Best animals for weeding large young food forest?

Hi guys!
We have a 10 hectare tropical food forest where we planted 11000 useful trees in a 3.2 Meter equilateral triangular spacing.Although we planted lots of cover crops seed, grasses and other weeds are appearing.
we are thinking about using Muscovies and geese to control the weeds until the trees are big enough to shade them out.
Obviously this would require hundreds of birds for the area (perhaps there are other animals that would be better at the maintenance without causing damage to the small trees?)
Should we use rotational grazing? If so what kind of fence material do we use and how do we move the fencing for the cells when there are hundreds of trees?
One other concern is will the birds get up into the branches jump over the fencing and escape.
Otherwise we can let them free range without rotational grazing, but I asume they would concentrate to heavily in some areas as well as completely neglect other areas.
My goal is to do all the weeding maintenance during the establishment years of the food forest simply using animals and not relaying on weed wackers, machetes or bush hogs.

Congratulations on your food forest!  It sounds wonderful!

How tall and big are your trees, now?

From what I've studied, since you are looking for weed control (more than pest control), you are correct in considering an intensive rotational grazing system rather than a free range extensive system, where the animals would be pickier eaters and let some weeds grow in patchwork.

I think your consistent tree pattern should make it relatively easy to use a series of electric fencing cells, leapfrogging along the property.  

It would be necessary to mow a path of weeds down prior to deploying temporary fence lines to prevent an electrical short of the fences, so you'd still need to have a trimmer or mower.

Dozens of tiny movable Salatin-style shelters small enough to fit between your trees might also be an option if you want to use chickens, rabbits, or guinea pigs with low risk of damaging trees.