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Preview: Behavioral Ecology - current issue

Behavioral Ecology Current Issue





Published: Tue, 19 Sep 2017 00:00:00 GMT

Last Build Date: Sat, 23 Sep 2017 04:43:35 GMT

 






Duetting behavior varies with sex, season, and singing role in a tropical oriole ( Icterus icterus )

2017-08-11

Abstract
Females and males of many animals combine their vocalizations into coordinated acoustic duets. Duets can mediate both cooperation and conflict between partners, and are common in tropical, sedentary species that may use duets for multiple functions year-round. To elucidate the full range of duet functions, we need to study the individual-level behaviors that generate duets throughout the year. We evaluated multiple functions of duetting behavior in female and male Venezuelan troupials (Icterus icterus) during the breeding and nonbreeding seasons, including territory defense, maintaining contact with a mate, and paternity guarding. In both sexes during both seasons, song initiation rates were predicted by conspecific solo and duet rates. However, troupials were more likely to answer their mate to form duets after conspecific duets than after conspecific solos, supporting a territory defense function of duets. Troupials that answered their mate to form duets were also more likely to move toward their mate (than duet initiators and soloists), suggesting that duet participation also functions to maintain contact. During the breeding season, males were particularly likely to fly toward their mate after answering to form a duet. This finding may indicate that males answer to guard paternity, although other predictions of paternity guarding were not supported. Examining individual-level behaviors during both the breeding and nonbreeding season revealed multiple functions of troupial duets. Our results are consistent with social selection acting on females and males to maintain contact and territories year-round, and possibly sexual selection on males for functions tied to the breeding season.



Stomatopods detect and assess achromatic cues in contests

2017-08-11

Abstract
Conspicuous, colorful displays are often used by animals to communicate within and between species. Previously, researchers have manipulated specific components of color signals (i.e., hue, total reflectance, and/or chroma) using paints, photographs, videos, or filters. However, these manipulations may not adequately mimic the spectrum of color signals outside the range of human perception. Thus, these methods are inappropriate for organisms with unconventional visual systems, such as stomatopods (mantis shrimp). Here, we describe a novel application of a femtosecond laser to increase total reflectance of the stomatopod meral spot, a distinct area on the raptorial appendage used in territorial contests. Ultrafast lasers provide a programmable way to precisely manipulate patch total reflectance of live stomatopods without causing collateral damage. We tested how experimentally increasing meral spot reflectance impacted receiver behavior during territorial contests. Contests in which receiver stomatopods faced an opponent with a lightened meral spot were shorter and receivers showed increased rates of agonistic behaviors. This result suggests that lighter meral spots indicate lower fighting ability; thus, receivers are more willing to engage in a contest. This research provides the first demonstration that stomatopods can detect and assess achromatic variation in contests. Furthermore, we demonstrate that ultrafast lasers provide a powerful tool to investigate achromatic signaling, particularly for organisms whose size, aquatic habitat, or visual system otherwise prevent realistic alterations to color signals (e.g., butterflies, jumping spiders, or decapod crustaceans). This study advances our knowledge about stomatopod visual communication and offers a valuable tool for future research.



Female anoles display less but attack more quickly than males in response to territorial intrusions

2017-08-10

Abstract
Fighting to defend a territory can be costly due to the risk of injury associated with physical combat. Therefore, many species rely on displays that allow individuals to assess one another, avoid escalation, and mitigate the costs of physical conflict. Most studies of territorial aggression have been conducted in the context of male–male competition, and although females of many species are also aggressive, direct comparisons of male–male and female–female aggression are rare. Consequently, the relative extent to which males and females of territorial species use behavioral displays and physical aggression to mediate intrasexual competition is generally unknown. To address this question, we experimentally introduced same-sex intruders onto the territories of male and female brown anole lizards (Anolis sagrei). We found that, although males were slightly more likely to attack an intruder than were females, males also allowed a greater amount of time to elapse before escalating to an attack, relative to females. Males also exhibited more aggressive display behaviors (dewlap extensions, push-ups, and head-bobs) before engaging in a physical attack. These results are consistent with the idea that, due to a potentially greater risk of injury, males may attempt to avoid escalating to physical conflict. The high rates of attack and low latency to attack that we observed for interactions between females also run counter to the general assumption that males are categorically more aggressive in territorial, polygynous species characterized by extreme male-biased sexual size dimorphism.



