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 Jan.,1911 CI.I.I*,CTIN; ,qOCI}RRO .X_N1) BI..x. CK Pt,'.TRI.'.I.,q IN I.OWF, R C.x.I.IF(}RNI3. 33 monlv. A favorite locality for burrows was in the loose loamy soil on the slope of the saddle at the east end of the island. A few were found nesting on a steep, treacherous, open cliff on the western exposure. Here the birds had burrowed in under loose, flat rocks; and a tunnel enlarged sufficiently- to admit one's hand would usually bring the entire immediate vicinity down on one's head. This mode was given up after a few attempts at dodging boulders and picking a "non-cactus" place for a foothold. In the'amphitheatre the nests were much more accessible, some burrows being not more'than ten inches in length, but others were dug out where the egg was de- posited five feet from the entrance. The longest btrrows were zig-zag tramels around loose boulders in the softest soil, and took cousiderable effort before the end was reached. The nests themselves were usually composed of matted grass and feathers with an under layer of sticks and pebbles. I found some with merely a scratched-out depression in the soft earth, with finely powdered loam heaped around the rim of the hollow to hold the eggs. The burrows showed but little Fig. 17. BURROW OF BLACK PETREL, EXPOSED TO SHOXV NEST CAVI'fX'; ENTRANCE AT LEFT signs of the incoming of the birds as compared with those of the Murrelets. I often found large caves, one measuring at least fifteen feet square, carpeted with soft earth which was sensitive to impressions. The floor of one large cave was a nmss of tiny overlapping Mnrrelet tracks. In this cave the Murrelets burrowed back in- to almost inaccessible crannies and crevices, where they were easily found, but hard to reach. They probably use these caves as convenient roosting grounds or for nocturnal love walks, as but few of the burrows in such localities were found to be nesting sites, and none contained more than fragments of faded egg shells. I used a candle for locating eggs in one particularly deep cave, and lying prone shoved the light down the shaft ahead of me until for want of oxygen it flickered and failed. This cave was a tight fit and my companion was luckily there and pulled me out by the heels. The sharp, thorny, buckthorn bushes completely obscure the hutrows of the Petrels on the brushy area, and offer great protection to them also, as our gloves in shreds were witnesses after a few hours work. Early in the season when the islands were visited, two birds were usually found in a burrow; later, brooding birds only.