By Nancy H. DeStefanis

Great blue herons currently have five active nests at Blue Heron Lake in Golden Gate Park.

Four of the nests are located in the giant pine tree on top of the island facing the Blue Heron Boathouse. The fifth nest is located around the corner on another island facing the waterfall. The herons have nested at the lake for at least 34 years.

Heron Watch, a free program, opens Saturday, April 12, from 10 a.m. to 1 p.m., for six Saturdays through May 17. Volunteers will show heron chicks through high-powered telescopes and answer questions.

Last year, nine chicks fledged on “Heron Island” opposite the boathouse.

For more information, visit sfnature.org. Nancy H. DeStefanis is the executive director of San Francisco Nature Education.