Escape behaviour of birds provides evidence of predation being involved in urbanization

Tourism influences escape behavior of lizards in relationship with human clothing color

Increased tourism pressure modifies animal behavior, including alterations in anti-predator responses and foraging activity. In areas with high tourist presence, animals may become accustomed to increased human activity and adjust the intensity of some defensive responses. An animal's anti-predation ability is usually estimated by measuring its Alert Initiation Distance (AID) and Flight Initiation Distance (FID). Both indexes are affected by multiple factors including the color of the observer's clothing. Animal behavior is also influenced by human presence, and individuals may become accustomed to increased human presence, e.g. in tourist areas. In this study, we analysed the escape behavior of the endemic Cyprus rock agama (Laudakia cypriaca) in relation to the observers clothing color. Our results showed that AIDs and FIDs of agamas in tourist areas were significantly shorter than those in non-tourist areas. Moreover, in non-tourist areas, AIDs and FIDs of agamas were significantly longer when the observer wore red clothes, compared to green and grey clothes. Our results may be helpful in planning research taking into account various colored clothing based on expected reptilian reactions. Furthermore, our results may determine the proximity at which humans interact with animals, considering clothing color, to prevent negative impacts especially on rare and protected lizard species.

Face masks in action: Birds show reduced fear responses to people wearing face masks during the COVID-19 pandemic in three Asian countries

The 2019 zoonotic pandemic (COVID-19), has led to a massive global lockdown that provides a good opportunity to study how wildlife responds to changes in human activity. Wearing a mask after the COVID-19 outbreak was widely used to prevent the spread of the causative pathogen. It has been shown that tree sparrows (Passer montanus) at two sites in south China exhibit reduced fear responses to people with face masks after a period of heavy exposure to them, whereas European studies showed the opposite, with no changes in the behaviour of the birds towards mask wearers in either rural or urban areas. To further study this, from October 2021 to January 2022, we conducted a flight initiation distance (FID) survey in Pakistan, Bangladesh, and Xi'an, China for a variety of field bird species by comparing the FID for researchers wearing masks to that for researchers not wearing masks to assess whether wearing masks in public places caused birds to adjust their flight response. Results from the three Asian countries showed that after a period of sustained contact with people wearing masks, in both rural and urban areas, birds were significantly more adapted to them and had a shorter FID to people wearing masks. We suggest that the rapid habituation of birds to people wearing masks with a reduced fear response could have some fitness advantage, allowing them to adapt rapidly to the new environmental conditions induced by COVID-19.

To Flee or Not to Flee: How Age, Reproductive Phase, and Mate Presence Affect White Stork Flight Decisions

Recognizing, assessing, and responding to threats is critical for survival in the wild. Birds, especially in their role as parents, must decide whether to flee or delay flight when threatened. This study examines how age, reproductive stage, and the presence of a mate influence flight initiation distance (FID) and nest recess duration in white storks. Analyzing the data with a generalized additive mixed model (GAMM), we found significant correlations between FID and age, reproductive stage, and presence of a mate. These results suggest that the trade-off between current and future reproduction shifts during critical breeding periods, such as incubation and nestling care. To increase breeding success, White Storks appear willing to take risks and extend their stay in the nest when offspring are most valuable and vulnerable. In the presence of a mate, individuals leave the nest earlier, suggesting possible sexual conflict over parental care. The duration of nest abandonment is consistent with FID, except for age. These results illustrate how parental age, brood value, vulnerability, and sexual dynamics influence white stork flight decisions in complex ways. Understanding these dynamics enriches our knowledge of bird behavior and adaptations to environmental challenges and highlights the complexity of parental decision making.

State of the art, gaps and future perspectives on common kestrel ecotoxicology

Anthropogenic activities have caused a steady decline of common kestrel (Falco tinnunculus) since the 1980 s. Effects, especially sublethal effects of contaminants, need to be investigated to ensure the conservation of this species. Data about countries, biological material, contaminants classes, and methodological approaches were collected from scientific publications to highlight gaps on common kestrel toxicology and ecotoxicology. We found that most studies have been conducted in Europe and in the field, underlining a lack of in vitro studies. The studies investigated mainly contaminant levels, while sublethal effects, evaluation of emerging contaminants and use of non-invasive or low-invasive samples were scarce. This work shows important gaps on toxicological status of the common kestrel, highlighting the importance of developing a non-lethal approach that combines responses at different levels of biological organization, as well as data on chemical contamination and on the environment in which the different populations inhabit.

