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Field Guides Tour Report
Northwestern Argentina 2014: Rincon del Socorro Extension
Oct 11, 2014 to Oct 16, 2014
Dave Stejskal & Willy Perez

Spotted Nothura (Photo by guide Dave Stejskal)

This was the third Rincon del Socorro extension we've offered, and it was a lot like the previous two -- fabulous birding in a setting both charming and elegant. If I could only figure out a way to do our entire Northwestern Argentina tour out of Rincon del Socorro!

This year was a little different due to our afternoon departure out of Buenos Aires. The late flight gave us a chance to go bird a spot that I hadn't been to in a while: Otamendi Reserve north of the city. That short visit on our first full morning proved to be very productive indeed, with both Curve-billed and Straight-billed reedhaunters, Diademed Tanager, Warbling Doradito, and many others making their way onto our triplist before we had to fly off to Posadas in south Misiones Province. Once there, we loaded up our transports and started off on our long and muddy drive to Rincon del Socorro -- perhaps the loveliest tourist lodge that I've ever been to in South America.

Our time at Rincon was spent in a variety of habitats, ranging from light thorny woodland to tall native grass, and from sprawling marshes to the beautiful Laguna del Ibera. Birds were not in short supply here, and we did exceedingly well. Our two main targets, the unique Strange-tailed Tyrant and the beautiful and rare Yellow Cardinal, were both found rather easily this year, and we had many memorable looks of each. The other prizes of our short stay here included numbers of Greater Rheas right on the grounds of our lodge, a nesting pair of rare Crowned Eagles, fabulous Rufous-sided Crake and a deep chestnut Least Bittern from the boat, a surprise pair of Black-and-white Monjitas, and an amazing eight species of beautiful Sporophila seedeaters, including such gems as Pearly-bellied, Dark-throated, Marsh, Rufous-rumped, and Chestnut! And the wildlife show was pretty darned good, too, with loads of strange Capybaras daily, multiple Marsh Deer and Brown Brocket Deer, that odd little Plains Viscacha, and several scary-looking Black Caiman. And all of this with excellent food and exquisite rooms to boot -- I can't wait to come back!


One of the following keys may be shown in brackets for individual species as appropriate: * = heard only, I = introduced, E = endemic, N = nesting, a = austral migrant, b = boreal migrant

Rheidae (Rheas)

Yellow Cardinal (Photo by guide Dave Stejskal)

GREATER RHEA (Rhea americana) – Rincon del Socorro is one of the best places that I know of to see this fabulous species - at almost arm's length, no less!
Tinamidae (Tinamous)
RED-WINGED TINAMOU (Rhynchotus rufescens) – Nicely seen by all on our drive to Rincon del Socorro from Posadas.
SPOTTED NOTHURA (Nothura maculosa) – We heard quite a few of these small tinamous and ended up seeing it very well on the grounds of Rincon del Socorro.
Anhimidae (Screamers)
SOUTHERN SCREAMER (Chauna torquata) – Unparalleled looks from the boat on the lake.
Anatidae (Ducks, Geese, and Waterfowl)
WHITE-FACED WHISTLING-DUCK (Dendrocygna viduata) – This is usually the most common whistling-duck throughout the north of the country.
BLACK-BELLIED WHISTLING-DUCK (Dendrocygna autumnalis)
BLACK-NECKED SWAN (Cygnus melancoryphus) – A flyby pair at Otamendi was a nice surprise!
COSCOROBA SWAN (Coscoroba coscoroba) – Our only birds were a pair with five cygnets at the newly revitalized Costanera Sur Reserve in Buenos Aires. [N]
MUSCOVY DUCK (Cairina moschata) – A flyby for some at the Ibera Lagoon.
RINGED TEAL (Callonetta leucophrys) – A gorgeous male the Costanera Reserve in B.A. was a real bonus!
BRAZILIAN TEAL (Amazonetta brasiliensis) – Gorgeous looks in flight!
SILVER TEAL (Anas versicolor) – A few of these on our first afternoon at the Costanera Reserve in B.A.
YELLOW-BILLED TEAL (FLAVIROSTRIS) (Anas flavirostris flavirostris) – A few of the nominate race birds in Buenos Aires.
ROSY-BILLED POCHARD (Netta peposaca) – A few gorgeous adult males at the Costanera Reserve.
Ciconiidae (Storks)
MAGUARI STORK (Ciconia maguari) – Many close birds along the roadsides at Rincon del Socorro.
Phalacrocoracidae (Cormorants and Shags)
NEOTROPIC CORMORANT (Phalacrocorax brasilianus)
Anhingidae (Anhingas)
ANHINGA (Anhinga anhinga)
Ardeidae (Herons, Egrets, and Bitterns)
LEAST BITTERN (Ixobrychus exilis) – The one bird that we saw at the Ibera Lagoon was an entirely dark chestnut individual, darker and more uniform than any other dark Least Bittern that I've ever seen anywhere - though I haven't seen too many of them, mind you!
RUFESCENT TIGER-HERON (Tigrisoma lineatum) – Not terribly common at Rincon del Socorro, but we did have some great views there.
COCOI HERON (Ardea cocoi) – Also called the White-necked Heron in some books. This is the S. American replacement species for our Great Blue Heron.
GREAT EGRET (Ardea alba)
SNOWY EGRET (Egretta thula)
CATTLE EGRET (Bubulcus ibis)
STRIATED HERON (Butorides striata)
WHISTLING HERON (Syrigma sibilatrix) – Several handsome individuals, including a few responsive ones.
BLACK-CROWNED NIGHT-HERON (Nycticorax nycticorax)
Threskiornithidae (Ibises and Spoonbills)
WHITE-FACED IBIS (Plegadis chihi)
BARE-FACED IBIS (Phimosus infuscatus) – They all seemed to be in the pampas this year.

