Land Use History: Hunting Ground to Urban Oasis
People have enjoyed Glen Canyon for hundreds of years. Ohlone Indians hunted on the site, and in the late eighteenth century it became grazing land for Mission Dolores. During Mexican rule in the 1840s, the park site was part of Jose Noe's Rancho San Miguel, and in early American times it was a haven for smugglers and cattle rustlers who allegedly hid in Devil's Cave and Dead Man's Cave.
In the 1850s Adolph Sutro bought 1,200 acres of Rancho San Miguel, including Glen Canyon. In 1886, with the help of school children, Sutro planted pines, Monterey cypress, acacia and blue gum eucalyptus, species which still thrive in the park today.
Glen Canyon had already become the site of the first commercial dynamite manufacturing operation in the United States. Run by the Giant Powder Company, the plant began operating in 1868 but was completely destroyed in an explosion the next year. In 1889 Adolf Sutro's heirs sold the land to the Crocker Real Estate Company, which constructed an amusement park with an aviary, bowling alley, small zoo, and attractions such as a tightrope walk across the canyon and balloon ascents. The area was purchased by the City of San Francisco in 1922 for $30,000.
In 1941, 0'Shaughnessy Boulevard was completed and cut off the watershed on the west side of the park, further diminishing Islais Creek. SilverTree Day Camp was established that same year. In the 1970s, a plan to widen O'Shaughnessy Boulevard and make it part of the freeway system was defeated by community opposition led by the "Gum Tree" ladies.
Volunteers working in Glen Canyon (Photo by Christopher Campbell)
Red-Tailed Hawk
This widespread and common raptor adapts well to new conditions and thrives in San Francisco. Gracefully soaring red-tails can be spotted hunting voles and gophers in parks, or rats and pigeons anywhere in the city. Glen Canyon has some of the largest grasslands in San Francisco making it home to field mice, birds, and even ground squirrels and snakes. Good hunting areas and large trees in the Canyon make it possible for several pairs of Red-tailed Hawks to nest in the area. As in all raptors, the female Red-tailed Hawk is one third larger than the male.
Red-Tailed Hawk, Buteo jamaicensis (Photo by David Marotta)
Red-Shouldered Hawk
The striking orange tones, striped tail and white wing patches of a Red-shouldered Hawk are often the best way to separate it from the more familiar Red-tailed Hawk. The smaller and more local Red-shouldered Hawk is better adapted to hunt within forests than its larger cousin and biggest competitor, the Red-tailed Hawk. The Red-shouldered Hawk is often seen hunting from a power pole or low in tree and hunts for gophers, lizards and grasshoppers, This hawk has become significantly more common in San Francisco in the last 10 to 20 years.
Red-Shouldered Hawk, Buteo lineatus (Photo by Yufeng)