Not all cities are the same: variation in animal phenotypes across cities within urban ecology studies

The sustained expansion of urban environments has been paralleled by an increase in the number of studies investigating the phenotypic changes of animals driven by urbanization. Most of these studies have been confined to only one urban center. However, as the types and strength of anthropogenic stressors differ across cities, a generalizable understanding of the effects of urbanization on urban-dwelling species can only be reached by comparing the responses of urban populations from the same species across more than one city. We conducted phylogenetic meta-analyses on data for animal species (including both invertebrates and vertebrates) for which measures about any morphological, physiological, or behavioral trait were reported for two or more cities. We found that morphological, physiological and behavioral traits of urban animals all differ similarly across cities, and that such phenotypic differences across cities increase as the more cities were investigated in any given study. We also found support for phenotypic differences across cities being more pronounced as the farther away cities are from each other. Our results clearly indicate that separate urban populations of the same species can diverge phenotypically, and support previous pleas from many researchers to conduct urban studies across several urban populations. We particularly recommend that future studies choose cities in different biomes, as urban adaptations may differ substantially in cities sited in different ecological matrices. Ultimately, a generalized knowledge about how organisms are affected by urbanization will only be possible when comprehensive biological patterns are similarly studied across separate and distinct cities

The ontogeny of antipredator behavior: age differences in California ground squirrels (Otospermophilus beecheyi) at multiple stages of rattlesnake encounters

Newborn offspring of animals often exhibit fully functional innate antipredator behaviors, but they may also require learning or further development to acquire appropriate responses. Experience allows offspring to modify responses to specific threats and also leaves them vulnerable during the learning period. However, antipredator behaviors used at one stage of a predator encounter may compensate for deficiencies at another stage, a phenomenon that may reduce the overall risk of young that are vulnerable at one or more stages. Few studies have examined age differences in the effectiveness of antipredator behaviors across multiple stages of a predator encounter. In this study, we examined age differences in the antipredator behaviors of California ground squirrels (Otospermophilus beecheyi) during the detection, interaction, and attack stages of Pacific rattlesnake (Crotalus oreganus) encounters. Using free-ranging squirrels, we examined the ability to detect free-ranging rattlesnakes, snake-directed behaviors after discovery of a snake, and responses to simulated rattlesnake strikes. We found that age was the most important factor in snake detection, with adults being more likely to detect snakes than pups. We also found that adults performed more tail flagging (a predator-deterrent signal) toward snakes and were more likely to investigate a snake’s refuge when interacting with a hidden snake. In field experiments simulating snake strikes, adults exhibited faster reaction times than pups. Our results show that snake detection improves with age and that pups probably avoid rattlesnakes and minimize time spent in close proximity to them to compensate for their reduced reaction times to strikes

What is the effectiveness of using conspecific or heterospecific acoustic playbacks for the attraction of animals for wildlife management? A systematic review protocol

Abstract Background Many animals are attracted to the sounds of their conspecifics and some are attracted to the sounds of other species. Therefore, wildlife managers have begun to capitalize on this attraction to lure animals to specific places by broadcasting vocalizations—a method referred to as acoustic playback. Playbacks have been conducted to attract animals for capture, encourage birds to use specific nest boxes, attract animals to safe locations where they can breed, or to lure animals to habitats away from human disturbances. However, there has been no evaluation of the general effectiveness of this intervention on the attraction of animals for wildlife management. We describe a protocol to systematically review the literature of the effectiveness of using playbacks so that conservation practitioners can make informed wildlife management decisions. Methods The review will examine primary field studies that use acoustic playbacks to attract animals for wildlife management. Playbacks could be of conspecifics, heterospecifics, or both. We will search various bibliographic databases, online search engines, and specialist websites for relevant studies. We will screen studies first on title and abstract, then on full text. We will only include studies that measure quantitative results. Relevant outcomes will include the attraction of animals to playbacks and encompass various management goals: to capture the animal, to persuade the animal to use a new breeding location, and/or to persuade the animal to settle in a location during the study duration. Studies must be based on comparison between conditions before and after intervention, on comparison between treatment and control plots, or both. Inter-reviewer consistency in article inclusion will be performed with 10% of the titles and abstracts and 10% of the full texts. We will critically appraise the literature based on study type and design, sample sizes, study duration, and other aspects of methodology. We will extract data and meta-data including various potential effect modifiers (e.g., taxon). Finally, we will evaluate the effectiveness of playbacks through a narrative synthesis of the evidence, and quantitative synthesis (i.e., meta-analysis) if sufficient data (more than two studies) of similar outcomes are found

Urban invaders are not bold risk-takers: a study of three invasive lizards in Southern California

Biological invasions threaten biodiversity worldwide, and therefore, understanding the traits of successful invaders could mitigate their spread. Many commonly invasive species do well in disturbed habitats, such as urban environments, and their abilities to effectively respond to disturbances could contribute to their invasiveness. Yet, there are noninvasive species that also do well in disturbed habitats. The question remains whether urban invaders behave differently in urban environments than noninvaders, which could suggest an "urban-exploiting" phenotype. In Southern California, the co-occurrence of invasive Italian wall lizards Podarcis siculus, brown anoles Anolis sagrei, and green anoles A. carolinensis, and native western fence lizards Sceloporus occidentalis offers an opportunity to test whether invasives exhibit consistent differences in risk-taking within human-altered habitats compared with a native species. We predicted that invasive lizards would exhibit more bold behavior by having shorter flight-initiation distances (FIDs) and by being found farther from a refuge (behaviors that would presumably maximize foraging in low-risk environments). Invasive populations had similar or longer FIDs, but were consistently found at distances closer to a refuge. Collectively, invasive lizards in urban habitats were not bolder than a native species. Reliance on nearby refuges might help species successfully invade urban habitats, and if a general pattern, may pose an added challenge in detecting or eliminating them

