According to CDFW Game Program Manager Craig Stowers, CDFW has instead focused primarily on routes that migratory deer move through, as they are highly traditional and tend to move through the same areas year after year. Then, once we identify where those areas are (mostly by finding road kills, but we can also identify through tracks in the snow and/or telemetry data), we work with Caltrans to mitigate those losses. CDFW has found lots of traditional migratory route areas in the state.
Some good examples of this kind of game fencing work include the miles of fencing and under crossings on I-395 from Bordertown up to the Inspection Station just south of the intersection of 395/89, fencing and under crossings on I-395 in the Bass Hill Wildlife Area just south of Susanville, the work done in the Loyalton-Truckee deer herd area and the work we completed last year in the I-280 area (in conjunction with Caltrans and UC Davis). Our job on that one was simply to catch the deer, which we did. Caltrans engineers and wildlife experts from UC Davis analyzed the movement data of those deer in an effort to modify roadside fencing and existing under crossings to cut down the number of deer hit on I-280. Regardless of location, it is a very expensive and time-consuming effort, not only to determine where to install the fencing and/or under crossings but also to build them.