As far as i know, nuts and seeds, whole grains, legumes and even fruits and vegatables such as Broccoli and banana for example are sources of protein. Just make sure you feed the proper amounts...
This is what i've read from birdsnways and avianweb websites and altered my grey's diet to exclude any animal-derived foods (which actually make a very small part of their usual diet). They need Protein and Calcium but can be obtained from vegan sources as well. Will copy/paste important parts for you here:
"Good Calcium Sources:
Beet Greens
Broccoli Leaves
Broccoli Stem
Cabbage (outside green leaves)
Celery
Chard
Chinese Cabbage
Collards (cooked)
Dandelion Greens
Endive
Kale
Kohlrabi
Lettuce Dark Green Leaf
Mustard Greens
Orange or Tangerine
Parsley
Spinach
Turnip Greens
Watercress
Watermelon
Yellow Wax Beans
Moderate Calcium Sources:Apples
Blackberries
Blueberries
Cabbage (inside white leaves)
Cantaloupe
Carrots
Green Beans
Guavas
Okra
Pears
Raspberries
Rutabaga
Squash
Strawberries
Turnips
Yams
Poor Calcium Sources:
Apricots
Asparagus
Bananas
Beets
Broccoli Flowers
Brussels Sprouts
Cauliflower
Cherries (pitted)
Corn
Cucumber
Eggplant
Grapes
Lettuce (head, iceberg)
Mushrooms
Parsnips
Peaches
Peas
Pineapple
Plums
Pumpkin
Radish
Sweet Potato
Tomato"
"Even though most dark leafy greens are rich in calcium, broccoli, rapini, turnip greens, collard greens and mustard greens are better sources than spinach, chard and beet greens because of the high oxalic acid content that blocks absorption of the calcium in spinach, chard, and beet greens.
Calcium-rich vegetable / fruits and greens are: bok choy, kale, parsley, mustard greens, cabbage, broccoli, carrots, dandelion greens, apricots, figs, endive, okra, garbanzo beans (chickpeas), pinto beans and kidney beans.
Please note that large raw beans - such as Anasazi, Black, Fava, Kidney, Lima, Navy, Pinto, and Soy - can cause toxicities when fed raw, causing digestive upsets for people and potentially for birds. Some experts recommend that large beans should be cooked to make them safe and digestible. Others counter that soaking beans for 24 hours starts the germinating process and that soaking makes the beans safe and digestible. For those who do not want to take any risks, it's best to cook large beans thoroughly before feeding to your birds. These beans are not recommended for general sprouting purposes. Certain uncooked dried beans contain enzyme inhibitors, are indigestible , and may cause visceral gout in birds. These enzyme inhibitors may prevent or decrease the utilization in the body of substances, such as trypsin and chymotrypsin, to produce nutritional deficiencies. Beans that can interfere with proteolytic enzymes are lima, kidney and soybeans. Cooking these beans for at least 2 hours destroys these enzyme inhibitors. Other dried beans do not appear to contain these enzyme inhibitors or, if present, are in low concentrations. To be on the safe side, it's best to cook ALL varieties of beans.
Other food sources of calcium: Baked eggshells, crushed and sprinkled over the food, oatmeal, almonds, walnuts, hazelnuts, sesame seeds, and tahini -- "nut butter" made of sesame seeds
Soaked and germinated "oil" seeds, like niger and rape seeds, are rich in protein and carbohydrates; while "starch" seeds, such as canary and millets, are rich in carbohydrates, but lower in protein.
To restore the balance between Omega-6 and Omega-3 essential fatty acids in your African Grey’s diet, you may want to include Flaxseeds every day. Eating whole flaxseed rather than flaxseed oils because you get the whole package: the protein, fiber, minerals and phytochemicals along with the omega-3. Flaxseeds are also the best source of the phytochemical lignan. Lignan is documented to have anti-bacterial, anti-fungal, anti-viral and anti-cancer properties"
links:
http://www.avianweb.com/africangreydiet.htm
http://www.birdsnways.com/wisdom/ww22eii.htm
After all, i'm not sure if your parrot is an African gray or not. There are some differences from a specie to another....