Over 170 birds in California are threatened or endangered because their climactic ranges are expected to shrink by half by 2080, according to a major study released last month by the National Audubon Society. The study, which took seven years to complete and assembled data from Christmas bird counts across North America as well as the North American Breeding Bird Survey, used climate change models to predict how the climactic ranges of 544 birds would be affected by global warming—in other words, what areas might become inhospitable, and where different species might be able to move to, based on temperature, precipitation and seasonal shifts. (The models, however, don’t examine other factors, such as habitat or food availability, which could further limit a bird’s ability to find new areas to inhabit.) The report also created so-called “climate prioritization rankings” for many states, which target areas that are most important for future conservation efforts; California has 50 major “climate refuges,” which includes Tomales Bay, Bolinas Lagoon and Corte Madera Marsh. “A lot of birds that we’ve identified as climate threatened or endangered are a lot of those birds that birders in West Marin are used to seeing,” said Mike Lynes, the policy director for Audubon California. “There will be sizeable shifts in their what areas are suitable for many birds.” Birds identified as climate endangered by Audubon includes the eared grebe, which, according to Audubon’s models, will lose 100 percent of its summer range in the United States, though its winter range fares better. (Over 1,000 were spotted at Tomales Bay at last year’s Christmas count.) Another bird, the western grebe, a red-eyed bird whose dramatic breeding rituals include running side by side across the surface of the water, will have its summer range plummet 89 percent; though its current winter range will drop by 42 percent, the models found that the latter range could expand into new areas, so that its winter range could jump by 31 percent. (There were 701 western grebe spotted last December along West Marin’s coast, also mostly at Tomales Bay.) But Mr. Lynes pointed out that if a bird has nowhere to spend the summer, a stable or potentially greater winter habitat means little. But, he added, Audubon wants to remain focused on what can be done to conserve habitat, not simply drown in “doom and gloom.” The report, he said, provides “a sense of how things will change, so we can protect what’s left and help make [birds] resilient.”