Behavioral Ecology最新文献

Wind is an important abiotic factor that influences an array of biological processes including animal behavior, but it is rarely considered in plant-pollinator interactions. Here, we investigate the impact of wind speed on plant-pollinator community structure under natural conditions. In our field experiment we observed threefold greater abundance of pollinators and double the species richness under low (< 0.5 m/s) versus moderate (> 2.5 m/s) wind speeds. Significant differences in plant-pollinator community structure were also observed, with Diptera most abundant under low wind conditions, and Hymenoptera predominant and Lepidoptera absent in windier conditions. Across three plant species, the foraging rates of both honey and bumble bees were 15% greater at low versus moderate wind speeds. Lastly, at greater wind speeds bees made more movements between plants, suggesting that wind may improve yield for crops that require cross-pollination. Overall, our findings show that wind is an important factor in determining which pollinator groups are active and that eusocial bees, which are often the most important pollinators, were little affected by moderate wind speeds. Our results raise several important issues for further study and suggest that the use of linear features such as trees and hedges that act as windbreaks may be beneficial to crop pollination and conservation efforts.

Birds that migrate from temperate areas to the Arctic to breed lose their strongest Zeitgeber of circadian organization when they cross the Arctic circle in spring - the 24h light-dark cycle. Under continuous daylight, diverse behavioral and physiological patterns have been detected in both free-ranging and laboratory animals. To better understand the evolution of plasticity in circadian clocks, it is essential to study behavioral and physiological rhythmicity in the context of a species' ecology. Employing a multifaceted approach, which included wildlife cameras, accelerometers, and noninvasive sampling of hormone metabolites, we investigated activity patterns and corticosterone rhythmicity in a migratory herbivore, the barnacle goose (Branta leucopsis), during its Arctic breeding season on Svalbard. We found that females showed a combination of both ultradian and diel rhythmicity in nest recesses and sleep during incubation. In both parents, these rhythms in activity continued also during the gosling rearing phase. During molt, many geese aligned activity with the prevailing tidal rhythm. Barnacle geese showed weak diel rhythmicity in excreted corticosterone metabolites (CORTm). This suggests that while Arctic geese may adopt an alternative Zeitgeber during the Arctic summer to maintain a diel rhythm, ultradian rhythmicity remains essential, allowing the geese to flexibly adjust their rhythms to environmental conditions.

Noise pollution is a global threat to biodiversity, significantly affecting acoustic communication in birds and other taxa. While European robins (Erithacus rubecula) adjust their songs in response to urban noise during the breeding season, little is known about song adjustments during the non-breeding season, when song plays a crucial role in survival by helping secure winter territories with adequate resources and shelter. To better understand the effect of noise on avian communication, we investigate whether robins modify their non-breeding song in noisy environments. We analyed the autumn songs of 25 robins exposed to varying background noise levels and found that robins increase the minimum frequency of their songs and extend phrase duration by singing fewer but longer syllables per phrase in noisy environments-adjustments that may mitigate acoustic masking. Our results provide valuable insights into the broader impact of urbanization on bird communication and highlight the need to consider non-breeding vocal behavior in conservation efforts. These findings underscore the year-round impact of noise pollution on birdsong, suggesting it affects various aspects of avian life history. However, it remains unclear whether these adjustments have evolutionary consequences for survival, as changes in key song parameters may affect how rivals interpret signals. Therefore, future studies should explore how vocal plasticity influences winter territory quality, predation rates, and individual survival.

Animal decisions trade-off the mortality risks of starvation and predation, and anti-predator behaviors generally incur a cost of reduced energy intake. Torpor and shallow rest-phase heterothermy are widespread physiological responses to starvation risk among small mammals and birds. Here, we present a field-based experimental test of the hypothesis that energy savings from torpor use can also reduce predation risk by moderating the energy cost of anti-predator behavioral responses in a small bird during winter. We manipulated perceived predation risk in wild populations of the superb fairy-wren (Malurus cyaneus) by playback of conspecific alarm calls during the daytime active-phase and tested for effects on body temperature measured continuously by telemetry during the nocturnal rest-phase. We found that alarm call playback was associated with subsequent rest-phase torpor bouts that were significantly deeper (minimum skin temperature: 28.7 ± 1.7 °C vs. 30.0 ± 1.5 °C) and longer (duration in torpor: 6.0 ± 2.7 h vs. 3.8 ± 2.3 h) compared to control periods. By demonstrating the connection between resting energy expenditure and energy costs of behavioral decisions during activity, our study has implications for understanding both the ecological functions of torpor and survival consequences of behavioral responses by small birds to environmental challenges.