Southern Screamer (Photo by guide Dave Stejskal)

PLUMBEOUS IBIS (Theristicus caerulescens) – Very few of both this and the next this year in the Rincon del Socorro area.
BUFF-NECKED IBIS (Theristicus caudatus)
ROSEATE SPOONBILL (Platalea ajaja)
Cathartidae (New World Vultures)
BLACK VULTURE (Coragyps atratus)
TURKEY VULTURE (Cathartes aura)
LESSER YELLOW-HEADED VULTURE (Cathartes burrovianus) – Plenty of these in the native grasslands around Rincon del Socorro.
Accipitridae (Hawks, Eagles, and Kites)
WHITE-TAILED KITE (Elanus leucurus) – Just a couple on our final afternoon.
BLACK-COLLARED HAWK (Busarellus nigricollis) – That very distinctive flight profile and that white head make this one an easy i.d.
SNAIL KITE (Rostrhamus sociabilis) – Not huge numbers anywhere, but they always seemed to be around.
LONG-WINGED HARRIER (Circus buffoni) – A couple of fine looks at this handsome harrier.
CINEREOUS HARRIER (Circus cinereus) – These birds may have been migrants here since I don't remember ever seeing them here before!
SAVANNA HAWK (Buteogallus meridionalis) – We saw far fewer than I would have predicted.
CROWNED EAGLE (Buteogallus coronatus) – We were really fortunate that this bird was nesting again on the property. It's got a huge range, but it's pretty darned rare everywhere (except Beni, Bolivia?) and always a thrill when you find one! I thought that we'd have to satisfy ourselves with just seeing a tiny bit of the bird on the nest, but the mate flew in just in the nick of time to give us all fabulous views in the scopes! [N]
ROADSIDE HAWK (Rupornis magnirostris) – Black-headed with buffy primaries here - unlike most of its range.
HARRIS'S HAWK (Parabuteo unicinctus) – Distantly at the Costanera Reserve.
WHITE-TAILED HAWK (Geranoaetus albicaudatus) – A pair along the side of the road on our way to Rincon del Socorro from Posadas.
Rallidae (Rails, Gallinules, and Coots)
RUFOUS-SIDED CRAKE (Laterallus melanophaius) – WOWWWW!!!! Could we have gotten a better look at this one?!!
RED-AND-WHITE CRAKE (Laterallus leucopyrrhus) – Pretty close at Otamendi... [*]
GIANT WOOD-RAIL (Aramides ypecaha) – A common roadside bird around Rincon del Socorro.
ASH-THROATED CRAKE (Porzana albicollis) [*]
PLUMBEOUS RAIL (Pardirallus sanguinolentus) – Quite good looks at Costanera Reserve in B.A.
PURPLE GALLINULE (Porphyrio martinicus)
COMMON GALLINULE (Gallinula galeata)
SPOT-FLANKED GALLINULE (Gallinula melanops) – This one swam through as we were trying to get a better look of the Wren-like Rushbird at the Costanera Reserve.
RED-FRONTED COOT (Fulica rufifrons) – The only coot that we could find at the Costanera Reserve this year.
Aramidae (Limpkin)
LIMPKIN (Aramus guarauna)
Charadriidae (Plovers and Lapwings)
SOUTHERN LAPWING (NORTHERN) (Vanellus chilensis cayennensis)
Jacanidae (Jacanas)
WATTLED JACANA (Jacana jacana) – This elegant little bird is very much underappreciated.
Scolopacidae (Sandpipers and Allies)

