I can recall my father telling me this as a child. And just recently heard it again on a news report on TV, of all places, but it simply isn’t true. (Sorry, Dad!)
Birds can digest many berries that humans can’t safely eat, even poison ivy berries. Dogs and cats (especially the latter) are even more sensitive to chemical compounds found in berries than humans and the choice of berries they can safely eat is even more restricted. They can be poisoned by grapes, for example.
Berries to Beware Of
Here are some examples of berries that are edible to birds, but poisonous to people and many pets:
Asparagus (Asparagus officinalis)
Baneberry (Actaea spp.)
Bittersweet (Celastrus spp.)
Bittersweet nightshade (Solanum dulcamara)
Boston ivy (Parthenocissus quinquefolia)
Buckthorn (Rhamnus spp.)
Chinaberry tree (Melia azedarach)
Clivia (Clivia spp.)
Common ivy (Hedera helix)
Cotoneaster (Cotoneaster spp.)
Cuckoo pint (Arum maculatum)
Daphne (Daphne spp.)
Deadly nightshade (Atropa belladonna)
Elderberry (Sambucus spp.)**
Euonymus (Euonymus spp.)
Garden huckleberry* (Solanum nigrum)
Golden dewdrop (Duranta erecta)
Herb-paris (Paris spp.)
Holly (Ilex spp.)
Honeysuckle (Lonicera spp.)
Horsenettle (Solanum carolinense)
Jasmin (Jasminum spp.)
Jerusalem cherry (Solanum pseudocapsicum)
Lantana* (Lantana spp.)
Lily of the valley (Convallaria majus)
Manchineel (Hippomane mancinella)
Mayapple* (Podophyllum spp.)
Mistletoe (Viscum spp. and Phoradendron spp.)
Moonseed (Menispermum spp.)
Poison ivy (Toxicodendron spp.)
Pokeberry (Phytolacca spp.)
Potato (Solanum tuberosum)
Privet (Ligustrum spp.)
Virginia creeper (Parthenocissus quinquefolia)
Yew*** (Taxus spp.)
*Unripe berries only
**The berries of some species are edible after cooking.
***The berry itself is edible when ripe, but the seed is poisonous.
Here’s a good rule to follow: if you don’t know for sure a berry is edible, don’t eat it!