Question: why do parrots have rings on their legs

title: Bird ringing
text: Mist net come in a variety of sizes and lengths according to the bird 's size . All nets are made from a black nylon material and come with 4 shelves to catch the birds once they fly into the net . When purchasing a mist - net for sparrows the height usually stays the same at 2.7 meters but varies in width at 6 meters to 18 meters at a 30mm mesh . Determining net size for large sparrows to jays are 2.6 meters high and varying in widths at 6 meters to 18 meters at a 38mm mesh . If the study requires the banding of large owls a specific net is required and it is made with a heavier material to withstand the talons of the owl at 60mm mesh . Banding hawks also requires a heavier material at 100mm or 127mm mesh . However , some nets for larger birds include an additional shelve at 5 instead of 4 .