Patricio Robles Gil / Silhouetted Capivara / Capibara (Hydrochoerus hydrochaeris) with Cattle Tyrant (Machetornis rixosa), which feeds on flies approaching the Capibara. Parana, Southern Brazil.

Patricio Robles Gil / Pale-legged Hornero (Furnarius leucopus) male and female birds building their mud nest on a branch. Parana, Southern Brazil.

Daniel Gomez / Atlantic rainforest cleared for agriculture, Parana State, Brazil, South America

Christophe Courteau / Rainbow in spray over Iguassu Falls, Parana state, Brazil.

Christophe Courteau / Tourists on walkway above Iguassu Falls, Parana state, Brazil.

Patricio Robles Gil / Male Bare Face Curassow (Crax fasciolata) with chick. Parana, Southern Brazil.

Patricio Robles Gil / Giant River Otter (Pteronura brasiliensis) with eel prey in its mouth. Parana, Southern Brazil.

Patricio Robles Gil / Toco Toucan (Ramphastos toco) perching with open beak. Parana, Southern Brazil.

Patricio Robles Gil / Savanna Hawk (Buteogallus meridionalis) taking flight. Parana, Southern Brazil.

Patricio Robles Gil / White-lipped Peccary (Tayassu albirostris / pecari) adults and piglets drinking at river bank. Parana, Southern Brazil.

Patricio Robles Gil / White-lipped Peccary (Tayassu albirostris / pecari) resting in shade on river bank. Parana, Southern Brazil.

Patricio Robles Gil / White-lipped Peccary (Tayassu albirostris / pecari) resting in shade. Parana, Southern Brazil.

Patricio Robles Gil / White-lipped Peccary (Tayassu albirostris / pecari) resting in shade and digging in river bank. Parana, Southern Brazil.

Patricio Robles Gil / Pale-legged Hornero (Furnarius leucopus) male and female birds building their mud nest on a branch. Parana, Southern Brazil.

Patricio Robles Gil / Rufescent Tiger Heron (Tigrisoma lineatum) swallowing fish. Parana, Southern Brazil.

Patricio Robles Gil / Female Jaguar (Panthera onca) on river bank. Parana, Southern Brazil.

Patricio Robles Gil / Green Iguana (Iguana iguana) on tree. Parana, Southern Brazil.

Patricio Robles Gil / King Vulture (Sarcoramphus papa) standing on sand. Parana, Southern Brazil.

Patricio Robles Gil / Jacare / Yacare Caiman (Caiman crocodilus yacare) feeding on large fish. Parana, Southern Brazil.

Patricio Robles Gil / Muscovy Duck (Cairina moschata) on river bank. Parana, Southern Brazil.

Patricio Robles Gil / Pied Lapwing / Plover (Vanellus cayanus) walking on river sands. Parana, Southern Brazil.

Patricio Robles Gil / Giant River Otter (Pteronura brasiliensis) adult resting on log. Parana, Southern Brazil.

Patricio Robles Gil / Greater Rhea (Rhea americana) entering water to cross the river. Parana, Southern Brazil.

Patricio Robles Gil / Female Jaguar (Panthera onca) with Jacare Caiman prey. Parana, Southern Brazil.

Patricio Robles Gil / Black Howler Monkey (Alouatta caraya) in dry months need to drink from the river, risking predation. Parana, Southern Brazil.

Patricio Robles Gil / Giant River Otter (Pteronura brasiliensis) feeding on an eel while Great Kiskadee (Pitangus sulphuratus) scavenges for scraps. Parana, Southern Brazil.

Patricio Robles Gil / Toco Toucan (Ramphastos toco) preening. Parana, Southern Brazil.

Patricio Robles Gil / Toco Toucan (Ramphastos toco) preening. Parana, Southern Brazil.

Patricio Robles Gil / Toco Toucan (Ramphastos toco) need to drink from the river in the dry season, exposing themselves to predation. Parana, Southern Brazil.

Patricio Robles Gil / Little Cuckoo (Coccyua minuta) perched. Parana, Southern Brazil.

Patricio Robles Gil / Large Yellow Anaconda (Eunectes notaeus) resting. Parana, Southern Brazil.

Patricio Robles Gil / Tourists watching a female Jaguar (Panthera onca) from a boat. Piquiri River, Parana, Southern Brazil.

Patricio Robles Gil / Capivara / Capibara (Hydrochoerus hydrochaeris) family resting on river sand bank. Piquiri River, Parana, Southern Brazil.

Patricio Robles Gil / Hyacinth Macaw (Anodorhynchus hyacinthinus) with open beak. Parana, Southern Brazil.

Patricio Robles Gil / Two Giant River Otters (Pteronura brasiliensis) playing on a log. Parana, Southern Brazil.

Patricio Robles Gil / Portrait of a Giant River Otter (Pteronura brasiliensis). Parana, Southern Brazil.

Patricio Robles Gil / Female Jaguar (Panthera onca) with her prey, a Yacare Caiman. Parana, Southern Brazil.

Patricio Robles Gil / American Darter / Anhinga (Anhinga anhinga) spreading its wings to dry them. Parana, Southern Brazil.

