Window mounted bird feeder are a great way to attract a variety of wild birds to your garden.
It can take some time for them to use a new window feeder for birds. Here's how to get birds feeding.

This the fastest and easiest way to get birds to use a window feeder is by using live mealworms as bird food.
Robins, great tits and blue tits are a popular variety of birds garden birds that use a window feeder and they love live mealworms.
Live mealworms are a great way to attract birds to a new window bird feeder (especially UK Robins). They wiggle and provide a visual stimulus to the birds so they are more likely to notice the feeder.
Fill the feeder with a handful of live mealworms to start with and then slowly mix in your preferred seed. Fill with a soft-bill food like I Love Robins or sunflower seeds to attract robins.

Humans, cats or dogs on the other side of the window will disturb a bird from wanting to feed.
To stop this, cover the window with sheets of newspaper or simply spray the window with water and coat with regular cooking tin foil. The water surface tension of the water keeps the foil onto the window and makes it completely opaque.
Once birds have accustomed to feeding on the window remove the foil.
If you have many windows in the house, particularly some that don't get as much activity as others (such as a study of backroom). Dedicate a particular window to become a "bird feeder window".
Feed the birds on a secluded window and let them become used to it. Leave it up for 1-2 weeks and then "window hop" your feeder from window-to-window to your desired location. This is easier to do if you have a window bird feeder with suction cups, as opposed to an stick on window bird feeder.
If this is not possible, leave the feeder on the window for 3 weeks. This is enough time for the birds in your garden to become used to the feeder and recognise it as a source of food.
Move the window feeder to its final location and the birds will continue to associate its shape with food.
Hang your clear window bird feeder alongside your regular feeders and wait for the small birds to use it. As they're already feeding, they'll be quick to move to this food source.
Wait a few days and move this feeder closer to the house. Preferably in slow increments towards your desired window.
The birds will then transition onto the window with little trouble.
Some final notes:
Birds, much in the same way as humans are fussy about which foods and where to eat. It can take 2 months before birds will start feeding; have patience and don't give up.