Increased grey wolf diurnality in southern Europe under human-restricted conditions

Wolves have been the archetype of wildlife persecution by humans for centuries all over the world, and still are heavily persecuted in some regions. Facultative diurnal/nocturnal wild mammals are known to become more nocturnal when persecuted. Conversely, little is known regarding the possibility of wolves becoming more diurnal if not persecuted. We took advantage of a 9-year natural experiment of restricted human access to a restored coal mine debris dump to study the daily activity patterns of wolves under conditions of infrequent human presence. Results were compared with a paired control site with frequent human use. Circadian wolf activity was monitored using camera traps (3 years in human-restricted site; 2 years in control). Additionally, data from two GPS-GSM-collared wolves monitored in a second control site were also analyzed. In our control sites, wolves were nearly inactive during daylight hours. In contrast, in the human-restricted site wolves extended their activity toward noon, with a daily activity peak between 10:00 and 12:00, and showed some activity throughout the entire circadian 2-h interval cycle considered. Wolves clearly had higher diurnality in the human-restricted area with 78% greater incidence of capture with remote cameras during the day than in the control site. We suggest that the shift toward increased diurnality was related to the loss of fear of humans. Evidence in support of this hypothesis comes from flight initiation distance (FID) data. Wolves showed relatively short FIDs when faced with a human observer (range 70-183 m) in broad daylight at the human-restricted site, but were so afraid of humans in the control site that we were unable to conduct FID trials there. Based on these results, we suggest that wolves may increase their diurnality in those European countries with currently increasing movement of human populations from rural to urban areas and that do not conduct lethal control of wolves. This would represent a historical landmark for a species that has been persecuted for many centuries. However, such behavioral shifts could bring new human-wolf conflicts that would require new policies.

Feather corticosterone reveals that urban great tits experience lower corticosterone exposure than forest individuals during dominance-rank establishment

Although the consequences of urbanization for the physiological health of animals are the focus of much active research, an overlooked aspect is how physiology could be indirectly modulated by the urban environment via changes in intraspecific behavioural interactions, particularly among gregarious species. Both urbanization and the establishment, as well as maintenance, of hierarchical rank position are processes that could incur physiological stress. Measurements of glucocorticoids (GCs) in relation to urbanization, however, have yielded inconsistent results. In most cases, GCs have been measured in blood, offering only a 'snapshot' of an animal's current physiological state. Because circulating GCs are incorporated into growing feathers or hair, measurements of feather/hair GCs offer a longer term measure of stress exposure reflecting the whole period of feather/hair growth. During two calendar years, we collected tail feathers from 188 urban and forest great tits (P. major) across multiple sampling sites and analysed corticosterone (CORT-the main GC in birds) levels, reflecting CORT exposure during the extended period in late summer and early autumn when great tits moult and winter flocks are formed. Urban individuals exhibited consistently lower feather CORT (fCORT) levels than forest birds indicating lower overall exposure to CORT during this period. The lower fCORT levels in urban individuals could represent an adaptation to cope with the more challenging urban environment, physiological constraints on stress axis function or a trade-off between the ability to respond to stressors and predation risk during moult. Despite the expectation that CORT responses to urbanization are highly context-dependent, the spatial consistency of our results and agreement with a multi-population study of fCORT in European blackbirds (Turdus merula) suggests a generalization of the effect of urbanization on CORT exposure during post-breeding moult (i.e. not site- or species-specific).

