Plant Trees for Wildlife
Trees provide nesting and roosting sites, a home for insects and other wildlife, and many are a great source of food. Every garden should have one there are trees to suit any site, no matter how small.
From: DK Books - How to Grow
Fruit trees, such as apples and pears, provide a sweet feast late in the year, but they are also rich sources of nectar when they blossom in spring. As soon as their first flowers open, these trees are alive with hungry bees, pollinating the flowers as they feed and ensuring a bountiful harvest later in the year. Native trees such as hawthorn (Crataegus) and elder, (Sambucus), are particularly good for wildlife, producing an abundance of nectar.
Even cultivars of native trees, such as 'Paul's Scarlet' hawthorn (below) and elder flowers, provide spring nectar for insects.
Food Sources for Birds
Berries are an attractive feature in a garden, glowing in the low autumn sun, and they also provide a sustained food source for birds and other animals that can last well into the winter months. If you have space, plant several fruiting trees that ripen at different times to ensure a long-lasting supply. Good choices for an abundance of berries are whitebeam (Sorbus aria), rowans (Sorbus), mulberries (Morus nigra), elderberry (Sambucus) and cherries (Prunus). No berries will go to waste — any windfalls are readily eaten by birds, small mammals and even butterflies. If you have a bumper crop of fruit and berries, consider freezing some to put out in late winter when food is scarce.
Mulberries are loved by people and birds alike (Image 1), and rowan berries (Image 2) are a food source that can last for many months. Windfalls benefit birds, ground-dwelling animals and insects (Image 3).
Trees become more valuable to wildlife as they get older; a mature tree will become home to birds that return, year after year. Trees with dense crowns and bare trunks are particularly prized by birds because they provide sheltered nesting sites and keep predators at bay. Once mature, a holly tree (Ilex) has everything: berries, dense growth and thorns that keep out all but the most determined intruders. Other excellent prickly trees are hawthorn (Crataegus), and blackthorn (Prunus spinosa). If you don't have space for mature trees, all three make great wildlife hedges that offer similar protection for nesting birds. Older trees require maintenance, and it is essential that you carry out any pruning and routine care outside of nesting time; otherwise, you risk upsetting nesting birds or fledglings, which is against the law.
Birds feel safe nesting in the thick, dense, impenetrable growth of holly (Image 1), and can hide in the dark foliage of the purple-leaved plum (Prunus cerasifera 'Pissardii', Image 2).