Balsam fir tops missing

[PoginyHill]

I've noticed fir saplings that have their leading stem missing. I had assumed it was moose browse, but I'm wondering if there is an insect that could be doing this. These fir stand 6-7ft tall and based on the pitch leaking out, I'm guessing the damage was rather recent.



All these have missing leaders:

[KEC]

Seems like if it were moose or deer that they would have eaten the part missing. Maybe look on the ground for those tips. Possibly squirrel damage. I'm just speculating. SD would likely have an idea.

[SwampDonkey]

Moose will get into a fir thicket and chow down. I've seen them hold up in fir like that and by spring there are piles of poo several inches thick. They will usually eat all the greenery not just tips alone. Hare will eat the tips of smaller fir.  Squirrels will eat tips and flower buds in late winter and spring. Grouse will eat tips and male flower buds also, about 10% of their diet. I'm leaning toward red squirrel since it looks severed off. No moose poo around?
 Under the red pines here are lots of tips a squirrel snipped last fall for the cones.

[KEC]

SD, I  knew that the origional post was right down your alley, or woods trail as the case may be. I like to read your posts on such subjects.

[PoginyHill]

No significant sign of moose lately, but have seen plenty in prior years. There have always been lots of fir tips from mature trees on the snow surface, but I haven't noticed just the leading stems being cut off like this before. At least to this extent.

[Southside]

Likely the eclipse did it. 

[PoginyHill]

Yesterday I came across several tops that were partially severed. I still don't have a clue as to what is causing this. From these pics, it looks like an insect might be to blame. If it was an animal, I don't think the tops would be hanging on like this.

[woodroe]

Interesting. I've got a big patch of under story young fir in that size range growing up in
a thinned pine stand I'll take a look through and see if anything like that is happening.
Have done a little trallside looking since you 1st brought it up but haven't seen that much
damage yet.
Edit: Nope, not seeing that here. Gazed across a hundred or more young fir tops while walking the dog this morning. 99 % of leaders are
in tack.

[beenthere]

Dissect the stems at those tips and see if there is a critter inside the stem, such as a borer that hatched from an egg laid in that stem tip. Dissect a non-broken one as well to make a comparison. A 10x power hand lens and a sharp knife should work well for this investigation.

Let us know what you find. Also, inquire at your state extension service or forestry office.

Possibility
https://www.maine.gov/dacf/mfs/forest_health/insects/balsam_shootboring_sawfly.htm

[SwampDonkey]

That's older wood than the sawfly would dine on. They want new succulent growth.

[PoginyHill]

I cut open a couple of the tops that had been cut or damaged or whatever, but were still present. Other than discoloration and maybe some fungus or rot, I didn't see anything obvious, like larvae or a hollow area.

[WhitePineJunky]

In my woods, the red squirrels do this to pine, spruce or balsam fir in the winter months

Ruffed grouse will eat ones generally under 3-4 feet if you get enough snow they can walk on and munch on the tops too, but they mainly stick to aspen it seems

[SwampDonkey]

Looks like it could be crushing damage, like from moose or deer. They can't snip it off like a rabbit.