Cuphea is a great shrub for the bees. It flowers all year round and I know the plants here in the nursery seem to have a constant stream of bees to them through out the day. Bees love blue, purple, yellow and white flowers, they also need to be single flowers rather than fancy ruffled double flowers so the bees can land on them, and have easy access to the pollen and nectar.
Some other smaller growing plants good for feeding bees are Hebes, Lambs Ears, Lavenders, Rata, Borage, Rosemary, Thyme and Catmint.
Bigger growing options for the bees are apple, pear and plum. Citrus (Lemon, Grapefruit and Orange Blossom are great). Broom, Tea Tree and Kanuka. Flowering Cherry, Eucalyptus, Cabbage Tree, Swamp Flax, Lemonwood, Pohutukawa, Tulip Tree, Lacebark, Bay Tree and Wisteria.
Now onto the birds
There are lots of native trees (and exotics) that are good for feeding the Pigeons, Tuis, and Silvereyes.
Large trees to feed Wood Pigeon
Taraire, Karaka, Nikau, Puriri, Kohekohe, Miro, Kahikatea, Titoki, Lacebark, Kowhai, Rewarewa, Tawapou, Wineberry, Totara, Ngaio, Guava, and Pigeon Wood.
Shrubs/small trees to feed Wood Pigeons
Tawapou, Mahoe, Karamu, Lancewood, Five Finger, Cabbage Tree, Red Mapou, Horopito, Coprosmas and Kawakawa.
Large trees to feed Tuis
Kowhai, Kahikatea, Rewarewa, Pohutukawa, Puriri, Wineberry, Rimu, Karo, Totara, Ngaio, and Bottlebrush.
Shrubs/small trees to feed Tuis
Flax, Five Finger, Putaputaweta, Puka, Lancewood, Red Mapou, Cabbage Tree, Coprosmas, Tree Lucerne, Grevillias, Flowering Cherries (not the invasive Taiwan Cherry), Feijoas, Bottlebrush, and Camellias.