That magnificent Crowned Eagle (Photo by guide Dave Stejskal)

UPLAND SANDPIPER (Bartramia longicauda) – Pointed out by Jack as it called. [b*]
SOUTH AMERICAN SNIPE (SOUTH AMERICAN) (Gallinago paraguaiae paraguaiae) – We found a few birds displaying over the grassland near Rincon del Socorro.
Columbidae (Pigeons and Doves)
ROCK PIGEON (Columba livia) [I]
PICAZURO PIGEON (Patagioenas picazuro) – Huge!!
SPOT-WINGED PIGEON (Patagioenas maculosa) – Pretty common once we got to Rincon del Socorro.
EARED DOVE (Zenaida auriculata)
PICUI GROUND-DOVE (Columbina picui) – An unmistakable tiny dove with black underwings and bright white outer tail feathers.
WHITE-TIPPED DOVE (Leptotila verreauxi)
Cuculidae (Cuckoos)
DARK-BILLED CUCKOO (Coccyzus melacoryphus) – We couldn't get them to come out into view! [*]
GUIRA CUCKOO (Guira guira) – They don't look much like anis, but that's what they are.
STRIPED CUCKOO (Tapera naevia)
SMOOTH-BILLED ANI (Crotophaga ani)
Strigidae (Owls)
TROPICAL SCREECH-OWL (Megascops choliba) [*]
BURROWING OWL (Athene cunicularia)
Trochilidae (Hummingbirds)
BLUE-TUFTED STARTHROAT (Heliomaster furcifer) – That look we had coming back from the first pair of Yellow Cardinals was really something!
GLITTERING-BELLIED EMERALD (Chlorostilbon lucidus) – Typically the most common hummer on this extension.
GILDED HUMMINGBIRD (Hylocharis chrysura) – A few around Buenos Aires at the start.
Alcedinidae (Kingfishers)
RINGED KINGFISHER (Megaceryle torquata) – Considering how much water there is in the Rincon del Socorro area, it's hard to figure why there are so few kingfishers.
AMAZON KINGFISHER (Chloroceryle amazona)
GREEN KINGFISHER (Chloroceryle americana) – One particularly close and cooperative male at the edge of the lake.
Picidae (Woodpeckers)
WHITE-BARRED PICULET (Picumnus cirratus) – Talk about confiding! We had spectacular, close views of this vocal male at our BBQ spot near the lagoon.
WHITE WOODPECKER (Melanerpes candidus) – A single bird seen well at the Crowned Eagle spot.
CHECKERED WOODPECKER (Veniliornis mixtus) – Strange to think that this one is no longer a Picoides and is now a Veniliornis.
GREEN-BARRED WOODPECKER (Colaptes melanochloros melanolaimus) – This form used to be split out as the Golden-breasted Woodpecker.
CAMPO FLICKER (Colaptes campestris) – The common open country woodpecker on this extension.
Falconidae (Falcons and Caracaras)
SOUTHERN CARACARA (Caracara plancus) – Now split from the Crested Caracara north of the Amazon basin (and ranging as far north as Texas & Arizona).
CHIMANGO CARACARA (Milvago chimango) – Really common here, especially where the grassland had just been burned.
AMERICAN KESTREL (Falco sparverius)
APLOMADO FALCON (Falco femoralis) – I'm not sure what that one bird was trying to catch in the middle of the road near Rincon del Socorro (an insect?).
Psittacidae (Parrots)

Scarlet-headed Blackbird (Photo by guide Dave Stejskal)

