A herd of elk has gone extinct in Prairie Creek Redwoods State Park. Why? Poor road design.
The Boyes elk were first documented in Boyes Meadows in 1937. By the late 1940s, their population ballooned to around 100, taking advantage of the newfound forage to jump in size. Over time the population settled; between 1950 to the late 1990s, the population fluctuated between 20-60 individuals. In 1998, there were 30 elk. By 2011, the herd was extinct.
In 1984, Caltrans began planning for a bypass around the old-growth of the park—today, we call the original road the “Newton B. Drury Bypass.” The original road, just two lanes through enchanting old-growth redwoods and elk-filled meadows—made traffic slow. The new 101 route was twice as big, four lanes, and allowed cars to zip by at 65 mph.
This “improvement” came at a cost. The new road opened in 1992. Construction of the road created meadows and clearings which were soon utilized by elk. Increased road kill soon followed. In places, the road is quite steep. Cars heading downhill (southbound) may find it difficult to stop or evade elk in the roadway. Similarly, elk may find avoiding humans more difficult.
In 2003, Caltrans installed a barrier to separate north and southbound lanes. The barrier, intended to keep cars from cross lanes, was also likely effective in limiting elk mobility, making attempts by elk to evade or avoid vehicles more difficult. Elk and other ungulates have a difficulty assessing vehicle speeds and distance, perhaps making last minute maneuvers, and things that inhibit that flight response, more important. Furthermore, these elk were habituated to humans, and the elk may have had difficulty determining which vehicles detected them and wanted to slow to observe and which vehicles did not detect them or wanted to poach them.
The road also facilitated poaching. The original road was square in the park; this new section of Highway 101 is remote and dark. Poachers have a low risk of getting caught. Again, the habituation of elk likely further enabled poachers by reducing the elk’s usual fear of humans.
Things may be getting better for elk in the area, but not thanks to Caltrans. The meadows along Highway 101 are slowly giving way to forests, as young conifer species and other successional plants began their invasion.
It may take a while before Boyes meadow is home to another herd of elk. A female elk could leave her herd and travel to Boyes meadow to give birth. After birth, the young could stick around with their mother (and potentially other mothers) to start a new herd. This possibility is thought to be “far flung.” Alternatively, the meadow could be recolonized—a small number of colonizing elk, pushed to the meadow by some disturbance, like a fire, and determine that they like it and way to stay. Or an existing elk herd could expand their home ranges, although this too is regarded as unrealistic as other elk herds are separate by a fair distance of thick forests.
For more on the Boyes herd and our fascinating Roosevelt elk, please read “Population Ecology of Roosevelt Elk: Conservation and Management in Redwood National and State Parks” by Dr. Butch Wekerly.