Past and future: Urbanization and the avian endocrine system

Urban environments are evolutionarily novel and differ from natural environments in many respects including food and/or water availability, predation, noise, light, air quality, pathogens, biodiversity, and temperature. The success of organisms in urban environments requires physiological plasticity and adjustments that have been described extensively, including in birds residing in geographically and climatically diverse regions. These studies have revealed a few relatively consistent differences between urban and non-urban conspecifics. For example, seasonally breeding urban birds often develop their reproductive system earlier than non-urban birds, perhaps in response to more abundant trophic resources. In most instances, however, analyses of existing data indicate no general pattern distinguishing urban and non-urban birds. It is, for instance, often hypothesized that urban environments are stressful, yet the activity of the hypothalamus-pituitary-adrenal axis does not differ consistently between urban and non-urban birds. A similar conclusion is reached by comparing blood indices of metabolism. The origin of these disparities remains poorly understood, partly because many studies are correlative rather than aiming at establishing causality, which effectively limits our ability to formulate specific hypotheses regarding the impacts of urbanization on wildlife. We suggest that future research will benefit from prioritizing mechanistic approaches to identify environmental factors that shape the phenotypic responses of organisms to urbanization and the neuroendocrine and metabolic bases of these responses. Further, it will be critical to elucidate whether factors affect these responses (a) cumulatively or synergistically; and (b) differentially as a function of age, sex, reproductive status, season, and mobility within the urban environment. Research to date has used various taxa that differ greatly not only phylogenetically, but also with regard to ecological requirements, social systems, propensity to consume anthropogenic food, and behavioral responses to human presence. Researchers may instead benefit from standardizing approaches to examine a small number of representative models with wide geographic distribution and that occupy diverse urban ecosystems.

Personality of hosts and their brood parasites

Brood parasites such as the common cuckoo Cuculus canorus exploit the parental abilities of their hosts, hosts avoid brood parasitism and predation by showing specific behavior such as loss of feathers, emission of fear screams and contact calls, displaying wriggle behavior to avoid hosts or potential prey, pecking at hosts and prey, and expressing tonic immobility (showing behavior like feigning death or rapid escape from predators and brood parasites). These aspects of escape behavior are consistent for individuals but also among sites, seasons, and years. Escape behavior expressed in response to a broad range of cuckoo hosts and prey are consistently used against capture by humans, but also hosts and brood parasites and predators and their prey. An interspecific comparative phylogenetic analysis of escape behavior by hosts and their brood parasites and prey and their predators revealed evidence of consistent behavior when encountering potential parasites or predators. We hypothesize that personality axes such as those ranging from fearfulness to being bold, and from neophobic to curiosity response in brood parasites constitute important components of defense against brood parasitism that reduces the overall risk of parasitism.

Individual quality and phenology mediate the effect of radioactive contamination on body temperature in Chernobyl barn swallows

Anthropogenic stressors, such as radioactive contaminants released from the Chernobyl and Fukushima Daiichi accidents, deteriorate ecological and evolutionary processes, as evidence for damaging effects of radioactive contamination on wildlife is accumulating. Yet little is known about physiological traits of animals inhabiting contaminated areas, and how those are affected by individual quality and phenology. We investigated variation in body temperature of wild barn swallows, Hirundo rustica, exposed to radioactive contamination from the Chernobyl accident in Ukraine and Belarus. We tested whether exposure to variable levels of radioactive contamination modified core body temperature of birds, and whether individual and phenological characteristics modulated radiosensitivity of body temperature. We showed that barn swallow body temperature varied with exposure to environmental radioactive contamination and that individual characteristics and phenology affected radioactive exposure. Increased radiosensitivity and up-regulation of body temperature were detected in birds of low body condition, high risk of capture, and in animals captured late during the day but early during the season. These results highlight the complex ways that the body temperature of a wild bird is impacted by exposure to increased radioactive contamination in natural habitats. By impacting body temperature, increased radioactive contamination may compromise energetic balance, jeopardize responsiveness to global warming, and increase risk of overheating.

Birds of different morphs use slightly different strategies to achieve similar reproductive performance following heatwave exposure

