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Nature Watch: Everything from Armadillos to Zebra Butterflies

Back on the Rock

When the Spanish explorer Don Juan Manual Ayala visited San Francisco Bay in 1775, the island we now call Alcatraz was little more than a mound of sandstone whitened by the droppings of many generations of seabirds. For the next 200 years, human use and alteration of the island all but eliminated the birds. But now, despite the nearly 5,000 people who visit the island daily, the birds of Alcatraz appear to be making a comeback.

The recovery started about a decade ago, when portions of the island were first closed to visitors and birds such as Brandt's Cormorants, Pelagic Cormorants, and Pigeon Gillemots steadily increased their numbers along the rocky slopes. Since then, Western Gulls have virtually taken over the top of the island. These ground-nesting birds normally nest on inaccessible rocky sea cliffs or islands to avoid predation and other sources of nest disturbance. Once humans were forbidden from portions of Alcatraz, the birds felt comfortable enough to nest amid the rubble of former buildings.

Alcatraz has also been discovered by several species that probably didn't nest there in the days before Europeans arrived. During the years when the island was used as a prison, tons of soil was imported from the mainland to allow the establishment of gardens and landscaping. The hardy plants that remain were allowed to grow wild and now cover significant parts of the island. A large colony of Black-crowned Night Herons has become established in the dense foliage of some of the low shrubs. Great Egrets also nest there, taking advantage of the trees that now grow on the protected east side of the island.

Most reference sources attribute the name "Alcatraz" to the Spanish word for "pelican," which is "alcarez." And while pelicans frequently visit the bay, it's doubtful they ever nested on Alcatraz. A look at the island today, particularly the west side, which is often completely covered with nesting cormorants, may reveal the true source of the name. We know that Don Juan Manual Ayala named the rock for the birds he saw there, but maybe he called it "alcatraceo," the Spanish word for "cormorant."