Red berries mean bird-dispersal

When you see a plant with red, fleshy berries, then its fruits are most likely eaten and dispersed around by birds.  Here is an example, the invasive species Amur honeysuckle (Lonicera mackii, Caprifoliaceae):

Birds are attracted to red, a color many other animals can't see, and since birds fly about, bird-dispersed plants are often widely spread, including to far away islands.

Keep in mind that about 50% of red fruits are toxic to humans, but not to birds, since their stomach acids are less strong, and their digestion works faster, so the toxins in the seeds are therefore not affecting the birds as strongly.

Do not eat any red berries if you aren't 100% sure what species it is. Unless you are a bird of course.
[photo by Vilseskogen, Flickr, Creative Commons]