For example:

• Robins: insects, worms, spiders, berries fruits, and sometimes seeds
• Blue tits: insects, spiders, caterpillars, seeds, nuts, and berries. Suet and fat balls
• Blackbirds: earthworms, insects, snails, fruits, berries, and apples
• House sparrows: seeds, grains, insects, fruits, berries
• Goldfinches: seeds (thistles), buds, and small insects
• Woodpeckers: insects, larvae, ants, beetles, nuts, tree sap
• Starlings: insects, earthworms, fruits, berries, and grains
• Chaffinches: seeds, buds, insects, spiders, and berries
• Dunnocks: insects, worms, spiders, seeds, and berries
• Greenfinches: seeds, buds, fruits, berries, and insects. Esp sunflower seeds

Small seeds are preferred by birds such as Goldfinches, Siskins, Redpolls, and Linnets.  

Peanuts and sunflower seeds for Greenfinches, Chaffinches, and House Sparrows.

Many birds can eat both smaller and larger seeds, for example, Greenfinches, however birds such as Siskins have a preference for small seeds to suit their smaller beaks. 

However, all of these diets vary by season and availability of food. Providing a diverse range is the best way to attract a large variety of species. 

Avoid seed mixtures that have split peas, beans, dried rice, or lentils as only large species can eat them dry.

Birds can have tinned meaty dog and cat food during dry warm summer when worms aren’t available. In fact, some seed mixes have dog biscuits already to bulk it out. However, they must be soaked or broken down first as birds can easily choke on them. 

There are also certain trees and shrubs which encourage certain birds due to their food sources:

Shrubs:

• Elder: clusters of small, dark berries rich in nutrients. Blackbirds, Thrushes, and Warblers feed on these.
• Hawthorn. Has small red berries (haws) that are a good food source, favoured by Blackbirds, Redwings, and Fieldfares. 
• Dog rose: climbing rose with bright red or orange fruits, persisting through winter, providing food when other fruits may not be available. Waxwings, Redwings, and Blackbirds love the fruits this shrub produces. 
• Guelder Rose. Produces clusters of red berries in Autumn. Blackbirds, Thrushes, and Finches enjoy these.

A variety of shrubs is perfect to provide staggered food throughout the year. 

Trees: 

• Silver birch. thin branches and small seeds for birds such as Siskins, Greenfinches, and Redpolls.
• Elder. produces clusters of dark purple berries which are enjoyed by Blackbirds, Thrushes, and Warblers.
• Rowan. These trees have bright red berries in the Autumn, loved by Blackbirds and Waxwings. 
• Crabapple. Crabapple trees bear small, colourful fruits that are enjoyed by Warblers and Thrushes. 
• Oak. These trees produce acrons whvch are eaten  by Jays, Woodpeckers, and Nuthatches.