Responses to extreme climatic events may differ between individuals of distinct morphs which differ in life-history strategies, resulting in climate change 'winners' and 'losers' within species. We examined the reproductive performance and carry-over effects on offspring of black- and red-headed Gouldian finches Erythrura gouldiae after exposure to simulated heatwaves of moderate or severe intensity. We expected black-headed pairs' reproductive performance to decline after the severe heatwave because only the condition of black-headed females deteriorates during such a heatwave. Supporting the fact that Gouldian finches of different morphs use alternative reproductive strategies, we found that black-headed females initiated egg-laying a month earlier than red-headed females after experiencing a severe heatwave. We also found that this severe heatwave resulted in shorter spermatozoa in males irrespective of their morph. Despite these effects associated with heatwave intensity, the overall reproductive performance of both morphs was not affected by this factor, which was possibly due to an increased nestling provisioning rate by parents after exposure to the severe heatwave. However, offspring still bore the cost of parental exposure to the severe heatwave, as they showed a reduced condition (lower plasma antioxidant capacity and transient lower breathing rate) and higher oxidative damage (at least in fledglings with black-headed parents). These results suggest that inter-morph phenotypic variability in the Gouldian finch does not result in clear differences in reproductive performance following heatwave exposure, despite basal phenotypic differences between morphs. Whether animals using alternative reproductive strategies are, in the end, differently affected by climate changes will likely depend on the capacity of their offspring to recover from altered developmental conditions.

The selection of anthropogenic habitat by wildlife as an ecological consequence of rural exodus: empirical examples from Spain

The increasing urbanization of the landscape is a major component of global change worldwide. However, it is puzzling that wildlife is selecting anthropogenic habitats despite the availability of apparently high–quality semi–natural (i.e. less intensively modified) habitats. Definitive explanations for this process are still lacking. We have previously suggested that colonization of the urban habitat is initially triggered by ecological processes that take place outside urban areas as a consequence of past rural exodus. Here we present a diverse array of examples of selection of several types of anthropogenic habitat by wildlife in Spain (including transportation infrastructure, human–exclusion areas, urban areas under construction, cities, reservoirs, quarries and landfills) in support of this idea. Wildlife is moving out of its historical ecological refuges and losing fear of harmless urban humans. Mesopredators are rebounding by mesopredator release, due to ceased human persecution, and shrubs and trees are claiming former agricultural habitats. Together, these factors force many species to move to urbanized areas where they find open habitats, food associated with these habitats, and protection against predation. Hence, the classical balance of costs and benefits that takes place once inside urban areas, would actually be a second step of the process of colonization of urban areas. A better understanding of the initial triggers of urban colonization could help us increase the biological value of human–made habitats for wildlife in the future.

Continent-wide genomic signatures of adaptation to urbanisation in a songbird across Europe

Urbanisation is increasing worldwide, and there is now ample evidence of phenotypic changes in wild organisms in response to this novel environment. Yet, the genetic changes and genomic architecture underlying these adaptations are poorly understood. Here, we genotype 192 great tits (Parus major) from nine European cities, each paired with an adjacent rural site, to address this major knowledge gap in our understanding of wildlife urban adaptation. We find that a combination of polygenic allele frequency shifts and recurrent selective sweeps are associated with the adaptation of great tits to urban environments. While haplotypes under selection are rarely shared across urban populations, selective sweeps occur within the same genes, mostly linked to neural function and development. Collectively, we show that urban adaptation in a widespread songbird occurs through unique and shared selective sweeps in a core-set of behaviour-linked genes.

Playing dead: lizards show tonic immobility without human handling

Tonic immobility, or the ability to play dead, is widespread among vertebrates. It is a last line of defence against a threat, and usually follows physical restraint. Here, I report two lizards exhibiting tonic immobility in the presence of humans, but remarkably, without any handling or physical contact. These two lizards belonged to an invasive population of the Italian Wall Lizard (Podarcis siculus), and both events took place in different years and situations, suggesting this behaviour may be more common than previously thought. There are rare documented cases of animals exhibiting this behaviour without handling; however, to my knowledge, this is the first description of a lizard displaying tonic immobility to humans, in the absence of handling. This is also the first incident of tonic immobility in the Italian Wall Lizard. I discuss these anecdotal events in the light of this invasive population inhabiting a highly urbanized location.

Being Dark is Better: A Feral Pigeon Plumage Polymorphism as a Response to Urban Environments in Slovakia

The purpose of this study was to determine the distribution and plumage phenotypes of the feral pigeon, Columba livia forma urbana (Gmelin, 1789), in Slovakia. Censuses carried out in the built-up areas of 16 towns and cities from November to February (2012–2018) counted and evaluated 3,123 individual birds. The most frequent were melanic colored birds (checker, T-pattern and spread phenotypes), which predominated in the population (51.6%, n = 1,613), followed by paler ones (42.1%, n = 1,316) and other types (6.2%, n = 194). A statistically significant difference was confirmed among the melanic and paler plumage phenotypes (χ2 = 81.49, df = 15, p < 0.0001). Correlation confirmed the different importance of city area and human density on the maintenance of dark and/or pale pigeons living in cities.

