1. Field Guide
Field guide refers to a book or manual with illustrations (text & sketches) on natural objects like plants and animals (in this case birds), with the purpose of helping the user to identify the birds in the field and to distinguish between similar appearing birds.
The equipment that is a high necessity for birding is a proper pair of binoculars. Best configurations are 7 x 35 or 8 x 40 (here the first number denotes the magnification and the second number the size of the objective lens in mm). A greater magnification than this makes the view unstable and makes it very difficult to locate or focus on the bird.
Field Note Book / Data Collection Form: To note our observations with date, for our records, which can be referred to in a future time. Also, unbiased observations may contribute to new findings in this field.
Camera: A camera, of any form may be, helps to boost this passion of bird watching. A basic DSLR with a lens of 70-300mm (or 250mm) focal length, in my opnion, is the cheapest available option for bird photography for a beginner. However, Point an shoot cameras available now a days are good enough if one just wants images of birds for the sake of keeping records of life birds.
Tripod: Can be used to minimize camera shakes resulting from hand movements during photography in the field. This however will restrict your mobility with the camera.
Spotting Scope: Telescopes especially designed for Bird watching. Primarily monoscope.
Sound Tools: For recording and playing bird sounds in the field.
Footwear/Boots, Hat, Clothes: wear natural color clothes.