142 LIFE-HISTORIES OF BIRDS 



and evenly chiselled." The average depth was about i^ 

 inches, diameter 5 inches at the most extended part, while 

 the external diameter varied from 1.25 to 1.60 inches. The 

 entrance was so small, proportionally to the size of the bird, 

 that a somewhat lengthy and violent struggle was frequently 

 made in entering or retiring. In one case, the nest was loca- 

 ted at a height of fifty feet above the water. 



The nests are easily discovered, as the non-sitting bird is 

 nearly always in the immediate vicinity, and, on the tree be- 

 ing approached, flies to the hole, and by a few calls brings 

 out his mate, when both fly backward and forward, uttering 

 cries of anxiety and alarm. The non-incubating bird has 

 also a peculiar habit of clinging motionless to the trunk just 

 underneath the hole, and ever and anon gazing, as it were, 

 with a somewhat pensive expression into the interior, al- 

 though the conformation of the latter utterly prevents the 

 mate or eggs from being seen. The anxiety manifested on 

 these occasions varies most remarkably ; some pairs exhibit 

 ing the deepest concern, as evidenced by their continual 

 cries, while others seek the nearest tree and watch with si- 

 lence and the utmost coolness the destruction of their home. 



The birds appeared to relieve each other duringthe incubat- 

 ing process at average intervals of a half hour ; the absent 

 bird appearing before the hole, would utter a lo\v call re- 

 sembling yew-tck twice repeated, which would be respond- 

 ed to by the mate within, when, a few notes of endearment 

 being interchanged, the sitting bird would yield her arduous 

 duty.. 



Mr. Brewster mentions having found several newly finish- 

 ed excavations in nearly every tree which he noticed. On 

 one occasion, four of these were cut open, which bore evi- 

 dences of having been newly constructed. They were all 

 as neatly finished as the one that contained the eggs. A num- 

 ber of dark-colored cavities were observed in addition to the 

 above, which were obviously made in former years. The 

 repeated failure to find more than one of these excavations 



