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Volume 26
Number 3
Winter 2009-2010
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Science Notes
Published: 15 Jan 2014 (online)  •  30 Jan 2014 (in print)
Applying community noise metrics in parks
Relating wildlife behavioral responses to noise to ecological consequences
  Tolerating noise and the ecological costs of “habituation”
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Tolerating noise and the ecological costs of “habituation”

By Jesse R. Barber, Frank Turina, and Kurt M. Fristrup

Ruddy turnstone on Alaskan tundra.

U.S. Fish and Wildlife Service/Tim Bowman

Ruddy turnstones forage by probing and flipping over stones along rocky shores in search of insects and other invertebrate prey. Animals that depend on specialized habitats may become tolerant of disturbance owing to lack of readily available, alternative habitats. In contrast to habituation, tolerance may carry ecological costs.

ANIMALS ARE SAID TO BE HABITUATED when their response to a novel stimulus diminishes over time. Habituation can be viewed as adaptive when the stimulus is irrelevant to the animals. Animals that exhibit tolerance of noise are often cited as evidence that noise impacts to wildlife are transient and of neutral ecological consequence. Both theory and observations refute the equation of noise tolerance with absence of impact.

At the Monkey Mia resort in Australia, a population of bottlenose dolphins (Tursiops spp.) has been exposed to tourism for more than 40 years. Experimental studies of dolphin reactions to boats documented much stronger responses by dolphins outside of tourist areas than inside tourist areas (Bejder et al. 2006). Two decades of surveys at these sites documented a decrease in the dolphin population inside tourist areas coinciding with an increase outside these areas. Dolphins have long generation intervals, so these studies implicate displacement of sensitive individuals, not habituation.

An apparent increase in noise tolerance may actually indicate more severe constraints on animal behavior (Gill et al. 2001). Declining foraging success and body condition can cause animals to diminish their responses to disturbance stimuli because they cannot afford decreased feeding rates (Stillman and Goss-Custard 2002). Recent work with turnstones (Arenaria interpres, see photo) has shown that birds whose food resources were experimentally supplemented flushed earlier and flew farther when approached (Beale and Monaghan 2004).

If animals demonstrate behavioral or distributional changes to acoustical disturbance, management action can be taken. However, in the absence of clear impacts, we suggest managers strive to ensure that (1) sensitive individuals have not already been displaced; (2) decreased body condition, critical habitat needs, social forces, lack of habitat experience, and/or expensive investment in territory formation are not preventing animals from reacting to the disturbance (Bejder et al. 2009); and (3) alternative explanations are not available. For example, in Grand Teton National Park, mother moose (Alces alces) have been giving birth closer to the road over the last 10 years. In the absence of data indicating that this shift protects moose calves from recolonizing, road-averse grizzly bears (Ursus arctos), this behavioral pattern may have been interpreted as evidence for habituation to the roadway (Berger 2007).

Managers should minimize wildlife exposure to noise and avoid habituation to noise wherever possible. However, in situations where acoustical disturbances to wildlife cannot be avoided, park managers should consider structuring human activities to foster habituation. A predictable timetable enhances opportunities for learning. Animals can distinguish between routine and anomalous occurrences of human noise; they might productively utilize habitats that they would otherwise avoid, or perform critical activities during times of reduced human presence. Scheduling can provide more control over interactions between visitors and wildlife, and offer more reliable opportunities to view wildlife under less perturbed conditions. Given increasing evidence of animals avoiding traffic on roads (e.g., Gagnon et al. 2005; Waller and Servheen 2005; Kerth and Melber 2009), scheduling of visitor access to protected lands will likely increase habitat connectivity, reduce wildlife collisions (thus increasing visitor safety), and increase overall habitat quality in the last of our wild places.


Beale, C. M., and P. Monaghan. 2004. Behavioural responses to human disturbance: A matter of choice? Animal Behaviour 68:1065–1069.

Bejder, L., A. Samuels, H. Whitehead, and N. Gales. 2006. Interpreting short-term behavioral responses to disturbance within a longitudinal perspective. Animal Behaviour 72:1149–1158.

Bejder, L., A. Samuels, H. Whitehead, H. Finn, and S. Allen. 2009. Impact assessment research: Use and misuse of habituation, sensitisation and tolerance in describing wildlife responses to anthropogenic stimuli. Marine Ecology Progress Series 395:177–185.

Berger, J. 2007. Fear, human shields and the redistribution of prey and predators in protected areas. Biology Letters 3:620–623.

Gagnon, J. W., T. C. Theimer, N. L. Dodd, S. Boe, and R. E. Schweinsburg. 2005. Traffic volume alters elk distribution and highway crossings in Arizona. Journal of Wildlife Management 71:2318–2323.

Gill, J. A., K. Norris, and W. J. Sutherland. 2001. Why behavioral responses may not reflect the population consequences of human disturbance. Biological Conservation 97:265–268.

Kerth, G., and M. Melber. 2009. Species-specific barrier effects of a motorway on the habitat use of two threatened forest-living species. Biological Conservation 142:270–279.

Stillman, R. A., and J. D. Goss-Custard. 2002. Seasonal changes in the response of oystercatchers Haematopus ostralegus to human disturbance. Journal of Avian Biology 33:358–365.

Waller, J. S., and C. Servheen. 2005. Effects of transportation infrastructure on grizzly bears in northwestern Montana. Journal of Wildlife Management 69:985–1000.

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Masthead Information
From landscapes to soundscapes: Introduction to the special issue
Measuring and monitoring soundscapes in the national parks
Integrating soundscapes into National Park Service planning
Excerpt from Governors Island General Management Plan
Conserving the wild life therein--Protecting park fauna from anthropogenic noise
Soundscapes monitoring and an overflight advisory group: Informing real-time management decisions at Denali
Soundscape management at Grand Canyon National Park
Tools of the trade: An example of using spectrograms to count fixed-wing aircraft
Visually impaired students help collect acoustic data in Grand Canyon National Park
Protecting the acoustic conditions at Great Sand Dunes National Park and Preserve
Generator noise along the U.S.-Mexico border
Airport expansion adjacent to San Antonio Missions
A program of research to support management of visitor-caused noise at Muir Woods National Monument
Modeling and mapping hikers’ exposure to transportation noise in Rocky Mountain National Park
Aircraft overflights at national parks: Conflict and its potential resolution
Managing the natural soundscape: The National Park Service as a learning organization
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