In numbers: How many whales are found dead on UK beaches?
Five sperm whales died and washed up on beaches in the east of England within days of each other. But how many of the sea creatures die every year on our shores?
Whales are stranded on UK beaches at a rate of more than five a month, according to the most recent figures from 2014.
There were 66 reports of stranded whales, 16 of which underwent post-mortem examinations.
Starvation and physical trauma, including attacks from other sea creatures, were the most common causes.
The biggest dead creature that year was a 15.3m (50 ft 2in) sperm whale on the Isle of Sheppey in Kent.
A post-mortem examination found the male whale died of "lack of recent feeding".
If whales become stranded while still alive rescuers attempt to get them back out to sea.
The shallow North Sea between Scotland and Norway can act as a natural trap for whales.
In June 2015 21 long-finned pilot whales became stranded at Staffin on Skye. Most were floated back to sea but several became stranded again.
Four sperm whales washed up on two beaches over the weekend in Lincolnshire and Norfolk and are all thought to belong to the same pod as 12 others that were found dead in Germany and the Netherlands last week. A fifth washed up on the east coast of England on Monday.
A killer whale was also found dead on the Scots island of Tiree on 3 January 2016. A post-mortem found she was likely to have drowned as a result of getting entangled in a fishing line.
The Cetacean Strandings Investigation Programme is examining the sperm whales' bodies to find a cause of death.
The organisation's data shows there were 66 whales of at least 11 different species stranded in the UK in 2014. Seven of them were sperm whales like the ones that washed up at the weekend. Most of them would have died, experts say.
The 16 stranded whales whose deaths were investigated in 2014 included three sperm whales.
Dr Peter Evans, director of Sea Watch Foundation, said sperm whales can get stranded together as they swim in groups.
"The whales normally keep in strong contact with one another by sonar, and it is possible that as a result, here they have responded to distress signals from one other which then has led to part of the group stranding together," he said.
"The waters off East Anglia are typically shallow and gently sloping and thus difficult for the whales to find navigational cues.
"They would typically use sonar signals to find their way out of such situations but the shallow waters and nearby sloping mud and sand banks, which make up the geography of these areas, is not ideal for them and can cause difficulties as is probably the case here.
"That is likely to be why these incidents are more frequent in the southern part of the North Sea than for example the west coast of the British Isles."
Dr Evans said not all strandings resulted in a post-mortem examination as in some cases whales or other cestaceans, such as porpoises, dolphins and turtles, can have died a long time earlier at sea and been washed ashore.