Prior information and social experience influence male reproductive decisions

2017-08-10

Abstract
Increasing attention has focused on understanding how past experiences can influence and explain variation in mating preferences among individuals. We examined how previous social experiences affected courtship preferences in Drosophila melanogaster by exposing individual males to different frequency distributions of high- and low-quality (HQ and LQ) females and by allowing them to copulate with either a HQ or LQ mate. For a male, a large female represents a high-quality mate while a small female is a low-quality mate. We subsequently quantified the courtship behavior of these individuals in the presence of one HQ and one LQ female. Two aspects of male courtship behavior were significantly influenced by prior experience. Males previously exposed to a population of 75% HQ females more often initially courted the HQ than LQ female and more strongly biased overall courtship activity toward the HQ female compared to males previously exposed to a population of 25% HQ females. Furthermore, for some males, the type of female a male mated with in the experience phase influenced the type of female he first courted in the test phase: males that experienced a population containing only 25% HQ females and who mated with a LQ female in the experience phase, more often courted the LQ female first in the test phase while all other males biased courtship toward the HQ female. Our results indicate that information gained about the relative abundance of mate quality types and previous mating experience can affect future mating behavior.



Nest decoration as social signals by males and females: greenery and feathers in starling colonies

2017-08-04

Abstract
The expression of elaborated displays provides reliable information to conspecifics about the quality of the signaler. Competition for breeding resources or mates is predicted to affect the expression of signals in both males and females; however, the literature has been typically focused on male behaviors. The spotless starling is an interesting example where both sexes decorate the nest to signal their condition and social status: males add green plants at the beginning of the breeding period, and females place foreign feathers during the incubation period. In this study, we investigate nest decoration by males and females in relation to the intensity of conspecific competition during the breeding period. We distributed nest boxes at either a high (HD) or a low density (LD) and recorded the amount of green plant material added before laying, the number of feathers at hatching, and the breeding productivity under these different density treatments. The amount of green plant material and the number of feathers at hatching were higher in HD than in LD nests. Furthermore, nest boxes at higher density had lower breeding productivity. Our results suggest that manipulating the density of nest boxes increased competition for breeding resources. The aggregation of males competing for territories and mates may stimulate them to add greater amounts of plants, and competition over those males or other resources for reproduction may induce females to add feathers. This study shows that social environment has the potential to influence the expression of signaling behaviors in both males and females.



Crowding leads to fitness benefits and reduced dispersal in a colonial spider

2017-08-04

Abstract
Density-dependent dispersal is a common dispersal strategy, mainly as a mechanism of escaping decreased fitness associated with high intra-specific competition. However, in group-living species, high density is expected to be beneficial for the individual, at least up to a certain threshold. A possible mechanism for maintaining an optimal density is negative density-dependent dispersal. In order to examine this hypothesis, we studied the effect of colony density on growth, dispersal and prey capture under different diets in the colonial spider Cyrtophora citricola (Forskål, 1775) (Araneidae). Colonies of C. citricola often reach high densities but the spiders are also capable of living solitarily. Previous studies showed that indirect benefits related to prey capture and predator defense may arise from colony-living, despite the lack of direct cooperation. We found that dispersal propensity of spiders decreased with increasing colony density, and that the effect was strongest when prey abundance was high. Additionally, site tenacity of spider hatchlings increased with greater density of adult females in colonies. Both results support a negative density-dependent dispersal strategy. As expected, body mass of spiders increased with density, suggesting that fitness increases with density (Allee effect). Variance in body mass was higher within dense colonies than among solitary spiders, therefore it is likely that spiders in the colony differ in their prey capture success, and consequently in body mass. This interplay between Allee effect, dispersal strategy and individual fitness may have an important role in the life history and distribution of colonial spiders and of other group-living species.



