The week in wildlife

Birds on a tree at sunset in Johannesburg Photograph: Guillermo Arias/AP Photograph: Guillermo Arias/guardian.co.uk The Okavango delta is seen from the air outside Jao Luxury Safari Camp in Maun, Botswana. It is the world's largest inland delta and is home to an abundance of wildlife Photograph: Chris Jackson/Getty Images Photograph: Chris Jackson/guardian.co.uk A giraffe in the Hluhluwe Imfolozi Game Reserve in Kwa Zulu-Natal Photograph: Daniel Dal Zennaro/EPA Photograph: Daniel Dal Zennaro/guardian.co.uk A cheetah ( Acinonyx jubatus ) at a game reserve , 50 miles from Port Elizabeth, South Africa Photograph: Robert Ghement/EPA Photograph: Robert Ghement/guardian.co.uk A butterfly lands on a flower in Cundy's Harbour, Maine, on the first official day of summer, 21 June Photograph: Pat Wellenbach/AP Photograph: Pat Wellenbach/guardian.co.uk A damselfish ( Stegastes nigricans ) selectively 'weed' algal gardens in the Indo-West Pacific region Photograph: Hata et al./BMC Evolutionary Biology Photograph: Hata et al./guardian.co.uk The juvenile osprey, which became known as the Lady of the Loch , who was thought to be on the brink of death this week Photograph: Kevin Hacker/Scottish Wildlife Trust Photograph: Kevin Hacker/guardian.co.uk A water lane running through tall cypress trees covered with Spanish moss on Caddo Lake near Uncertain, Texas. Visitors to this lake tucked away in Texas' forested northeast corner find a mysterious labyrinth of swamps and bayous that are home to a vast array of wildlife – from owls to eagles to alligators Photograph: Jamie Stengle/AP Photograph: Jamie Stengle/guardian.co.uk A bird cleans the eye of a rhino while another sits on its head at Kruger National Park, South Africa Photograph: Christophe Simon/AFP/Getty Images Photograph: Christophe Simon/guardian.co.uk A bird sits on a branch at Kruger National Park, some 50 miles from Nelspruit, South Africa Photograph: Pierre-philippe Marcou/AFP/Getty Images Photograph: Pierre-philippe Marcou/guardian.co.uk A dolphin swims in the Barataria Bay near oil from the Deepwater Horizon spill in near Grand Isle, Louisiana Photograph: Charlie Neibergall/AP Photograph: Charlie Neibergall/guardian.co.uk A group of male chimpanzees attack an adult male from another community. The victim is at the bottom of the pile of attackers and hidden from view. Chimpanzee gangs kill to seize new territory , a new study has found Photograph: John Mitani/University of Michigan Photograph: John Mitani/guardian.co.uk A young adult male, who participated in the lethal attack , leaps on the dead body of the victim Photograph: John Mitani/University of Michigan Photograph: John Mitani/guardian.co.uk Posidonia Meadows reflect pollution levels in the Mediterranean Photograph: Antonio Tovar-Sánchez et al/SINC Photograph: Antonio Tovar-Sánchez et al/guardian.co.uk A bee which has been fitted with a tiny radio ID tag to monitor its movement as part of research into whether pesticides could be giving the insects brain disorders Photograph: Andrew Martin/BBSRC/PA Photograph: Andrew Martin/BBSRC/guardian.co.uk Stallions fight for their position in the herd in Rauris, Austria Photograph: Kerstin Joensson/AP Photograph: Kerstin Joensson/guardian.co.uk The Houbara bustard is a sandy-coloured resident of deserts , with its distribution ranging from North Africa to Mongolia. Females that observed highly displaying male birds in the experiment were more fertile and had a greater breeding success due to an increased allocation of testosterone into their eggs, leading to an increase in the growth rate in chicks Photograph: Adeline Loyau, UFZ/CNRS Photograph: Adeline Loyau, UFZ/guardian.co.uk A caracal walks in the evening light in Ngamiland district in Maun, Botswana Photograph: Chris Jackson/Getty Images Photograph: Chris Jackson/guardian.co.uk A baby beluga whale named Nala swims with her mother Aurora moments after being born at the Vancouver Aquarium in Vancouver in 2009. The aquarium announced on 22 June that Nala died of a respiratory condition overnight and had been sick for two weeks Photograph: Andy Clark/Reuters Photograph: Andy Clark/guardian.co.uk