With whirring blades, shearers recently clipped the thick wool from the 300 ewes at Jensen Ranch in Tomales. Skilled shearers are in high demand this time of year, as the days grow warm. The ranch hires professionals, who arrive in a mobile trailer, because “it’s incredibly labor intensive. It’s a trade, but also an art,” said Jim Jensen, a sixth-generation rancher. The fluffy wool is hard to handle, so it must be packed into dense…