The week in wildlife

A squirrel holds a nut while sitting on the branch of a tree in Kosovo Photograph: Valdrin Xhemaj/EPA

An elk walks in a field within the 19-mile exclusion zone around the Chernobyl nuclear reactor near the abandoned village of Krasnopolie. Still inhospitable to humans, the zone – a contaminated area around the site of the nuclear reactor explosion of 1986 – is now a nature reserve and teems with wild animals Photograph: Vasily Fedosenko/Reuters

An Omaniundu reed frog (Hyperolius sankuruensis). Conservationists have announced they have found two species of African frog and a Mexican salamander that had been thought to be extinct Photograph: Jos Keilgast/AFP/Getty Images

The brassia gireoudiana orchid, exhibited in San Jose, Costa Rica. The exhibition was part of the project 'Storage of orchid seeds for sustainable use' which gathered 30 experts from 20 countries worried about the future of this flower and the purpose of consolidate a seed bank in which 23 institutions of several countries are working Photograph: JEFFREY ARGUEDAS/EPA

Bass rock in the Firth of Forth, Scotland, the largest single rock colony of northern gannets in the world, taken by photographer Jason Hawkes, as part of the Britain from the Air exhibition. Photograph: Jason Hawkes/PA

The winner of the underwater group and overall winner of the competition: 'Flight of the Rays' by Florian Schulz from Germany, which shows an unprecedented congregation of Munkiana Devil Rays in Mexico An incredible picture of rays swimming through the ocean in a colossal school has scooped top prize in the Environmental Photographer of the Year 2010 awards. The thousands-strong group of Munkiana Devil Rays were spotted in Baja California Sur, Mexico, by German conservation photographer Florian Schulz. Organised by the Chartered Institution of Water and Environmental Management (CIWEM), Winning photographers will have their images showcased in a free international exhibition at The Air Gallery in London from October 25-30. Photograph: Florian Schulz/Barcroft Media

The sun sets behind a burned tree and smoke from a forest fire at the Brasilia national park. After 118 days without rain, fires caused by the drought have destroyed about 28% of the national park, according to the local fire department Photograph: Ricardo Moraes/Reuters

A screengrab showing a male Bengal tiger taken from the documentary, Lost Land of the Tiger. A few seconds of film showing tigers roaming wild in the foothills of the Himalayas could provide the 'missing link' to an ambitious plan to try to save them from extinction Photograph: BBC/PA

Perched on a flower, a praying mantis in the morning sun during the last days of summer Photograph: Rick Roach/AP

A harvest mouse balancing between two ears of wheat in Alsace, France Photograph: Biosphoto/SpecialistStock/Barcroft

A new species of sea slug has been discovered by a UCSB marine scientist Photograph: UCSB

A female (left) and male (right) northern buffed-cheeked gibbon. German scientists said they had discovered a new rare and endangered ape species in the tropical rainforests between Vietnam, Laos and Cambodia by its distinctive song. The new type of crested gibbon, one of the most endangered primate species in the world, is called the northern buffed-cheeked gibbon or Nomascus annamensis, a statement from the German Primate Centre (DPZ) said Photograph: Tilo Nadler/AFP/Getty Images

The UK's oldest known Arctic tern has been discovered on the Farne Islands, 30 years after it was ringed as a chick, the National Trust said today. The bird was originally ringed on the islands off the coast of Northumberland on June 28, 1980, when it was just a few days old Photograph: John Walton/PA

A rare albino turtle at the Sea Turtle Reserve Centre in Kosgoda. The Kosgoda Centre is a turtle conservation project which collects turtle eggs from the beaches for hatching before poachers remove them as they are considered a delicacy. Once hatched the small turtles are released. Sri Lankan waters are home to several common as well as rare species of marine and freshwater turtles Photograph: M.a.pushpa Kumara/EPA

White rhinos await buyers in pens at the annual auction in the Hluhluwe-Imfolozi national park. South Africa has suffered a huge increase in poaching of the endangered animals whose horns are prized as aphrodisiacs in Asia and elsewhere Photograph: Mike Hutchings/Reuters

Wildebeest after crossing the Mara river during a migration in the Masaai Mara game reserve. Plans for a new road that would cause the Serengeti ecosystem to 'collapse' is attracting international concern Photograph: Thomas Mukoya/REUTERS