Males in many species possess sexually selected weapons that they use to fight for mating opportunities. It is well established that male-male competition can lead to physical injuries for males. However, very few studies have looked at the physical consequences for conspecific females. We hypothesized that living with males in a species with male-male competition would result in female injury. Because larger female invertebrates typically have greater reproductive output, they have higher resource value for males and can elicit aggression and fighting. Thus, we further hypothesized that larger females in this context would receive more injuries. For this study, we focused on the leaf-footed cactus bug, Narnia femorata (Hemiptera: Coreidae), a species of insect in which males fight using their spiny and enlarged hindlegs. In just 2 h of observation, we documented males competing with other males in 61% of 103 trials. In 43% of these 63 competitions, females were physically contacted and sometimes attacked with a kick or squeeze. We left insects in social groups for 74 h and found that females living with multiple males had a higher likelihood of obtaining injuries (26.2% of 103 trials) compared to those living only with females (9.7% of 103 trials). In addition, larger females were more likely to be injured compared to smaller females. Our study highlights the harm that females can experience in species with male-male competition.

Animals must acquire new information through learning to adjust their behavior adaptively. However, learning ability can be constrained by conditions experienced during early development, when the brain is especially susceptible to environmental conditions. For example, temperature can result in phenotypically plastic adjustments to growth, metabolism, and learning in ectotherms. In vertebrates, thermal conditions can increase the production of glucocorticoid (GCs) - 'stress' hormones. Maternal GCs can be transmitted to offspring during development, potentially impacting their learning abilities. GCs and thermal environments are, therefore, predicted to have interactive effects on the development of learning in ectotherms. Here, we investigated the combined effects of prenatal corticosterone (CORT) - the main GC in reptiles-and incubation temperature on associative learning using two species of lizards, Lampropholis delicata and L. guichenoti. We manipulated CORT levels and temperature in a 2 × 2 factorial design, and then subjected juveniles to a color-associative learning task. We predicted that elevated CORT and low temperatures would impair associative learning. However, both species showed similar learning rates independently of treatment. Our results suggest that these two species may have evolved mechanisms to maintain learning performance despite prenatal challenges. We also found that color affected decision-making in both species. Overall, we observed a non-learned preference towards blue, underscoring the need to carefully select the color used in cognitive tests involving visual stimuli.

Heatwaves, increasingly common and intense due to climate change, are increasing mortality rates and disrupting vital functions. Recent research has begun exploring their impact on cognition. Since cognition underlies key fitness-related behaviors, such as foraging, predator avoidance, and mate choice, understanding the cognitive costs of heatwaves is crucial. Here, we investigate whether heatwaves impact cognition using male guppies (Poecilia reticulata) as a vertebrate model. We focused on males due to their behavioral consistency in cognitive tests and because they were previously observed to alter sexual behavior after a heatwave. Males were exposed to a 5-d experimental heatwave (32 °C) or control treatment (26 °C). The chosen temperatures are ecologically relevant for the species, fall within their natural habitat's thermal range, and reflect extreme climatic events that are projected to become even more frequent and severe under future climate scenarios. Following treatment, all fish were tested at 26 °C for spatial memory and learning, mate choice, inhibitory control, and anti-predator responses. We also conducted histopathological evaluations of brain tissue to investigate potential central nervous system lesions. The results show that heatwave exposure declined maze solving efficiency, affected mate choice-related cognitive capacities, and led to suboptimal anti-predatory responses. No effects were observed on inhibitory control or habituation. Importantly, heatwave exposure induced morphological alterations in the central nervous system, potentially explaining the observed changes in cognitive performance. Our study provides a comprehensive evaluation of heatwave impacts on cognitive function, highlighting the need of investigating their subtle yet significant effects to fully understand how heatwaves influence fitness beyond survival.

