Use one of these.. I got it off eBay for a few pounds early one morning use either wood or scafffold and scaffold clips for a lean-too frame
Lay two 10 foot 4 x4 against a wall bottonm ends 4 feet from the wall block the se end to stop them moving with sand bags or similar or qanchor the uprights to the wall at the top Screw . bolt on a 4 x4 cross member at the point where where the cross member is 18 inches off the wall at the top end .
Doing it this way is so easy , you can rotate the bird and also get it at the right height every time no matter how big the bird is. It's good for hoisting deer etc as well as normal small holding heavy lifting .
This hoist will lift 2 tonne so should eaisly drag up a 100 pounder without even trembling.

If that is too big or pricey there are s one or two rope hoists lifting 120 kg for about £8 inc P&P
This item number is for one auction item as new and is creeping up in pennies ..might be worth a fiver or so inc the P&P
It finishes in four days time .
ebay item number 260920469250 ..
I have one of these 6 to 1 ratio ( Pull one pound to move six . one sixth of the length of rope pulled ) small hoists , My 10 yr old Munchking used it either on a three legged frame or off a tree with extension chains to drag 21 nine foot concrete H section fence posts ( bloody heavy ) off the pile across the garden and then I used it to hoist them up in the air and lowered them into a three foot hole for concreteing in by my pal .
I did replace th cheap cord with a much longer length of parachute type cord so we could get a 15 foot pull in one go as the pile of posts was in the midddle of the garden .
If you thinking of going this route also think of using a well screwed on /fitted cleat to tie off the cord when things are in the right place/plosition.