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May, x9o 4 I THE CONDOR 69 nests--they were made largely of snmll stones! Where the nests were in cracks or holes in the faces of boulders, the stones were usually merely mixed with the sticks and weeds of the nest itself, but in one case where the nest was in a crack of a slanting boulder over which four-footed egg hunters might make their way, the stones were piled up in front along the edge of the crack leaving little room for any but the owner to enter. This was also the case with a nest placed in the crack of a cut bank. The most curious feature about the use of the stones was that where the site admitted, there ?vas generally a mass of stones leading away from the nest--like a gravel walk from a door. One of the two ground nests that we found--built so far back under a rock that the young could be seen only when they raised their heads for food--had a striking pave?nent. On counting the stones of walk and entrance, I was surprised to find that there were fifty, and there were doubtless many more mixed in with the materials of the nest. The stones, like most used by the wrens were bits of sandstone, varying from half an inch to an inch and a half ROCK WREN NESTS IN FACE OF BOULDER in length. Those in figure 2 are quite characteristic, although they are not so flat as many that are used. One nest in a hole in a rock about three feet from the ground, had a wide entrance paved with them very much like that of figure 2. Eighty-three stones were counted here, and there were many more mixed in with the mass of the nest. The largest number that I counted belonged to the nest shown in figure 2. It had two lmndred and svty stones, none of them less than half an inch in length! In addition to the stones and the soft grassy nest lining there was a quart can full of coarse sticks, many of them four or five inches long and as large around as a lead pencil. Tiffs nest is now on record in the National Museum. Two possibilities suggest themselves in explanation of this astonishing work of the wrens. In a general way it is in line with the wrenish habit of making bulky nests--a matter of protection perhaps, like the great accumulations of the wood rats. In special cases where the entrance to the nest is partially closed by the stones, the purpose can be easily understood. Protective reasons do not apply, however, to the masses of stones leading away from the nest, sometimes as far as