ARRIVAL IN RELATION TO SUNSPOTS 223 



The arrivals of the cuckoo, lark, and swallow were respectively 9, 3, 

 and 1 day later at sunspot maxima than at minima. The cuckoo 

 exhibited the relation quite clearly, the lark much less, and the swallow 

 but little, the conclusion being that some birds manifest in their 

 migratory movements a relationship to the 11.5 cycle of solar and 

 climatic variations. This theme was further developed and some 

 interesting predictions made in a later paper (1925). However, in a 

 recent article (1936) MacLulich concludes that correlation coefficients 

 between sunspots and dates are too small to be significant. 



Wing has carried this study forward in a series of papers dealing 

 with several species of migrants in the United States (1934, a, b; 

 1935). These comprise the loon, pied-billed grebe, sandhill crane, 

 brant, chimney swift, kingbird, and purple martin. His results are de- 

 scribed as follows: "In the two cases just pointed out, we appear to 

 have a case of differential response to the sun. The loons and grebes 

 M'ere stimulated to early movements by both the highs (maxima) and 

 lows (minima) of the sun, while the crane moved early only at the 

 highs. The kingbird (and purple martin) reaches a high directly 

 with the sun, its cycle being the same as the cycle of the crane. The 

 chimney swift, however, parallels the half-cycle as in the loon and the 

 grebe, the peaks of its cycle coming at both the maxima and minima 

 of the sun. . . . The opposing character of the two cycles, the brant 

 going up when the Wolf [sunspot] numbers go down, best described 

 as a 180° difference in phase, contrasts strongly with the kingbird- 

 crane cycle (in phase with the 11-year sunspot cycle) and the chimney- 

 swift-loon-grebe cycle, half the 11-year." 



Since the total number of species concerned in both investigations 

 was but 10, it was deemed desirable to take a much larger number 

 into account in order to afford a more adequate test of the assump- 

 tion, as well as to throw light on the three different types of behavior. 

 For this purpose, three of the longest records available in this country 

 were selected, namely. Wood and Tinker at Ann Arbor (50 years), 

 Jones at Oberlin (36 years), and Brimley at Raleigh (32 years). With 

 respect to the earliest date of arrival for each species, it was found 

 that this had occurred on the year of maximum (INI) or minimum 

 (m) for 64 out of 217 species at Ann Arbor between 1880 and 1906, 

 and for 25 out of 171 species from 1906 to 1930. In the Oberlin 

 record, there were 16 earliest arrivals at m and 15 at ]\I, or a total 

 of 31 species at these extremes by contrast with 128 on other years. 

 For Raleigh, 9 earliest arrivals fell at m and 16 at M, giving a total 

 of 25, to 115 at other times. The respective ratios for the four records 

 are 64:153, 25:146, 31:128, and 25:115, while the corresponding per- 