The power of community science to quantify ecological interactions in cities

Abstract Studying animals in urban environments is especially challenging because much of the area is private property not easily accessible to professional scientists. In addition, collecting data on animals that are cryptic, secretive, or rare is also challenging due to the time and resources needed to amass an adequate dataset. Here, we show that community science can be a powerful tool to overcome these challenges. We used observations submitted to the community science platform iNaturalist to assess predation and parasitism across urbanization gradients in a secretive, ‘hard-to-study’ species, the Southern Alligator Lizard (Elgaria multicarinata). From photographs, we quantified predation risk by assessing tail injuries and quantified parasitism by counting tick loads on lizards. We found that tail injuries increased with age and with urbanization, suggesting that urban areas are risky habitats. Conversely, parasitism decreased with urbanization likely due to a loss of hosts and anti-tick medications used on human companion animals. This community science approach generated a large dataset on a secretive species rapidly and at an immense spatial scale that facilitated quantitative measures of urbanization (e.g. percent impervious surface cover) as opposed to qualitative measures (e.g. urban vs. rural). We therefore demonstrate that community science can help resolve ecological questions that otherwise would be difficult to address

Lizards' response to the sound of fire is modified by fire history

Many animals survive wildfires; however, the mechanisms used to detect and respond to fire have been poorly studied. Sensory cues like sight and sound are used to recognize threats (e.g. predators) and elicit escape responses in prey. Similarly, these cues might be used to detect an approaching wildfire. We tested whether the western fence lizard, Sceloporus occidentalis, responds to the sound of fire as a threat. We predicted that lizards living in burned areas would be more sensitive to the sound of fire than lizards in adjacent and urban areas, where fire suppression could have induced relaxed selection on fire responsiveness. We compared the behaviours of lizards following an experimental playback where we broadcast the sound of fire along with other control sounds (a predator, a common nonpredatory bird and a novel nonpredatory bird). We conducted our playbacks in 2019 in recently burned areas (using the survivors from the 2018 Woolsey Fire, southern California, U.S.A.), unburned adjacent areas and urban areas. We found that in burned areas, lizards responded more to the sound of fire than all three controls, but in urban areas, they responded more to both the sound of a predator and the sound of fire. Our results suggest that lizard responses to fire sounds are greater in an area that has recently experienced a wildfire than in an unburned area, and that urban areas create a complex evolutionary landscape that also increased antipredator behaviour for other biologically relevant stimuli.This work was supported by Ministry of Economy and Competitiveness and Ministry of Science, Innovation and Universities from the Spanish Government (grant numbers CGL2015-64086-P, PGC2018-096569-B-I00 and BES-2016-078225)

Downsizing for downtown: limb lengths, toe lengths, and scale counts decrease with urbanization in western fence lizards (Sceloporus occidentalis)

Urbanization induced habitat loss and alteration causes significant challenges for the survival of many species. Identifying how species respond to urbanization can yield insights for the conservation of wildlife, but research on reptiles has been narrowly-focused. We compared morphology among four populations of western fence lizards (Sceloporus occidentalis) to determine whether a common native species affected by urbanization exhibits morphological differences consistent with habitat use. We quantified habitat differences across four sites in Los Angeles County, California, USA that varied in level of urbanization, measured how lizards used microhabitats, and assessed variation in body size, limb length, toe length, and scalation of lizards collected from each site. Urban and suburban populations of fence lizards mostly used human-made substrates while lizards from more natural areas mostly used natural woody substrates. Lizards from the most urban site also exhibited the widest breadth of substrates used, indicating that urban sites might offer more variable microhabitats. Urban lizards had reduced limb lengths and toe lengths consistent with how they used microhabitats and other habitat characteristics (e.g., percent impervious surface cover). Urban lizards also had fewer dorsal scales, which might be associated with changes in ambient temperature (e.g., urban heat island effect), given that lizards with fewer and larger scales typically have reduced evaporative water loss. Our results uniquely differ from past studies on lizard responses to urbanization, indicating that work on diverse taxa is necessary to assess the potential varied pathways of morphological adaptations to urban environments

Data from: Fear no colors? Observer clothing color influences lizard escape behavior

Animals often view humans as predators, leading to alterations in their behavior. Even nuanced aspects of human activity like clothing color affect animal behavior, but we lack an understanding of when and where such effects will occur. The species confidence hypothesis posits that birds are attracted to colors found on their bodies and repelled by non-body colors. Here, we extend this hypothesis taxonomically and conceptually to test whether this pattern is applicable in a non-avian reptile and to suggest that species should respond less fearfully to their sexually-selected signaling color. Responses to clothing color could also be impacted by habituation to humans, so we examine whether behavior varied between areas with low and high human activity. We quantified the effects of four T-shirt colors on flight initiation distances (FID) and on the ease of capture in western fence lizards (Sceloporus occidentalis), and we accounted for detectability against the background environment. We found no differences in lizard behavior between sites. However, lizards tolerated the closest approaches and were most likely to be captured when approached with the T-shirt that resembled their sexually-selected signaling color. Because changes in individual behavior affect fitness, choice of clothing color by people, including tourists, hikers, and researchers, could impact wildlife populations and research outcomes