NANDAY PARAKEET (Nandayus nenday) – This small population at the Costanera Reserve in B.A. is the result of escaped cage birds in the city.
MONK PARAKEET (Myiopsitta monachus) – There are surprisingly few psittacids at Rincon del Socorro, and this one is, by far, the most common.
BLUE-CROWNED PARAKEET (Aratinga acuticaudata) – A couple of small flocks only at Rincon del Socorro.
Thamnophilidae (Typical Antbirds)
RUFOUS-CAPPED ANTSHRIKE (Thamnophilus ruficapillus) – One of our Otamendi write-ins. Not many antbirds this far south in S. America!
VARIABLE ANTSHRIKE (Thamnophilus caerulescens) [*]
Furnariidae (Ovenbirds and Woodcreepers)
NARROW-BILLED WOODCREEPER (Lepidocolaptes angustirostris) – This one is usually the only woodcreeper we get on this extension.
RUFOUS HORNERO (Furnarius rufus) – The National Bird was seen daily.
WREN-LIKE RUSHBIRD (Phleocryptes melanops) – Nicely on our first afternoon at the Costanera Reserve.
CURVE-BILLED REEDHAUNTER (Limnornis curvirostris) – Another one of our Otamendi write-ins, we saw this one minutes after we saw the Straight-billed Reedhaunter there!
FRECKLE-BREASTED THORNBIRD (Phacellodomus striaticollis) – The only regular thornbird species in the B.A. area.
GREATER THORNBIRD (Phacellodomus ruber) – Nicely from the boat on the lake. This one is always associated with water. [N]
LARK-LIKE BRUSHRUNNER (Coryphistera alaudina) – Nesting right outside of Mike's room at Rincon del Socorro! [N]
STRAIGHT-BILLED REEDHAUNTER (Limnoctites rectirostris) – This one's a real rarity in Argentina, and Otamendi is the best place to see it. Smashing looks!
SULPHUR-THROATED SPINETAIL (Cranioleuca sulphurifera) [*]
STRIPE-CROWNED SPINETAIL (Cranioleuca pyrrhophia) – Killer views of this beauty near the ranch buildings at Rincon del Socorro.
BROWN CACHOLOTE (Pseudoseisura lophotes) – We never really nailed this one on the extension, but caught up nicely on the main tour.
CHOTOY SPINETAIL (Schoeniophylax phryganophilus) – A little stunner!
YELLOW-CHINNED SPINETAIL (Certhiaxis cinnamomeus) – Several very close individuals from the boat on the lake. [N]
SOOTY-FRONTED SPINETAIL (Synallaxis frontalis) [*]
SPIX'S SPINETAIL (Synallaxis spixi) [*]
Tyrannidae (Tyrant Flycatchers)
CRESTED DORADITO (Pseudocolopteryx sclateri) – Willy spotted one of these scarce little flycatchers in the grass off the road near Rincon del Socorro, but it dropped back down before more than a couple of folks could see it.
WARBLING DORADITO (Pseudocolopteryx flaviventris) – A fabulous encounter at Otamendi.
LARGE ELAENIA (Elaenia spectabilis) – Our best was on that first stormy morning at Rincon del Socorro.
SMALL-BILLED ELAENIA (Elaenia parvirostris) – Many migrants passing through during this extension.
SOOTY TYRANNULET (Serpophaga nigricans) – Intimately tied to watery habitats.
WHITE-CRESTED TYRANNULET (Serpophaga subcristata) – Several on that first afternoon at the Costanera Reserve in B.A.
SOUTHERN SCRUB-FLYCATCHER (Sublegatus modestus) – We found a responsive pair on our walk to look for the Yellow Cardinal at Rincon del Socorro.
PEARLY-VENTED TODY-TYRANT (Hemitriccus margaritaceiventer) [*]
BRAN-COLORED FLYCATCHER (Myiophobus fasciatus) – Nicely on that first afternoon in B.A.
VERMILION FLYCATCHER (Pyrocephalus rubinus)

Spectacled Tyrant (Photo by guide Dave Stejskal)

SPECTACLED TYRANT (Hymenops perspicillatus) – Fab looks on the first afternoon at the Costanera Reserve in B.A. The locals call it "Pico de Plata" (Silverbeak).
YELLOW-BROWED TYRANT (Satrapa icterophrys) – A gorgeous little flycatcher that's never common anywhere, in my experience.
GRAY MONJITA (Xolmis cinereus) – A few along the side of the road on our ride back to Posadas.
WHITE MONJITA (Xolmis irupero) – About as conspicuous as a bird could be.
BLACK-AND-WHITE MONJITA (Xolmis dominicanus) – A pair of these scarce flycatchers was a very nice find on our way back to Posadas from Rincon del Socorro. A very local species in n.e Argentina.
BLACK-BACKED WATER-TYRANT (Fluvicola albiventer) – A couple of great views at the Laguna de Ibera. This one was once lumped with the more northerly Pied Water-Tyrant.
WHITE-HEADED MARSH TYRANT (Arundinicola leucocephala) – There's nothing quite like it in the New World.
STRANGE-TAILED TYRANT (Alectrurus risora) – This was one of the big, big targets on this short extension, and it didn't disappoint. I lost track of how many stunning males we saw in the tall native grass near our lodge!
CATTLE TYRANT (Machetornis rixosa) – Those long legs are an adaptation for life walking on the ground.
SWAINSON'S FLYCATCHER (Myiarchus swainsoni swainsoni) – This race winters far to the north in the Amazon and Orinoco basins.
GREAT KISKADEE (Pitangus sulphuratus)
STREAKED FLYCATCHER (SOLITARIUS) (Myiodynastes maculatus solitarius) – This cavity-nesting species is a close relative of our Sulphur-bellied Flycatcher.
CROWNED SLATY FLYCATCHER (Empidonomus aurantioatrocristatus) – Most birders visiting S. America see their first Crowned Slaty Flycatcher during the austral winter while scanning the treetops from a canopy tower in Amazonia.
TROPICAL KINGBIRD (Tyrannus melancholicus)
FORK-TAILED FLYCATCHER (Tyrannus savana) – Lots of these on the move during our visit.
Tityridae (Tityras and Allies)
GREEN-BACKED BECARD (Pachyramphus viridis) [*]
CRESTED BECARD (Pachyramphus validus) – A male at the eagle nest was a nice surprise there.
Vireonidae (Vireos)
RED-EYED VIREO (MIGRATORY CHIVI) (Vireo olivaceus chivi)
Hirundinidae (Swallows)
BLUE-AND-WHITE SWALLOW (Pygochelidon cyanoleuca) – A couple of southbound migrants at the Costanera Reserve in B.A.
BROWN-CHESTED MARTIN (FUSCA) (Progne tapera fusca) – This highly migratory race winters as far north as northern S. America, and rarely as far north as Panama & Costa Rica.
WHITE-RUMPED SWALLOW (Tachycineta leucorrhoa) – Just now returning from the wintering grounds to the north.
BANK SWALLOW (Riparia riparia) [b]
BARN SWALLOW (Hirundo rustica) [b]
CLIFF SWALLOW (Petrochelidon pyrrhonota) [b]
Troglodytidae (Wrens)
HOUSE WREN (SOUTHERN) (Troglodytes aedon bonariae)
Polioptilidae (Gnatcatchers)
MASKED GNATCATCHER (Polioptila dumicola dumicola) – This one doesn't occur much farther south than southern Buenos Aires province.
Donacobiidae (Donacobius)

Straight-billed Reedhaunter (Photo by guide Dave Stejskal)

BLACK-CAPPED DONACOBIUS (Donacobius atricapilla) – Great views right next to the boat of this sole member of the newly recognized monotypic family Donacobiidae.
Turdidae (Thrushes and Allies)
RUFOUS-BELLIED THRUSH (Turdus rufiventris) – This one is more common in the wetter habitats, and the next is more common where it's a bit drier.
CREAMY-BELLIED THRUSH (Turdus amaurochalinus) – This species always quivers its tail while it's perched.
Mimidae (Mockingbirds and Thrashers)
CHALK-BROWED MOCKINGBIRD (Mimus saturninus) – By far, this is the most common mockingbird species in this part of Argentina.
WHITE-BANDED MOCKINGBIRD (Mimus triurus) – We had decent views of this flashy southbound migrant near our first Yellow Cardinal at Rincon del Socorro.
Sturnidae (Starlings)
EUROPEAN STARLING (Sturnus vulgaris) [I]
Parulidae (New World Warblers)
MASKED YELLOWTHROAT (SOUTHERN) (Geothlypis aequinoctialis velata) – Lots in Buenos Aires Province on the first two days.
TROPICAL PARULA (Setophaga pitiayumi) [*]
GOLDEN-CROWNED WARBLER (Basileuterus culicivorus) – These have colonized the Costanera Reserve in Buenos Aires.
WHITE-BROWED WARBLER (Myiothlypis leucoblephara) – We found a nicely responsive individual at our BBQ lunch spot. The Atlantic Forest specialty gets into far n.e. Argentina.
Thraupidae (Tanagers and Allies)
RED-CRESTED CARDINAL (Paroaria coronata) – Also known as the Brazilian Cardinal.

Maguari Stork (Photo by guide Dave Stejskal)

YELLOW-BILLED CARDINAL (Paroaria capitata) – Several around the lake this year.
ORANGE-HEADED TANAGER (Thlypopsis sordida) – A few in the little patch of woods at our BBQ lunch spot.
DIADEMED TANAGER (Stephanophorus diadematus) – Another Atlantic Forest specialty, we all had decent views of this unique tanager in the trees at Otamendi.
BLUE-AND-YELLOW TANAGER (Pipraeidea bonariensis bonariensis) – The bird at the Costanera Reserve was a little bit of a surprise there.
SAYACA TANAGER (Thraupis sayaca) – This common tanager replaces the Blue-gray Tanager in southern S. America.
LONG-TAILED REED FINCH (Donacospiza albifrons) – A few nice encounters with this one, including at Otamendi Reserve n. of B.A.
BLACK-AND-RUFOUS WARBLING-FINCH (Poospiza nigrorufa) – Quite a few of these beauties in Buenos Aires Province.
BLACK-CAPPED WARBLING-FINCH (Poospiza melanoleuca) – Looks a little like a giant gnatcatcher.
SAFFRON FINCH (Sicalis flaveola)
GRASSLAND YELLOW-FINCH (GRASSLAND) (Sicalis luteola luteiventris) – This race was once split out and called the Misto Yellow-Finch back when the Sibley & Monroe World Checklist was all the rage.
LESSER GRASS-FINCH (Emberizoides ypiranganus) – More of these than I usually get at Rincon del Socorro. Sometimes called the Gray-cheeked Grass-Finch.
GREAT PAMPA-FINCH (EASTERN) (Embernagra platensis platensis) – This nominate form is likely to be re-split from the inland race sometime soon (they were originally described as separate species).
RUSTY-COLLARED SEEDEATER (Sporophila collaris) – This seedeater is really closely tied to marshy habitats (more so than the others).
DOUBLE-COLLARED SEEDEATER (Sporophila caerulescens) – Unlike the other seedeaters following this one on the list, this species is usually found in light, scrubby woodland, not the lush native grassland that the next six species are found in.
PEARLY-BELLIED SEEDEATER (Sporophila pileata) – This species was once called Capped Seedeater before it was split into two recently. This one has the more restricted range of the two, the other (Copper Seedeater) being found from s. Brazil north to the Guianas. Of the six grassland species here, this one seems to be the most difficult to find.
TAWNY-BELLIED SEEDEATER (Sporophila hypoxantha) – Usually the most common Sporophila out in the grassland here.
DARK-THROATED SEEDEATER (Sporophila ruficollis) – All of the males that we saw were pretty pale, so I suspect that they may have been 1st-year birds. This was probably the 2nd most common Sporophila out in the grasslands.
MARSH SEEDEATER (Sporophila palustris) – This one and the next two were really great ones to get, and we had gorgeous males of all three (I'm not sure how you'd i.d. them if they weren't gorgeous males!).
RUFOUS-RUMPED SEEDEATER (Sporophila hypochroma) – This one can look surprisingly similar to the Tawny-bellied, but that underpart color (especially the throat) is a darker, richer chestnut.
CHESTNUT SEEDEATER (Sporophila cinnamomea) – Unmistakable with that gray cap set off by the all dark chestnut body. Gorgeous!
YELLOW CARDINAL (Gubernatrix cristata) – YESSSSS!!!!!!! Dangerously depleted by bird trappers around the country, this gorgeous, and now exceedingly rare, species took some work that first afternoon to find it. We did come away with terrific views of a pair of these at close range, but we had an even easier time of it the following morning. If we had only known... Still, a fantastic bird to see and enjoy!
GRAYISH SALTATOR (Saltator coerulescens) – Including at least one bird that appeared to be a Grayish X Green-winged intergrade!
GREEN-WINGED SALTATOR (Saltator similis) – Outstanding views of a very cooperative bird at the eagle nest. Another Atlantic Forest specialty that barely gets into Argentina.