Marginal predation: do encounter or confusion effects explain the targeting of prey group edges?

2017-07-27

Abstract
Marginal predation, also known as the edge effect, occurs when aggregations of prey are preferentially targeted on their periphery by predators and has long been established in many taxa. Two main processes have been used to explain this phenomenon, the confusion effect and the encounter rate between predators and prey group edges. However, it is unknown at what size a prey group needs to be before marginal predation is detectable and to what extent each mechanism drives the effect. We conducted 2 experiments using groups of virtual prey being preyed upon by 3-spined sticklebacks (Gasterosteus aculeatus) to address these questions. In Experiment 1, we show that group sizes do not need to be large for marginal predation to occur, with this being detectable in groups of 16 or more. In Experiment 2, we find that encounter rate is a more likely explanation for marginal predation than the confusion effect in this system. We find that while confusion does affect predatory behaviors (whether or not predators make an attack), it does not affect marginal predation. Our results suggest that marginal predation is a more common phenomenon than originally thought as it also applies to relatively small groups. Similarly, as marginal predation does not need the confusion effect to occur, it may occur in a wider range of predator–prey species pairings, for example those where the predators search for prey using nonvisual sensory modalities.



A comparative analysis of the behavioral response to fishing boats in two albatross species

2017-07-22

Abstract
Anthropogenic food resources have significantly modified the foraging behavior of many animal species. They enhance large multi-specific aggregations of individuals, with strong ecological consequences. It is challenging to predict how individuals or species can differ in their reaction to these resources. For instance, there are wide variations in seabird species abundance behind fishing boats, and individual variations in interaction rates. Whether this is reflecting variations in fine-scale encounter rates or rather variations in attraction strength is poorly quantified. Here we compare the response of Wandering (WA) and Black-browed (BBA) albatrosses to fishing boats operating in sub-Antarctic waters. We use GPS tracking data from both birds and boats (Vessel Monitoring System). Attraction distances were similar between the 2 species (up to 30 km). BBA foraged further from fishing grounds and encountered boats less frequently than WA, but once they encountered a boat BBA were more strongly attracted (80% vs. 60% chance) and had a higher level of active interaction, compared to WA. Furthermore, in the absence of boats, BBA were rarely observed foraging over the habitat where the fisheries mainly operate, in contrast with WA. We thus report qualitative and quantitative differences in the response of these 2 species to the same fishing fleet. WA, the larger, more dominant and more generalist species was unexpectedly less attracted to fishing vessels. Comparing our results with previously published studies, we suggest that energetic requirements of individuals may be a crucial predictor for assessing risks of interactions with anthropogenic food resources.



Leopard distribution and abundance is unaffected by interference competition with lions

2017-07-22

Abstract
Competition can have profound impacts on the structure and function of ecological communities. Despite this, the population-level effects of intraguild competition on large carnivores remain largely unknown, due to a paucity of long-term studies that focus simultaneously on competing species. Here, we comprehensively examine competitive interactions, including their demographic consequences, between 2 top predators, lions Panthera leo and leopards P. pardus. We tested the hypothesis that lions, as the dominant competitor, limit the distribution and abundance of leopards, using dietary, spatial, and life-history data collected concurrently on the 2 species. Dietary overlap between lions and leopards was limited, with lions targeting large- to very large-sized prey and leopards small- to medium-sized prey. Leopards did not actively avoid lions, either predictively or reactively, except in riparian woodland where the likelihood of encountering lions was highest. Lions accounted for more than 20% of leopard mortality, but this appeared to be compensatory. Observed and modeled population growth was similar between the 2 species, with both exhibiting net emigration. Our findings suggest that lions do not suppress leopard populations or limit their distribution, at least in our study area. Adequate availability of suitably-sized prey apparently enabled resource partitioning between lions and leopards, facilitating their coexistence. The potential for competition increases in areas devoid of large prey and should be considered in recovery efforts for the 2 species. Our study provides novel empirical evidence that intraguild competition does not always have population-level consequences for subordinates, even if they suffer from strong inference competition with dominant competitors.



