December i6, 1892. J 



SCIENCE. 



343 



of the flora. The whole number of species is 136. The group of 

 paludose plants contains 48 names, of which 2 are trees, 6 shrubs, 

 33 perennials, and 8 annuals. These plants are not representative 

 of the true arid flora of the valley, for they have in most cases an 

 abundant supply of water. Comparatively few of these species 

 are confined to the desert, many of them occur in the humid 

 regions of intramontane California, several extend quite across 

 the southern United States and Mexico, and a few are found 

 throughout the subtropical region of the world. It is a general 

 law, of which this part of the Death Valley flora is but a single 

 example, that aquatic and paludose plants do not follow those 

 laws of distribution which govern a true terrestrial flora. 



The second group of plants constitutes the arid flora of the 

 region. Of trees there are none, shrubs 20, perennials 18, and of 

 annuals 50. Fourteen of the perennials are suffrulescent at base 

 and carry on the functions of life throughout the year above 

 ground. Three of the remaining four are grasses, the stems of 

 which also retain some vitality through the winter. One plant 

 only, Cucurhita palmata, is a true perennial, but it does not grow 

 in the very arid parts of the valley, and comes almost in the cate- 

 gory of moist-soil plants. Functionally, therefore, the arid flora of 

 Death Valley is made up of shrubs and annuals. The reason for 

 this state of affairs is found in the extreme heat and dryness of 

 the climate, these being the two, or we may almost say the only, 

 types of vegetation adapted to such conditions. 



The geographic affinity of the arid flora of Death Valley is clear. 

 A few species, such as Mentzelia rejiexa and Oxystylia lutea, are 

 known only in the immediate vicinity of the valley, but nearly all 

 the others are common to the desert region of south-eastern Cali- 

 fornia, Arizona, and north-western Mexico. The topographic 

 position of Death Valley, as the deepest basin (480 feet below sea- 

 level) in this desert area, renders the valley capable of supporting 

 a vegetation belonging characteristically to the southern portion 

 of the region. Several southern species, so far as the present data 

 show, reach their northern limit in Death Valley. 



The adaptive modifications of the flora are practically the same 

 as those of the general vegetation of the surrounding desert, and 

 will be discussed in considerable detail in the report of the expe- 

 dition. 



NOCTURNAL SONGSTERS, AND OTHER BIRD-NOTES. 



BY ROBERT RIDGWAT, M.S., CURATOR OF THE DEPARTMENT OF BIRDS, 

 U. S. NATIONAL MUSEUM. 



Dr. Gibbs's interesting article on birds that sing in the night, 

 in Science for Dec. 2, reminds me that much may yet be written 

 on this subject. Some of our best songsters are unfortunately 

 not represented in that portion of the country (Michigan) of 

 which Dr. Gibbs writes; otherwise, his list of night singers would 

 not only have been considerably longer, but would have included 

 at least two species, the mocking-bird and the yellow-breasted 

 chat, that are every whit as notable as the nightingale itself. 

 The night-singing habit of the mocking-bird is well known to all 

 who are familiar with this " master of song." It is as much a 

 characteristic of the bird as its powers of mimicry, for not all 

 mocking-birds mimic, of which, however, more presently. 



Next to the mocking-bird in this regard, though perhaps it 

 would be better said equally with it, is the yellow-breasted chat, 

 a bird remarkable for the oddity of its song rather than for its mu- 

 sical quality. Its notes are, however, loud and emphatic, and 

 therefore are sure to attract attention whenever heard at night- 

 time. Its nocturnal song — in no respect that I can discover dif- 

 ferent from that which it sings by day — has been familiar to me 

 from boyhood, first in southern Illinois, then in California and 

 other far-western States, latterly in Maryland and Virginia. A 

 pair of chats live during summer close by my home (in a suburb 

 of Washington), and few are the nights in May and June when 

 the male does not sing, at more or less frequent intervals, the 

 whole night through. I once thought that moonlight nights 

 were particularly apt to excite birds to sing; but this particular 

 chat kept no account of the almanac. His most brilliant per- 

 formance, or at least the occasion which most compelled my in- 

 terest, was during a specially dark night, when I purposely kept 



awake to make observations. From the time that darkness set- 

 tled until 3 o'clock in the morning (when I shortly fell asleep) 

 the longest interval between his songs was twenty minutes, but 

 during the greater portion of the night he had scarcely finished 

 one performance than another was begun. 