The Cohabitation of Humans and Urban Cats in the Anthropocene: The Clash of Welfare Concepts

Simple Summary

Current cultural shifts in Western countries have changed the position of the cat to a companion animal, and its traditional role as a pest controller is no longer recognized by city dwellers. In a growing number of theoretical and field studies, the hunting abilities of cats and their high fertility are perceived as environmental risks. Bringing together theoretical perspectives from human–animal studies, animal ethics, population ecology, and biosemiotics, I highlight the existence of two different ecological (and even cultural) communities inhabiting urban environments: the culture of feral cats and the humano–cat culture of pets. Arguments are given for the essential role of feral cats in the population dynamics of the species when a growing number of pet cats are routinely neutered. Whereas neutering is presented by animal shelters and veterinary institutions as a universal means for improving cat welfare, it is at odds with the psychobiological needs of cats as viewed by a laissez-faire approach. This leads us to the conclusion that instead of one type of management of free-roaming cats, individual solutions should be sought to achieve a balance between the welfare of cats, other species, and human cultures in diverse urban environments.

Abstract

Urban environments are inhabited by several types of feline populations, which we can differentiate as feral cats, free-roaming pets, and confined pets. Due to a shift in the cultural representation of cats from pest controllers to companion animals, cats living semi-independently of humans are perceived increasingly negatively, while the pet population has become the object of intense care. A regulative approach converges with a concern for welfare in the operation and educational campaigns of municipal shelters, which through their implementation of neutering policies have proven to be key players in the contemporary relation of urban cats and humans. The generally widespread notion of cat welfare associated with a secure life comes into tension with the fact that the psychobiological needs of feral cats are significantly different than those of pets. It becomes apparent that individual interactions between humans and cats in urban environments in the Anthropocene are increasingly influenced by the intervention of institutions that can be characterized as seeking to administer the wild.

Which Traits Influence Bird Survival in the City? A Review

Urbanization poses a major threat to biodiversity worldwide. We focused on birds as a well-studied taxon of interest, in order to review literature on traits that influence responses to urbanization. We review 226 papers that were published between 1979 and 2020, and aggregate information on five major groups of traits that have been widely studied: ecological traits, life history, physiology, behavior and genetic traits. Some robust findings on trait changes in individual species as well as bird communities emerge. A lack of specific food and shelter resources has led to the urban bird community being dominated by generalist species, while specialist species show decline. Urbanized birds differ in the behavioral traits, showing an increase in song frequency and amplitude, and bolder behavior, as compared to rural populations of the same species. Differential food resources and predatory pressure results in changes in life history traits, including prolonged breeding duration, and increases in clutch and brood size to compensate for lower survival. Other species-specific changes include changes in hormonal state, body state, and genetic differences from rural populations. We identify gaps in research, with a paucity of studies in tropical cities and a need for greater examination of traits that influence persistence and success in native vs. introduced populations.

Land-sharing vs. land-sparing urban development modulate predator-prey interactions in Europe

Urban areas are expanding globally as a consequence of human population increases, with overall negative effects on biodiversity. To prevent the further loss of biodiversity, it is urgent to understand the mechanisms behind this loss to develop evidence-based sustainable solutions to preserve biodiversity in urban landscapes. The two extreme urban development types along a continuum, land-sparing (large, continuous green areas and high-density housing) and land-sharing (small, fragmented green areas and low-density housing) have been the recent focus of debates regarding the pattern of urban development. However, in this context, there is no information on the mechanisms behind the observed biodiversity changes. One of the main mechanisms proposed to explain urban biodiversity loss is the alteration of predator-prey interactions. Using ground-nesting birds as a model system and data from nine European cities, we experimentally tested the effects of these two extreme urban development types on artificial ground nest survival and whether nest survival correlates with the local abundance of ground-nesting birds and their nest predators. Nest survival (n = 554) was lower in land-sharing than in land-sparing urban areas. Nest survival decreased with increasing numbers of local predators (cats and corvids) and with nest visibility. Correspondingly, relative abundance of ground-nesting birds was greater in land-sparing than in land-sharing urban areas, though overall bird species richness was unaffected by the pattern of urban development. We provide the first evidence that predator-prey interactions differ between the two extreme urban development types. Changing interactions may explain the higher proportion of ground-nesting birds in land-sparing areas, and suggest a limitation of the land-sharing model. Nest predator control and the provision of more green-covered urban habitats may also improve conservation of sensitive birds in cities. Our findings provide information on how to further expand our cities without severe loss of urban-sensitive species and give support for land-sparing over land-sharing urban development.

