Wildlife-human conflict in relation to urban foraging

The influx of wildlife into cities is enlivening for urban dwellers and beneficial for ecological integrity, yet detrimental for these creatures as human-wildlife conflicts arise.  Urban food sources attract regionally-native species perceived as a threat to human safety, such as bears, big cats, and coyotes. These mammals scavenge urban environments in search of discarded food and fallen fruit, and are endangered by encounters with humans which may warrant euthanization.

Keeping in mind urban food as an attractant for wildlife, a six-year long study conducted in Aspen suggests  the use of urban areas by black bears in particular ‘is reversible and fluctuates with the availability of natural food resources’(1).  Factors affecting natural forage availability include climatic influences like prolonged snowpack, major drought or flooding, and development-driven habitat fragmentation resulting in broken food webs and diminished ecological function (e.g. reduction of seed dispersal and pollination due to blockage of species flow and suppression of environmental patterns that regulate these processes.)  Therefore, ‘threatening’ wildlife may enter city limits not because they prefer it, but because their natural habitat many not sustain the richness of biodiversity that would supply the necessary calorie intake of such large mammals.  Presented is a brief exploration of ‘native species foraging buffers’: a strategy to prevent human-wildlife conflict through revegetation of natural areas.

Forage buffers are based on species natural diets and instinctive movement across boundaries, specifically between designated habitat and urban environments.  

Native Plant Palette

Plants are the base of the food web(2), and in conjunction with a carnivorous food supply,  large mammals commonly have omnivorous diets consisting of plants, berries, nuts, legumes in addition to insects, rodents, and other small creatures of prey.  For instance, once bears emerge from hibernation, they forage primarily on plants after scavenging for dead and vulnerable meat.  Forage buffers vegetated with a diversity of locally-native plants, to which predators and a range of wildlife have evolved to rely on during active parts of the year, would augment naturally occurring vegetation to sustain many trophic levels.  The intended effect is a lower reliance on urban food sources, thereby lessening the number of encounters with and death of large wildlife in cities.


Species Movement Patterns

Native forage buffers are attuned to species diet and instinctive movement across the landscape.  Research shows that movement across a boundary depends on its form(3).  Edges of natural habitats, where ecologies overlap, are typically more densely vegetated in ways that reduce or inhibit movement across.  Change in movement pattern is also caused by straight form (Figure 1.A), where wildlife tend to move along rather than across.  Species movement into urban environments is in part encouraged by soft, rather open and convoluted edges that are prime ares for passage from parks and open space (Figure 1.B).  A series of straight, wide, and shrubby forage buffers parallel to soft borders would act as a diversion layer as large wildlife approach urban areas (Figure 1.C).  These compact and fruitful layers of vegetation would theoretically: occupy wildlife with a natural, more nutritious and satisfying food palette; provide a safer, less distressing foraging environment; and would also maintain a safe distance between the urban boundary and potentially threatening wildlife.

Further research will inform logistics of the native species forage buffer concept, including critical details such as sufficient distance from urban areas as to not inadvertently encourage passage.  Studies may draw attention toward influential wind patterns, human activity, leavings, and other sources that wildlife might trace back to the city.  Other considerations to investigate include: methods of revegetation; plant material procurement; and strategized placement in response to points of entry and frequency of passage.  Lastly, public education of forage buffers as prime native species foraging sites would be a critical component in supporting responsible naturalist and recreationalist behavior in proximity to large wildlife in their designated natural habitat.

References:

  1. Baruch-Mordo S, Wilson KR, Lewis DL, Broderick J, Mao JS, et al. (2014) Stochasticity in Natural Forage Production Affects Use of Urban Areas by Black Bears: Implications to Management of Human-Bear Conflicts. PLoS ONE 9(1): e85122. doi:10.1371/journal.pone.0085122
  2. Tallamy, Douglas W. 2009. Bringing Nature Home, How you can sustain wildlife with native plants . Portland: Timber Press, Inc.
  3.  Forman, Richard T. T. 2014 Urban Ecology: Science of Cities. Cambridge: Cambridge University Press.

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