8 December 2014
Last updated at 18:08
The Duke of Cambridge has met US President Barack Obama at the White House as part of a three-day visit.
Prince William held talks with President Obama in the Oval Office, in advance of a speech to the World Bank on wildlife crime.
President Obama said work to protect endangered species was “very important”.
The prince also joked with the president about the “chaos” surrounding the birth of Prince George.
Prince William and his wife, the Duchess of Cambridge, arrived in New York on Sunday night. He travelled to Washington alone while Catherine remained in New York where she visited a Harlem-based organisation supporting families.
At the White House, the prince told the president about his son’s arrival, saying: “The excitement of the event and everything else was just chaos.”
He also predicted a “busy year” in 2015, when Catherine is due to give birth to the royal couple’s second child.
BBC royal correspondent Nicholas Witchell said the prince had enjoyed access “most politicians can only dream about”.
The prince and president spoke for around 20 minutes
The duke paid tribute to his father and grandfather when he spoke at the World Bank
Catherine visited the Northside Centre for Child Development in Harlem on Monday
Catherine was greeted with cheers when she arrived
There has been “huge excitement” in New York, the British consul general in the city said
Later, in a speech at the World Bank, the prince said: “In my view, one of the most insidious forms of corruption and criminality in the world today is the illegal wildlife trade.”
He attacked those who “loot our planet to feed mankind’s ignorant craving for exotic pets, trinkets, cures and ornaments derived from the world’s vanishing and irreplaceable species”.
Paying tribute to his father, the Prince of Wales, and his grandfather, the Duke of Edinburgh, he said: “They helped to bring about a revolution in attitudes towards our natural environment.”
‘Loss to humanity’
He added: “From them, I learned that our relation to nature and wildlife goes to the heart of our identity as human beings. From our sheer survival, to our appreciation of beauty and our connection to all other living things.
“Seen in this light, the extinction of any of the world’s species of animals is a loss to all humanity.”
He said wildlife crime “goes to the heart of our security”, “distorts economic development” and “fuels sources of conflict”.
Meanwhile, Catherine visited Harlem’s Northside Centre for Child Development.
She was greeted with cheers from well-wishers when she arrived at the centre, which provides educational and mental health services to children and families.
Later, the couple will attend an NBA basketball match.
Ahead of the visit, Danny Lopez, the British consul general in New York, said there had been “incredible interest” in the royal couple.
He said there was “huge excitement” from people in the city.