Eastern Grey Kangaroo (Macropus giganteus) Vigilance Behaviour Varies between Human-Modified and Natural Environments

Simple Summary

Urban landscapes are increasing across the globe, causing wildlife to face new challenges and driving behavioural change. Wildlife in these urban landscapes must adapt their behaviour to survive. We investigated vigilance behaviour in urban and non-urban populations of eastern grey kangaroos. We found that the difference in land use alone did not affect their vigilance behaviour, but kangaroos spent more time vigilant in areas of high human population density. Season and sex also influenced the amount of time spent vigilant: more time was spent vigilant in winter and in female kangaroos. This is the first study to compare the vigilance behaviour between urban and non-urban populations of a large mammal across regions, giving the first insight into how kangaroos adapt their behaviour in urban environments.

Abstract

Rapid increases in urban land use extent across the globe are creating challenges for many wildlife species. Urban landscapes present a novel environment for many species, yet our understanding of wildlife behavioural adaptations to urban environments is still poor. This study compared the vigilance behaviour of a large mammal in response to urbanisation at a landscape level. Here, we investigate urban (n = 12) and non-urban (n = 12) populations of kangaroos in two regions of Australia, and the relationship between kangaroo vigilance and urbanisation. We used a linear modelling approach to determine whether anti-predator vigilance and the number of vigilant acts performed were influenced by land use type (i.e., urban or non-urban), human population densities, kangaroo demographics, and environmental factors. Kangaroo behaviour differed between the two study regions; kangaroo vigilance was higher in urban than non-urban sites in the southern region, which also had the highest human population densities, however no effect of land use was found in the northern region. Season and sex influenced the vigilance levels across both regions, with higher levels seen in winter and female kangaroos. This study is the first to compare urban and non-urban vigilance of large mammals at a landscape level and provide novel insights into behavioural adaptations of large mammals to urban environments.

Comparative urbanization of birds in China and Europe based on birds associated with trees

Urbanization effects on living organisms are spatially heterogeneous. Here we quantified the abundance of birds per tree in forested urban and rural habitats for 85,829 trees mainly in China and Europe. A population model was based on the assumption that: 1) birds have a normally distributed habitat preference; 2) an increase in population size linked to the habitat preference; 3) a population size dependent on the habitat preference; and 4) the removal of a certain fraction of individuals giving rise to extinction. We tested for large-scale differences in the impact of urbanization on the frequency distribution of the difference in abundance between urban and rural habitats in China and parts of Europe. The difference in the frequency distribution of urban population density of birds in trees minus rural population density of birds in trees in China and Europe was statistically significant, suggesting that the abundance of birds differed between trees in urban and rural habitats, but more so in China than in Europe. We hypothesize that more pronounced differences in China than in Europe may have arisen due to the Four Pests Campaign in 1958-1962 that resulted in death of hundreds of millions of birds (mainly tree sparrows Passer montanus, but also numerous other less common species that were starting to become urbanized around 1960). Species that were less common in 1960 could not sustain reductions in population size in urban areas and hence these species are still rare or absent in urban areas today 60 years later.

