The reticulated giraffe, or Giraffa camelopardalis reticulata, is a subspecies of giraffe known for its distinctive coat pattern of large polygonal patches separated by white lines. It is primarily found in northeastern Kenya, southern Ethiopia, and Somalia. Reticulated giraffes live in loose social groups and primarily feed on acacia leaves, which they reach with their long necks. They play a crucial role in their ecosystem by promoting tree growth and seed dispersal. Although majestic, they are vulnerable due to habitat loss and poaching. Their population is declining, leading to their classification as a vulnerable species by the IUCN.

The Rufous Antpitta is a secretive bird found in the humid montane forests of South America, primarily in Ecuador and Peru. It is characterized by its reddish-brown plumage and compact size, measuring about 16 cm in length. This bird is more often heard than seen, as it prefers to stay hidden in dense undergrowth. It feeds mainly on insects and other small invertebrates found by foraging on the forest floor. The Rufous Antpitta is a solitary bird, except during the breeding season. It builds its nest on the ground, hidden among fallen leaves. Although its habitat is threatened by deforestation, it is currently classified as Least Concern by the IUCN.

The red-necked grebe is a water bird found primarily in lakes, ponds, and wetlands across Europe and Asia. It is easily recognized by its contrasting plumage, with a reddish-orange head and neck during the breeding season and more subdued plumage outside of it. This grebe primarily feeds on fish, aquatic invertebrates, and aquatic plants, which it captures by diving underwater. It is also known for its spectacular courtship displays.

The Redwing, or Turdus iliacus, is a small migratory bird belonging to the Turdidae family. It is characterized by its reddish-brown plumage on the back and reddish flanks, contrasting with its white belly. Its melodious song is often heard in the forests and parks of Europe and Asia, where it feeds mainly on berries and insects. In winter, it migrates south, sometimes reaching North Africa. The Redwing is a sociable bird, often seen in flocks, especially during migration. It typically nests in trees or shrubs, building a cup-shaped nest with twigs and mud.

The Red-breasted Merganser is a slender diving duck, measuring about 52 to 58 cm in length with a wingspan of 67 to 82 cm. The male features a dark green head with a shaggy crest, a white collar, a rusty speckled chest, and a thin red bill. The female has a reddish-brown head with a more subdued crest, a grayish body, and a duller red bill. This duck inhabits coastal waters, estuaries, bays, and large lakes, favoring saline or brackish areas. It primarily feeds on small fish, but also consumes crustaceans, aquatic insects, and amphibians, captured using its serrated bill adapted for fishing. A migratory species, it nests on the ground near water, often concealed under vegetation or in rocky crevices. Although listed as Least Concern by the IUCN, the Red-breasted Merganser is sensitive to water pollution, coastal habitat destruction, and human disturbances.

The rhinoceros iguana is a large herbivorous lizard endemic to the Caribbean, reaching 65–136 cm including tail, with a robust body and a head adorned with bony protrusions resembling horns. It inhabits dry forests, scrublands, and rocky coastal areas of Hispaniola and surrounding islands, feeding on leaves, flowers, and fruits. Solitary and territorial, breeding occurs in the spring, when males display head bobs and body push-ups to defend territory and attract females.

The Red Kangaroo is one of the most iconic and largest species of kangaroos in Australia. It is easily recognizable by its red-brown fur and large size, with adult males reaching over 2 meters in length, including their tail. The Red Kangaroo lives in the dry and semi-arid regions of the Australian Outback, where it primarily feeds on grasses and plants. This animal is an excellent jumper and uses its powerful hind legs to travel at high speeds, often performing impressive leaps. While it is mainly active at dusk and dawn, it can also adapt to the extreme temperatures of its environment.

The Rock Ptarmigan is a mountain bird adapted to the harsh conditions of high peaks. It measures about 35 to 40 cm in length and weighs between 350 and 650 g. In winter, its plumage is entirely white, allowing it to blend into the snow, while in summer, it has a brown-red plumage with dark spots to better blend into the rocks and grasses of the mountains. The Rock Ptarmigan primarily inhabits mountainous regions of Europe, Asia, and North America at high altitudes, where it feeds on plants, seeds, berries, and young shoots. Due to its thick plumage and feather-covered legs, it is well adapted to cold conditions but is also vulnerable to climate change, particularly to the loss of its mountainous habitat. The species is protected in some areas but remains sensitive to human disturbances, such as mountain tourism and temperature changes.

The Mazama americana, or red brocket, is a small deer native to South America. It is characterized by its reddish coat and modest size, standing about 70 to 80 cm at the shoulder. This deer prefers dense forests where it can hide from predators. It is mostly solitary except during the breeding season. Its diet consists of leaves, fruits, and young shoots. Although relatively discreet, it plays a crucial role in seed dispersal, aiding forest regeneration. Its population is threatened by deforestation and hunting, leading to its classification as a vulnerable species by the IUCN.

