Friday, October 17, 2014

Migration decision mystery

The blue jays are migrating past our observatory these days. They come by in groups of from five to forty and have been doing so for several weeks; perhaps a thousand have passed by so far.

There is a great decision making mystery with the blue jay migration. It is well known and described here:
And here:

It appears that individual birds decide each year whether to migrate southward or not. There are large numbers of migrants every year but any given blue jay may or may not be among them.

The question is how each bird makes this annual migration decision? For example, what factors does the bird consider?

It has been suggested that the weather and the food supply may be important. This may be true but it does not explain why some birds in the same place leave while others stay. It may have to do with each bird's personality, which might be quite complex. Perhaps the birds that migrate are literally those who feel like doing so.

Another possibility is that these are actually group decisions. Birds make a lot of collective decisions, in ways that are poorly understood. How a flock decides which way to fly, without a leader, is the classic example of group decision making and it is poorly understood. Blue jays migrate in groups. Perhaps they also decide who will go that way. (Horses also make group decisions, such as where to graze.)

The point is that blue jay migration is a clear case of something that is actually widespread and poorly understood, namely animal decision making.

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