They do it more under certain conditions, and a new study suggests they do it out of selflessness.
In the animal kingdom, there is an excellent competition for food. Finding food to survive is so difficult at times that some species take advantage of the deaths of other animals and feed on their carcasses, as happens, for example, on the bottom of the Pacific Ocean. For this reason, the habit of parrots to eat only a part of the food they have at their disposal, throwing away the rest, may seem strange: not much is known yet about this peculiar behavior, but a research recently published in the scientific journal Nature, to which 11 researchers have worked, has tried to identify the causes.
Discarding food is an uncommon habit among the animals, even if it has been observed with a specific frequency, especially among those who eat fruits, such as, for instance, monkeys. However, no detailed study of the extent and rate of this behavior has been done so far: researchers have focused on parrots and wondered whether it occurred among all species and in all habitats and whether it was unintentional or deliberate behavior.
Parrots, a familiar name by which we mean the group of birds scientifically called “Psittaciformes”, can be distinguished in almost 400 species: researchers have examined 103 of them, traveling through 17 countries and five continents and found in all species the tendency to waste food. Most of the observations were made in the wild, on animals in their habitat, while a smaller part was built on animals in captivity, to which food was given: parrots usually feed on seeds and grains, even if they happen to supplement their diet with fruits, insects or carcasses of dead animals.
The researchers during their observations have found the habit to discard the food in all countries and all the examined species: when they feed, usually the specimens catch the fruit they want to eat, maybe digging out the seeds, and then, after having given some bites to the fruit, they throw it down from the branch. Nuts and seeds are the food they leave most around, but they do the same thing with flowers and shoots, among other things. Among animals in captivity, the average amount of food wasted is 21.2% of the total, while among those in their habitat, it is 11.8 for fruit and 14.6 for seeds. Also, a clear difference has been observed in the amount of food wasted between different species: some, in practice, “throw” more food.
However, it seems that this behavior is not dictated by chance. The 11 researchers hypothesized that parrots throw food away so that other species can benefit; although there is still uncertainty, the researchers explain in Nature that the fact that most of the food thrown away by parrots were found near trees suggests that the reason for this behavior is to make food available to species that otherwise could not reach it. According to the researchers, among the animals that benefit from this dispersal activity are mammals, reptiles, birds, insects, and fish, some of which can then do additional dispersal activity for other species.
The data collected also highlight three conditions in which parrots tend to discard more food: when the fruit and seeds are unripe, when they are out of mating season (if they have young to breed they become more thrifty) and when the plant from which they get their food is exotic and little known to them. Furthermore, researchers explain that the fact that the dispersed food is mostly unripe does not prevent it from ripening later on, once dispersed, becoming a source of nourishment not only for other animals but also for the soil and many species of plants.
Finally, there is also another aspect that could be linked to the parrots’ interest in picking fruit that is still unripe: the fact that this improves the quality and sweetness of the fruit at a later time. Esther Sebastián-González, one of the researchers who took part in the study, told the New York Times that “in production for humans, the fruits are cut off to make the harvest better. So maybe the parrots are doing something similar. They’re pruning the trees for sweeter, bigger fruits in the future.”