Food abundance, prey morphology, and diet specialization influence individual sea otter tool use

2017-07-21

Abstract
Sea otters are well-known tool users, employing objects such as rocks or shells to break open invertebrate prey. We used a series of generalized linear mixed effect models to examine observational data on prey capture and tool use from 211 tagged individuals from 5 geographically defined study areas throughout the sea otter’s range in California. Our best supported model was able to explain 75% of the variation in the frequency of tool use by individual sea otters with only ecological and demographic variables. In one study area, where sea otter food resources were abundant, all individuals had similar diets focusing on preferred prey items and used tools at low to moderate frequencies (4–38% of prey captures). In the remaining areas, where sea otters were food-limited, individuals specialized on different subsets of the available prey and had a wider range of average tool-use frequency (0–98% of prey captures). The prevalence of difficult-to-access prey in individual diets was a major predictor of tool use and increased the likelihood of using tools on prey that were not difficult to access as well. Age, sex, and feeding habitat also contributed to the probability of tool use but to a smaller extent. We developed a conceptual model illustrating how food abundance, the prevalence of difficult-to-access prey, and individual diet specialization interacted to determine the likelihood that individual sea otters would use tools and considered the model’s relevance to other tool-using species.



Mutual plumage ornamentation and biparental care: consequences for success in different environments

2017-07-19

Abstract
According to the good parent and differential allocation models, parental behavior could depend on the individual’s own quality, and it could be adjusted to the coinvestor’s parental care and sexual ornamentation. These investment patterns may interact with environmental conditions and offspring quality in determining reproductive success. Few studies have considered ornament-related own and partner care of both parents and their consequences in relation to environmental conditions. In a brood size manipulation experiment on collared flycatchers (Ficedula albicollis), we measured nestling feeding rates, white patch sizes and plumage reflectance properties of both parents, and quantified nestling growth and reproductive success. We found little relationship between ornamentation and own feeding rate irrespective of manipulation. Parental quality, measured as nestling biomass production per unit feeding effort, was related to male structural plumage brightness in a manipulation-dependent manner. Male wing patch size and the female’s structural plumage brightness were linked to the partner’s feeding rate, and this did not vary with experimental environment. Finally, relationship of prefledging nestling size with male forehead patch size was environment-dependent, and this pattern was apparently due to intrinsic nestling characteristics. Reproductive success only partly reflected these findings. Our results indicate how integrated studies of mutual ornamentation and mutual care with environmental and offspring quality may help us better grasp the selection forces shaping sexual ornaments.



Effects of individual-based preferences for colour-banded mates on sex allocation in zebra finches

2017-07-11

Abstract
Sex allocation theory predicts that females mated to attractive males produce more sons than females mated to unattractive males. However, previous tests of this hypothesis have obtained mixed results. We suggest that females differ in the traits they find attractive. To test this proposition, we assessed female zebra finches’ preferences for males banded with red or green plastic leg bands and then tested the sex allocation pattern of females paired with preferred and non-preferred males. Although most females preferred red-banded males, 34% of females consistently preferred green-banded males. The sex ratio at laying and hatching was not influenced by paternal preferred status. However, the fledging sex ratios differed between females paired with preferred and non-preferred males due to sex-biased chick mortality; sons of females paired with preferred males were born heavier and were more likely to survive than daughters. Our results indicate that female zebra finches show individual variation in their preferences for colour banded males, although females do not seem to adjust the offspring sex ratio in response to their mate’s band colour. However, the differential post-hatch mortality suggests females may differentially allocate resources into male and female eggs according to their individual mate preferences.



Male genital titillators and the intensity of post-copulatory sexual selection across bushcrickets

2017-07-10

Abstract
Animal genitalia are diverse and a growing body of evidence suggests that they evolve rapidly under post-copulatory sexual selection. This process is predicted to be more intense in polyandrous species, although there have been very few comparative studies of the relationship between the complexity of genital structures in males and measures of the degree of polyandry. In some bushcricket families, males possess sclerotized copulatory structures known as titillators, which are inserted into the female’s genital chamber and moved rhythmically. Like other genital structures, bushcricket titillators are widely used as important taxonomic characters and show considerable variation across species in structure, shape, and the extent to which they are spined. Here, we examine relationships between the presence/absence of titillators, titillator complexity, and both mating frequency and the degree of polyandry in bushcrickets, using phylogenetic comparative analyses. Using published sources combined with original observations, data were obtained for the mean level of polyandry, the duration of the male and female sexual refractory periods, and the level of complexity of titillators. To analyze data, we fitted phylogenetic generalized least squares models. No significant relationships were found between titillator presence or complexity and either the level of polyandry, duration of the male’s sexual refractory period, or the ratio of the female and male sexual refractory periods. The duration of the female’s refractory period, however, was positively associated with titillator presence and negatively associated with titillator complexity. The data therefore partially support the hypothesis that post-copulatory sexual selection drives genital evolution in this taxon.



Aquatic prey use countershading camouflage to match the visual background

2017-07-10

Abstract
An animal’s 3D form, combined with the directional lighting that is typical of many natural light environments, often results in the production of self-shadows, which may increase prey detectability to visual predators or vice versa. In terrestrial animals, countershading patterning, a luminance gradient from dark dorsal to pale ventral pigmentation, acts to counterbalance this effect by essentially reversing the distribution of light incident across the body surface. Although widespread among aquatic predators and prey, it is unclear whether countershading facilitates camouflage through elimination of self-shadows (self-shadow concealment [SSC]), enhances the match between an animal’s radiance and that of the background for multiple viewing angles (background matching [BM]), or a combination of both. We used clay models of a color-changing freshwater fish to determine the optimal patterning for SSC in different light environments, and we compared this to the skin reflectance profile of fish held under the same conditions. Fish adjusted their countershading pattern in response to changes in the light environment, but the observed reflectance profiles did not match the modeling predictions for optimal SSC. Thus fish adjusted their body pigmentation to match the viewing background rather than to conceal their ventral shadows. We suggest that different selection pressures resulting from the dissimilar characteristics of light in air and water have resulted in convergence of similar countershading phenotypes in terrestrial and aquatic prey.



Why does the rate of signal production in ectotherms vary with temperature?

2017-07-05

Abstract
The rate of signal production by social ectotherms is often temperature dependent. This has been typically attributed to an underlying thermal constraint on physiology, but there are other reasons why signal rates might be correlated to temperature. We tested 3 hypotheses. The maximal performance hypothesis: temperature limits motor activity at cold and hot temperatures, which predicts a hump-shape function between signal rate and temperature. The metabolic rate hypothesis: the available energy released by metabolism increases exponentially with temperature, which predicts an exponential increase in signal rates with temperature. The recipient availability hypothesis: the number of potential receivers varies with temperature, and signalers change their signal rates accordingly, which predicts an indirect association between signal rate and temperature. We tested these hypotheses using field data on the rate of advertisement display production by territorial Jamaican and Puerto Rican Anolis lizards from a variety of thermal environments, coupled with extensive observations on one montane population of A. gundlachi. In both cases, the slopes of display rate as a function of ambient temperature were statistically indistinguishable from slopes predicted by the performance hypothesis. Support for the other 2 hypotheses was weak or equivocal. This is the first study to test alternative hypotheses of why signal rates and temperature in ectotherms are correlated and to indicate that thermal performance curves measured in the lab can reliably predict important social behavior in the field.



Wild dwarf mongooses produce general alert and predator-specific alarm calls

2017-07-05

Abstract
Many species produce alarm calls in response to predator threats. Whilst these can be general alert calls, some are urgency-based, indicating perceived threat level, some are predator-specific, indicating the predator type present, and some encode information about both urgency level and predator type. Predator-specific calls given to a narrow range of stimuli and which elicit a specific, adaptive, response from the receiver are termed functionally referential. Differing escape strategies, habitat structural complexity and sociality may favor the evolution of functionally referential calls. A study of one captive group of dwarf mongooses (Helogale parvula) suggested their alarm calls could transmit information about species, distance, and elevation of predators. Using recordings of natural predator encounters, predator presentations and audio playbacks, we investigated the alarm-call system in 7 wild dwarf mongoose groups. We recorded 11 different alarm-call types given to 9 stimulus categories. Of the 5 commonly emitted alarm-call types, 3 appeared to be non-specific and 2 predator-specific, given to aerial and terrestrial predators respectively. The remaining 6 call types were rarely produced. Furthermore, aerial alarms were given to a narrower range of stimuli than their terrestrial alarm calls, which were given to both visible terrestrial predators and secondary cues of predators. Unlike other mongoose species, dwarf mongoose seem to use the same alarm-call type for both physically present terrestrial predators and secondary cues of their presence. We argue that detailed knowledge of species’ alarm-call systems under natural conditions can shed light on the evolutionary emergence of different types of alarm calls.



Dominance, gender, and season influence food patch use in a group-living, solitary foraging canid

2017-07-05

Abstract
In patchy environments, foragers adopt different strategies to acquire resources depending on their internal state and external physical and social environment: this has important fitness consequences. Linking individual variation in patch use to tangible characteristics is key to understand many higher-level ecological processes. We studied patch use by red foxes (Vulpes vulpes) in the city of Bristol, UK. We placed camera traps in gardens where householders provisioned foxes (patches) to investigate whether 1) foxes discriminated between patches based on food availability, quantified as provisioning frequency (predictability) and the energy value of provisioned food; and 2) individual patch use varied with dominance, gender, and season. Increased frequency of provisioning encouraged more foxes to visit and to stay longer in patches. All foxes visited the most predictable patches first each day, but females were more selective and generally more efficient foragers than males. Females increased foraging effort during cub rearing, whereas males reduced patch use in the dispersal and mating season. Dominants and subordinates shared patches spatiotemporally, possibly facilitated by relatedness and familiarity between group members. However, dominants visited more food patches on their territory, spent more time in predictable patches and fed earlier than subordinates. Subordinates may compensate for competition by visiting patches of lower quality or outside their territory, which is inefficient and risky. Our results demonstrate gender differences in behavioral motivation, show how subordinates forego foraging efficiency to mitigate intra-group competition and reveal how human provisioning influences fox space use in urban areas.



Do prevailing environmental factors influence human preferences for facial morphology?

2017-07-04

Abstract
Prevailing environmental factors influence preferences for attractive traits across many species. In humans, debate surrounds the role of environmental pathogens and economic development in determining facial attractiveness. We tested whether women and men’s preferences for facial dimorphism, symmetry, skin tone, and adiposity differ among Melanesian participants from 3 islands (Espiritu Santo, Efate, and Tanna) in Vanuatu in the South West Pacific. These islands vary in their historical malarial pathogens respectively from pronounced to almost absent and are characterized by within and between island differences in economic development, ranging from urbanized market-based economies to remote rural horticultural communities. We found no support for the hypothesis that masculine male faces or feminine female faces are more attractive in environments with higher exposure to malarial pathogens or urban development. However, preferences for facial symmetry were highest in islands with higher malarial rates, possibly as symmetry indicates health and guides mate selection in disease rich environments. However, past evidence linking symmetry and health is weak, and we therefore interpret our findings cautiously. Women from peri-urban communities preferred male faces with lighter skin to rural and urban participants. Men from urban areas stated higher preferences for symmetry than peri-urban and rural male participants. All other effects were not statistically significant. While cross-cultural studies comparing preferences between disparate cultures provide evidence of associations between environmental effects and preferences for some facial traits, our results suggest these associations might not always persist at more fine-grain scales within small-scale societies.



Early to rise, early to breed: a role for daily rhythms in seasonal reproduction

2017-06-28

Abstract
Vertebrates use environmental cues to time reproduction to optimal breeding conditions. Numerous laboratory studies have revealed that light experienced during a critical window of the circadian (daily) rhythm can influence reproductive physiology. However, whether these relationships observed in captivity hold true under natural conditions and how they relate to observed variation in timing of reproductive output remains largely unexplored. Here we test the hypothesis that individual variation in daily timing recorded in nature (i.e. chronotype) is linked with variation in timing of breeding. To address this hypothesis and its generality across species, we recorded incubation behavior data to identify individual patterns in daily onset of activity for 2 temperate-breeding songbird species, the dark-eyed junco (Junco hyemalis aikeni) and the great tit (Parus major). We found that females who first departed from their nest earlier in the morning (earlier chronotype) also initiated nests earlier in the year. Date of data collection and ambient temperature had no effect, but stage of incubation influenced daily onset of activity in great tits. Our findings suggest a role for daily rhythms as one mechanism underlying the observed variation in seasonal timing of breeding.



Camouflaging moving objects: crypsis and masquerade

2017-06-17

Abstract
Motion is generally assumed to “break” camouflage. However, although camouflage cannot conceal a group of moving animals, it may impair a predator’s ability to single one out for attack, even if that discrimination is not based on a color difference. Here, we use a computer-based task in which humans had to detect the odd one out among moving objects, with “oddity” based on shape. All objects were either patterned or plain, and either matched the background or not. We show that there are advantages of matching both group-mates and the background. However, when patterned objects are on a plain background (i.e., no background matching), the advantage of being among similarly patterned distractors is only realized when the group size is larger (10 compared to 5). In a second experiment, we present a paradigm for testing how coloration interferes with target-distractor discrimination, based on an adaptive staircase procedure for establishing the threshold. We show that when the predator only has a short time for decision-making, displaying a similar pattern to the distractors and the background affords protection even when the difference in shape between target and distractors is large. We conclude that, even though motion breaks camouflage, being camouflaged could help group-living animals reduce the risk of being singled out for attack by predators.



Seasonal variation in behavioral thermoregulation and predator avoidance in a small mammal

2017-06-06

Abstract
Understanding behavioral responses of animals to the thermal environment is of increasing importance under changing climate regimes. Thermoregulatory behaviors, such as exploitation of thermal refugia or temporal partitioning of activity, can buffer organisms against hot and cold thermal extremes but may conflict with other life history needs. Our objective was to evaluate strategies for behavioral thermoregulation by a small-bodied endotherm to test hypotheses about tradeoffs between thermal and security needs across seasons. We quantified the influence of both thermal and security properties of habitat on selection of rest sites by pygmy rabbits (Brachylagus idahoensis), and we identified environmental and endogenous factors affecting levels of activity during summer and winter. Behavioral strategies varied seasonally in response to both thermal challenges and risk of predation. During summer, rabbits selected rest sites with high concealment and low shortwave radiation, but activity levels were independent of ambient temperature. During winter, however, security, but not thermal properties, influenced selection of rest sites, and activity was positively correlated with ambient temperature during the most thermally stressful periods of the day (dawn, dusk, and night). The types of nuanced behavioral plasticity that we documented in response to the thermal environment is likely to be overlooked in evaluations of species tolerance to changing climates. Understanding the potential for behavior to buffer individuals as well as the limits of behavior to shield populations from consequences of climate change is critical for effective conservation of vulnerable species.