Birds differ in their parent-offspring interactions, and these differences may be caused by environmental variation. When food is plentiful, the chicks that are begging the most are fed the most. When food is scarce, parents instead feed the largest offspring. This change could due to offspring adjusting their behaviour, or to confounding factors not directly related to current food availability, such as brood size. Alternatively, it could equally be due to parents responding to signals differently based on their experience of food availability in the recent past, for example, over the past weeks. We tested between these competing explanations experimentally, by manipulating food availability in a population of wild great tits, Parus major. We then standardised food availability, and manipulated offspring size and behaviour by creating mixed cross-fostered broods just before filming. This isolated the effect of parental strategies while holding food availability, offspring begging and size constant across treatments, but with sufficient variation within broods to generate usable information for parents. We found that when parents had experienced plentiful, supplemented food prior to filming, they were: (1) more likely to preferentially feed the chicks that were begging the most; and (2) less likely to preferentially feed larger chicks. Chicks, on the other hand, did not differ in their behavior in relation to the environmental conditions they had experienced previously, but instead begged in relation to their immediate feeding history and their nestmates' begging intensity. Overall, our results suggest that parents have more control over food distribution than suggested by scramble competition models, and that they can flexibly adjust how they respond to both offspring signals and cues of offspring quality in response to food availability. Consequently, different signalling systems are favoured depending on environmental conditions and predictability and parental plasticity.

Ecological niches are closely intertwined with cognition in many animal lineages. For example, diet breadth is linked with performance on tasks measuring learning and exploration in several vertebrates, with generalists often exhibiting faster learning and more exploratory behavior than specialists. We compared associative learning performance and exploratory tendencies between dietary specialist and generalist bee (Anthophila) species using a closed-environment task with free-moving bees called the free-moving proboscis-extension response (FMPER). We found lower participation rates than expected, especially among specialist species, which hindered our ability to answer our primary question. Because participation rates of specialist species were so low, we combined our data with another published dataset that reported results from the same learning task but for several different bee species (again including specialists and generalists) to investigate the relation of diet breadth with associative learning and exploration across a broader species assemblage. Phylogeny-informed generalized linear mixed models indicate that neither specialists nor generalists increased accuracy throughout the task, although bees of both diet breadths became faster at drinking from the rewarding strip. Bees decreased their drinking latency-a measure of exploration-throughout the experiment, with no effect of diet breadth. However, specialists became less likely to participate over the course of the task compared to generalists. Our results suggest that specialist and generalist bees have experienced similar selection for associative learning abilities, and that specialists are hesitant to continue interacting with novel stimuli. Our study highlights the importance of developing cognitive tasks that measure abilities equally across the full range of life history traits.

The color polymorphisms of prey species are often maintained by apostatic selection. In particular, rarer morphs are thought to be at an advantage because attentional constraints result in predators forming search images, which are based on the most abundant prey morph. Predatory species can also be polymorphic and predator morph abundance may be maintained by a similar mechanism, given prey are also likely to form search images to ensure fast and appropriate anti-predatory responses. Alternatively, given that the predator polymorphism may be driven by other ecological factors (eg niche divergence or sexual selection), prey may instead be highly sensitive to the relative visual saliency of different predatory morphs, which in turn could impact predator morph abundance. Here, by combining empirical observations with a field experiment, we assessed how the relative abundance and saliency of different color morphs of the predatory trumpetfish (Aulostomus maculatus) influenced the behavioral responses of a typical prey species, the bicolor damselfish (Stegastes partitus). We found that more abundant predator color morphs were less salient in damselfish vision (relative to the background) than less abundant color morphs. By presenting 3D models of each morph to damselfish, we found that they did not respond differently to more abundant or more salient morphs. Our results suggest that both the relative abundance and saliency of predator morphs could contribute towards the search images used by prey. Specifically, each morph could have relatively equal detectability if their abundance and saliency have antagonistic effects on search-image formation in prey.