I have been watching dust bathing for some time. Locations preferred are in full sun and dry usually with a good view when birds are standing. Now I am starting to play around with different materials to determine what the birds are actually looking for when comes to the actual material. Generally it is literally a silty loam in terms of particulate size but they will also make use of decidedly organic soils. They also seem partial to wood ash. Another material identified today is alfalfa cubes that have been shredded. What is of particular interest is how the birds sense the locations. Is it appearance, temperature, taste or smell? All four may be at play. A group of juvenile games will be used to test where dust bathing materials will be placed in large rubber feed bowls in same general area. First will look for preferences with respect to materials.
Mine love wood ash. I've only had chickens about 6mo., but for many years I would watch the wild birds (Cardinal, Carolina Wren, etc.) dust bathe in the ashes I dumped at the edge of the woods. They even made use of the ashes in winter, just like chickens do. I rake my run and clean it regularly, but I put pine needles and leaves in there, they also like to dust bathe in those as well.
