Understanding bird collisions with man‐made objects: a sensory ecology approach

Sensory ecology investigates the information that underlies an animal’s interactions with its environment. A sensory ecology framework is used here to seek to assess why flying birds collide with prominent structures, such as power lines, fences, communication masts, wind turbines and buildings, which intrude into the open airspace. Such collisions occur under conditions of both high and low visibility. It is argued that a human perspective of the problems posed by these obstacles is unhelpful. Birds live in different visual worlds and key aspects of these differences are summarized. When in flight, birds may turn their heads in both pitch and yaw to look down, either with the binocular field or with the lateral part of an eye’s visual field. Such behaviour may be usual and results in certain species being at least temporarily blind in the direction of travel. Furthermore, even if birds are looking ahead, frontal vision may not be in high resolution. In general, high resolution occurs in the lateral fields of view and frontal vision in birds may be tuned for the detection of movement concerned with the extraction of information from the optical flow field, rather than the detection of high spatial detail. Birds probably employ lateral vision for the detection of conspecifics, foraging opportunities and predators. The detection of these may be more important than simply looking ahead during flight in the open airspace. Birds in flight may predict that the environment ahead is not cluttered. Even if they are facing forward, they may fail to see an obstacle as they may not predict obstructions; perceptually they have no ‘prior’ for human artefacts such as buildings, power wires or wind turbines. Birds have only a restricted range of flight speeds that can be used to adjust their rate of gain of visual information as the sensory challenges of the environment change. It is argued that to reduce collisions with known hazards, something placed upon the ground may be more important than something placed on the obstacle itself. Foraging patches, conspecific models or alerting sounds placed a suitable distance from the hazard may be an effective way of reducing collisions in certain locations. However, there is unlikely to be a single effective way to reduce collisions for multiple species at any one site. Warning or diversion and distraction solutions may need to be tailored for particular target species.     

Foraging Benefits in a Colour Polymorphic Neotropical Orb Web Spider

Conspicuous body colouration in sedentary predators such as orb web spiders seems paradoxical as potential prey can see and avoid the webs. Several studies have demonstrated that rather than deterring prey, the colours act as sensory traps for flower‐seeking insects. In chromatically polymorphic species, the existence of more than one colour morph may lead to differing levels of prey attraction. To explore these issues, we studied a neotropical orb web spider, Verrucosa arenata, which shows colour polymorphism with predominantly white or yellow abdomen colours. We asked whether a particular morph is dominant in the population, and whether a particular morph is associated with enhanced foraging success and body condition. Here we showed that although yellow morphs attracted more prey, white morphs were in better body condition. We showed that model prey such as honeybees are able to discriminate between the morphs. We discuss these findings in relation to the functional significance of bright body colouration and colour polymorphism in spiders.     

Filtering and polychromatic vision in mantis shrimps: themes in visible and ultraviolet vision

Stomatopod crustaceans have the most complex and diverse assortment of retinal photoreceptors of any animals, with 16 functional classes. The receptor classes are subdivided into sets responsible for ultraviolet vision, spatial vision, colour vision and polarization vision. Many of these receptor classes are spectrally tuned by filtering pigments located in photoreceptors or overlying optical elements. At visible wavelengths, carotenoproteins or similar substances are packed into vesicles used either as serial, intrarhabdomal filters or lateral filters. A single retina may contain a diversity of these filtering pigments paired with specific photoreceptors, and the pigments used vary between and within species both taxonomically and ecologically. Ultraviolet-filtering pigments in the crystalline cones serve to tune ultraviolet vision in these animals as well, and some ultraviolet receptors themselves act as birefringent filters to enable circular polarization vision. Stomatopods have reached an evolutionary extreme in their use of filter mechanisms to tune photoreception to habitat and behaviour, allowing them to extend the spectral range of their vision both deeper into the ultraviolet and further into the red.     

