A metal post is best to mount your bird table on to make it impossible for cats and difficult for squirrels to climb. It is much easier, however, to attach the table to a wooden post and slide a length of plastic drainpipe or similar over it to make it unscalable.
Drive the post into the ground (allow for about a foot of post in the ground) or make it freestanding with a cross-shaped base. The table needs to be 4-6 feet (1.2-1.75 m) off the ground. The best height will depend on the level you will be viewing from, the agility of the neighborhood cats and the height of the person in charge of stocking and cleaning the table.
Whichever way the post is fixed the table must be firm. If on a cross-shaped base, make the feet long enough to stop the table from blowing over. If wind is a problem you could peg the feet down or put rocks on them. Use small metal angle brackets at the top of the post to fix the table, or small blocks of wood (or plastic blocks from DIY stores) which can be screwed to the post from the side and the table from below.
To hang a table, use screw-in eyes or hooks to each corner and attach lengths of wire or a light metal chain (avoid lines which can be chewed through by squirrels). To stop the table from spinning round, the chain needs to be hung from more than one point, so make loops of the chains at either end of the table and hang it from a horizontal branch (or your washing line). To protect a tree from being cut by the chain, thread the chain through a section of garden hose.
Bird tables can be fixed to window ledges with angle brackets, chains or angled supports depending on the site.
A ground feeding tray
For those birds that prefer to feed on the ground, a low-level bird table can be provided. This should be mounted no more than 10 cm off the ground (to allow the grass to ‘breathe’) and moved fractionally each time you put out food. This prevents both the build up of droppings in one part of the garden and damage to your lawn. Remember, beware of cats under shrub cover.
Cats and squirrels can be pests on a bird table. Cats keep the birds away and squirrels eat the food. Although unsightly, 1.5″ (4 cm) wire mesh around the table can stop squirrels and cats, but it will also keep away larger birds such as thrushes, woodpeckers and jays. An alternative is an inverted biscuit tin fixed at the top of the post supporting the table. This can stop cats and squirrels from climbing up to the table. You could also try plastic bottles, fixed so they revolve, and slipped along the post.
Starlings, house sparrows, collared doves and the crow family may monopolize a bird table. An overhanging roof may deter larger species but you are unlikely to stop them feeding altogether. Provide food in several places, which should at least give other birds a chance.
Break food such as bread into smaller pieces so that large pieces cannot be snatched and carried off. Put food on the table, on the ground and in a variety of feeders (spreading food over a large area reduces squabbling). Loose food should only be sufficient for a day, to reduce the chance of attracting vermin at night. If pigeons increase, discourage them by containerizing all food: high numbers cause problems.
Hygiene and maintenance
Clean your bird table regularly and never allows old food to accumulate. Dirty tables can harbor dangerous bacteria left by sick birds and start an outbreak of disease. Brush off debris every time you put out fresh food and scrub the table with a mild disinfectant solution every few weeks: more frequently if sick birds visit. Move the table from time to time to stop the accumulation of droppings underneath.
Some bird diseases can be transmitted to people. Although the risk is small, it is worth taking sensible hygienic precautions.
Annual maintenance is best carried out in autumn. Clean the tables, tighten/replace screws and make sure it is still a safe place for birds to feed. Don’t expect a wooden bird table to last for ever. As it weathers, it becomes more difficult to clean and after a couple of seasons it is best to burn it and make a new one.