WHAT THE SCIENCE SAYS . . .
California Spotted Owl
THE CALIFORNIA SPOTTED OWL: A Technical Assessment of Its Current Status
Summary of major factors of concern in habitats of California spotted owls in the Sierra Nevada, reasons for those factors and their impacts on the owls.
|Factor||Reason(s) for the factor||Impact on spotted owls|
|Decline in abundance of very large, old trees||Selective logging of the largest trees from stands||Loss of owls preferred nest sites|
|Long recovery period for spotted owl habitat after logging||Selective logging of the largest trees from stands||Less of total landscape in suitable owl habitat at any given time|
|Ingrowth of shade-tolerant tree species, creating unnaturally dense stands with ground to crown fuel ladders||Selection harvest; aggressive fire suppression; sheep grazing, which created ideal seedbeds for conifer germination late last century||Increased threat of stand-destroying fires|
|Excessive build-up of surface fuels||Aggressive fire suppression over the last 90 years, leading to higher densities of trees, more competition for space and water, so a higher death rate of trees||Increased threat of stand-destroying fires|
|Loss of large-diameter logs from the decaying wood source on the ground||Intentional fires by sheepherders; selective logging of largest trees; piling and burning logs after logging; domestic fuel-wood removal||Potential decline in flying squirrel densities via loss of fungi that are a dietary staple for the squirrels|
|Decline snag density||Selective logging of the largest trees from stands; salvage logging; fuel wood removal||Loss of potential nest sites|
|Disturbance and/or removal of duff and topsoil layers||Sheep grazing; mechanical disturbance from logging equipment, skid trails, and so on; increase surface fuel that burn hot enough to destroy the duff layer||Potential decline in flying squirrel densities via loss of fungi that are a dietary staple for the squirrels|
|Change in composition of tree species (fewer pines) and black oaks, more firs and incense cedar||Selective logging of the largest trees, particularly pine species, from stands; aggressive fire suppression||Some loss of next sites|