Most people can recognize a budgerigar when they see one, but it’s still interesting to take a closer look at the unique physical appearance of this popular pet bird. There are many variations in terms of colors and patterns, but the following information applies strictly to natural budgies that haven’t been bred to achieve different color variations.
   

• Basic Characteristics – The average budgerigar is approximately seven inches in length and weighs between 1.1 and 1.4 ounces. They have wingspans of 10 inches to 14 inches. Common budgies’ bodies are light green. Their mantles, which consist of their backs and wings, typically have yellow undulations and black markings.
     
• Forehead and Face – Adult budgies have yellow faces. Small purple patches are also found on their cheeks. Until they get their adult plumage, immature budgies have black-colored stripes from their foreheads to their ceres or noses.
     
• Throat Spots – Black spots appear on both sides of a budgerigar’s throat (Binks 23).
     
• Tail Feathers – When standing, a budgie’s tail is dark blue or cobalt in color. Upon stretching or taking flight, the yellow coloring of the outside tail feathers is revealed.
     
• Bill and Legs – A budgie’s legs are usually bluish-gray in color, and it has an olive-gray bill.
     
• Toes – Budgies are unique in the avian world because they have zygodactyl toes (Birmelin 16), which means that the second and third toes face forward and the first and fourth toes face backward. This characteristic makes budgerigars adept climbers and allows them to perch comfortably.
     
• Beak – Another distinct thing about the budgie is its beak. The upper portion of its beak is strong and smooth, and it is much larger than the lower portion of the beak. When a budgie’s beak is closed, the lower portion is completely covered. Due to the puffy, fluffy feathers that cover a budgie’s face, its beak appears to be almost flush and points down in a distinctive way. The budgie can close its beak very tightly, which allows it to keep a firm grip on food, nesting materials and other things.
     
• Cere – The cere is the part of the face that contains the nostrils, and you can determine the sex of a budgie by looking at it (Lohr 12). In males, the cere is royal blue in color. In non-breeding females, its color ranges from pale brown to white. In breeding females, it is brown. Immature budgies’ ceres are pink, so it’s not always possible to determine the sex of a very young parakeet by looking at its cere.
     
• Plumage – It should also be noted that a budgie’s plumage fluoresces in UV light (Alderton 38), which may come in handy during courtship. Oils in the feathers protect them from moisture, which keeps these small birds from being weighed down and unable to fly. Budgies molt naturally from time to time, and the long feathers in their wings and tails provide adequate balance.
     
• Color Vision - Human beings have trichromatic vision, which means that our eyes have three cone cell types. We are unable to see colors in the UV spectrum. Budgies, on the other hand, have tetrachromatic vision, which means that their eyes have four cone cell types. They are able to see colors in the UV spectrum, and they take full advantage of it when mating and foraging.