Escape behaviour of birds in urban parks and cemeteries across Europe: Evidence of behavioural adaptation to human activity

Urban environments are very heterogeneous, and birds living in the proximity of humans have to adapt to local conditions, e.g. by changing their behavioural response to potential predators. In this study, we tested whether the escape distance of birds (measured as flight initiation distance; FID) differed between parks and cemeteries, areas characterized by different microhabitat conditions and human conduct, that are determinants of animal behaviour at large spatial scales. While escape behaviour of park populations of birds was often examined, cemetery populations have not been studied to the same extent and a large-scale comparison is still missing. Overall, we collected 2139 FID estimates for 44 bird species recorded in 79 parks and 90 cemeteries in four European countries: Czech Republic, France, Italy and Poland. Mixed model procedure was applied to study escape behaviour in relation to type of area (park or cemetery), environmental characteristics (area size, coverage by trees, shrubs, grass, chapels, tombstones, flowerbeds, number of street lamps) and human activity (human density, pedestrians speed and ratio of men/women). Birds allowed people closer in cemeteries than in parks in all countries. This pattern was persistent even when focusing on intraspecific differences in FID between populations of the most common bird species. Escape distance of birds was negatively correlated with the size of parks/cemeteries, while positively associated with tombstone coverage and human density in both types of habitat. Our findings highlight the ability of birds to adapt their behaviour to different types of urban areas, based on local environmental conditions, including the character of human-bird interactions. Our results also suggest that this behavioural pattern may be widespread across urban landscapes.

Parallel behavioral and morphological divergence in fence lizards on two college campuses

The spread of urban development has dramatically altered natural habitats, modifying community relationships, abiotic factors, and structural features. Animal populations living in these areas must perish, emigrate, or find ways to adjust to a suite of new selective pressures. Those that successfully inhabit the urban environment may make behavioral, physiological, and/or morphological adjustments that represent either evolutionary change and/or phenotypic plasticity. We tested for effects of urbanization on antipredator behavior and associated morphology across an urban-wild gradient in the western fence lizard (Sceloporus occidentalis) in two California counties, Santa Barbara and San Luis Obispo. We compared college campuses in both counties with adjacent rural habitats, conducting field trials that allowed us to characterize antipredator behavior in response to the acute stress of capture. We found notable divergence between campus and rural behavior, with campus lizards more frequently exhibiting diminished escape behavior, including tonic immobility, and lower sprint speeds. Furthermore, campus females had significantly shorter limbs, and while this did not explain variation in sprint speed, those with shorter limbs were more likely to show tonic immobility. We hypothesize that these parallel behavioral and morphological changes on both campuses reflect adjustment to a novel environment involving changes in predation and human presence.

Risk perception of vervet monkeys Chlorocebus pygerythrus to humans in urban and rural environments

Like other animals, primates respond to predation using behavioural adaptations. Hence, they should optimise their escape strategy under the risk of predation, and flee at a distance, referred to as flight initiation distance (FID), when the fitness-related benefits of staying are balanced against the costs of escape. However, there is an absence of FID studies in primates. In this study, we used vervet monkeys Chlorocebus pygerythrus, a medium-sized African cercopithecoid, as a model species to investigate the influence of environment type (urban and rural), group size (defined as the number of visible neighbours), sex and age on FID when approached by a human. We found significantly shorter FID among urban than rural monkeys; urban individuals delayed their escape compared to rural individuals. We found no relationship between FID and sex and age class, but FID was positively correlated with group size in both settings; urban monkeys live in smaller groups than monkeys in rural areas. As FID and group size are important predictors of predation risk perception in primates, results suggest that, despite probable effects of habituation, vervet monkeys in Uganda adjust their antipredator behaviour when coping with novel environments within human settlements. Our findings are consistent with some previous studies of risk perception in animals, and indicate that FID could be used as an alternative measure for predation risk in primates.

How Nature-Based Tourism Might Increase Prey Vulnerability to Predators

Tourism can be deleterious for wildlife because it triggers behavioral changes in individuals with cascading effects on populations and communities. Among these behavioral changes, animals around humans often reduce their fearfulness and antipredator responses towards humans. A straightforward prediction is that habituation to humans associated with tourism would negatively influence reaction to predators. This could happen indirectly, where human presence decreases the number of natural predators and thus prey become less wary, or directly, where human-habituated individuals become bolder and thus more vulnerable to predation. Building on ideas from the study of traits associated with domestication and urbanization, we develop a framework to understand how behavioral changes associated with nature-based tourism can impact individual fitness, and thus the demographic trajectory of a population.