Gifts given to royals when they were children, including the youngest Prince George, go on display today at Buckingham Palace.
The princes made royal internet history as they appeared for a live question and answer session today.
Hong Kong is acting as the gateway for illegal ivory entering China - where the item is high in demand.
Prince William has suggested that reporters gathered in flood-hit Datchet should "come and help instead of throwing cameras around."
The Duke of Cambridge was speaking to ITV News reporter Rupert Evelyn shortly after being pictured alongside his brother Harry helping to move sandbags in the Berkshire village.
Princes William and Harry wanted to show their support for the flood victims, Kensington Palace have said, after the pair were spotted helping unload sandbags in Datchet, Berkshire this morning.
A spokesman from Kensington Palace said:
They wanted to show their support for the flood victims and have joined the armed forces relief effort.
Princes William and Harry have been spotted helping move sandbags in flood-hit Datchet.
The royals turned up at 7am at Datchet Golf Club where they helped load sandbags onto a crane, according to local reporter John Dickens.
Here's a snap of Prince Harry and Will helping out with the Household Cavalry this morning in Datchet. http://t.co/9xrMyhFlMM
Datchet has been heavily affected by the ongoing floods crisis and with further heavy rain due, there have been fears the situation could deteriorate.
Prince William approached journalists from the Guardian and said: “Why don’t you put your notebook down and give us a hand with the sandbags?”
William and Harry were spotted along with Prince Harry helping move sandbags in flood-hit Datchet.
However after reporters agreed to help, aides intervened and said it would not be possible due to a lack of appropriate clothing.
Princes William and Harry have been filmed helping unload sandbags in a private trip to the flood-hit village of Datchet in Berkshire.
Dressed in waterproofs and wellingtons, the royals helped shift heavy sandbags onto the back of an army truck.
The princes were spotted working with the team of 20 members of the Household Cavalry and Network rail staff by a Guardian reporter.
A royal aide told the newspaper that the pair had been working with members of the Army unit this morning in numerous locations and that it was a "private effort" to help.
The Duke of Cambridge has hailed tomorrow's major international summit on the trafficking of endangered wild animals as the "beginning of the end of this despicable trade".
Speaking at a Natural History Museum reception attended by conservation charities, philanthropists and leading wildlife campaigners Prince William said:
"Tonight we are here with a single, shared purpose - to use our collective influence to put a stop to the illegal killing and trafficking of some of our world's most iconic and endangered species."
During the event William met one of the world's biggest action movie actors Jackie Chan who is in London to launch an anti-poaching video for the organisation WildAid of which he is an ambassador.
Prince William's decision to go hunting in Spain shortly before he makes a speech at a conservation conference is just 'poor PR' and should not distract from the major issues, an expert has told Daybreak.
Will Travers from the Born Free Foundation said hunting and poaching "were not the same thing", with the latter being a "£12bn international illegal wildlife trade".
Prince William will give a speech tonight to mark the imminent start of an international conference that aims to tackle the threat to the world's endangered animals.
William will make an address at a Natural History Museum reception as world figures prepare to discuss ways of saving animals like elephants, rhinos and tigers tomorrow.
His father Prince Charles will give a speech at the London Conference on the Illegal Wildlife Trade being hosted by the Government at Lancaster House on Thursday. William will also attend and it will be hosted by the Prime Minister.
William has joined forces with the Prince of Wales to record a video message calling on the world to act now to save endangered animals.