These adorable cats – which are twins – showcase their contrasting blue and green eyes. The cats have a condition called heterochromia iridis, which causes each eye to vary in color. (Photo by @sis.twins/Caters News Agency)

These stunning images look to highlight the amazing natural beauty that can be found across the United States. The U.S. Department of the Interior (DOI) recently released their Best of 2015 list, featuring a variety of animals, weather conditions and landmarks. Included in the list are gleaming auroras, adorable groups of otters and owls, and breath-taking shots across the likes of the Grand Canyon and national parks. Each of the spectacular shots, all of which were taken during 2015, featured on the Department of the Interiors Instagram account throughout the year, taken by both members of staff and members of the public. Here: Arches, National Park. (Photo by Caters News)

An adorable baby owl has proved to be a real heart-breaker thanks to its heart-shaped head. Although Griffin the Lesser Sooty Owl might look like a feather duster, the tiny eight-week old chick will soon be ready to fly. And the heart outline that surrounds his giant eyes and beak means he is set to be the star of the bird show at Taronga Zoo, Sydney. (Photo by Caters News Agency)

In his adorable series of images, photographer Andrius Burba takes a look at all kinds of furry and fantastic moggies – from underneath. From furry fluff-balls to hairless kitties, felines from all corners of the globe make up the creative photographer's latest project. Andrius, from Lithuania, created a technique whereby his camera is hidden in a Perspex box, that the cats are encouraged to walk across – resulting in some truly wonderful captures. (Photo by Andrius Burba/Caters News Agency/Underlook)

David and Lana Fechter have recently adopted two adorable Siberian bear cubs that were rejected by their mother at a Chicago zoo. The two nine-week-old male cubs, Lewis and Clark, are being kept in an inside closure and are being bottle fed. When the twins get bigger and more independent, they’ll be be given a large natural enclosure with ponds and ridges to live in at Shalom Wildlife Sanctuary.

A adorable bear cub cant get enough of playing buckaroo – as it hangs onto its mum splashing about in a river. His mum was attempting to catch a fish supper for the pair as the plucky cub continued to jump on her back. And as she was concentrating on her meal the young bear became a distraction. So she sprung into life with him on her back before he was tossed into the water much to his delight. (Photo by Lisa Sidorsky/Caters News)

This adorable and unlikely pair of best friends are inseperable. Kitty the kitten was abandoned and Buttons the Jack Russell was rejected by his mum. They eat, sleep and play together while they are being hand reared at our centre in Old Windsor, Berkshire. We would love for them to find a new home together when they are ready to leave our care in the near future.