… the way of founding a swallow bank; for modern influence was making these things as scarce as hollow trees.
Without detailing my various failures or the causes, I give in brief the methods which led to success.
On the bank of my lake, I selected a site that looked southward. On a rocky ledge for foundation, I built a stone wall that enclosed a space 12 feet long x 4 feet deep and 6 feet high, leaving some drainage holes at the bottom. This I filled with loose stone. Leaving the front at the 6-foot level, I raised the two sides and the bank 3 feet higher. I fastened some heavy plank temporarily across the front, then proceeded to build my bank.
First I laid down a 6-inch stratum of sandy clay, well wetted and hammered down over the whole area enclosed in the stone walls. Over this I laid one inch of concrete. Next, a layer of clay, 3 inches thick, and again an inch of concrete; then a layer of clay 4 inches, and concrete; so on, varying the thickness of clay till the top was reached, and the last layer of concrete, tilted backward, formed the roof.
After leaving all for a month to set, I removed the boards and put up a sign “To Let”. It was too late in the season for large results; but before many months, I had 2 pairs of sand swallows, a pair of kingfishers, and a pair of phœbes, availing themselves of my hospitable offer.
Making a Hollow Tree
Many years ago I realized that the modern foresters were destroying all the hollow trees, — which meant robbing a quarter of our woodland birds and animals of their home sites.
To offset this on my own land, I built one or two artificial hollow trees, and urged my friends to do the same. The reward was immediate and ample.
My first effort was a huge trunk, 35 feet high and 6 feet through. It had ladders and stories inside, so I could climb up unseen, and observe the tenants. (See Country Life in America, Nov., 1908.) But it was very expensive, and I found that a less commodious tree did as well.
For the guidance of those who wish to try this new style of bird box, I give instructions that are the result of my own experience.