Paul:
No, there not bunkers, in my opinion, never were. In that area in the crook of the dogleg is a bunch of rolling sort of mounds and pits that's just the way the land always was in there. There all still there. I've been in there a bunch of times---although of course never looking for my own ball! 
But if for some odd reason those things are bunkers, well then---revelation of all revelations!!! Seeing as how large those conifer trees are scattered through the middle of all of them (I'll guarantee you they aren't man-made bunkers) I guess that just flat-ass PROVES that Crump really did intend to have tree overgrowth throughout even his own bunkers and sand waste areas as much of the course is today! 
You fellows are really great at completely outthinking yourselves!
Who knows, maybe this was the nefarious work of that little English accountant look-alike, Harry Colt. You never did get back to me about his tree planting schemes and possible hole visibility isolation on Sunningdale Old and Hamilton in Canada. How about that? I want answers and I want them by quiting time today!!!
Tom
I still reckon those are bunkers in the trees, particularly that one on the fairway edge! Not saying that I think it was a good idea, but that's what I see.
As you commanded, here are some Colt writings about trees. Which gives insight into what he would have recommended to Crump. Even if he ignored it, like a drunken numbskull, and started building bunkers in trees(!)
Colt is often credited as the first architect to have tree planting schemes, for lanscape effect. Sunn Old is usually cited as the first example (see Cornish and Whitten). I'm not entirely sure about how accurate this is (since it's hearsay). From his writing he appears to appreciated trees for landscape but dislike them as hazards. I think it's likely that Crump would have been of the same opinion. Isolation is not mentioned by Colt, but the wooded heathland courses did have much isolation, with big routings, combined with spacious fairways
1912
"And this landscape might have been improved, and made still more pleasing to the eye by planting judiciously off the course irregular clumps of whins, or broom, or rough grasses, or possibly small birch trees and Scotch firs."
1912
"Golfers are, moreover, now becoming more and more sensitive to the artistic side of golf courses, and the man whoh just ploughs around in an entirely golfing spirit is becoming rare every day. I know it well from the outcry that is raised if a hole is changed and an intruding Scotch for tree has to be sacrificed."
Writing about parkland golf:
"The trees are however always a difficulty. It is hard to condemn a fine old specimen oak or beech because it comes into the line of play. It is more or less accepted fact that trees are not the best hazards, for the obvious reason that they unfortunately afford but slight opportunity for the display of golfing skill in extricating the ball from its clutches. Moreover, during the fall of leaf they are always a nuisance, and it is exceedingly difficult to grow satisfactory turf under their shade; but they are undoubtably charming features in a landscape view."
Regarding forest courses:
"It is essential to make the clearing bold and wide, as it is not very enjoyable to play down long alleys with trees on either side, and better effects can be obtained from a landscape point of view if this be done."
1920
"Trees are a fluky and obnoxious form of hazard, but they afford rather good protection, and if a clump of these exists at such a spot it might well be considered justifiable to leave it standing."
"In cases where the ground is covered densely with trees, it is often possible to open up beautiful views by cutting down a little additional timber. In such cases it would be unwise merely to clear certain narrow lanes which are required for play. The "landscape" effect should also be studied, and although great care must be taken not to expose and unpleasant view in the process, every endeavour should be made to obtain a free and open effect. Swinley Forest, St George's Hill and Stoke Poges may be cited as cases in which tree-cutting has greatly improved the views, and in the case of the two first-mentioned clubs a great deal more felling has been done than would have been necessary from a purely golfing point of view."
On the other hand, where very few trees exist every effort should be made to retain them, and in every case the architect will note th quality of the timber with a view to retaining the finest specimens."