Use black mesh or insect screen and use pegs to clip it into place.
Others install overhead fishing line about 450cm apart above your trees.
Rex Marshall had been using school socks on his mangos for a couple of years with some success. It seems to reduce fruit fly and flying fox strikes as well.
Flocks of birds were raiding broccoli – was able to solve the problem by spraying with chili pepper. Did it only once and the birds never came back. Wonder if this method could also work on other pests as once the animal gets a hot mouthful they associate the pain with the crop. Ref: Oscar – Hawaii
Gardening Australia tip from a viewer – to deter birds from taking your latest crop of fruit, hang a transistor radio in the tree and turn on the music!