White-barred Piculet (Photo by guide Dave Stejskal)

GOLDEN-BILLED SALTATOR (Saltator aurantiirostris) – The most common saltator that we encountered throughout Argentina.
Emberizidae (Buntings and New World Sparrows)
GRASSLAND SPARROW (Ammodramus humeralis)
RUFOUS-COLLARED SPARROW (Zonotrichia capensis)
Cardinalidae (Cardinals and Allies)
HEPATIC TANAGER (LOWLAND) (Piranga flava flava) – Some authors split this one into three or four species. This one would be the Lowland Hepatic-Tanager (P. flava) if it was split.
Icteridae (Troupials and Allies)
WHITE-BROWED BLACKBIRD (Sturnella superciliaris) – Some distant birds out in the grassland near Rincon del Socorro on our last afternoon there.
SCRUB BLACKBIRD (Dives warszewiczi) – This was a surprise find at Costanera Reserve, to say the least! Certainly an escaped cagebird (it's from n.w. South America), it's apparently been in the area for a couple of months now.
CHOPI BLACKBIRD (Gnorimopsar chopi) – We found a little group of these along the roadside on our way back to Posadas.
SCARLET-HEADED BLACKBIRD (Amblyramphus holosericeus) – Stunning views at Otamendi of this brilliant blackbird!
UNICOLORED BLACKBIRD (Agelasticus cyanopus) – Common in the marshes at the edge of the Ibera Lagoon. The females are quite different in appearance from the males.
YELLOW-WINGED BLACKBIRD (Agelasticus thilius) – It's really difficult to see that yellow shoulder unless the male happens to fly.
CHESTNUT-CAPPED BLACKBIRD (Chrysomus ruficapillus) – That chestnut cap and throat are so dark, you really have to see it at close range under near ideal lighting conditions to pick it out from the black plumage.
YELLOW-RUMPED MARSHBIRD (Pseudoleistes guirahuro) – We had both this and the next species nearly side-by-side at Rincon del Socorro for nice comparisons.
BROWN-AND-YELLOW MARSHBIRD (Pseudoleistes virescens) – This is the only marshbird that makes it down to Buenos Aires Province.
BAY-WINGED COWBIRD (Agelaioides badius) – These aren't really cowbirds at all, and they are actually parasitized by the Screaming Cowbird! The name ought to be changed to simply the Baywing.
SCREAMING COWBIRD (Molothrus rufoaxillaris) – Difficult to separate visually from the very similar Shiny. The voice, however, is very distinctive.
SHINY COWBIRD (Molothrus bonariensis)
VARIABLE ORIOLE (Icterus pyrrhopterus) – Recently split from the Epaulet Oriole, this one occurs south of that species.
SOLITARY BLACK CACIQUE (Cacicus solitarius) – Never in flocks - always solo or in pairs.
Fringillidae (Siskins, Crossbills, and Allies)
PURPLE-THROATED EUPHONIA (Euphonia chlorotica) – The only euphonia in the area.
HOODED SISKIN (Spinus magellanicus) – In Buenos Aires Province only on this extension.
Passeridae (Old World Sparrows)
HOUSE SPARROW (Passer domesticus) [I]


Plains Vizcacha (Photo by guide Dave Stejskal)

NINE-BANDED ARMADILLO (Dasypus novemcinctus) – Several folks got a look from the vehicles along the entrance road into Rincon del Socorro.
EUROPEAN BROWN HARE (Lepus europaeus) [I]
CAPYBARA (Hydrochaeris hydrochaeris) – Always around and always confiding - a little too confiding on the roads!
PLAINS VISCACHA (Lagostomus maximus) – This is the only place where I've seen this strange critter anywhere! Great views of multiple individuals on the grounds of our lodge.
PAMPAS FOX (Pseudalopex gymnocercus) – Not an uncommon predator out here.
NEOTROPICAL OTTER (Lontra longicaudis) – One surprised the lead vehicle by crossing the road right in front of us as we started our journey back to Posadas from Rincon del Socorro.
MARSH DEER (Blastocerus dichotomus) – We ended up seeing a fair number of these uncommon deer at Rincon del Socorro, where they're apparently doing quite well.
PAMPAS DEER (Ozotoceros bezoarticus) – A quick drive-by look for some on our way to Rincon del Socorro from Posadas.
BROWN BROCKET DEER (Mazama gouazoubira) – Only a couple of these tiny deer at Rincon del Socorro.


Totals for the tour: 197 bird taxa and 9 mammal taxa