Pronghorn Study Finds Migration Trends

WILDLIFE MUST move to thrive and survive, however the habitat connectivity they rely on for spring and fall seasonal migrations continues to be fragmented by housing, roads, fences, energy facilities and other human-made barriers.

An article focused on migration routes of pronghorn, recently published in the scientific journal PLOS ONE, shed new light on the important factors and the cumulative effects from habitat conversion and fragmentation of migratory routes.

…where the antelope roam…

…where the antelope roam
(Photo: Public Domain)

“Novel applications of wildlife tracking technology have given us insights of the determinants of pronghorn migration routes across vast landscapes and seasons,” said Andrew Jakes, wildlife biologist for the National Wildlife Federation. “Our findings affirmed the importance of open grassland and sagebrush habitats as important migration habitat. We could also document the extent to which natural changing conditions such as foraging quality, and human-created features, such as road density and fossil fuel infrastructure (i.e., oil and gas wells) shape pronghorn migration routes. Integrating these multi-scale predictions into one spatial map will be highly valuable to wildlife managers and habitat managers.”

The 6-year study followed 185 GPS-collared pronghorn as they moved across international borders, from Saskatchewan and Alberta, Canada to Montana in the United States. Key study findings also revealed:

Large landscapes, such as grasslands, and the quality of forage (NDVI) is a critical determinant of pronghorn migration

At large scales, pronghorn avoided areas with high road density and areas with high fossil fuel infrastructure from oil and gas development.

During fall migration, herds tend to follow river systems, so that they can arrive at winter range quickly, however this is not important during spring as pronghorn recover from the previous winter and prepare for fawning.

Paul Jones, senior wildlife biologist for Alberta Conservation Association asserted “When we stand on a small piece of native prairie here in Alberta, Canada looking towards our neighbors to the south we loose perspective of the bigger picture and what is happening on the big stage. What this research has highlighted is how pronghorn are indicative of how wildlife try to edge out a living on a highly fragmented landscape and that jurisdictional boundaries are just lines on a piece of paper. It also shows that pronghorn at the northern periphery of their range are sitting on the edge of a precipice ready to fall off if we lose these migration routes and they are no longer able to move in response to fluctuating conditions.”

The mapping of migration habitat for ungulates, such as pronghorn, is a topic of high conservation relevance, yet their migration routes, and what determines them in an everchanging landscape, are still not fully understood. “We see this approach as a holistic view of identifying important migration habitat across entire landscapes and can help conservation planning and management decisions for a wide-ranging species like pronghorn. Agencies around the West have shown their commitment to addressing migration needs, especially for ungulates,” said Jakes.

Mark Hebblewhite, wildlife biology professor at University of Montana concurs. “Our paper is a great example of the need for Montana Fish, Wildlife and Parks’ recently released wildlife movement and migration strategy to help conserve migratory species, like pronghorn, here in Montana.”

–TF&G Staff Report

New Lighting System Helps Deer Avoid Cars

RESEARCHERS WITH the U.S. Department of Agriculture’s (USDA) Wildlife Services (WS) program recently applied for a patent (U.S. Patent Application No. 16/668,253) for a new vehicle-based lighting system to prevent deer-vehicle collisions during low-light conditions.

Through a series of experiments with free-roaming white-tailed deer, researchers at the WS program’s National Wildlife Research Center (NWRC) found the use of a rear-facing light-emitting diode (LED) light bar‒which illuminates a larger portion of the vehicle’s front surface than standard headlights alone‒resulted in fewer dangerous deer-vehicle interactions. The likelihood of dangerous interactions decreased from 35% to only 10% of vehicle approaches when using a rear-facing light bar plus headlights versus just headlights alone. The reduction in dangerous interactions appeared to be driven by fewer instances of immobility or “freezing” behavior by deer when the light bar was used. The study “Frontal vehicle illumination via rear-facing lighting reduces potential for collisions with white-tailed deer” is highlighted in the latest issue of the journal Ecosphere.

“This new lighting system takes advantage of a deer’s predator avoidance behavior (also known as flight behavior),” states lead author and former NWRC researcher Dr. Travis DeVault who currently serves as the associate director of the University of Georgia’s Savannah River Ecology Laboratory. “We predicted that light reflected from the front surface of the vehicle would provide a more reliable looming image to deer, thus encouraging the deer to move out of the path of the approaching vehicle.”

The “looming” appearance of approaching vehicles with normal headlights (top) versus headlights plus the new rear-facing LED light (bottom).
(Photo: USDA)

When an object “looms,” it becomes increasingly larger to the perceiving animal, helping the animal realize that the object is an approaching object versus one that is stationary.

In the United States and Canada, deer cause the majority of animal-related injurious and deadly road collisions. Many of the mitigation measures designed to reduce vehicle collisions with deer and other wildlife are road-based rather than vehicle-based. Road-based mitigation measures include devices and methods intended to influence animal behavior (e.g. roadside reflectors and mirrors, repellents, hazing) and driver behavior (e.g., warning signs, speed limits, animal detection systems), as well as vegetation management and highway lighting designed to increase visibility of wildlife to drivers, and wildlife population management. A vehicle-based system, such as the rear-facing LED light bar, advances efforts to reduce wildlife deaths and increase driver safety on roads.

The patent-pending technology can be incorporated as an after-market device, like a brush guard or bumper, or can be embedded in the vehicle as part of the manufacturing process.

USDA is currently seeking a licensing partner to build and market the technology. For more information, please contact NWRC’s Technology Transfer Program Manager john.d.eisemann@usda.gov.

WS is a program with the USDA Animal and Plant Health Inspection Service. Its mission is to provide Federal leadership and expertise to resolve wildlife conflicts to allow people and wildlife to coexist. The program’s efforts help people resolve wildlife damage to a wide variety of resources and to reduce threats to human health and safety. Funding for the WS program is a combination of federal appropriations and cooperator-provided funds.

The NWRC is the research unit of the WS program. It is the only Federal research organization devoted exclusively to resolving conflicts between people and wildlife through the development of effective, selective, and socially responsible methods, tools, and techniques.

–TF&G Staff Report

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