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Residents of U.S. cities and suburbs are diverse in just about every way you can imagine, including race, ethnicity, income, education, political affiliation, family structure and species. Yes, you read that correctly. Humans and birds and wildlife are living side-by-side in greater numbers than ever before; often obliviously, usually harmoniously. But clashes do occur over noise, property damage, theft, trespassing — all the usual culprits. Managing human-wildlife conflict offers a new income stream opportunity for pest control businesses, as many have recognized, but there are challenges, too.

The traditional focus of the pest control industry has been on critters with a decided lack of charisma. Think cockroaches, termites, bed bugs, ants and other spineless creatures. Mice and rats, too, of course, but these mammals evoke little sympathy from paying customers thanks to some sticky relationship baggage dating back to a 12th century plague pandemic (never mind that rodents weren’t the true culprit — we Homo sapiens know how to hold a grudge). Lethal control methods are the industry norm, and generally accepted by a heterogeneous human population. A homeowner with a roach problem wants them dead, dead, DEAD. As soon as possible, please…like, yesterday. Whatever it takes as long as there’s no negative impact on the health and welfare of people and their pets.

However, a homeowner who does not want to rent out the attic to a raccoon, or host a free 24-hour salad bar and invite the local herd of white-tailed deer, or turn the fireplace flu into a daycare center for young chimney swifts, probably, often adamantly, does NOT want these animals killed. Research strongly suggests Americans increasingly think of wild animals, particularly birds and mammals, similarly to the way they regard their companion animals.

A radio tuned to 24-hour talk radio at loud volume and placed in a basement, attic or outbuilding may be just the thing to encourage an uninvited guest to move along (and really, can you blame them?).

There are several non-lethal approaches to managing human-wildlife conflict, including: prevention (e.g., exclusion); behavior modification; habitat modification; humane population control; translocation; and our topic du jour, harassment. By “harass” what I really mean to say is “scare” those pesky wild neighbors — not to death, of course, but to depart. Vacate. Get the hell outta Dodge. This goal is achieved by adding some novel component to the environment — some new sight, sound or smell.

VISUAL STIMULI. Scare tactics that rely on visual stimuli are the most common, and the most broadly applicable. Both birds and mammals are sensitive to lights, movement and threatening images. In the case of nocturnal creatures, the solution may be as simple as floodlights directed at problem areas. Strobe lights have been used successfully in attics and other building spaces that are otherwise attractive to wildlife as denning locations but rarely used by the human residents (with the exception of the occasional disco-theme dance rave).

Balloons, with or without eyespots, can be used outdoors to protect gardens and landscaping but they must be replaced every few days as they deflate — a potentially expensive and time-consuming proposition. Flags, reflective tape, aluminum pie tins, propellers and other objects that move in a breeze are useful, easy to install and relatively inexpensive. Moreover, the wind causes their movement to be erratic, less predictable and therefore the novelty lasts longer. Unfortunately, clients may not always appreciate the new addition to their viewscape any more than the wild creatures do.

Decoys and silhouettes are another popular choice because they are readily accessible, easy to install and are not overtly intrusive to the human visual field. They rely, at least in part, on an instinctive response to a visual stimulus, such as the distinctive outline of a hawk in flight, to elicit an alarm response in the target species. A model hawk or owl placed on the roof or on a pole will immediately alert the local prey species to the presence of their age-old predator. Eventually, though, if the decoy never changes its perch, even the most timid field mouse will start to notice that this particular, decrepit and probably paralyzed raptor’s bark is way worse than its bite.

AUDITORY STIMULI. Loud noises of any kind are frightening, or at least annoying, to most animals, humans included. A radio tuned to 24-hour talk radio at loud volume and placed in a basement, attic or outbuilding may be just the thing to encourage an uninvited guest to move along (and really, can you blame them?). Sirens and pyrotechnic devices are effective, no doubt, but must be used judiciously to avoid causing explosive outbursts by the human population. For this reason, bioacoustics is an attractive area of research. Distress calls and predatory sounds get results but are less disturbing to people. Additionally, these types of sounds are meaningful to the target species at much lower decibel levels than, for example, a propane exploder. Sometimes a whisper is more noticeable than a shout.

SCENT. Many wildlife species have a strong sense of smell that helps them locate food and recognize the presence of predators, so there would seem to be potential for using scent as a scare tactic, particularly for mammals. However, there are downsides to this approach that have limited application and popularity. For example, most scents degrade quickly when exposed to the environment, so treatments must be reapplied often. Predator urines, or reasonable facsimiles, are available from various sources but are rarely a popular choice. They stink, thus the cure may be deemed worse than the disease.

FINAL THOUGHTS. The obvious problem with any bird or wildlife control technique that relies on novelty is that eventually it becomes an established part of that landscape and, as a result, no longer novel. Initially there may be an immediate improvement that is gratifying for provider and client alike, but this sense of satisfaction can be quite short-lived. No single tool or method will work long-term, particularly if the habitat is otherwise appealing and population levels and pressures are high. The best outcomes are achieved when short-term scare tactics are followed up with habitat and behavior (both human and non-human) modification.

Dr. Kieran Lindsey loves looking for wild things in all the wrong places…so she became an urban wildlife biologist. She also has way too much fun as the official Animal-Vehicle Biologist for NPR’s “Car Talk.” Read her blog at www.nextdoornature.org.