They are man made structures that serve as feeders to attract birds in the wild. It may be of different sizes and formats. Besides the basic "T" format, you can tie up on a small tree dead branches with small nails on it to attach fruit pieces. Those T kinds are better to place them near the branches of a nearby tree and with minimum height of one meter from the ground.
The food to be offered depend on which kind of bird you intend to atract. For tanagers, euphonias, caciques, thrushes and other frugivores is recommended banana. But you can also use papaya, mango, avocado or orange. For granivorous birds, seeds like millet and sunflower along with corn. After installation, the birds take some time to discover and get used to this new offering of extra food.
It is strongly recommended the cleaning and removal of waste daily. The birds do not become dependent on the feeder, it becomes just an extra food supply. Which is very welcome in the winter months when there are few fruiting trees.
Water Containers and Hummingbird Feeders
One just being a broad shallow bowl or fountain containing tap water. The hummingbird feeder is the classic bottle type containing water with regular sugar in the proportion of 75 to 25 for hummingbirds, bananaquits and tanagers. [Not recommended for homes where do live cats as the feeder becomes a trap for birds]
Both can be placed along with the fruits at conventional bird tables, where tanagers, dacnises and bananaquits will also benefit from the sweet water. For hummingbirds, the bottle type is recommended to be hung. The daily cleaning is extremely important especially in containers where sugar is used.
Hummingbirds do not become dependent to sweet water, it becomes just a supply of extra food. Which are very welcome in the winter months when there are fewer flowering trees.