The Birds' Calendar 



nous, which shall we consider the cause, and 

 wliich the effect? The credit of the species 

 seriously depends upon the answer. The fact 

 that they show great courage and fidelity in the 

 defence of their offspring when danger threatens, 

 makes it a reasonable inference that they can 

 only be charged with being practical rather 

 than sentimental. 



The latest lingering migrant among the 

 thrushes was the *' olive-backed," the least at- 

 tractive of all the thrushes in appearance, being 

 of a uniform and dull olive color on the back. 

 It did not finally disappear till the second 

 week in June, and during the last week in May 

 it was the commonest bird in the Park, not 

 even excepting the robin. In the Ramble I 

 could hardly go ten feet without stirring up at 

 least one or two. Until just previous to their 

 departure they uttered only an occasional harsh 

 call-note, in striking contrast to that of the 

 wood thrush, which is so delicious ; but three 

 or four days before they left I heard the first ef- 

 fort of song, not full-voiced, but soft and veiled, 

 as is often the case when a species begins to sing 

 in spring. 



The appearance of a bird is positive — you can 

 tell the day and hour ; its disappearance is neg- 



i88 