Units and passages: A view for evolutionary biology and ecology

Many authors, including paleobiologists, cladists and so on, adopt a nested hierarchical viewpoint to examine the relationships among different levels of biological organization. Furthermore, species are often considered to be unique entities in functioning evolutionary processes and one of the individuals forming a nested hierarchy.I have attempted to show that such a hierarchical view is inadequate in evolutionary biology. We should define units depending on what we are trying to explain. Units that play an important role in evolution and ecology do not necessarily form a nested hierarchy. Also the relationships among genealogies at different levels are not simply nested. I have attempted to distinguish the different characteristics of passages when they are used for different purposes of explanation. In my analysis, species and monophyletic taxa cannot be uniquely defined as single units that function in ecological and evolutionary processes.The view discussed in this paper may provide a more general basis for testing competing theories in evolution, and provide new insights for future empirical studies.     

Led by the nose: Olfaction in primate feeding ecology

Olfaction, the sense of smell, was a latecomer to the systematic investigation of primate sensory ecology after long years in which it was considered to be of minor importance. 1 This view shifted with the growing understanding of its role in social behavior 2 and the accumulation of physiological studies demonstrating that the olfactory abilities of some primates are on a par with those of olfactory‐dependent mammals such as dogs and rodents. 3 , 4 Recent years have seen a proliferation of physiological, behavioral, anatomical, and genetic investigations of primate olfaction. These investigations have begun to shed light on the importance of olfaction in the process of food acquisition. However, integration of these works has been limited. It is therefore still difficult to pinpoint large‐scale evolutionary scenarios, namely the functions that the sense of smell fulfills in primates’ feeding ecology and the ecological niches that favor heavier reliance on olfaction. Here, we review available behavioral and physiological studies of primates in the field or captivity and try to elucidate how and when the sense of smell can help them acquire food.     

Spots and stripes: ecology and colour pattern evolution in butterflyfishes

The incredible diversity of colour patterns in coral reef fishes has intrigued biologists for centuries. Yet, despite the many proposed explanations for this diversity in coloration, definitive tests of the role of ecological factors in shaping the evolution of particular colour pattern traits are absent. Patterns such as spots and eyespots (spots surrounded by concentric rings of contrasting colour) have often been assumed to function for predator defence by mimicking predators'' enemies'' eyes, deflecting attacks or intimidating predators, but the evolutionary processes underlying these functions have never been addressed. Striped body patterns have been suggested to serve for both social communication and predator defence, but the impact of ecological constraints remains unclear. We conducted the first comparative analysis of colour pattern diversity in butterflyfishes (Family: Chaetodontidae), fishes with conspicuous spots, eyespots and wide variation in coloration. Using a dated molecular phylogeny of 95 species (approx. 75% of the family), we tested whether spots and eyespots have evolved characteristics that are consistent with their proposed defensive function and whether the presence of spots and body stripes is linked with species'' body length, dietary complexity, habitat diversity or social behaviour. Contrary to our expectations, spots and eyespots appeared relatively recently in butterflyfish evolution and are highly evolutionarily labile, suggesting that they are unlikely to have played an important part in the evolutionary history of the group. Striped body patterns showed correlated evolution with a number of ecological factors including habitat type, sociality and dietary complexity. Our findings question the prevailing view that eyespots are an evolutionary response to predation pressure, providing a valuable counter example to the role of these markings as revealed in other taxa.     

Avian colour perception predicts behavioural responses to experimental brood parasitism in chaffinches

Hosts of cuckoos have evolved defences allowing them to discriminate and reject parasite eggs. Mechanisms of discrimination are mostly visually mediated, and have been studied using approaches that do not account for what the receiver (i.e. host) actually can discriminate. Here, for the first time we apply a perceptual model of colour discrimination to study behavioural responses to natural variation in parasite egg appearance in chaffinches Fringilla coelebs. Discrimination of parasite eggs gradually increased with increasing differences in chromatic contrasts as perceived by birds between parasite and host eggs. These results confirm that colour differences of the eggs as perceived by birds are important integral parts of a matching signal used by chaffinch hosts.     

Visual fields and foraging ecology of Blacksmith Lapwings Vanellus armatus

The visual fields of Blacksmith Lapwings Vanellus armatus show the characteristics of visual guided foragers that use precision pecking for prey capture – a binocular field of narrow width and limited vertical extent, with the projection of the bill close to its centre and a large blind area above and behind the head. The topography of the total field, particularly the binocular field, is similar to that of European Golden Plovers Pluvialis apricaria. We suggest that the ‘foot‐trembling’ behaviour associated with foraging in Plovers is not under visual guidance but forces the escape of hidden prey, which is detected when the prey item moves into the binocular field to enable its capture in the bill. Foot‐trembling thus functions to extend the effective foraging area of a bird beyond the limits of its visual field.     

The causal pie model: an epidemiological method applied to evolutionary biology and ecology

A general concept for thinking about causality facilitates swift comprehension of results, and the vocabulary that belongs to the concept is instrumental in cross‐disciplinary communication. The causal pie model has fulfilled this role in epidemiology and could be of similar value in evolutionary biology and ecology. In the causal pie model, outcomes result from sufficient causes. Each sufficient cause is made up of a “causal pie” of “component causes”. Several different causal pies may exist for the same outcome. If and only if all component causes of a sufficient cause are present, that is, a causal pie is complete, does the outcome occur. The effect of a component cause hence depends on the presence of the other component causes that constitute some causal pie. Because all component causes are equally and fully causative for the outcome, the sum of causes for some outcome exceeds 100%. The causal pie model provides a way of thinking that maps into a number of recurrent themes in evolutionary biology and ecology: It charts when component causes have an effect and are subject to natural selection, and how component causes affect selection on other component causes; which partitions of outcomes with respect to causes are feasible and useful; and how to view the composition of a(n apparently homogeneous) population. The diversity of specific results that is directly understood from the causal pie model is a test for both the validity and the applicability of the model. The causal pie model provides a common language in which results across disciplines can be communicated and serves as a template along which future causal analyses can be made.     

A simple method for measuring colour in wild animals: validation and use on chest patch colour in geladas (Theropithecus gelada)

Adaptive hypotheses about colour variation are widespread in behavioural ecology, and several methods of objective colour assessment have been proposed and validated for use in a wide variety of taxa. However, to date, the most objective and reliable methods of assessing colour are not readily applied to wild animals. In the present study, we present a simple method for assessing colour in unrestrained, wild subjects using digital photography. The method we describe uses a digital camera, a colour standard, and colour analysis software, and can be used to measure any part of the visible colour spectrum. We demonstrate that the method: (1) is accurate and precise across different light conditions; (2) satisfies previous criteria regarding linearity and red, green, and blue equality; and (3) can be independently validated visually. In contrast with previous digital methods, this method can be used under natural light conditions and can be readily applied to subjects in their natural habitat. To illustrate this, we use the method to measure chest colour in wild geladas ( Theropithecus gelada ). Unique among primates, geladas have a red patch of skin on their chest and neck, which, for males, is thought to be a sexually selected signal. Offering some support to this hypothesis, we found differences in chest 'redness' for males across different age groups, with males in their reproductive prime exhibiting the reddest chests.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 231–240.     

Colour, design and reward: phenotypic integration of fleshy fruit displays

The functional or structural linkage among traits [phenotypic integration (PI)] within complex structures can constrain the evolutionary response of individual traits. To analyse whether frugivores with distinct sensory ecology have shaped the patterns of fruit diversification differently, we compared PI values of fleshy fruits that are consumed by birds and mammals. We used phylogenetic comparative analyses of PI among 13 morphological, nutritional and visual fruit traits from 111 Mediterranean plant species. Results showed that morphological traits had higher PI values than nutritional and colour traits. Visual and nutritional traits show positive phylogenetic covariance, while negative covariation occurs between fruits size and nutrients. Importantly, fruits consumed by birds were relatively more integrated than fruits consumed partly or solely by mammals. Hence, we show that major groups of mutualistic frugivores can shape the covariance among some fruit traits differently and thereby influence fruit diversification.     

The ecology of differences: assessing community assembly with trait and evolutionary distances

Species enter and persist in local communities because of their ecological fit to local conditions, and recently, ecologists have moved from measuring diversity as species richness and evenness, to using measures that reflect species ecological differences. There are two principal approaches for quantifying species ecological differences: functional (trait‐based) and phylogenetic pairwise distances between species. Both approaches have produced new ecological insights, yet at the same time methodological issues and assumptions limit them. Traits and phylogeny may provide different, and perhaps complementary, information about species' differences. To adequately test assembly hypotheses, a framework integrating the information provided by traits and phylogenies is required. We propose an intuitive measure for combining functional and phylogenetic pairwise distances, which provides a useful way to assess how functional and phylogenetic distances contribute to understanding patterns of community assembly. Here, we show that both traits and phylogeny inform community assembly patterns in alpine plant communities across an elevation gradient, because they represent complementary information. Differences in historical selection pressures have produced variation in the strength of the trait‐phylogeny correlation, and as such, integrating traits and phylogeny can enhance the ability to detect assembly patterns across habitats or environmental gradients.     

The merging of community ecology and phylogenetic biology

The increasing availability of phylogenetic data, computing power and informatics tools has facilitated a rapid expansion of studies that apply phylogenetic data and methods to community ecology. Several key areas are reviewed in which phylogenetic information helps to resolve long-standing controversies in community ecology, challenges previous assumptions, and opens new areas of investigation. In particular, studies in phylogenetic community ecology have helped to reveal the multitude of processes driving community assembly and have demonstrated the importance of evolution in the assembly process. Phylogenetic approaches have also increased understanding of the consequences of community interactions for speciation, adaptation and extinction. Finally, phylogenetic community structure and composition holds promise for predicting ecosystem processes and impacts of global change. Major challenges to advancing these areas remain. In particular, determining the extent to which ecologically relevant traits are phylogenetically conserved or convergent, and over what temporal scale, is critical to understanding the causes of community phylogenetic structure and its evolutionary and ecosystem consequences. Harnessing phylogenetic information to understand and forecast changes in diversity and dynamics of communities is a critical step in managing and restoring the Earth's biota in a time of rapid global change.     

Local adaptation and divergence in colour signal conspicuousness between monomorphic and polymorphic lineages in a lizard

Population differences in visual environment can lead to divergence in multiple components of animal coloration including signalling traits and colour patterns important for camouflage. Divergence may reflect selection imposed by different receivers (conspecifics, predators), which depends in turn on the location of the colour patch. We tested for local adaptation of two genetically and phenotypically divergent lineages of a rock‐inhabiting lizard, Ctenophorus decresii, by comparing the visual contrast of colour patches to different receivers in native and non‐native environments. The lineages differ most notably in male throat coloration, which is polymorphic in the northern lineage and monomorphic in the southern lineage, but also differ in dorsal and lateral coloration, which is visible to both conspecifics and potential predators. Using models of animal colour vision, we assessed whether lineage‐specific throat, dorsal and lateral coloration enhanced conspicuousness to conspecifics, increased crypsis to birds or both, respectively, when viewed against the predominant backgrounds from each lineage. Throat colours were no more conspicuous against native than non‐native rock but contrasted more strongly with native lichen, which occurs patchily on rocks inhabited by C. decresii. Conversely, neck coloration (lateral) more closely matched native lichen. Furthermore, although dorsal coloration of southern males was consistently more conspicuous to birds than that of northern males, both lineages had similar absolute conspicuousness against their native backgrounds. Combined, our results are consistent with local adaptation of multiple colour traits in relation to multiple receivers, suggesting that geographic variation in background colour has influenced the evolution of lineage‐specific coloration in C. decresii.     

小型哺乳动物生理生态学研究与进化思想

动物生理生态学是一门利用生理学的手段和方法研究与动物的生存和繁殖相关的生态学问题的交叉学科,
旨在阐明动物对环境适应和进化的生理机制。在近70 年的发展历程中,进化生物学的思想和理论越来越紧密地
融入到生理生态学的研究中,同时生理生态学的研究结果也在充实着进化生物学理论的发展。本文根据作者多
年的研究经历,从动物的体型和代谢特征、消化生理、生态免疫和冬眠等几个侧面,简述了小型哺乳动物生理
生态学的某些研究进展和进化思想对该领域的影响。