YIKES...now I see. Looks like he brushed on water based paint while they were hanging there, hence the poor coverage. I would suggest going to any hobby shop like Hobby Lobby and go to their model paint section. You should be able to find a suitable color to use. Air brushing is always a better alternative but I assume you don't have one.
Pete, I will have to disagree on needing a base coat before you add "color".
I just spray on my mallard green/yellow and give it a slight wash with black...DONE. If you want to fix the shrinkage issue just "paint" on a layer or two of watered down (matte finish) Modge Podge before re-painting and then a coat after you paint it. This will fill in all the "voids" and give the bill a nice "rubbery" natural look.
As far as hanging dead mounts...reference. reference, reference.