The blue-footed booby (Sula nebouxii) is a marine bird in the family Sulidae, which includes ten species of long-winged seabirds. Blue-footed boobies belong to the genus Sula, which comprises six species of boobies. It is easily recognizable by its distinctive bright blue feet, which is a sexually selected trait. Males display their feet in an elaborate mating ritual by lifting their feet up and down while strutting before the female.

Geese fight during the annual Geese Fight Day in the northern Serbian village of Mokrin, some 160km (100 miles) from Belgrade February 22, 2015. Every year in the last week of February, goose fights are held in the northern Serbian village of Mokrin. Left alone, male geese, or ganders, are unlikely to fight each other, hence why females are brought along for whose affections the ganders then fight until one or the other gives up. (Photo by Marko Djurica/Reuters)

Lily Winter (top) and Lana Austin (back) match up during the “Atomic 6 – Atomic Fighter” wrestling show at the Azvex Brewery in Liverpool, Britain, 21 February 2024. Atomic Pro Wrestling was started in 2023 by wrestling enthusiasts and former training mates Matt Davies, Declan McCarthy (stage name Declan Sands) and Chris Welsh as a way to showcase emerging male and female wrestling talent from England’s North and North West regions, which they felt were being overlooked and under-represented. In contrast to the highly polished world of televised WWE (World Wrestling Entertainment), Atomic takes a DIY approach, holding shows at a local brewery large enough to make way for the ring, and where customers can enjoy craft beer as they watch the wrestling matches from up close. (Photo by Adam Vaughan/EPA/EFE)

A family of baby brown bears appear to be dancing to Ring a Ring o' Roses as their mother relaxes behind a tree nearby. At just a few months old, two young males and one female gather in a circle, clutch each others' hands and begin to dance to the popular nursery rhyme. It's almost like a scene from a school playground as the bears joyfully play together, tapping their feet and moving around in a circle. (Photo by Valtteri Mulkahainen/Solent News & Photo Agency)

A female Kurdistan Workers Party (PKK) fighter stands near a security position in Sinjar, March 13, 2015. Women fighters at a Kurdistan Workers Party (PKK) base on Mount Sinjar in northwest Iraq, just like their male counterparts, have to be ready for action at any time. Smoke from the front line, marking their battle against Islamic State, which launched an assault on northern Iraq last summer, is visible from the base. Many of the women have cut links with their families back home; the fighters come from all corners of the Kurdish region. (Photo by Asmaa Waguih /Reuters)

A female Kurdistan Workers Party (PKK) fighter works on her laptop while watching a Kurdish TV station at a base in the Sinjar mountains, March 11, 2015. Women fighters at a Kurdistan Workers Party (PKK) base on Mount Sinjar in northwest Iraq, just like their male counterparts, have to be ready for action at any time. Smoke from the front line, marking their battle against Islamic State, which launched an assault on northern Iraq last summer, is visible from the base. Many of the women have cut links with their families back home; the fighters come from all corners of the Kurdish region. (Photo by Asmaa Waguih/Reuters)

A golden huddle by Minqiang Lu, China. Two females and a male golden snub-nosed monkey huddle together to keep warm in the extreme cold. Threatened by forest loss and fragmentation, this endangered species is confined to central China. Restricted to living high up in the temperate forests, these monkeys – here in the Qinling mountains in Shaanxi province – feed mostly in the trees, on leaves, bark, buds and lichen. In heavy wind and snow, Minqiang walked up the mountain carrying his equipment. He stayed for half an hour in temperatures of –10C opposite the tree where the group was huddled before achieving this eye-level composition. (Photo by Minqiang Lu/Wildlife Photographer of the Year)

The maid-themed cafe in Hangzhou, China on September 29, 2016. A cafe has been bringing in droves of new customers after hiring young women to dress up in Frech maid costumes while serving diners. Curious coffee- and coffee-lovers are coming from all corners of Hangzhou, capital of East China's Zhejiang Province, to get a taste of the “maid cafe” experience. The business is said to have been opened by a man surnamed Yu and his friends, all whom are natives or graduates of the city. The all-female staff who donned the black and white French maid outfits are also students currenting living or studying in Hangzhou, allowing them to marry their passion for serving with the part-time job. (Photo by AsiaWire)