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The parrots make Sue Bierman Park their home because of its tall Lombardy poplars (Populus nigra ‘Italica’). These trees offer good perches, with great visibility—helping the parrots watch for hawks, their most common predator. During breeding season, the birds like to nest in Canary Island date palm trees (Phoenix canariensis). When this palm’s fronds break off the trunk, a small hole or indentation is often created. With a little industrious digging, the parrots can turn these spots into perfect nesting holes.

During most of the year, the flock rarely leaves the city’s northeast quadrant, an area ranging from the Ferry Building environs to Telegraph Hill, Russian Hill, North Beach, Fort Mason, and the eastern edge of the Presidio. But as tree fruits begin to ripen in less dense parts of the city during the summer and fall, the parrots make an annual trek to the Castro, Cole Valley, and other neighborhoods to the south and west. They seem to know exactly when and where to visit.

During summer months, plum trees on the streets and in the backyards of these neighborhoods beckon the parrots. Even though the city discourages planting fruit-bearing trees on the streets, in July and August many backyard specimens fill with ripe plums—irresistible to the parrots. They perch in the trees, methodically grabbing the fruit and eating it from the tight grasp of their claws. Another parrot favorite is the English hawthorn tree (Crataegus laevigata), whose fruit also ripens in July and August.