To be fair, you can't really see much of it here because the birds were at the front and near the top so I only took a photo of the small part they were in. The cage is bigger than you might think from the picture (big enough for them to fly) and has a decent amount of vegetation.
This is getting silly now - this is clearly a tiny part of the enclosure and it looks dark because the birds and cage roof are silhouetted a bit against the sky.