The Golden Eagle is one of the most majestic raptors, easily recognized by its golden-brown plumage and imposing silhouette. This large eagle is widely distributed across the Northern Hemisphere, from the mountains of Europe and Asia to the more arid regions of North America. It primarily hunts medium-sized mammals but can also target larger birds. The Golden Eagle is a solitary bird, known for its flying prowess and its ability to cover great distances in search of food. During the breeding season, the Golden Eagle performs spectacular courtship displays, where males execute aerial acrobatics to impress females.

The Royal Albatross is one of the largest and most majestic species of albatross, easily recognizable by its long, tapered wings that can span up to 3 meters. This seabird, which frequents the Australian and Antarctic oceans, is a master of gliding flight, capable of covering vast distances without flapping its wings. The Royal Albatross hunts fish and squid, which it captures with great precision by diving from the air. During the breeding season, the Royal Albatross performs complex courtship dances to attract a mate, an impressive display that reflects the majesty of this bird.

The Alauda razae, commonly known as the Razo Skylark, is a bird species endemic to the island of Razo in the Cape Verde archipelago. This medium-sized bird, with its light brown plumage streaked with black, is perfectly adapted to its insular environment. It is known for its melodious and complex song, often performed in flight. The Razo Skylark is a terrestrial bird that prefers the open and arid areas of the island, where it primarily feeds on seeds and insects. Unfortunately, this species is critically endangered due to habitat loss and predation by introduced species. Conservation efforts are underway to protect this unique bird and its fragile habitat.

The roan antelope, Hippotragus equinus, is a large African herbivore known for its reddish-brown coat and long, ringed horns. It primarily inhabits the savannas and wooded grasslands of sub-Saharan Africa. Males are slightly larger than females, reaching up to 1.5 meters at the shoulder and weighing around 300 kg. Both sexes have horns that can grow up to a meter long. The roan antelope is a gregarious animal, living in small herds led by a dominant female. It is known for its wary nature and ability to vigorously defend its young from predators.

The Red-and-green Macaw, scientifically known as Ara chloropterus, is a large parrot species native to the tropical rainforests of South America. It is renowned for its striking red plumage, complemented by green and blue on its wings and tail. These macaws are highly intelligent and social, often seen in pairs or small family groups. They feed primarily on fruits, nuts, and seeds. With a length of about 90 to 95 cm and a wingspan that can be quite impressive, they are a sight to behold. In captivity, they can live up to 50 years, making them a long-term commitment for bird enthusiasts.

The Ribbon-tailed Astrapia is a fascinating bird endemic to the mountainous forests of Papua New Guinea. Recognizable by its long, ribbon-like white tail, the male displays an iridescent black plumage with green and violet highlights. The female, more discreet, has brownish tones. This bird primarily inhabits tropical rainforests at altitudes between 1800 and 3500 meters. It feeds mainly on fruits, insects, and small animals. Its behavior is rather suspicious, making it difficult to observe. The breeding period is poorly documented, but it is known that the male performs spectacular courtship displays to attract the female.

Native to the mountains of New Guinea, Rothschild's astrapia is a bird with vibrant colors, featuring an outstanding plumage of iridescent green, blue, and purple. The male is particularly spectacular, with a long tail and feathers adorned with bright colors. This bird is primarily frugivorous but also feeds on insects and small animals. Threatened by habitat loss, Rothschild's astrapia is a protected species.

The Red Knot, or Calidris canutus, is a remarkable migratory bird belonging to the Scolopacidae family. Known for its impressive migrations, it travels thousands of kilometers between its Arctic breeding grounds and its southern hemisphere wintering areas. This medium-sized bird features a distinctive reddish breeding plumage, which becomes duller in winter. It primarily feeds on mollusks, crustaceans, and insects found in mudflats and beaches. The Red Knot plays a crucial role in coastal ecosystems, helping regulate prey populations. Its survival is threatened by habitat loss and climate change, making it a species of conservation concern.

The red-breasted goose is a small migratory goose (55–65 cm wingspan) with contrasting black-and-white plumage and a bright russet breast. It breeds in Arctic coastal tundra near waterways and winters in temperate wetlands of Europe and Asia. During the breeding season, males and females actively defend their nesting territory with head-forward displays and harsh calls.

The reed bunting is a small passerine bird found primarily in wetlands, reed beds, and marshes across Europe, Asia, and North Africa. It is easily recognized by its streaked brown plumage, light belly, and distinctive markings on the head, particularly the black-and-white patterns. This small bird primarily feeds on seeds and insects found in grasses and reeds.

The Red-whiskered Bulbul, or Pycnonotus jocosus, is a bird with distinctive plumage, recognizable by its pointed black crest and white cheeks adorned with red patches. Its chest is white, contrasting with its brownish belly. This bird is native to Southeast Asia but has been introduced to other parts of the world. It frequents various habitats, from forests to urban gardens. The Red-whiskered Bulbul is a sociable bird, often seen in small groups. Its melodious and varied song is appreciated by bird enthusiasts. Although primarily frugivorous, it also feeds on insects. Its adaptability allows it to thrive in diverse environments.