The Ring-tailed lemur is an iconic lemur from Madagascar, easily recognizable by its long, black and white ringed tail. It primarily inhabits dry forests and rocky areas in the south of the island. This social primate lives in matriarchal groups that can number up to 30 individuals. Active during the day, it spends much of its time foraging for food, mainly fruits, leaves, and flowers. The Ring-tailed lemur is also known for its morning sunbathing, sitting facing the sun to warm up. Unfortunately, this species is threatened by deforestation and hunting, leading to a decline in its wild population.

The Ruddy Kingfisher, or Halcyon coromanda, is a medium-sized bird known for its striking purple plumage and robust red bill. It primarily inhabits the tropical and subtropical forests of Southeast Asia, where it feeds on small fish, insects, and crustaceans. This bird is often seen near water bodies, using its keen eyesight to spot prey. Although generally discreet, its melodious call can be heard at dawn and dusk. The Ruddy Kingfisher is a migratory bird, moving to warmer regions during winter months. Its population is stable, but it remains vulnerable to deforestation.

The ring ouzel is a passerine bird found primarily in the mountains and coniferous forests of Europe, Asia, and the Middle East. It is easily recognized by its dark plumage, white chest that contrasts with its black belly, and the white ring around its neck. This small bird primarily feeds on berries, insects, and small fruits, which it finds mainly in bushes and forest floors.

The Red Kite is a large bird of prey, measuring about 60 to 70 cm in length, with a wingspan of 1.5 to 1.8 meters. It typically weighs between 1.2 and 1.5 kg. This raptor is distinguished by its reddish-brown plumage on the back and wings, with a lighter head and a deeply forked tail, giving it a characteristic silhouette in flight. The Red Kite primarily inhabits open forests, agricultural areas, and meadows, where it hunts small mammals, birds, insects, and carrion. It is an excellent glider and uses thermal currents to stay aloft effortlessly, allowing it to spot prey from a distance. The Red Kite is also a social bird, often seen in groups during the migration period, although it is generally solitary outside this time. While its population remains relatively stable, it faces threats such as habitat loss, pollution, and collisions with power lines.

The Rufous Motmot is a medium-sized tropical bird, measuring between 38 and 43 cm in length. It is identifiable by its bright blue crown bordered by a black band, green back, and rufous chest. Its long tail ends with two racket-shaped feathers, characteristic of the genus. Found in the humid forests of Central and South America, it frequents forest edges and open woodlands. Omnivorous, it feeds on insects, small vertebrates, and fruits. It nests in tunnels dug into banks or slopes, where the female typically lays 3 to 4 white eggs. Although currently listed as Least Concern, deforestation poses a threat to its natural habitats.

Elephantulus rufescens is a small insectivorous mammal endemic to East Africa, measuring 10–15 cm with reddish fur and a distinctive elongated snout. It inhabits dry savannas, scrub, and forest edges, feeding on ants and small invertebrates using its long hind legs and sensitive muzzle.

The Red-crested Pochard is a medium-sized diving duck, measuring between 53 and 58 cm in length with a wingspan of 84 to 88 cm. The male is notable for its rounded, bright reddish-orange head, vivid red bill, black chest, and white flanks. The female is more subdued, with brown plumage, pale cheeks, and a dark bill. This species inhabits eutrophic lakes and ponds rich in aquatic vegetation, often bordered by reed beds. It primarily feeds on aquatic plants like pondweeds and charophytes, but also consumes aquatic invertebrates, including mollusks and insects. Migratory, the Red-crested Pochard winters around the Mediterranean and the Black Sea. Although listed as Least Concern by the IUCN, it is sensitive to the degradation of wetlands.

The Red Panda, also known as the Lesser Panda, is a small mammal native to the mountains of the Himalayas and southern China. It measures between 50 and 65 cm in length, with a bushy tail of 30 to 50 cm, and weighs between 3 and 6 kg. Its coat is predominantly reddish, with white patches around the eyes, ears, and muzzle. The Red Panda is primarily arboreal, living in temperate and mountainous forests, where it feeds on bamboo, fruits, berries, roots, and occasionally insects. Although it is an excellent climber, it is also active on the ground. The Red Panda is a vulnerable species, primarily threatened by habitat loss, deforestation, and illegal hunting.

The Raggiana Bird-of-paradise, or Paradisaea raggiana, is an iconic bird of the Paradisaeidae family, endemic to Papua New Guinea. It is renowned for its spectacular plumage, especially in males, who display bright red and orange feathers, along with elongated central plumes. These birds are famous for their impressive courtship displays, where males perform complex dances to attract females. They primarily inhabit tropical rainforests, feeding on fruits, insects, and small animals. Their melodious song and complex social behaviors make them a fascinating subject for ornithologists. Although their habitat is threatened by deforestation, they remain relatively common within their range.

The Republican Paradise-flycatcher is a small bird native to the lowland forests of Sulawesi Island in Indonesia. It measures about 20 cm in length, with a long tail that can reach up to 15 cm, and weighs between 25 and 30 g. What distinguishes the Republican Paradise-flycatcher is its bright coloration, with vivid green, blue, and red feathers and a magnificent crest shaped like a veil. The male, in particular, displays extravagant feathers during courtship displays to attract females. This bird primarily feeds on fruits, seeds, and insects. Although the Republican Paradise-flycatcher is not in immediate danger, deforestation and hunting pose potential threats to its natural habitat.