Several others of our birds may properly be termed ' ' habitual " 

 night-singers. Here, about my home, I hear every night during 

 the nesting season (unless it be storming) songs of the chipping 

 sparrow, the field sparrow, the indigo bird, and the golden- 

 crowned thrush, or oven bird ; not merely once, but repeatedly. 

 The night-song of the last-named bird is quite the same as that 

 which John Burroughs says is the love-song; but I am puzzled 

 to know whether at night, in the darkness, the singer launches 

 from his high perch into the air, as is his habitduring the waning 

 light of daytime. I have heard the night-song of the oven bird 

 so often and been so impressed with its exquisite though transient 

 beauty, that I feel sure Burroughs was right when he suggested 

 that Thoreau's "mysterious night- warbler " was really no new 

 bird at all, but one he was otherwise familiar with ; in short, was 

 none other than the oven bird. Speaking of Burroughs, recalls 

 an erroneous statement in one of his charming books (" Birds 

 and Poets," p. 98). He says: " No bird can look our winters in 

 the face and sing, as do many of the English birds." Surely had 

 he passed a winter south of the parallel of 40" in the United 

 States he could hardly have made this assertion. Here about 

 Washington, and westward to beyond the Mississippi, the Caro- 

 lina wren sings the winter long; and the colder, more crisp, the 

 weather, if only the wind does not blow, the louder rings his pow- 

 erful o'lrol. So, also, does the tufted titmouse heed not the cold 

 of winter, but bravely whistles his cheery tune of pe to, pe to, 

 pe to — some would not call it a song, but it is loud and clear 

 enough, and surely is no mere call-note. The cardinal, too, sings 

 more or less all winter, and so do the white throated and tree 

 sparrows, though there are periods, caused doubtless by meteoro- 

 logical conditions, to us intangible, but of which the birds take 

 note, when birds are little heard. 



Among the many myths of popular bird-lore is that of the 

 mocking-birds' habit of mimicry, of which a hint was given in a 

 previous paragraph. In making this statement I would empha- 

 size the word habit, as distinguished from the term faculty; since 

 I would not for a moment deny this bird's ability (as a rule) to 

 mimic far better than any other. The point is, that mimicry is 

 not so much a habit of the mocking-bird as most people suppose. 

 The reason for the popular error is very simple: The natural 

 song of the mocking-bird is so varied, and is characterized by such 

 wonderful compass, rapidity of change, and brilliancy of execu- 

 tion that persons not specially familiar with birds' notes natur- 

 ally suppose the medley to be in large part borrowed ; and the 

 listener is further confirmed in this belief by the more or less fre- 

 quent interpolation of what he recognizes as unquestionable imi- 

 tations of the notes of other birds. Individual mocking-birds 

 differ greatly in the character and quality of their songs, some 

 being inveterate mimics while others seldom if ever spoil their 

 own incomparable song by imitation. I recently possessed one 

 of the best songsters of this species it was ever my pleasure to 

 hear. His song was wholly his own; almost infinitely varied, 

 wonderfully mellow and clear, bewildering in the rapidity of its 

 changes, and surpassingly brilliant in execution. Yet, with all 

 this, if any one of his notes suggested the note of any other bird 

 I am sure it was not intentional. 



Not only do birds' songs differ materially according to the indi- 

 vidual, but often each individual possesses a more or less extensive 

 repertoire, the separate parts or tunes of which are so different 

 from one another that, heard without the singer being seen, they 

 might readily be attributed to different birds. This is particularly 

 true of the cardinal grosbeak; and I have not the slightest doubt 

 some observers have received an unfavorable impression of this 

 bird's song from having first, or perhaps only, heard one of the 

 less attractive tunes of an individual which half an hour later 

 might be singing a song totally different, and far finer. A pet 

 cardinal, which I had for several years, sang sis very distinct 

 songs, besides minor variations. A remarkable peculiarity of this 

 bird (though one which I believe to be characteristic of the species) 



