Other winged creatures at Pier 94
By Noreen Weeden
If you’re familiar with Golden Gate Bird Alliance, you’ve probably heard about our work restoring Pier 94 as habitat for wildlife on the southeastern San Francisco waterfront. You may have seen photos from our monthly volunteer work days, or you may have read lists of bird sightings there.
But birds aren’t the only winged creatures benefitting from our Pier 94 work!
On Saturday, April 4, we invited Liam O’Brien to join our group of 16 volunteers and introduce them to the butterflies of Pier 94.
Liam is a stage actor who about nine years ago became an enthusiastic and expert lepidopterist. An advocate for San Francisco’s butterflies, he works on the “Tigers on Market Street” project for Nature in the City and was the recipient of Bay Nature magazine’s 2014 Environmental Education Local Hero award.
Liam started by asking the volunteers if butterflies are pollinators. Contrary to many people’s assumptions, the answer is no!
Butterflies do drink nectar from flowering plants and fruit, with a tongue or proboscis that has evolved in length to take advantage of a specific plant. Unlikes bees with their short legs and body designed to efficiently collect, carry, and transfer pollen, butterflies are more like long-legged cranes with bodies that remain far from the pollen.
Rather than a pollinator, the butterfly’s role in its ecosystem is primarily as a food source. Butterflies have a short yet active life of just 10 to 12 days. The female typically lays 80 to 100 eggs. Eighty percent of all butterfly eggs are eaten by creatures crawling on the host plant. Then 80 percent of the larvae and pupae are parasitized by native wasps and flies. (Wasps and flies lay eggs inside the larvae, and the young eat their way out.) Finally, 80 percent of all the adults — the pretty, flying phase when we humans notice them — are eaten by a variety of birds, lizards, and even spiders.
San Francisco has 34 species of butterflies — a manageable number for experienced birders! Two species are specific to the wetlands along the bay and can be seen at Pier 94.
Painted lady at Pier 94 / Photo by Liam O’Brien
During our April 4 work day, Liam grabbed his net and we followed slowly. The Western pygmy blue (Brephidium exile) butterfly associates with pickleweed. The sandhill skipper (Pilotes sabuleti) depends on salt grass.…