The Red-legged Partridge is a medium-sized galliform bird, about 33 cm in length. It features a reddish-brown back, bluish-grey chest, and flanks striped with black and white. Its white throat is bordered by a black horseshoe-shaped collar, and it has red legs and beak. Native to southwestern Europe, it inhabits dry open areas, scrubby hills, farmlands, and fallow fields. Non-migratory and ground-dwelling, it prefers running to flying when disturbed. Its diet mainly consists of seeds, young shoots, and insects, the latter being crucial for chicks. Although listed as Least Concern by the IUCN, the Red-legged Partridge is declining in some areas due to habitat loss, overhunting, and hybridization with introduced farm-reared birds.

Psittacula krameri, the rose-ringed parakeet, is a parrot 38–40 cm in length with bright green plumage, a distinctive pink neck ring in adult males, and a red–orange bill. Native to South Asia, it occupies parks, orchards, agricultural lands, and urban environments, feeding on seeds, fruits, and flowers. Social and vocal, it nests in tree cavities and may switch mates within the same breeding season.

The Red Phalarope is a medium-sized aquatic bird, measuring about 20 to 22 cm in length with a wingspan of 40 to 46 cm. It is distinguished by its bright breeding plumage, featuring a gray back, white head, and reddish chest. Outside the breeding season, its plumage becomes duller, with gray and white tones. This bird is known for its reversed breeding roles, where females are more colorful and court males. It primarily feeds on small aquatic invertebrates, which it captures by swimming in circles to create whirlpools that bring food to the surface.

The Red-breasted Sapsucker, or Sphyrapicus ruber, is a medium-sized bird belonging to the woodpecker family. It is easily recognizable by its bright red head, black and white back, and pale yellow belly. This bird is primarily found along the west coast of North America, inhabiting coniferous and mixed forests. It mainly feeds on tree sap, which it extracts by drilling holes in the bark, but it also consumes insects and fruits. The Red-breasted Sapsucker is a partial migrant, moving southward in winter. It is known for its distinctive drumming, used for communication and territory marking.

The rose-colored shrike is a small predatory bird found primarily in bushes, hedgerows, and open fields across Europe, the Middle East, and Central Asia. It is easily recognized by its light gray plumage, reddish head, and strong, hooked beak. This bird primarily feeds on insects, small birds, and rodents, which it captures by ambush and sometimes impales on branches with its beak. It is also known for its territorial behavior and constant vigilance.

The Red-backed Shrike is a medium-sized bird primarily found in hedgerows, scrubland, and open meadows across Europe and Asia. It measures about 20 to 23 cm in length and weighs between 40 and 50 g. Its plumage is characterized by a silvery-gray head, a brown back, and a whitish breast. It also has a distinctive black stripe running through its eyes. The Red-backed Shrike is an excellent hunter, primarily feeding on small birds, insects, rodents, and sometimes small reptiles. It is known for its "impaling" behavior, where it spikes its prey on thorns or barbed wire to store it. While its population remains stable in some regions, it can be threatened by habitat loss, the destruction of hedgerows, and the intensification of agriculture.

The rock pigeon, or Columba livia, is a familiar bird in urban and rural environments. With typically gray plumage and iridescent neck feathers, it features two distinct black bands on its wings. Often seen in large flocks, it feeds on seeds, crumbs, and other food scraps. Highly adaptable, it thrives in various habitats, from coastal cliffs to bustling city centers. The rock pigeon is renowned for its homing ability, which humans have historically used for message delivery. Its prolific breeding, with multiple broods per year, contributes to its widespread global presence.

The Red-throated Pipit is a small migratory bird belonging to the Motacillidae family. It is easily recognizable by its reddish throat, which is particularly visible in males during the breeding season. This passerine measures about 14 to 15 cm in length, with a wingspan of 25 to 27 cm. Its plumage is brownish with dark streaks on the back and flanks, allowing it to blend effectively into its natural habitat. It primarily inhabits tundras and wet meadows in summer, while migrating to warmer regions in winter, notably in Africa and South Asia. Its song is a melodious trill often heard in the vast expanses where it nests.

The red-throated pipit is a small migratory passerine bird found primarily in meadows, mountains, and Arctic areas across Europe and Asia. It is easily recognizable by its streaked brown plumage, red-orange throat, and furtive movement. This bird primarily feeds on insects and seeds, which it captures by running or foraging in the grass. During the breeding season, it performs song flights, a characteristic that makes it easy to spot in its habitat.

The Red-throated Diver is a seabird found primarily in the cold waters of the North Atlantic, particularly in Northern Europe and Canada. It measures about 50 to 60 cm in length, with a wingspan of 80 to 100 cm, and weighs between 1.5 and 2 kg. Its plumage is primarily gray and white, with a dark back and a light breast. The Red-throated Diver is an excellent diver, primarily feeding on fish and crustaceans, which it catches by diving underwater. It has well-adapted legs for swimming and spends a significant amount of time foraging for food at sea. While its population remains relatively stable, this species is vulnerable to human disturbances and marine pollution.