Distance: 14 miles round trip on trail and use trail
Summit Elevation: 4316' (Vicker), 3000' (Yaeger Mesa), 4313' (Horsethief)
Elevation Gain: 3875'
Elevation Gain (in Empire State Buildings): 3.10
Round trip time: 5 hours 45 minutes
Recommended water: 156 oz.
Parking/Fees: Adventure Pass
Difficulty: Strenuous (combined)
Yaeger Mesa is a unique feature deep in Trabuco Canyon in the Santa Ana Mountains. This is the remote heart of the range where the last wild grizzly bear in California was shot in 1908. I planned a loop that would go over Vicker BM, down Trabuco Canyon trail, up Yaeger Mesa, then down and up West Horsethief trail and over Horsethief Peak. I avoided the awful Trabuco Canyon road and started from Main Divide Road by the Falcon Campground. It is a short climb up the road to Los Pinos saddle. Just before the saddle, I veered along a firebreak to visit Vicker BM about a 100' above the road. I was pleasantly surprised to find a benchmark, though no register. Vicker would be my highest elevation of the day, topping Horsethief Peak by 3'. After a short stay, I went down the firebreak on the other side to Los Pinos saddle.
Los Pinos saddle is the junction of Main Divide, Los Pinos trail, and the Trabuco Canyon trail. This was my first time on the Trabuco Canyon trail as it descends into the canyon through a rare stand (in the Santa Anas) of pines and cedar. The tall trees and dense brush provided a canopy of cover, dimming the light of an already overcast day. Despite the lack of water this year, the upper trail was lush, with a little poison oak lurking on the side of the trail. I pushed myself down into the canyon at a quick pace, trying to give myself a little extra time for route finding to Yaeger, and knowing it would be slow climbing out. About half way down the canyon, the trees and brush drop off providing great views into Trabuco Canyon. I met a couple of hiking groups on the trail on the way down, but fewer than the Holy Jim highway.
I passed the junction with West Horsethief trail to continue down to 2400' to look for a trail up to Yeager Mesa. Apparently, until 2009, the mesa was a private inholding, but is now owned by the USFS. The other trail to the mesa I know about comes down from Los Pinos summit along Bell Ridge. It would have been a cleaner loop for me to go that way, but I wanted to hike Trabuco Canyon trail. There were several side trails descending to the bottom of the canyon, and I ended up passing the one that crosses the canyon and heads up to Yaeger Mesa. Instead, I descended all the way to 2246' where I spotted a duck and followed it into the canyon, looking for some way up. I went in circles looking for a trail, and ended up wasting about 30 minutes and some energy thrashing around the brush and boulders. Eventually, I headed back up and took the most likely looking trail along the canyon wall, and it turned out to be right. It is a steep climb up loose dirt to the mesa, and once I arrived, I wandered around the upper and lower mesa, a cool geological formation. After a short lunch break, I headed down and spotted the wreck of a PT-19 (WWII era two-seat trainer). (The GPX for this hike was uploaded to peakbagger under vicker and horsethief, I can email you the waypoint file as well if you request it.)
Back in the canyon, I started the 1600' climb out along West Horsethief trail back to Main Divide Road. The switchbacks are long and there is not much new to see along this stretch except great views of the mesa. When I got back to the road, I took a right and got my first clear view of Horsethief Peak. The road gave up some elevation before I reached it. The first firebreak I came to went up from the north. It starts with a 15' dirt wall and the last hundred feet is completely overgrown in spots with manzanita and other brush. I came prepared with my machete and hacked a path through the worst of it. Even though I cleared some of it, I still recommend avoiding the north firebreak and going up the south firebreak which is clear of obstructions. I found no benchmark or register at the top of this unofficial peak. After taking a few photos, I went down the south firebreak and headed back. I ran out of water just before reaching the Los Pinos saddle again, so I increased my recommended water on this hike. When I got back to my car, I downed another bottle of water before heading home. Temps were in the low 60s all day. This loop would be killer in the summer heat.
Gear update: I replaced my old Camelbak Rim Runner with the Alpine Explorer model. It is very similar but has more storage (27L vs 22L) and a handy quick access pouch. I think the Alpine has the most storage of any Camelbak hiking pack. The Rim Runner was great, but a little short on space for very long day hikes. OTOH, I am not known for packing light. The other new piece of gear I used on this hike was the Gerber Gator machete (about $25). The blade is 18" with a saw blade on top. With the handle, it is 24" long. It came with a sheath and it was sticking up out of my pack most of the day. I needed it for one short section on Horsethief Peak and it was very effective. Of course, hacking through brush is slow business, and I only cleared enough to make it through the worst parts.