Tuesday, October 28, 2014

Eating versus investigating, two clear cases of decision making

It is important to recognize situations where animals clearly have a decision to make. These constitutes experiments of sorts, that is controlled conditions where behavior can be clearly observed. It does not matter that these conditions are created for other purposes.

Recently we have created two situations in which our observation herd of horses had to choose between eating and what I will call investigating, for want of a better term. In both cases they chose investigating, which is interesting.

In the first case we let the herd into a small field for the first time. It is fall and the grasses in their regular fields has been eaten down so that it is very short, just an inch or two tall inmost places. In fact we have begun feeding hay when the weather is bad.

The new field was thick with grass, over a foot tall in most places. The horses have never been in this field but it is across a fence from one of their regular fields so well known to them after several years of seeing into it. This field is also rather complex as it has two cross fences with gates in different places.

When we turned the horses into this new field they clearly had two options. They could start eating the new grass or they could explore the field. They chose to explore the field, in a very decisive manner.

They stayed together and covered the territory, getting into every section and corner, which took about five minutes. They did not eat during this time. Then they suddenly stopped exploring and started eating. We have now put them into this field four times and the investigating behavior has not been repeated. They know where they are it seems.

As an aside, they have done a lot of what we call grazing in motion, so the grass is being clipped pretty uniformly in the entire field.

The second case arises when we feed hay. There are seven horses in the observation herd, so we scatter the hay in at least that many small piles. The horses could simply pick a pile and start eating, perhaps after sorting for dominance, but that is not what happens.

Instead, the horses actively investigate the hay. It appears that every horse looks at every pile but it would take careful video analysis to determine this. There is certainly a great deal of milling about among the piles. I have seen this behavior repeatedly and will study it more closely.

These two cases illustrate a simple point. If we recognize when animals have big decisions to make we can study their decision making.  It can be surprising.

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.