Patricio Robles Gil / Black-capped Donacobius (Donacobius atricapilla). Classification is unclear for this species, but it is thought to be related to the Trogons, Wrens or Thrushes. Parana, Southern Brazil.

Patricio Robles Gil / White-lipped Peccary (Tayassu albirostris / pecari) herd, adults and young. Parana, Southern Brazil.

Patricio Robles Gil / Giant River Otter (Pteronura brasiliensis) feeding on eel. Parana, Southern Brazil.

Patricio Robles Gil / Capivara / Capibara (Hydrochoerus hydrochoeris) parent carrying its baby on its back while swimming across a marsh. Parana, Southern Brazil.

Patricio Robles Gil / Crane Hawk (Geranospiza caerulescens) perched. Parana, Southern Brazil.

Patricio Robles Gil / Pied Lapwing / Plover (Vanellus cayanus) walking on river sand. Parana, Southern Brazil.

Patricio Robles Gil / Silver-beaked Tanager (Ramphocelus carbo / bresilius) bathing and drinking by the River Piquiri. Parana, Southern Brazil.

Patricio Robles Gil / Male Jaguar (Panthera onca) swimming across the River Piquiri wearing a radio location collar. Parana, Southern Brazil.

Mark Moffett / Carpenter Ant (Camponotus sp) tending scale insects, Parana River, Argentina

Mark Moffett / Carpenter Ant (Camponotus sp) tending scale insects, Parana River, Argentina

Mark Moffett / Carpenter Ant (Camponotus sp) pair tending scale insects, Parana River, Argentina

Mark Moffett / Argentine Ant (Linepithema humile) group feeding on dead fish on the river banks, Parana River, Argentina

Mark Moffett / Red Imported Fire Ant (Solenopsis invicta) attacking Argentine Ant (Linepithema humile), Parana River, Argentina

Mark Moffett / Red Imported Fire Ant (Solenopsis invicta) pair tending scale insects, Parana River, Argentina

Luciano Candisani / Parana Pine (Araucaria angustifolia) female cone showing edible seeds, Brazil

Mark Moffett / Ant (Pheidole ferox) nest entrance was formed from underground soil excavation and deposition by worker ants, Parana River, northern Argentina

Mark Moffett / Argentine Ant (Linepithema humile) grabbing the leg of a fire ant in a fight to control the dead grasshopper they are standing on, the fire ant is exuding venom from her stinger used to slash her atta...

Mark Moffett / Argentine Ant (Linepithema humile) group eating a piranha on the banks of the Parana River, northern Argentina

Luiz Claudio Marigo / Aerial view of Pimenta Bueno town, on the banks of the River Ji-paraná, Rondônia State, Western Brazil.

Luiz Claudio Marigo / Araucaria / Parana pines (Araucaria angustifolia) in the Itaimbezinho Canyon, Aparados da Serra National Park, Rio Grande do Sul State, Southern Brazil.

Luciano Candisani / Parana Pine (Araucaria angustifolia) forest, Sao Bento Do Sapucai, Brazil

Luciano Candisani / Parana Pine (Araucaria angustifolia) female cones, Brazil

Luciano Candisani / Itaipu Dam, the largest in the world, Parana River near Iguacu Waterfalls, Brazil

Luciano Candisani / Machadinho Dam, small hydroelectic plant in Parana River, Brazil

Luciano Candisani / Parana Pine (Araucaria angustifolia) forest, southern Brazil

Luciano Candisani / Ocelot (Leopardus pardalis) portrait, Atlantic Forest, Brazil

Ross Couper-Johnston / Aerial view of Parana river, before dam construction, Argentina / Paraguay border, South America

Luiz Claudio Marigo / Atlantic rainforest with flowering Cassia and Tibouchina trees, Serra da Graciosa, Brazil Parana, S Brazil

Luiz Claudio Marigo / Atlantic rainforest with Quaresmeira trees {Tibouchina sp} Serra da Graciosa, Brazil

Luiz Claudio Marigo / Atlantic rainforest, Serra da Graciosa, Parana, S Brazil

Mark Moffett / Harvestman (Phalangodidae) an arachnid, close-up portrait showing fused abdomen which differentiates Harvestmen from other spiders, Parana State, Atlantic Forest, Brazil

Claus Meyer / Timber plantation and soybeans on Terra Roxas near the Itaipu reservoir, Parana state, southern Brazil

Claus Meyer / Sao Francisco Falls, 186 meters high, cascading over cliff in an amphitheater carved from basaltic rock lined with Araucaria pines (Araucaria angustifolia), Prudentopolis, southern Brazil

Claus Meyer / Sao Francisco Falls, Parana, southern Brazil

Mark Moffett / Catfish specimen of a new species, held in researcher's hand, Salto Morato Reserve, Parana State, Atlantic Forest, Brazil

Mark Moffett / Cotiara (Bothrops cotiara) portrait on rock, Parana State, Atlantic Forest, Brazil

Claus Meyer / Sao Francisco Falls, 186 meters high, cascading over cliff in an amphitheater carved from basaltic rock lined with Araucaria pines (Araucaria angustifolia), Prudentopolis, southern Brazil