Trees are an essential habitat for many of Whidbey’s bird species, and the Douglas fir is one of the most important components of the local forests.

Island naturalists and Coupeville residents Steve and Martha Ellis will illustrate this premise Thursday, Sept. 11 for the Whidbey Audubon Society’s monthly public program.

The free event is at the Coupeville Recreation Hall at 901 N.W. Alexander St. on the corner of Coveland Street. Socializing begins at 7 p.m., a meeting is at 7:15 and the program begins at 7:30.

The Ellises have led walks and given talks on a wide range of natural history topics for more than 20 years. Steve Ellis is a former president of Whidbey Audubon Society; Martha Ellis is a member of the Washington Native Plant Society.

The presentation follows the 1,000-year history of a Douglas fir from seed to nurse log. Birds, mammals, amphibians, invertebrates and plants that rely on this beautiful conifer are introduced, including Red Crossbills, Townsend’s Warblers, Pacific Wrens, Varied Thrush and other birds associated with the iconic Douglas fir. The couple include a story about a triangle of tree, squirrel and jay.

Trees and the wildlife that make a living among them is the theme for the monthly public programs of the Whidbey Audubon Society’s 2014–2015 season. The society meets on the second Thursday of each month from September to June, except December.