The java finches are twice daily offered a meal of brown rice at the house. I switched to the rice because they reportedly fed on rice back in Java and there is no husk remains to clutter the yard as was the case with bird seed.
The spotted and zebra doves also join in the meal. I noticed that when the feeding table was crowded, some of the java's would take a break from the field and alight on the top of a dove while finishing a piece of rice. It seemed they could get a better view of the table and then jump down in a good spot for the next morsel. For the most part, the doves would ignore the java's riding them and go about their own feeding. Sometimes they would open their wings to throw off their rider.
This dove riding has been going on now for a few months. I took the above photos at various times during this period. Then one day I noticed that a juvenile java that is just starting to get into its adult plumage was not only landing on a dove but actually staying on the dove for as long as possible and even attempting to groom the dove's feathers as I see adult couples do for each other. Raging hormones? Below is a sequence of shots of this youngster riding a dove on one such occasion.
A couple times the dove opened it wings in attempt to unseat its rider but the java remained.
At one point, most of the birds had been spooked into flight but the dove and rider remained. In the image below, the java has its beak into the dove's plumage and is grooming it.
There are often quarrels on the table during the feeding and some behavior that seems to be either a case of dominance display or possibly a "quickie" at the table. I caught the tail end of one of these encounters below: