Part V: An unexpected by-product
A grey squirrel lapping maple sap oozing from nails in the trunk.
When I installed my pipe nest box on the Norway maple at the back of the yard, I sited it on the south east side of the trunk in order to catch the morning sun.
About a week later, we had some unseasonably warm weather and it looked like i had sited it right, as the early morning sun was striking directly on the box. But something else was happening. A grey squirrel was straddling the trunk below the box and was lapping at fluid oozing from the four galvanised nails that I had whacked through the strapping into the trunk to secure the box.
The nails I used were about an inch long, but i had inadvertently “tapped” the tree by puncturing the xylem in the sap wood just below the bark. A combination of cold nights below zero, and warm sunny days had started sap flow in the tree.
The raw sap is so dilute that it barely tastes sweet to humans; Norway maple sap is about 1-2% sugar compared to sugar maples at 2.5-4%. Gallons and gallons of water must be evaporated off the raw sap before we get anything resembling pancake topping. Perhaps the squirrels have a more acute sense of taste, perhaps the water and amino acids would also be welcome.
The warm spell was short-lived. Two days later, we were back to typical winter day time temperatures at or below zero and the sap run halted. But this incident has prompted me to consider a design modification. Rather than nailing the boxes to the tree, perhaps binding the nestbox to the trunk with cable ties would be better. I’ll report on this in a future column.
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