Eastern Kingbird Eating Fruit

I was amazed to see this Eastern Kingbird diving into the Mulberry tree on Nutter's Battery and coming away with an unripe berry in it's beak. I knew that, according to John Terborgh in his book Where Have the Birds Gone?, Eastern Kingbirds

. . .become avid fruit eaters in the nonbreeding season . . . in their Amazonian winter homes . . . I have seen 50 or 60 kingbirds pour into the crown of a single tree and begin snatching fruit . . . The species is the most abundant North American migrant in eastern Peru from the end of September through early November, a period that coincides with the fruiting peak of their favorite lauraceous trees. Later in the season, ripe lauraceous fruit becomes relatively scarce, and the big flocks of kingbirds disappear.

This kingbird has nested, for the past two years, in a Black Locust tree just a stone's throw from the Mulberry tree pictured here. I imagine an abundant supply of fruit is one of the reasons the birds are attracted to this area and both male and female probably supplement their protein-laden meals of insects with a fresh fruit desert.

I am not sure if this is a Red Mulberry (native to North America) or a White Mulberry (the "silkworm" Mulberry of Chinese origin.)