Nick Garbutt / Veterinarian from Project Oncafari measuring teeth and jaw of Jaguar (Panthera onca palustris) female trapped following the death of a Cow. Caiman Lodge, southern Pantanal, Mato Grosso do Sul, Brazil....

SCOTLAND: The Big Picture / Conservationist from The Royal Zoological Society Scotland / RZSS measuring the size of a Scottish wildcat's (Felis silvestris grampia) testes. Inside RZSS mobile vet unit, Strathsprey, Cairngorms Nat...

SCOTLAND: The Big Picture / Field worker measuring bill of Golden eagle (Aquila chrysaetos) chick, Glen Tanar Estate, Aberdeenshire, Scotland, UK, June 2015.

Sebastian Kennerknecht / Snow Leopard (Panthera uncia) biologist, Shannon Kachel, and veterinarian, Ric Berlinski, measuring canine tooth of male during collaring, Sarychat-Ertash Strict Nature Reserve, Tien Shan Mountains, e...

Sebastian Kennerknecht / Snow Leopard (Panthera uncia) wild biologist, Shannon Kachel, and ranger, Ulan Abulgaziev, measuring metatarsal pad width of male during collaring, Sarychat-Ertash Strict Nature Reserve, Tien Shan Mou...

Sebastian Kennerknecht / Mountain Lion (Puma concolor) biologists, Chris Fust and Justine Alyssa Smith, measuring canine teeth of sub-adult male during collaring, Santa Cruz Puma Project, Santa Cruz, Monterey Bay, California

Nick Upton / Roisin Campbell-Palmer of the Royal Zoological Society of Scotland using callipers to measure the tail of an Eurasian beaver (Castor fiber). Beaver from escaped population on River Otter. Project over...

Wendy Shattil / Black-crested titmouse (Baeolophus atricristatus) in the hand, biologist from Texas Parks and Wildlife measuring beak length during bird ringing session. Southmost Preserve, The Nature Conservancy res...