After seeing this question which had this animation:
I was left wondering whether this behavior was "normal" or at least healthy. I know sometimes when an animal exhibits odd behavior there's something wrong with it, even if the behavior is normal for other animals, such as humans, or even considered cute.
So is there something wrong with this bird, or has it just learned that a cute behavior causes the bread dispensers people to give it food?
I raised both domestic and wild breeds of geese and other water fowl for a number of years. Eating human foods such as bread are notoriously poor for birds, especially wild breeds including bird rescue work. They like it, but it is like allowing kids to have candy as a main course for dinner. Some of the issues it can cause are manifested in leg and feet problems.
Without seeing further video or the bird, it actually walking and running around, I could not say with any certainty if this bird is effected. At first glance, it appears to be chattering as it is doing it, which I would interpret as just being a "happy dance", it claiming the treat and wanting more. Looking closer though, I would have some concern. The goose was stepping on its own feet and the feet were toed in. They can do this, and I have seen healthy birds do so, but it is not typical. This is far more common with birds with injuries or structural issues of the legs. The bird is not showing other visible signs that I would normally look for with nutritional caused deformities so I suspect it may be fine, but I would have loved to have seen it moving across the field to confirm that.
If I were to actually observe the bird, other signs I would look for would be angel wing, structural bowing of the legs, flayed hips, over weight, none of which are apparent so the bird is likely fine with the exception of possible angel wing. The gif clip is way to short and single angle so I cannot tell on angel wing. The bird would also walk like this if its legs were pegged, such as fishing line between them, but no visible sign of that without much clearer angel and resolution.
Paul Lydon could be right. The behavior is designed to encourage worms to come to the surface, to make it easier for the geese to find and eat.
From the same Wikipedia page he quoted, entitled Worm Charming:
Worm charming is a behavior also observed in the animal kingdom, especially among birds. The methods used vary; however, tapping earth with feet to generate vibrations is widespread. One common example is the "Seagull dance". The wood turtle also seems to be adapted for worm charming, as it is known to stamp its feet – a behavior that attracts worms to the surface and allows the turtle to prey on them.
This lengthy scientific article is generally focused on the behavior of moles in Florida. However, it makes mention of herring gulls:
Previous investigations have revealed that both wood turtles and herring gulls vibrate the ground to elicit earthworm escapes
The following is from an article discussing that behavior in seagulls, which has also been observed by Paul Lydon. It's interesting and seems pertinent.
According to The Seagull Rain Dance:
Although seagulls will predominately feed on seafood they are also capable of finding sources of food inland for example worms.
Seagulls use this behavior in an attempt to imitate rain.
The seagulls can be observed “dancing” and stamping their feet on grassy areas by raising and lowering each foot in turn. The movement of their feet on the grass causes vibrations which are similar to that created by rain. The vibrations cause worms to move to the surface believing it is raining. This rhythmic beat is repeated, the gulls can then be observed scrutinising the ground waiting for their easy snack to emerge.
The article references work done by Nikolaas Tinbergen, a Dutch ethologist and ornithologist, who earned a Nobel Price for his work in animal behavior. Tinbergen believes four questions that are asked of any animal behaviour can be applied to this observed behaviour of the seagull dance. His belief is that every behavior has a cause, development, evolution and function.
The cause of this “dancing” behaviour could be attributed to periods of rain in which the seagulls can take advantage.
The dance is a learned trick to coax worms to the surface. Earthworms stay underground unless flooded out by rainwater. The vibrations sent into the ground resemble that of rain or an approaching mole.
The seagull dance is a taught behaviour and develops with age. The elder seagulls can be seen teaching young the padding motion on grass. The dance is therefore a learned or possibly inherited behaviour.
Environmental factors play a role in the dance as it is more commonly seen in birds which have to supplement their diet or have moved inland away from the coast. The rain dance is used by other bird species also, for example similar tactics can be observed in thrushes.
While this doesn't specifically mention the bar-headed goose, I think it can apply under sections of the above sources. First, that those bar-headed geese are eating in an inland location, and, second, that the rain dance is used by other species.
As for the bread feeding, the goose seems to stop the dance briefly when the bread comes. Maybe it can't dance and eat bread! Maybe it doesn't need to. That's not something I found in the research.
I have seen gulls do exactly that. It is known as:
Worm charming, worm grunting, and worm fiddling are methods of attracting earthworms from the ground. The activity is usually performed to collect bait for fishing but can also take the form of a competitive sport in areas such as east Texas. As a skill and profession worm charming is now very rare, with the art being passed through generations to ensure that it survives
See: Wikipedia Link
I'm not sure why this goose is doing it when being fed but it is probably related to the behaviour described in the article above.
