September 14, 2015
We drove for about 45 minutes south of our hotel on the main highway towards Argentina, and then just before we left the department of Santa Cruz at the border of Chuquisaca, we turned east through the town of Boyuibe. From here a dirt track ostensibly leads through cattle ranches all the way to Paraguay, but I’ve never been more than about 50 miles down it. I was first here in 2001 on an exploratory trip with two friends, and as the first birders to ever come here, we were very thrilled with how many chaco specialties we were able to find. Most exciting was our discovery of Black-legged Seriemas. By now many guides and birding tour companies have brought their groups here for the most reliable and accessible Black-legged Seriemas anywhere. This was only my fifth time to this area of sandy soils, dry scrub, and thorny woodland known as the Chaco.
Tropical Parula is one of the most abundant birds here, and any amount of pishing and owl imitations will bring in at least a pair.
Lark-like Brushrunner is not as common but very conspicuous as they run along the sides of the road and, well, amongst the brush. There are so many unique members of the furnariid family that names have been coined for each of them. This is the only brushrunner, and there’s only one streamcreeper, one firewood-gatherer, one chilia, one rushbird, one reedhaunter, one wiretail, etc.
There are several canasteros, however, in the same family. Short-billed Canastero is not rare here either, but much less conspicuous, and I used a bit of playback to get this bird to sit up.
Yet another member of Furnariidae is this Chaco Earthcreeper, one of the most secretive members of the group. It took us quite a while to see one well. It and its close relative the Bolivian Earthcreeper are not really much like other earthcreepers and should have been called bromeliad-creepers, as they only occur where there are dense thickets of spiny, terrestrial bromeliads.
Finally, after hearing a few of these, we connected with a trio of Black-legged Seriemas crossing the road. Then they were everywhere. I estimated that we saw at least 11 and heard at least 9 more today. This and the much more common and widespread Red-legged are not only the sole members of the family Cariamidae, they are now convincingly the only members of the entire order Cariamiformes, a sister group to the falcons and parrots. I don’t know what line of evidence originally placed them in the order Gruiformes with the cranes, trumpeters, rails, Limpkin, finfoots, and flufftails, but it must have been pretty speculative.
A scarce bird here is the Checkered Woodpecker, amazingly similar in habitat, behavior, and voice to our Ladder-backed Woodpecker.
We have nothing in North America that resembles the Crested Gallito, a tapaculo and the only member of its genus. Considering its dense habitat and very secretive nature, maybe the Australian scrub-birds are a parallel. We were extremely lucky finally to find a bird that sat up long enough for a binocular view, let alone long enough for me to get this photo. I’ve heard it here before, but never saw one so well.
Here’s the group birding on the Boyuibe road while Carlos and Benita are preparing lunch in the back.
At lunch was this Battus polydamas, Polydamas Swallowtail, laying eggs on an Aristolochia that wasn’t in bloom.
The same butterfly also went up for nectar in this orange-flowering bush, which as close as I can tell seems to be a Cestrum sp.
The chaco of Bolivia is the only place where I’ve seen this Callicore sorana, Zigzag Eighty-eight.
On our way back to Boyuibe we stopped by some ponds, pretty much the best activity in the heat of the day. (The cold from two days ago is a dim memory, and the forecast for tomorrow says the temps are already supposed to reach 102°F).
A migrant Baird's Sandpiper was at one pond.
A common bird in captivity (and sometimes showing up in North America as an escaped bird), Ringed Teal is much more attractive as a wild bird.
We had two surprise raptors for the day. One was a Zone-tailed Hawk that was doing very well in passing as a Turkey Vulture, and the other was this Aplomado Falcon that flew in front of the bus. Amazingly, it perched long enough for everyone to get out and enjoy it.