Well firstly that is wiki - I would follow the sources stated for more indepth understanding
As for what it means (am I no ornathologist- SP) but I would assume it means that the wings have a higher load capacity (can carry more wieght, more power) and are not made for long distance crusing flights but more for quick and sharper turns - maneuverable.
Technicall speaking there is no enclosure that is perfect - in the past zoos were made only to show off the exotic animals for far nations - a case of cramming as many into as small a space as possible. Today zoos are a boardline thing - on the one hand they need the income from tourists to keep feeding and caring for thier stock - whilst on the other they try to get enclosures as big as they can - they never are big enough though. In the end its a trade off- if the animal is not in the cage it is in the wild - if its habitate is gone and/or poachers have wiped out much of the species then chances are in the wild the species will die out - in the zoo it canbe preserved and by keeping bloodlines fresh (new stock and interzoo trades of animals for breeding) health captive stock can be kept and increased with an aim to releasing into the wild -- which has to coinside with habitate restoration programs and often monitering programs to keep poachers away