Tim, I think they are big enough but above my line of sight - would have no hope of lifting a big bird into one! Angle of pic probably has distorted it a good bit. Richard (RnB's waterfowl) will be able to fill you in more - he had at least his Toulouse there and may put up pics later. I was so glad that I had lower pens for the Muscovy especially since it was impossible to park close to the pavillion.
PS I cropped pic tightly to cut out the card with name of owner etc...