The Red-tailed Hawk, or Buteo jamaicensis, is a widespread diurnal raptor in North America. It is easily recognizable by its distinctive red tail, although juveniles have a duller tail. Its plumage ranges from dark brown to light brown, with a typically paler belly. This opportunistic predator primarily feeds on small mammals but can also capture birds and reptiles. The Red-tailed Hawk is often seen perched on poles or soaring in circles in the sky. It adapts to various habitats, from forests to open grasslands, and is known for its piercing and distinctive call.

The Rough-legged Buzzard, or Buteo lagopus, is a medium-sized bird of prey known for its feathered legs, which help it endure cold climates. It features a brown plumage speckled with white, with a white tail barred with black. This raptor is often seen hovering, scanning the ground for prey, mainly rodents. It breeds in arctic and subarctic regions but migrates southward in winter. The Rough-legged Buzzard is a solitary bird, although it can be seen in small groups during migration. It prefers open habitats such as tundras, grasslands, and agricultural areas.

The Tockus erythrorhynchus, or red-billed hornbill, is an African bird known for its long, curved red bill. It measures about 42 to 50 cm in length and weighs between 120 and 170 grams. Its plumage is mainly gray with white spots on the wings and a black tail. This bird is often seen in small groups or pairs, feeding primarily on insects, small reptiles, and fruits. It is known for its social behavior and loud calls. The red-billed hornbill is a diurnal bird that prefers savannas, open woodlands, and shrublands. It plays an important role in the ecosystem by controlling insect populations.

The Rhinoceros Hornbill, or Buceros rhinoceros, is an impressive bird known for its size and distinctive appearance. It is easily recognizable by its prominent horn-shaped casque, which gives it its name. This casque, although large, is hollow and lightweight. The bird's plumage is primarily black, with white feathers on the tail and white markings on the wings. Its eyes are surrounded by brightly colored bare skin, often red or orange. The Rhinoceros Hornbill inhabits the tropical forests of Southeast Asia, particularly in Malaysia, Thailand, and Sumatra. It plays a crucial role in its ecosystem as a seed disperser, aiding in forest regeneration.

The Red-throated Caracara, Ibycter americanus, is a fascinating bird of prey belonging to the Falconidae family. It is distinguished by its bright red throat and black and white plumage. This bird is primarily found in the tropical forests of Central and South America, where it plays an important ecological role as a predator of insects and small vertebrates. The Red-throated Caracara is known for its social behavior, often observed in noisy family groups. It is also recognized for its ability to dislodge wasp nests, feeding on the larvae. Although its conservation status is currently "least concern," deforestation poses a potential threat to its natural habitat.

The Caribou, or Reindeer in Europe, is a large cervid adapted to cold and northern environments. It is easily recognizable by its distinctive antlers, which are present in both males and females, a unique trait among cervids. Its thick, woolly coat, typically brown with lighter shades on the belly and neck, allows it to survive in the harshest climates. Caribou populations are found primarily in arctic and subarctic regions, including Iceland, where they were introduced and have thrived in the mountainous and tundra landscapes. The Caribou is a migratory species, undertaking long seasonal migrations to find food resources. It primarily feeds on lichens, grasses, and tundra plants, which it digs out from under the snow during the winter. The Caribou plays a crucial role in its ecosystem by affecting vegetation and serving as prey for large carnivores such as wolves. However, it is threatened by climate change and habitat loss.

The Redshank is a medium-sized wader with distinctive plumage that changes with the seasons. During the breeding season, the male displays vibrant colors, with a black head and reddish chest, while the female has more subdued tones. Outside the breeding season, both sexes adopt a more muted plumage, often gray-brown with shades of white and black. The Redshank is primarily found in wetlands, estuaries, and lakeshores, where it feeds on small invertebrates, aquatic insects, and occasionally worms and crustaceans. This migratory bird is known for its long-distance migration, between its breeding grounds in northern Eurasia and its wintering areas in southern Asia and North Africa. While its population remains generally stable, the Redshank is vulnerable to threats such as habitat destruction, pollution, and hunting. The species is protected in some areas where it is found.

The Roe Deer is an elegant, small cervid, recognizable by its slender figure and long legs. It has a coat that changes with the seasons: reddish-brown in summer, becoming more gray-brown in winter. Males carry antlers, which grow back each year and are generally smaller than those of other cervids. The Roe Deer primarily lives in forests, wooded areas, and heathlands, where it hides during the day and becomes more active at dusk and night, particularly for feeding. Its diet is varied, consisting of leaves, fruits, young shoots, and bark. While it is generally discreet and solitary, it can sometimes be seen in small groups, especially in winter. The Roe Deer is an agile and fast animal, capable of covering large distances in a short time when threatened. While its population remains relatively stable, it faces threats from hunting and habitat loss.

