The week in wildlife – in pictures

Fans of Barbara Kingsolver's latest book Flight Behaviour will breathe a sigh of relief knowing that the monarch butterflies have migrated safely to their butterfly sanctuary in the central Mexican state of Michoacan this year, and not ended up lost in the Appalachian mountains due to climate change as the book imagines. Biologist Felipe Martinez, sub-director of the reserve, said the butterflies' arrival has been delayed due to several cold fronts hitting Mexico and continued rain storms. In 2000, Mexico established a 56,000-hectare reserve for the butterflies in Michoacan and part of the state of Mexico, containing some 6.7 million trees Photograph: Edgard Garrido/Reuters

Roe deer run across a field near Aerzen, Germany Photograph: Christoph Schmidt/Corbis

A murmuration of starlings above the small village of Rigg, near Gretna, in the Scottish Borders. The weight of the resting birds on power lines caused some power localised power outages in the village. Numbers of starlings, a 'red-listed' species of conservation concern which dropped to a record low in the 2012 RSPB Big Garden Birdwatch, declined by a further 16% this year Photograph: Owen Humphreys/PA

Autumn trees at Underbank reservoir in West Yorkshire Photograph: Rui Vieira/PA

A family of polar bears trudges through a snow storm, near Churchill, Hudson bay, Canada. Melting sea ice is forcing polar bears on to dry land – and, increasingly, into contact with humans Photograph: Norbert Rosing/NGC/Getty

Ravens from northern Poland and Russia arrive in the southern Czech town of Židlochovice. The birds are migrating to avoid the colder weather during the winter further north before returning in mid-March Photograph: Radek Mica/AFP/Getty Images

An elephant is pictured near an electric fence marking the boundary of Udawalawe national park, Sri Lanka. More than 7,300 wild Sri Lankan elephants – a subspecies of the Asian elephant – roam the island nation, according to data from wildlife authorities Photograph: Ishara S.kodikara/AFP/Getty Images

A bald eagle returns to its nest after catching a fish at the Conowingo Dam on the Susquehanna River in Maryland, US. The eagles gather around the dam and grow in numbers towards the year's end Photograph: GARY CAMERON/Reuters

Anson Wong, a prominent figure in the illicit smuggling of endangered reptiles, is being officially investigated by Malaysia's wildlife department following the airing of an exclusive documentary by Al Jazeera. Wong, dubbed 'the lizard king' and 'the Pablo Escobar of animal trafficking', has been caught twice by authorities and has served eight years in jails in the US and Malaysia Photograph: Lee Ali/Return of the Lizard King/Al Jazeera

The threatened island fox (Urocyon littoralis), numbering less than 100, can only be found on the Channel Islands of California Photograph: George H.H. Huey/Corbis

A bird soaked with oil shelters among rocks after an oil pipeline explosion in Qingdao, Shandong province, China. Asia's top oil refiner Sinopec has cut production for at least two of its refineries after the pipeline blast which killed 55 people, industry sources said Photograph: Stringer/Reuters

A buffalo (and two avian hangers-on) at the Masai Mara national reserve, Kenya. To pursue food and water, a large number of wild animals made their second migration trip of this year to the Kenyan reserve due to drought in the Serengeti national park in Tanzania Photograph: Meng Chenguang/Corbis

A hyena eats a wildebeest in the Masai Mara reserve Photograph: Meng Chenguang/Corbis

A tiny fish swims in front of the mouth of a lemon shark (Negaprion brevirostris) in the Bahamas Photograph: Barcroft Media

A hippo is seen in the Gambia River in Niokolo-Koba national park, Senegal. Located in a well-watered area along the banks of the Gambia river, the gallery forests and savannahs of Niokolo-Koba have a very rich fauna, among them Derby elands (largest of the antelopes), chimpanzees, lions, leopards and a large population of elephants, as well as many birds, reptiles and amphibians Photograph: Wu Xiaoling/Corbis

Salam, an African lion, stands on the branches of a tree at the Ramat Gan safari near Tel Aviv, Israel. Tree-climbing lions are relatively uncommon and are best known for their populations in Uganda's Queen Elizabeth national park and Tanzania's Lake Manyara national park. The Zoological Center Tel Aviv-Ramat Gan (commonly known as the Safari Ramat Gan) is the largest collection of wildlife in human care in the Middle East. The 250-acre site consists of both a drive-through African safari area and a modern outdoor zoo Photograph: Ariel Schalit/AP

Around 10 million trees are estimated to have died as a result of the St Jude storm that swept across England last month, according to Forestry Commission figures released on Friday Photograph: Matthijs Wetterauw/Alamy

A sloth hangs from a tree on the outskirts of Colón city, Panama. The sloth population was saddened this week to learn of the departure of Shiona Tregaskis from the Guardian environment desk, but wished her well in her new position on technology. The sloth is among her favourite animals Photograph: Carlos Jasso/Reuters