Reference no: EM133305839

Assignment: Please only the email Part here : Email to the author Summarize your editorial changes in an email to P. W. Bateman and P. A. Fleming. Begin by saying something positive about the study. Then briefly summarize the kinds of editorial problems you encountered and the changes you have proposed. Draw attention to any queries or suggestions. Conclude on a collegial note, perhaps by expressing interest in their research. Of course, the entire email should be written with diplomacy and respect. The email should be three hundred words.

For this assignment, continue to edit the Bateman and Fleming article, moving on to the introduction and reference list.

Does human pedestrian behaviour influence risk assessment in a successful mammal urban adapter?

P. W. Bateman and P. A. Fleming

Abstract

Optimal escape theory predict that animals should moderate their flight responses according to the level of risk represented by a potential predator. It should apply even when organisms are habituated to disturbance, moreover, how animals respond to human presence is likely to determine their success exploiting urban habitats. Urban animals should be sensitive to cues that inform them about levels of risk, allowing them to reduce costs by not overreacting to innocuous stimuli; while ensuring that they are nevertheless reactive to genuinely threatening stimuli. We tested this at a highly urbanized site in New York City, where eastern grey squirrels appear to pay little attention to humans. Squirrels were approached tangentially on a trajectory that took the observer within ∼2m of them and we measured alert distance, flight initiation distance (FID) and distance fled for each focal individual. Squirrels showed little sign of being alerted to the pedestrian if he remained on the footpath and did not look at them (only 5% of individuals moved away) but 90 percent of squirrels moved away, with longer FUD and flight distance, when approached by a pedestrian that moved off the footpaths and looked at them. Squirrels therefore modulate their reactions when pedestrians behave in a predictable manner (i.e. remaining on the footpaths) and are also sensitive to the direction of attention of humans, reducing unnecessary responses, and are thereby likely to be increasing their ability to persist in this urban environment. Previous studies have emphasized the behavioral plasticity of successful urban wildlife species. In this study, we emphasize the importance of disturbance monitoring by successful urban exploiters, allowing them to vary their behavioural responses according to the level of risk to which they are exposed.

Introduction

Cities are challenging environments for many species of wildlife, presenting a loss of natural resources (i.e., habitat and food) and high levels of anthropogenic disturbance, that is pedestrian traffic, vehicular traffic and industrial noise (Lowry, Hill, & Wong, 2012). Despite this, some species do extremely well in urban environments. Successful "urban adapters" (McKinney, 2006) are generally species that show high levels of opportunistic behavior (i.e. are habitat or

trophic generalists and can exploit novel niches; Bateman & Fleming, 2010, Lowry et al., 2012), or, in the case of birds, are also more egregious or sedentary (Kark et al., 2007) or have large breeding ranges, high fecundity, dispersal and survival (Møller, 2008). Behavioural flexibility and adaptive adjustments are therefore identified as a feature of successful urban species and are likely to be important in facilitating resource use, avoiding disturbance and enhancing communication (Lowry et al., 2012; Sol, Lapiedra, & Gonzalez-Lagos, 2013).

A major aspect of behavioural flexibility in urban adapters are how such animals are able to modify their anti-predator behaviour towards humans, which may be regarded as 'predation-free predators' (Beale & Monaghan, 2004). Models of optimal escape theory predict that individuals should flee when costs of staying outweigh costs of flight, based on the variables of risk posed by the predator, the cost of fleeing, the potential to rely on other defensive tactics, and the size of the prey group (i.e., increased vigilance and predator dilution) (Ydenberg & Dill, 1986; Patricelli & Blickley, 2006; Cooper & Frederick, 2007). Animals should, therefore, assess the degree of risk represented and dynamically adjust their antipredator behaviour accordingly.

In urban environments, where there is a high level of background disturbance, the success of urban wildlife may rely on their abilities to clearly distinguish between genuinely threatening and nonthreatening stimuli and become habituated to some human activity. Although animals still need to be sensitive to the level of threat because of human presence, living without fear in the vicinity of humans is identified as a key behavioural trait of urban adapters (Kark et al., 2007).

Ideally, successful urban adapters should be able to ignore non-threatening stimuli, minimizing opportunity and energetic costs, and also potentially allow exploitation of additional resources. There are subtle cues that could inform fleeing decisions by organisms, which they could use to reduce costs associated with fleeing when unnecessary and hence influence flight initiation distance (FED). For example, being sensitive to the direction of attention of an approaching human ("looking at" or "looking away") has been demonstrated recently to influence escape responses of birds (Bateman & Fleming, 2011; Lee et al., 2013) and reptiles (Cooper, 1998, 2011). Another cue to risk perception that has received little attention is the predictability of the behaviour of humans-a human who behaves in a way that diverts from 'usual' human behaviour (e.g., approaches from a different direction to most pedestrians) may be perceived as a higher risk and therefore influence escape responses, even if their behaviour is not more threatening per se. Sensitivity to such "unusual" behaviour would be dependent on long-term habituation of the animal to predictable human behavior.

Eastern grey squirrels (Sciurus carolinensis) are extremely successful urban adapters, and can be found in high densities in urban parks where they face reduced predation and become habituated to human presence, to the point where they show minimal avoidance behaviour of people (Engelhardt & Weladji, 2011). Eastern grey squirrels also have a lower giving-up density (i.e. take more seeds from localized sources) in urban areas than non-urban areas, possibly indicating lower sensitivity to predation. We examined the behaviour of a population of eastern grey squirrels in a highly urbanized area - the lower east side of Manhattan, New York. We predicted that squirrels would show highly reduced antipredator behaviour because of habituation to human presence (as demonstrated by Cooper et al., 2008; Engelhardt & Weladji, 2011), but should still discriminate between different levels of threat posed by people, and appropriately dynamically upgrade their antipredator response. We therefore tested two experimental treatments. Firstly, as urban squirrels have become used to humans by exposure to normally unvarying behaviour (walking on footpaths), we tested what happens when pedestrians show "unusual" behaviour (walking on the grass between footpaths). Second, we tested whether these squirrels retain the ability to discriminate between a pedestrian who passes by without looking directly at them, and a pedestrian who has their attention directed toward the animal.