In WW2, Royal Air Force bombers carried homing pigeons as emergency survival equipment in watertight containers (photo of one in this article)

This article says: "The British Royal Air Force determined that one in every seven of its crewmen who were rescued after being forced down at sea owed his life to a message sent by pigeon."

Here are two articles on the most famous case:

The pigeon that saved a World War II bomber crew

Winkie the RAF Pigeon who Saved the Life of a Bomber Crew

Here's a wartime report citing this and two other cases as "a few examples", from 15 Feb 1944
The use of Pigeons by the RAF

Reading the citations, it seems that 7 of the 32 homing pigeons awarded the Dickin Medal in WW2 were released from crashed RAF aircraft:

Pigeons at War the RAF and the National Pigeon Service

However, these days, personal locator beacons (PLBs) are less bulky and require less feeding than pigeons.

I was going to go with a pigeon over a PLB til I read the last line!

Whilst BAU continues, I have more faith in PLBs, emergency radios, satellite telephones and the like than in homing pigeons.

Pigeons are perhaps worth considering in a post apocalyptic scenario. They are fairly easy to keep and can be bred for best homing instinct. Eat the failures !

O/T trivia, a major London hospital used homing pigeons until recently, to carry blood samples from the ward to a lab in another building.
The distance was modest, but pigeons were quicker and cheaper than a human messenger.

The carrier pigeons were also used in Vietnam, for solders whom did not exist in countries that did not exist either.
So I have been told

It's fascinating that such a system could be so successful! The modern brain boggles ... but then it wasn't floating in the icy Channel, hoping beyond hope for rescue.

(BTW, I really think you should have posted this on March 32. It would have messed with us completely. )

My kid had an apartment in Albany, NY, in a 19th century building. It had a dedicated carrier pigeon window with shelving and desk built around it. The local historians reported that the building was home to a local industrialist who communicated from home with staff at his factory across the river in Rensselaer. It must have been a pretty reliable system if it was worthwhile to create architecture to support it.

Tochuina tetraquetra

Homing Seal Slug