That's the most common reason I think. Like everything related to behaviour the keeping circumstamces have a major influence.
Take the escort call. This basic test is what happens if a hen makes this call and her rooster is brought to her.
Then what happens if another rooster is brough to her.
I've brought food instead of a rooster. They eat but still call inbetween beak fulls.
I've brought best mate hens to the one calling. Sometimes they both end up calling.
If after repeated trials only the hens rooster stops her calling then it's a first step in saying the hen was calling for her rooster if nothing else shuts her up.
It goes on from there. What happens if she calls and hasn't laid an egg. What does the rooster do when he hears that call. I must have watched hundreds of these exchanges.
After seeing an event and recognising a sequence the next step is to form a theory as to why it happens. If it all hangs together the theory looks promising.
If a lot of keepers even in not so similar circumstances report similar behaviour the theory starts to look more solid.
With lab style experiments one usually already has a theory. It's necessary to set up the experiment. At the end of the majority of such lab experiments all that can be said is under these conditions, this is what happened. They don't tell you anything about what might happen in other conditions.
My view is the behaviour in field observations and then theory building is more likely to give what can be described as natural basic behaviour of which there will be modifications depending on circumstances.
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tell him to open his ears and get those words out clearly . It must take very long to dry..Is the rest of the allotment in a much better state and this is really due only to the mistreatment of the chicken runs soil ?
Full stop 
