The best way to guarantee breakfast in bed for some small African birds is falling asleep on your dinner plate—even if it's a giraffe's armpit.

Scientists have long known that yellow-billed oxpeckers hang out on massive African mammals like giraffe, water buffalo, and eland during the day—an often beneficial relationship that provides hosts with cleaner, healthier skin. These small brown birds can often be seen perched on top or hanging off the animals, picking through their hair in search of tasty parasites like ticks.

But a series of rare photos from a large multi-year camera trap study in Tanzania's Serengeti National Park have revealed that the birds actually roost on some of their hosts overnight. The National Geographic Society