After some discussion about our main excursion on our final full day, we decided on a combination of varzea and terra firme birding, involving both a long ride in the dugout and some substantial hiking. Another option would have been to visit the parrot and parakeet clay licks on the other side of the Napo River, but after I explained to my father how many tourists clutter up the viewing conditions there, we opted for a more unpredictable but rewarding experience on part of the Coto Trail, where we hoped to find two roosting Crested Owls at the principle destination.
The long dugout ride was peaceful but relatively unproductive in terms of seeing new birds. Fortunately, Adrien was in top form at the back of the canoe, spotting the Chestnut-Capped Puffbird perched motionless in the dense varzea forest. Domingo also pointed out a Speckled Chachalaca, and we had quick but clear looks at a surprised Sungrebe as it dove into cover. After noting the Amazonian White-Tailed Trogon, Gilded Barbet, and Green-and-Gold Tanager, we reached the dock at the far western end of Challuacocha and were ready to begin the Coto Trail.
Just a few minutes later Domingo was producing some deep booming calls from inside his chest, imitating the Salvin's Curassow, I believe. Suddenly, he turned to me and said, "Gray-Winged Trumpeter!" The race was on as we chased them doggedly down the trail back towards the dock, every once in a while catching a quick glimpse of their loose gray flight feathers in the dark greens of the understory. After literally running several hundred meters, we finally caught up with them as they flushed from the ground into the trees above the dock, getting good looks at them before they crossed to the other side of the water. Truly, the Sani community must make a concerted effort not to over hunt their land, as these terrestrial birds have become increasingly rare in Ecuador.
This invigorating experience was a joyful way to begin our hike, and we greeted our next two birds with more than the usual excitement and enthusiasm. First, we discovered the Chestnut-Belted Gnateater, a gorgeous male, bounding about territorially in response to playback, and then we finally caught a male Wire-Tailed Manakin on the lek. The manakin elicited quite a response from Adrien who gasped in amazement at its coloration, although we couldn't make out its tail from a distance. I've heard these manakins have the most incredible display routine, rotating 360 degrees in unison about a bare branch, but as every other lek I've visited has been empty, I was happy just to finally see the bird.
After encountering an understory mixed flock with the Fulvous Shrike-Tanager, Cinereous Antshrike, Black-Banded Woodcreeper, and Chestnut-Wing Hookbill, we heard a noisy racket in the canopy on the other side of the trail. A large group of Ivory-Billed and Lettered Aracaris were following a troop of Common Woolly Monkeys as they crashed through the trees. Adrien then pointed out a White Hawk that was perched impressively in a palm off to the side of the commotion, a great spot from deep inside the forest. As there was a lot to look at, we spent the next half an hour gaping about and taking photographs of the scene while Domingo chirped at the monkeys until they approached us for a closer look.
I have been fixated on antswarms and antbirds for a long time now, so it's difficult for me to talk about what happened next. Suffice it to say that we soon came across an antswarm with at least four antbirds in attendance, all of which I saw clearly except for the White-Plumed Antbird, which for some reason I could never lock onto despite Domingo frantically pointing three of them out with his laser and subsequently scaring them off. This bird has become my top target bird in Ecuador and ultimately shouldn't be that difficult to encounter providing I take a few more trips to the eastern lowlands. Still, I became increasingly more disappointed as the morning drew on, slowly realizing that I had missed an excellent chance to observe this shy but spectacular denizen of terra firme forest. 
As we pushed on towards the Crested Owl roost, I found an unabashed Lanceolated Monklet just off the trail and later a Solitary Cacique gleaning insects in the subcanopy above a small stream, both birds being no small consolation. While the owls weren't where they were supposed to be, we did encounter the Purplish Jacamar on the way back to where the swarm had been. Sadly, the ants had moved deeper into a dense marshy area, and the antbirds were impossibly out of reach. I tried to keep my spirits up as we gradually made our way back to the lodge, first spotting an adult Ornate Hawk-Eagle in the distance and then finding two Tropical Screech-Owls roosting in some short palms near the lake. After lunch I even found an active Ferruginous Pygmy-Owl in the swamp behind our cabin, giving chase to a Straight-Billed Woodcreeper. It had been a wonderful morning with some surprising and spectacular birds, but I couldn't help thinking how I would have traded the multiple Bicolored, Scale-Backed, and Sooty Antbirds I had seen at the swarm for just a single glimpse of the White-Plumed Antbird.
