摘要: Climate change and its resulting effects on seasonality are known to alter a variety of animal behaviors including those related to foraging, phenology, and migration. Although many studies focus on the impacts of phenological changes on physiology or fitness enhancing behaviors, fewer have investigated the relationship between variation in weather and phenology on risk assessment. Fleeing from predators is an economic decision that incurs costs and benefits. As environmental conditions change, animals may face additional stressors that affect their decision to flee and influence their ability to effectively assess risk. Flight initiation distance (FID)-the distance at which animals move away from threats-is often used to study risk assessment. FID varies due to both internal and external biotic and physical factors as well as anthropogenic activities. We asked whether variation in weather and phenology is associated with risk-taking in a population of yellow-bellied marmots (Marmota flaviventer). As the air temperature increased marmots tolerated closer approaches, suggesting that they either perceived less risk or that their response to a threat was thermally compromised. The effect of temperature was relatively small and was largely dependent upon having a larger range in the full data set that permitted us to detect it. We found no effects of either the date that snow disappeared or July precipitation on marmot FID. As global temperatures continue to rise, rainfall varies more and drought becomes more common, understanding climate-related changes in how animals assess risk should be used to inform population viability models.

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摘要: For songbirds, the post-fledging period is critical for development and survival, as young must learn to get food, practice flying, and identify predators to become independent from their parents and disperse or migrate. Obligate avian brood parasites, like cuckoos and cowbirds, lay eggs in nests of other bird species that provide parental care until the parasite's young become independent. The information on the post-fledging period in songbirds is limited due to the difficulty in following and observing fledglings and it is even scarcer for brood parasites. We studied the behavior, survival, and age of independence of Shiny Cowbird (Molothrus bonariensis) fledglings raised by 2 hosts that differ markedly in body size: the House Wren (Troglodytes aedon) and the Chalk-Browed Mockingbird (Mimus saturninus). We radio-tracked individuals from a few days before they left the nest until they disappeared from the natal territory. We found: (1) chicks left the nest when they were 11-15 days of age and the age of fledgling did not differ between the 2 host species, (2) after leaving the nest, they spent most of the time perched in a hidden place without begging but as they grew, the proportion of time perched without begging decreased and begging in hidden and exposed places increased, (3) we observed approaches between adult parasitic females and young in host territories, (4) young abandoned the host territory and joined conspecific flocks when they were 35-39 days of age, and (5) the estimated post-fledging survival was between 12.5% and 20.8%.

摘要: Non-signaling functions of coloration include thermoregulation (thermal melanism hypothesis), protection against ultraviolet radiation (photo- protection hypothesis), and concealment from predators (crypsis hypothesis). We investigated whether dorsal coloration in 19 populations of spiny-footed lizards, Acanthodactylus erythrurus, across the Iberian Peninsula varies according to these functions. We captured adult males and females in each population and calculated standardized dorsum brightness estimates from photographs. We also calculated standardized ground luminosity estimates and gathered information on latitude, altitude, mean annual temperature, and mean annual solar radiation for each location. Males showed a higher percentage of black coloration and a more contrasted dorsum than females, suggesting different selection pressures on dorsal coloration in both sexes. Furthermore, males showed a darker dorsum and a higher percentage of black coloration at higher altitudes and when the ground was darker. In contrast, females exhibited a darker dorsum only when the ground was darker and a higher percentage of black coloration only at higher altitudes. We also observed that the variation of dorsum luminosity within males and the variation of dorsum luminosity among females within populations were both positively related to the variation of ground luminosity among different points within locations. Latitude, temperature, and solar radiation were not significantly related to dorsal coloration in either sex. Our results support the photoprotection and crypsis hypotheses in males and, to some extent, in females, whereas the thermal melanism hypothesis is weakly supported in both sexes. These findings suggest that there is local adaptation in the dorsal coloration of the spiny-footed lizard.

摘要: Animal species exhibit a wide range of coloration and patterns, which are under strong selection and often linked to individual quality, influencing mate choice, recognition, signaling, and interspecific interactions such as predator avoidance. In amphibians, coloration can vary based on individual traits as well as environmental conditions, including the coloration of their environment. In this study, we described the dorsal coloration (body coloration reticulated by dark patches) in 676 Western spadefoot toads (Pelobates cultripes) from the French Atlantic coast, comparing color variations across different substrates. In addition, we assessed color change in 18 toads transferred between bright and dark substrates. We demonstrated that the dorsal coloration varies based on capture locations (beach vs. inland) and associated substrate types (bright vs. dark), suggesting background color matching. We showed more pronounced effects in females, which might reflect varying predation risks. Experimentally, we showed that individuals can rapidly adjust their coloration to match the substrate within 24 h. Rapid color changes in response to substrate type indicate significant pigmentation plasticity. Bright individuals from sandy substrates showed less dorsal background (body) color change than dark inland individuals, while patch coloration responded differently depending on the substrate of origin. These findings highlight the complex interactions between substrate type, sex, and pigmentation plasticity. These interactions have potential costs and benefits, which might be linked to melanin production, which warrant further investigation.