The raccoon dog, or Nyctereutes procyonoides, is a canid native to East Asia, known for its thick fur and distinctive facial mask resembling that of a raccoon. This omnivorous mammal adapts to various environments, from forests to wetlands. Primarily nocturnal and crepuscular, it feeds on small animals, fruits, and vegetation. Although often solitary, it can form monogamous pairs. Introduced to Europe for fur farming, it has established itself in some regions. Its adaptability and varied diet make it a resilient species, though its impact on local ecosystems is sometimes debated.

The Red-faced Cisticola is a small bird with brownish plumage and a distinctive red face. It is primarily found in wetlands and grasslands of sub-Saharan Africa. Known for its complex and melodious song, it is often heard during the breeding season. This passerine builds ball-shaped nests using grasses and spider webs, typically well-hidden in dense vegetation. The Red-faced Cisticola is an active bird, often seen hopping from one stalk to another in search of insects. Although quite common, its habitat is threatened by deforestation and agricultural expansion.

The Ruby-throated Hummingbird is one of the most iconic species of hummingbirds in North America, easily recognizable by the bright red color of its throat, which gives it its name. This small bird has bright metallic green plumage on its back and a white chest. It has a long, slender beak and an extendable tongue that it uses to extract nectar from flowers. In addition to nectar, it also consumes insects and spiders for protein. The Ruby-throated Hummingbird is a migratory bird, covering long distances between its breeding range in North America and its wintering grounds in Central America. It is known for its rapid and agile flight, capable of hovering in place by beating its wings up to 80 times per second. While its population remains generally stable, it is threatened by habitat loss due to urbanization and climate change, which affect food resources and breeding conditions.

The Rufous hummingbird is a fascinating species of hummingbird, recognized for its small size and brilliant feathers in shades of copper and red. Native to North America, it migrates each year between the United States and Mexico. This hummingbird primarily feeds on nectar, which it collects using its long bill and extendable tongue. It is often seen hovering in place, a feat made possible by its extremely agile wings. The Rufous hummingbird is also known for its territorial behavior, especially when defending its favorite flowers.

The Ruff is a medium-sized wader bird, easily recognizable by its colorful plumage and relatively large size for a bird in its family. The male is particularly distinctive during the breeding season, with vibrant plumage ranging from brown and white to red and orange, and a large ruff that surrounds its head. Outside the breeding season, the male loses its bright colors and presents a more subdued plumage similar to the female. This wader inhabits wetlands, marshes, and riverbanks across Europe and Asia. During the breeding season, males engage in spectacular courtship displays to attract females, including throat inflations and dances. The Ruff primarily feeds on small invertebrates and aquatic plants. It migrates south for the winter. While its population remains relatively stable, it is threatened by habitat loss due to the draining of wetlands and pollution.

The Rock Rattlesnake, or Crotalus lepidus, is a medium-sized venomous snake, typically measuring between 50 and 70 cm in length. It is characterized by its gray or brownish coloration, often marked with dark crossbands, allowing it to blend into its rocky environment. This snake is primarily found in the mountainous regions of the southwestern United States and northern Mexico. It prefers rocky and arid habitats, where it can easily hide. Although venomous, it is generally not aggressive towards humans and prefers to flee rather than bite.

The Ranitomeya reticulata, commonly known as the reticulated poison frog, is a small, brightly colored frog native to the humid rainforests of South America, particularly in Peru and Ecuador. It is renowned for its vibrant skin, featuring a complex pattern of black reticulations on a bright yellow or orange background, making it a fascinating specimen for herpetologists and frog enthusiasts. This species is diurnal and primarily feeds on small insects and arthropods. Although its skin is toxic, it poses no threat to humans unless handled improperly. The Ranitomeya reticulata plays a crucial role in its ecosystem by regulating insect populations and serving as prey for certain predators.

The Russian Desman, or Desmana moschata, is a small semi-aquatic mammal belonging to the Talpidae family. It is primarily found in the wet regions of Russia and Ukraine. This peculiar animal has a long, flexible snout and a flattened tail, which allow it to move easily in water. Its dense, waterproof fur protects it from the cold, while its webbed feet facilitate swimming. The Russian Desman is a nocturnal animal, feeding mainly on aquatic insects, small fish, and crustaceans. Unfortunately, it is threatened by habitat destruction and water pollution, leading to a significant decline in its population.

The Red-necked Nightjar is a fascinating nocturnal bird, primarily found in southern Europe and northern Africa. It is distinguished by its mottled brown plumage, which allows it to blend perfectly into its environment. Its rufous throat and long tail are characteristic features. This master of camouflage is often difficult to spot during the day, as it rests motionless on the ground or on low branches. It is most active at dusk and night, feeding mainly on insects caught in flight with its wide beak. Its soft, repetitive song is often heard during summer nights. Although its habitat is threatened by urbanization and intensive agriculture, it remains relatively common in some areas.

The red-footed booby is a remarkable seabird, easily recognized by its red feet and its white and brown plumage. It primarily lives on tropical islands in the Pacific and Indian Oceans, where it nests on cliffs or trees near water. It feeds mainly on fish, which it catches by diving from heights. It is a social species living in colonies, but it faces threats due to habitat loss and human disturbances.