As my iPod had become disabled that morning due to the intense humidity, we were left without playback in the afternoon, limiting our birding options somewhat (much to Adrien's dismay this also cost us a good chance at seeing both the Striated Antthrush and Thrush-Like Antpitta that had been calling off the Coto Trail). We agreed to visit another owl roost on Domingo's father's property a half an hour up the Napo and then to hit the river island again for a final shot at the spinetails. After a long but beautiful trip in the afternoon sun, we arrived at the roosting site, where yet again the Spectacled Owls were missing. We also heard a Yellow-Billed Nunbird calling nearby but were helpless to see it without playback, Domingo explained. Amazingly, the Brown Jacamar responded to Domingo's whistling imitation of its call, perching high in a cecropia tree right on the northern bank of the Napo, where I looked for it last time with Oscar Tepuy.
We disembarked from our motorized boat at the opposite end of the island from which we explored previously. The wild screams of Black Caracaras rang out from the cecropia trees as we searched the scrub for signs of the spinetails. This was sort of a lost cause without playback, so we turned our attention to a pair of Spot-Breasted Woodpeckers perched in a nearby tree. After appreciating an Oriole Blackbird that flew into the tree dramatically, we returned the boat to seek out the Amazonian Umbrellabird that can often be seen crossing the Napo River in the late afternoon.
Domingo purposely ran the boat aground on a sandbar that was barely exposed above the surface, allowing us to turn off the motor and taken in the beautiful evening. On the south side of the river a dark thunderstorm was booming, but the sun was shining brilliantly to the north, creating a gorgeous full rainbow that was so close that I couldn't fit but a small part of it in my telephoto lens. We marveled at the Chestnut-Eared Aracari, Blue-Winged Parrotlet, and Plum-Throated Cotinga in the rich light until we finally spotted the Amazonian Umbrellabird crossing downriver, notably larger and less steady in flight than the common Russet-Backed Oropendolas that were streaming overhead. After hearing several more call cow-like from either side of the river, we broke the spell with the motor and returned triumphantly to the lodge.Notable birds seen: Capped Heron, King Vulture, White Hawk, Ornate Hawk-Eagle, Black Caracara, Speckled Chachalaca, Sungrebe, Gray-Winged Trumpeter, Blue-Winged Parrotlet, Blue-Headed Parrotlet, Tropical Screech-Owl, Ferruginous Pygmy-Owl, Black-Throated Hermit, White-Necked Jacobin, Olive-Spotted Hummingbird, Glittering-Throated Emerald, Brown Jacamar, Purplish Jacamar, Chestnut-Capped Puffbird, Lanceolated Monklet, Swallow-Winged Puffbird, Gilded Barbet, Chestnut-Eared Aracari, Ivory-Billed Aracari, Lettered Aracari, Spot-Breasted Woodpecker, Chestnut-Winged Hookbill, Black-Banded Woodcreeper, Fasciated Antshrike, Cinereous Antshrike, Scale-Backed Antbird, Sooty Antbird, Bicolored Antbird, Chestnut-Belted Gnateater, Southern Beardless-Tyrannulet, Streaked Flycatcher, Plum-Throated Cotinga, Bare-Necked Fruitcrow, Amazonian Umbrellabird, Wire-Tailed Manakin, Blue-Crowned Manakin, Lawrence's Thrush, White-Breasted Wood-Wren, Musician Wren, Green-and-Gold Tanager, Fulvous Shrike-Tanager, Solitary Cacique, Oriole Blackbird.