Although it was later in the season than we would have liked, we arranged a trip from Oaxaca city (where we'd been attending a meeting) over the Sierra Juarez to Valle Nacional on May 21-24 2011. Four days were about right for this expedition, as we would have been too hurried in three days. Our targets were the 20+ species with limited range or endemic to the high elevation pine-oak forest, cloud forest, and Atlantic slope foothills. The route was simple, Mexico 175 over the mountains to Valle Nacional. The road has its share of potholes, slips, and slow trucks and takes 5 or 6 hours driving straight through to get from Oaxaca to Valle Nacional.I'll start with the logistics. We arranged for this trip with local guide Eric Antonio Martinez (mirmidons_1987 AT yahoo.com) (http://mexico-birding.com/) and rode in his Malibu, which had plenty of room for the group and our luggage. The car also had tourist plates, which is required for anyone offering a guide service. Eric was an excellent driver, never bringing on the "white-knuckle syndrome" or motion sickness that these curvy mountain roads can bring on. He knew the area well, and knew which pull-offs provided good bird habitat and safe conditions, and he had a good sense of humor. I would travel with him again and hope to do so this year.
The weather was as expected, fairly cool at higher elevations and hot in the lowlands. We stayed at the Hotel Valle Real on the main street in Valle Nacional. The only hotels available are in Oaxaca city or Valle Nacional. The Valle Real had hot running water, wonderful air conditioning, and a delightful owner Lorena who made us coffee every morning at a ridiculously early hour for non-birders. The hotel was basic for those used to 4-star opulence, but it was clean and comfortable and cool. We ate evening meals at the Restaurant Desgarennes, which had a daily meal option of soup, rice and beans, and a meat entree that was invariably delicious. The beer was cold, and the staff very accomodating.As far as the birding goes, we start on Monday at 5:30 AM with Eric picking us up on time (as always!) and taking us up to La Cumbre in search of the Fulvous Owl found originally by Rich Hoyer. On the way up, a Mexican Whip-poor-will was sitting in the road and stayed put while we stopped the car. The Fulvous Owl flew in and sat over us, hooting a series of monotone hoots and not sounding like a Barred Owl. What a great way to start the trip!
We spent about five hours walking in the dry pine-oak forest, with Red Warblers so abundant they were dismissed with comments like "just another Red Warbler" - what heresy! We saw Black Thrush, Gray-breasted Wood-Wren, Gray-barred Wren, Rufous-capped Brush-Finch, Brown-backed Solitaire, Golden-browed Warbler, and many more. We walked a few kilometers up the Corral de Piedras Road and though we saw many Stellar's Jays and a few Gray-barred Wrens, we did not see any of our target Dwarf Jays. Uh-oh! Missing an endemic at one of the best places to find them was disheartening, but we needed to keep moving. We stopped for coffee and then headed off over the pass.
After passing the mirador at the summit, we parked and walked a short distance down a forest trail through more humid pine-oak forest. Eric quickly spotted an elusive Crested Guan, which was eating fruit in the canopy and ran off after tiring of watching us. A flock of Unicolored Jays came in to investigate us, and a gorgeous Blue-crowned Chlorophonia came in to check us out. Yes, I really must carry the camera more often and get a decent flash! While Brown-backed Solitaire is at La Cumbre, from the mirador on the only Solitaire we saw was the well named Slate-colored Solitaire. Eric found a nest on this trail, with four small chicks. Although they sing in the canopy they nest in hollows on the ground - in our case next to the trail.
We continued on, and made a final stop for the day a bit farther on where a Ruddy Quail-Dove whooshed by, bright orange in the sun, and highland birds including Flame-colored Tanager, White-throated Thrush, and Red-legged Honeycreeper stopped by to check us out. White-collared Swifts were pretty common up high, but most were in molt except for this bird, which looks like a youngster lacking the pale collar below.
The next morning we headed back up to walk a forest trail for a couple of kilometers. The trail was shaded and the forest intact. We were looking for interior forest birds, and these shy birds can be tough. Flocks of Barred Parakeets buzzed by overhead, coming lower later in the morning but always going somewhere fast. We had great looks at a pair of Spectacled Foliage-gleaners working their way through the forest. Hummingbirds included Bumblebee, Emerald-chinned, Garnet-throated, and the common Azure-crowned. Azure-hooded Jays were all around at as times, and were glimpsed moving through the trees or in flight and finally one flew in clear view with the sun on its bright blue hood. Here's a morpho that flew by.
We spent nearly an hour playing peek-a-boo with a Mexican Antthrush. The Mexican Antthrush's rising bouncing-ball call was in contrast to the decending call of the Black-faced, but the AOU still considers them conspecific. I finally realized the Mexican Antthrush was at the top of the hill perched in a bush looking at us when it flew over our heads! We watched it run back up the hill in plain view, and then it perched in the open for Eric and I, showing off its bare skin eyering and nearly all black head and breast. Here's a Yellow-bellied Elaenia that was on Highway 175 nearby.
The next two days were a blur of early mornings at different elevations and short walks on Highway 175 (with surprisingly little traffic at times). In the lower more open habitats we saw Blue-crowned (Lesson's) Motmot, White-winged Tanager, Rufous-breasted Spinetail, Blue Ground-Dove, Long-billed Gnatwren, Thick-billed Seedfinch, Yellow-faced Grassquit and more.
One afternoon Eric suggested that we go to Tuxtepec to see Sumichrast's Wren, which Robert immediately dubbed the Sumo-wrestler Wren. I had no idea we were only an hour's drive from this micro-endemic! I was ecstatic about the opportunity to look for this bird, and the others could see my excitement so we were off in the 100F+ weather. We got to the site, an area of limestone ridges and a mule track that had polished the limestone. The heat was radiating off the stones, and I wondered more than once what possessed us to make this trek and how unlikely it was to see such a rare bird under such hot conditions. But the wren didn't get that memo, and it came out in the open and sang for us, sounding more like a Canyon Wren than anything else. Another answered it, and we took the time to track down a Ferruginous Pygmy-Owl on the way out.
We drove slowly for several kilometers on the way back, picking up open country species including Aplomado Falcon, Fork-tailed Flycatcher, Roadside Hawk, Groove-billed Ani, Altamira Oriole, Blue-black Grassquit, Variable Seedeater, and more.Another afternoon we walked along the river near Valle Nacional, getting our best looks at Keel-billed Toucan and Band-backed Wrens. Amazon and Ringed Kingfishers were along the river.
On the last day we were trying for a few target that we'd missed along the way. Surprisingly, new birds kept appearing even on the last day. We stopped at a pull-off we'd been to before, and found that the female becard we'd been speculating on before was nowhere to be seen, but the male - clearly a Gray-collared Becard - was singing in front of the nest she'd been working on, so that solved that question! A bit farther up the mountain we had a White-faced Quail-Dove rocket across the road, bright chestnut with a strikingly pale head. We were all a bit shocked (fortunately we were all looking the right direction) when the bird flew back across the road!Up higher in drier pine-oak forest a stop yielded a pair of Great Black Hawks, another stop yielded a whistling Black Hawk-Eagle. An Eastern Wood-Pewee and an Olive-sided Flycatcher were migrants (as were Yellow-bellied Flycatchers).
We got back to La Cumbre late in the afternoon and spent two hours looking and listening for Dwarf Jays. Finally, Eric spotted one - and then there were two - and then we'd all seen the pair! What a way to end the trip! 
Other highlights included Ocellated Thrasher (distant views), Dusky Hummingbird, Pileated Flycatcher, and of course the spectacular ruins. 
Later on we stopped at the famous Tule Tree or Big Tree, a huge bald cypress in the town of Santa Maria de Tule, Oaxaca. I can't begin to imagine the amount of biomass in this one single tree. 
We went on up into the pine-oak - watching a mix of familiar and unfamiliar birds, Red-shafted Flicker, Mountain Trogon, Crescent-chested Warbler, Slate-throated Redstart, Collared Towhee, Lincoln's Sparrow, and a host of beautiful songsters - Orange-billed and Rufous-capped Nightingale-Thrushes and Brown-backed Solitaire.