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摘要: Eyespots have been shown to perform an anti-predator function by intimidating predators. However, whether predators are deterred by the eyespots' mimicking eyes of higher-order predators, or by the conspicuousness of the spots, is still being debated. The anti-predator mechanism of eyespots, which involves the predator's visual perception and cognition, urges to be examined. To explore the eye mimicry hypothesis and conspicuous signal hypothesis, we designed prey with deceptive eyespots eliciting 2-dimensional (2D) or 3-dimensional (3D) visual illusions for domestic chicks (as predators). For 2D visual illusion, we provided prey with occluded eyespots for chicks. Chicks can complete the occluded eyespots into a full 2D concentric circle by the amodal completion mechanism, that is, one of visual illusion. For 3D visual illusion, we created the crescent-shaped sparkles on the eyespots to simulate a visually 3D eye. Our result indicated that (1) 2D: chicks hesitated more when facing preys with occluded eyespots than facing preys with broken eyespots and (2) 3D: compared to prey with no-sparkle eyespots, chicks spent more time approaching prey with sparkle eyespots and were more likely to approach them tangentially. Thus, the visual illusion perceived by chicks would impact the anti-predation effectiveness of eyespots. Eyespots that more closely resemble the real eyes, especially those with 3-dimensionality, provided more effective protection. Our study supported the eye mimicry hypothesis from the perspective of visual illusion.

摘要: Alarm calls in bird vocalizations serve as acoustic signals announcing danger. Owing to the convergent evolution of alarm calls, some bird species can benefit from eavesdropping on certain parameters of alarm calls of other species. Vocal mimicry, displayed by many bird species, aids defense against predators and may help brood parasites during parasitism. In the coevolutionary dynamics between brood parasites, such as the common cuckoo ( Cuculus canorus), and their hosts, female cuckoo vocalizations can induce hosts to leave the nest, increasing the probability of successful parasitism and reducing the risk of host attacks. Such cuckoo calls were thought to mimic those of the sparrowhawk. However, owing to their similarity to alarm calls, we propose a new hypothesis: Female cuckoos cheat their hosts by mimicking the parameters of the host alarm call. In this study, we tested this new hypothesis and the sparrowhawk mimicry hypothesis simultaneously by manipulating the syllable rate in male and female common cuckoo vocalizations and playing them in front of the host Oriental reed warbler ( Acrocephalus orientalis) for examination. The results indicate that similar to a normal female cuckoo call, a female call with a reduced syllable rate prompted the hosts to leave their nests more frequently and rapidly than male cuckoo calls. Additionally, the male cuckoo calls with increased syllable rate did not prompt the host to leave their nests more frequently or quickly compared with the male cuckoo calls with a normal syllable rate. Our results further confirm that female common cuckoos mimic the vocalizations of Eurasian sparrowhawks ( Accipiter nisus), reveal the function mechanisms underlying such mimicry, and support the theory of imperfect mimicry.

摘要: The microbiome of mammals has profound effects on host fitness, but the process, which drives the assembly and shift of mammalian micro- biome remains poorly understood. To explore the patterns of small mammal microbial communities across host species and geographical sites and measure the relative contributions of different processes in driving assembly patterns, 2 sympatric desert rodent species ( Dipus sagitta and Meriones meridianus) were sampled from 2 geographically distant regions, which differed in the environment, followed by 16S rRNA gene sequencing. The microbiomes differed significantly between D. sagitta and M. meridianus, and linear mixed modeling (LMM) analysis revealed that microbial diversity was mostly affected by species rather than the environment. For each rodent species, the microbiome diversity and structure differed across geographical regions, with individuals from lower rainfall environments exhibiting greater diversity. The null modeling results suggested dispersal limitation and ecological drift rather than differential selective pressures acting on the microbiome. In addition, each group had a different core genus, suggesting that the taxonomic composition of the microbiome was shaped most strongly by stochastic processes. Our results suggest that variation in the microbiome between hosts, both within and among geographic rodent populations, is driven by bacterial dispersal and ecological drift rather than by differential selective pressures.These results elucidated the diversity patterns and assembly processes of bacterial microbiomes in small desert mammals. Deciphering the processes shaping the assembly of the microbial community is a premise for better understanding how the environment-host-microbe interactions of mammals are established and maintained, particularly in the context of increased environmental disturbances and global changes.

摘要: Vocal individuality is essential for social discrimination but has been poorly studied in animals that produce communal signals (duets or choruses). Song overlapping and temporal coordination make the assessment of individuality in communal signals more complex. In addition, selection may favor the accurate identification of pairs over individuals by receivers in year-round territorial species with duetting and long-term pair bonding. Here, we studied pair and individual vocal signatures in the polyphonal duets of rufous horneros Furnarius rufus, a Neotropical bird known for its long-term pair bonds. Hornero partners engage in duets to deter territorial intruders and protect their partnership year-round and can discern duets from neighbors versus strangers. Using a dataset of 471 duets from 43 pairs in 2 populations, we measured fine-scale acoustic features across different duet levels (e.g., complete duets to non-overlapping syllable parts) and analysis levels (pair or individual). Permuted linear discriminant function analyses classified pairs and individuals more accurately than expected by chance (means: 45% and 47% vs. 4 and 2%). Pair identity explained more variance in the multivariate acoustic features of duets than individual or population identities. The initial frequency of the duet showed strong potential for encoding pair identity.The acoustic traits contributing most to individual vocal signatures varied between sexes, which might facilitate the simultaneous assessment of duetters' identities by receivers. Our study indicates that vocal individuality may exist even in species with intricate and innate communal signals and elucidates the mechanisms employed by horneros in their social discrimination ability.