that the introduction of white rhino calves into an existing group of young rhinos caused minimal stress in existing group members. Although these findings should be treated with caution when generalizing to other captive populations due to the small and heterogeneous sample, our findings may have management implications for rhino orphanages as well as zoos and breeding centers where non-breeding pairs are frequently maintained.

Starvation decreases behavioral consistency in a Neotropical harvestman Abstract 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.

Do males pay more? A male-biased predation of common lizard ( Zootoca vivipara ) by great grey shrike ( Lanius excubitor ) Abstract Predation is one of the most important factors affecting biology, ecology and behaviour of the prey. We have studied predation of the common lizard (Zootoca vivipara) by the great grey shrike (Lanius excubitor) in farmland habitats in western Poland. Shrike caches were used as a source of information about preyed lizards. Shrikes hunt significantly more adult males than females, juveniles and sub-adults; the pattern was similar over all three study years. Male lizard had longer activity time than female; therefore, they seem to be under predation pressure for a longer time during breeding season. Capture and count transect data of common lizard populations living within and outside shrike territories showed significant seasonal differences: within shrike territories, there was lower proportion of males than females; moreover, in some territories, the number of males in the lizard population was negatively correlated with the number of males impaled by shrikes. Our findings suggest that in this particular predator-prey system, shrikes may be a strong selective force for lizards’ population dynamics. Male-biased predation could be caused by differences in the behaviour of adult male and female lizards, namely longer activity of males and differences in space and refuge use.

Observations on the mating behavior of a dryinid and first record of sexual cannibalism in the hymenoptera Abstract Sexual cannibalism is a phenomenon that has been reported in a wide variety of invertebrate predators. In arthropods, it has been documented mostly in arachnids. The Dryinidae, a small cosmopolitan family of aculeate hymenopterans, are exclusively parasitic of the hemipteran suborders Cicadomorpha and Fulgoromorpha. They include some species that have been successfully employed in biological control programs. The ecology and biology of the Dryinidae is generally little known. In this short communication, studying biological traits of Gonatopus chilensis, a parasitoid of planthoppers, we report two novel facts for dryinid species: occasionally virgin females were re-mated by the same male, and after mating, occasionally young females caught the male and devoured its gaster. This is the first record of sexual cannibalism for the family Dryinidae and, to our knowledge, for the order Hymenoptera.