The swallow grouped in the passerine family of birds the Passeriformes, which includes over 50% of bird species. These birds are grouped in this order because they are commonly, referred to as songbirds also known as chirping or perching birds.
The swallow, which can fly over 50 kilometres per hour, is located in the UK and has adapted to dodging obstacles such as large building. The Swallows have particularly adapted to hunt small insects, like grasshoppers and small spiders searching for their prey in public gardens and park bushes. They have short bills, strong jaws and a wide gape which allow it to be efficient flyers and have outstanding vision.
Swallows have a quite smooth retina slightly curved multi-layered structure which contains the photosensitive rod and cone cells (Photoreceptor cells which are responsible for colour vision and no colour vision). In the swallow there may be 80% cone cells and only 20% rod cells which are quite as they have very, good colour vision. Nearer to the centre of the retina is the Fovea (the fovea is responsible for sharp central vision) in the Swallow unlike some birds it has a double Fovea which allows it incredibly developed side angle viewing. The Swallow has an optic nerve (bundle of nerve fibres which carry messages from the eye to parts of the brain). The pectin is folded tissue which projects from the retina. It is well supplied with blood vessels and keeps the retina supplied with nutrients.
Many things affect the Swallow as it lives in an urban, city habitat. Pollution is the main factor which affects the Swallow and in general birds. Many different types of pollution affect the Swallow The birds that communicate at lower frequencies are unable to communicate due to noise pollution which affects their ability to attract a mate and even socialize with birds in their particular habitat. However, light is not as bad as the cone cells which are responsible for colour vision can visualize better in high light which could help the Swallow raid gardens- this may be why you can see the Swallow on wires.

Swallow