Good question.

You might check your scale if you haven’t already. A 12 oz. can of coke weighs 355 + about 15 for the can = 370 grams. If you have room put three on your scale you should get 1110 to 1120 grams. If not just add or subtract anything above 1120 or less than 1110 to your macaw’s weight.
Weigh your bird in the morning at the same time for a week before he eats or drinks. If his weight is trending up or down, keep weighing him until it stabilizes. A stable weight should be the same for a week + or – about 10 grams. It’s not uncommon for macaw’s weight to very about 10% during the year. For flighted birds most of this comes from them adjusting weight to accommodate dropped flight feathers.
The official B&G weight range is 900 to 1200 grams for flighted birds with no consistent difference between mails and females. The Bolivian B&G’s tend to be a bit larger birds at the high end of this range. Clipped B&G’s usually run at the low end of the range.
I think that macaws that regularly fly in the house will run about a hundred grams heavier than wild macaws just because they pack on extra anaerobic flight muscle to deal with the shorter flights. This can be a little bit of a vicious cycle. The more flight muscle the heaver the bird the heaver the more flight muscle they will pack on. They often seem to get like little quarter horses, explosive short flights but fade faster on long outside flights. In any case flighted birds are rarely over weight but because in house flighted birds operate with less margin of flight reserve they often go into a flight and attitude slump when they molt. Molting causes about a 10% loss if lift capabilities. The bird will notice this and become a little apprehensive about difficult flights and will often mope around until he eventually loose some weight to compensate for it.
Although most vets would describe them as “not fat but robust”, I think 1150 to 1250 grams in the morning with an empty crop is a healthy weight for a B&G that regularly fly’s in the house. Macaws that eat big meals and fill up on water in the evening may add 40 60 grams to the morning weight. A three year old may add another 100 grams to his body weight over the next couple of years from age but generally diet, exercise stress and time of year will have the most affect on weight.
It would be interesting to find out the weight of a couple of the B&G’s in Nate’s group of flyers.
Hope this helps.

Mike Bross
Phoenix AZ

I'm pretty sure we have one that's 1400 and visibly overweight (has cleavage), but that doesn't really tell you much. Actually we haven't got many B&Gs at this point. The one regular attendee has wing that broke and healed crooked (pet shop owner just returned the bird to the breeder rather than getting a vet, grrrrrr) so she doesn't fly... I'm not sure what she weighs though. We have lots of GWM flying around, I can probably get some weights for those but they're going to be a bit heavier than a B&G should be.

Just for the heck of it, here's a Google search:
http://www.google.com/search?q=%22blue+and+gold%22+macaw+weight+grams

You can actually see a bunch of opinions right on the google page without even clicking any links. The bottom end of the range is usually 800-900, and the top end 1100-1300, which matches what Mike said. I wonder, though, if those values came from wild birds that were captured and weighed, or from pet birds. And if both data are available, I wonder how they compare.

Nate Waddoups
Redmond WA USA

Thanks, Mike and Nate. i'll check my scale and do some sequential weighing. Zazu is in the middle of a heavy moult right now. i wasn't sure if he just seemed extra heavy since i've been spending so much time with Mouse and Pongo U2, who's always been a bit bony and additionally lands like a feather.

Zazu really doesn't do enough flying (still outgrowing clip) to account for any extra muscle weight IMO. So he really does seem to be tending to chubby, which is what his vet said before i adopted him last year. i think more than anything he needs exercise...