occupation; but guarded on the outside by a ledge which we had difficulty in 

 descending. When the ledge rose again to the proportions of a guardian wall, 

 we were compelled to consider the well proper, a black hole at least a hundred 

 feet deep with about a five to one grade, — that is, the bottom about one hundred 

 feet further down was about twenty feet further west. I first dropped a big 

 boulder down, both because it was threatening to go itself, and to test the depth. 

 Out from under its ricocheting passage darted a Leucosticte, midway. Perhaps 

 the damage was already done, but, anyway, the fever for removing loose rocks 

 was so strong upon us that we sent others down the well, reckless of possible 

 damage to Leuco's eggs. But cooler counsels soon prevailed. Anxiously we 

 thought, "Perhaps that Leuco's nest is not very far back from the wall, after all." 

 So the larger obstructions which remained were lifted one by one and passed up 

 to be cast off outside. 



While we were deliberating as to the use of the rope, the Leuco fluttered 

 into the well, and lighted at the entrance of one of the possible side tunnels. 

 Evidently, what she saw displeased her, for she flew away again. Soon she re- 

 turned and went further, apparently covering the nest. But she was ill at ease 

 and her quick departure filled me with further forebodings. Sure enough, when 

 I had wormed my way down thirty feet or so, the eggs flashed into view, four of 

 them, but one of them marked by an ominous-looking black spot, which proved, 

 indeed, to be a gash. When I arrived, at last, at the nest level, puffing and wet 

 and bedraggled — the walls were oozing icy water — I found that every egg had 

 been struck by tiny flying particles of rock. Two were quite badly caved, but 

 all are savable, and the nest is an elegant and generous structure of compacted 

 mosses which in itself would have been worthy of preservation. The gloomy 

 chamber in which the nest reposed was not over fourteen inches in total depth 

 from the side wall, and the wonder is that the eggs were not scrambled. 



Of the further descent and of the discovery that the nest on the outside 

 wall contained young birds a day old, I need not speak. We found the rope was 

 useless, because of the danger of falling rocks. We had to keep close together, 

 so that whatever was inevitably dislodged might not acquire a dangerous momen- 

 tum. We wormed our way up, therefore, as we had wormed down, viz., by brac- 

 ing our backs against one wall and gluing palms and toes to the other. The 

 round trip consumed exactly two and a half hours. Viewed dispassionately from 

 the outside, the undertaking looks foolhardy enough. I am quite sure I would 

 not go down the same wells to recover a fifty dollar purse; but I am equally sure 

 that either of us would go as far, or further, for a set of Leuco's eggs. "94/4-19 

 Sierra Leuco" now reposes in the cabinets of the Museum of Comparative Oology 

 and they are not for sale. 



Well; this is not a monograph of the Leucosticte — nor a biography of the 

 author. What follows must briefly summarize the experience of those glorious 

 days. It is only by spending continuously the months of June and July in Leuco 

 country that one comes to realize how sharply the resident population of Leucos 

 divides upon the question of nesting sites. The cliff-nesters find their favorite 

 sites available in June, and they, accordingly, fall to early in the month. The 

 moraine, or rock-slide nesters expect their home sites to be buried in snow until 

 late in June; and, subject to the variation of the seasons, nest complements may 

 be expected in such situations at any time from the 1st to the 20th of July. The 

 noisy scenes of courtship, therefore, may extend from the middle of May to the 

 middle of July; but the actual nesting is conducted so quietly, so decorously, 

 that the inexperienced student is likely to be utterly deceived. 



Theoretically, it ought to be perfectly easy to trace a building female in 

 such exposed situations as constitute the habitat of the Sierra Leuco. But, 

 practically, one marvels when they do build. At least Leucosticte psychology 

 has not yet been codified. Some females transport materials surreptitiously and 

 spend days at it. Others build furiously while the fever is on, and are done. 

 One bird which I had traced at midday had started her nest under a boulder on 

 the side of the central moraine of the Grand Cirque, at a point not three feet 

 distant from the retreating snowbank, and on a level with it. She secured her 



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