Whales and dolphins strandings have happened so many times in the last months that I've decided to write down a little summary.

I take the chance however to take a deeper look into the matter.
First of all, even if the frequency of the beachings has lately been really high, this shoud not deceive us because cetaceans strandings have always occured in human history as you can see in the following drawings from 1577 and 1598 (enlarge them clicking on it, they are wonderful documents)

Three Beached Whales, a 1577 engraving by Dutch artist Jan Wierix, depicts stranded Sperm Whales.

Stranded whale at Katwijk in Holland in 1598.

and in this picture from 1902 (compare it with THIS picture from one of the strandings of this year... the situation seems pretty similar, isn't it?)

A mass stranding of Pilot Whales on the shore of Cape Cod, 1902.

So, speaking about the causes of these terrible events we should not forget a lot of natural circumstances that have always caused them:

• rough weather, weakness due to old age or infection, difficulty giving birth, and navigational mistakes , taking in consideration that a single stranded animal (especially if it's the leader) can prompt the entire pod to respond to its distress signals and become stranded, are the most common causes
• hunting too close to shore and following the preys in shallow waters is another common cause
  
• In some cases predators (such as killer whales) have been known to panic whales, herding them towards the shoreline
• Another proposed cause is that the echolocation system used by many whales can have difficulty picking up very gently-sloping coastlines.
• A controversial theory attributes the strange behaviour to radical changes in the Earth's magnetic field just prior to earthquakes and in the general area of earthquakes.
• "Follow-me" strandings occur when larger cetaceans follow dolphins and porpoises into shallow coastal waters. The larger animals may be familiar with faster moving dolphins in their area and become habituated to following them. If an adverse combination of tidal flow and seabed topography is encountered, the larger species are at much higher risk of being trapped.

Unfortunately it seems that another cause has been added by men the sonar noise pollution possibly explaining the huge numbers of recent strandings:
There is evidence that very loud noise from anti-submarine warfare sonar may hurt whales and lead to their beaching. On numerous occasions whales have been stranded shortly after military sonar was active in the area, suggesting a link. Reasons as to how sonar may cause whale deaths have also been put forward by scientists after necropsies found internal injuries in stranded whales. In contrast, whales stranded due to seemingly natural causes are usually healthy prior to beaching.


The following are the strandings that hit the news in the last months, clicking on the picture or on the title will take you to the corresponding post: