Birds are an incredibly diverse animal group. This is reflected in the large differences between some of the species with regards to their plumage, as you can see in this short list of facts about bird feathers.
Greatest number of feathers: Whistling Swan, at 25,216.
Lowest number of feathers: Ruby-throated Hummingbird, at 940.
Longest feathers: Onagadori, a domestic strain of red jungle fowl, at 34.75 feet (10.59 m) long.
Longest tail feathers: Crested Argus Pheasant, at 5.7 feet (1.73 m) long.
Longest tail coverts: Indian Peafowl and Green Peafowl, at 5.24 feet (1.60 m) long.
Widest tail feathers: Crested Argus Pheasant, 5.1 inches (13 cm) wide.
Longest tail feathers relative to body length: Fork-tailed Flycatcher, at 10.75 inches (27 cm).
Longest primary feathers relative to body length: Permant-winged Nightjar, at 2 feet (60 cm).
Shortest tails: virtually non-existent in Kiwis, Emus, Rheas and Cassowaries.
Most secondary flight feathers: Wandering Albatross and Royal Albatrosses with 40 secondaries and 11 primaries on each wing.
Source of these facts: The Bird Almanac, by Dr. David M. Bird