I can't give you sizes, only suggest them. My past B&G macaw (JaJaBinks) had a leg injury & chewed her leg open. She got past 2 plastic/acrylic collars, one with a huge plate like acrylic flange. Finally I discovered a sock/towel collar she could not get past. The previous 2 collars allowed her to lift her leg high enough to keep chewing it, but the sock collar did not. The only problem was eating, as they hold food in their feet & also need to bend their head down to eat out of food bowls. So we had to crack nuts & offer her food by hand or in shallow bowls, on plates, etc. until she healed.
A sock/towel collar is strips of a terry cloth kitchen hand towel cut in strips about an inch wider than your birds neck. We used a white towel, but any color will do. So you need to grasp your bird by the neck & estimate the length. Keep in mind you need to stretch the birds neck to get the correct length. Measure from base of jaw to base of neck. Then add 1 inch. Next you need the top of a crew sock. For my macaw we were able to use my husbands sock. For a love bird I'd guess a child's sock may work. For my macaw we had to use 2 pieces of a hand towel, so it'd be thick enough. One may be too much for a love bird. It needs to be thick enough the bird can not bend it's head down much at all. You cut the sock just below the top part were the elastic ends & the foot part begins. I suggest a 2nd person to help to hold the bird & put this all on. Wrap the towel around the birds neck, letting enough space you can easily slide your thumb under it, below the bottom beak. If it's too tight the bird can not breath or swallow right. Start at the side of the neck or back of neck, so the end is not below beak. Once you get that done turn the top of the cut sock inside out & slide it over your fingers. Then slide it over the birds head, turning it right side out as you pull it over the wrapped towel. Once in place tuck the top & bottom of the sock top under the towel. Take a pencil & slide it down inside the towel & push the feathers back in place. Your done. Now watch to see if your bird can bend it's head down. If so it's not thick enough. Add more towel strip, as needed. Also your bird may have a little balance issue while wearing it. A bird vet told me this was the most humane collar she had ever seen on a bird. It doesn't rub the skin causing chafing/sores. You can not shower the bird until it's healed, as you would need to take the collar off. Even taking it off long enough to shower & dry the bird may resort to chewing. They can do a lot of damage in minutes. It's best to let it on the whoel time. As I said you will need to find ways to feed the bird until it's healed. I attached photos of my B&G with her leg injury & pics of the collars.
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First she chewed it, then she ripped long pieces of skin off. The bird vet plucked the feathers off her leg.
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First collar vet put on. Acrylic bubble collar screwed together & taped. She managed to rip it apart. It also chafed her neck.
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Second collar. Also screwed together & caused more chafing. She got past it & ripped the long pieces of skin off her leg.
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We added this wide acrylic flange to the T collar, which she also got past.
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The sock/towel collar. You can see it needs to go from jaw to base of neck & be thick enough to prevent bending the head.
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Once she got used to it not much slowed her down. She wore the collar for several weeks until she was fully healed.
