Hi, This is Dr. Knafo. From your color description, it does sound like you have a Quaker or Monk parakeet. The molting of feathers is normal and occurs several times through the year depending on nutrition and environmental factors. However, as you have said, feather picking or what we often call "feather destructive behavior" can be caused by emotional or psychological problems in birds. Certainly, medical problems can cause feather picking (skin infection for example). Given the scenario you describe, this bird could be very stressed from its isolation in the store when no one is there. Birds are very social flock animals and when they are alone they are stressed. This bird would benefit from a few things: first, feed 75% complete pelleted diet like Zupreme, Roudybush, Lafebers or another reputable bird food company. There are available at PetSmart or most other pet supply stores. The other 25% should be fresh produce like sweet potatoes, beans, carrots, berries, etc. Only a minor part of the diet should be seeds, nuts, or people food treats (no more than 5-10% of the diet). Poor diet sets bird up for nutritional deficiencies (vitamin A, E, C, calcium, etc) and excesses (mainly excess fat with regard to seeds). This can cause a host of diseases that are serious so good nutrition is the foundation of a healthy bird. Second, as you suspect this bird needs to be with other birds or with people to alleviate stress. Its possible that those feathers were naturally molted and not plucked by the bird, but if this set-up continues, this bird is at risk of developing "Quaker self-mutilation syndrome." We don't know for sure the underlying cause of this syndrome, but once its set in motion and a Quaker parrot is causing self-mutilation it can be very hard to treat. Best to do all we can to prevent it in the first place. Avian vets can be searched on the Association of Avian Veterinarians website. The third thing is that this bird should have an exam by an avian savvy veterinarian to ensure its otherwise healthy. Parrots can harbor infectious diseases contagious to people, and if the bird is in a store through which the public comes, then people which compromised immune systems (chemotherapy, organ transplant, elderly, etc) could be at risk of contracting a disease like Chlamydia (psittacosis) which could be serious. I hope this has been helpful information for you. Please let me know if I can be of further assistance.
Take care, Dr. Knafo