HARDWJCKE'S SCIENCE-GOSSIP. 



25 



AN INQUIRY INTO THE ALLEGED HABIT OF HIBER- 

 NATION AMONG NORTH AMERICAN SWALLOWS. 



By CHARLES C. ABBOTT, M.D. 



[Continued from page 3.] 



tf-E 



ML. 



ONTINUING our 

 consideration of 

 these bank -swal- 

 lows, let us now 

 pass to the time 

 of their annual dis- 

 appearance, late in 

 autumn, or at the 

 onset of winter. 

 Two conditions 

 cause the change 

 of locale, or, at 

 least, the disap- 

 pearance f r o m 

 their summer 

 haunts ; a much 

 lower temperature, 

 and absence of 

 insects, their only 

 food. Now, the 

 onset of , severe 

 frosts may be early in October, or delayed until 

 November, but this alone does not decide the move- 

 ments of the swallows ; for often they have wholly 

 disappeared before October) and . then a year may 

 pass, "with flitting swallows skimming o'er the lea, 

 undaunted by the chill November fogs. The sup- 

 posed regularity of their comings and goings is not 

 applicable to their New Jersey haunts, howsoever it 

 may be in more northern localities.' 



"What therefore I have seen of their movements in 

 autumn, that has possible bearing upon alleged hiber- 

 nation, is this : First, the effect of age. Now, it is 

 as evident as that birds'grow old, that, in due course 

 of time, these migratory swallows will reach that 

 condition of decrepitude when they can make their 

 migratory journey from south to north, or 'vice 

 versa, for the last time.' In such case, there must 

 necessarily be a large number that are left behind,' 

 when the main body depart each year, unless it can 

 No. 218.— February 1SS3. 



be shown that these age-worn birds die in the course 

 of the summer at the north, or during their winter 

 sojourn in the south. Both statements are true. The 

 result of a summer's study of a colony of bank 

 swallows, revealed the fact that a number of old 

 unpaired swallows flitted feebly about the bluff, but 

 never appeared to wander far from it. They were 

 seen, often sitting at the openings of the nests in the 

 cliff, and were taken for young birds. They were 

 not fed by old birds, having young to look after, and 

 fared scantily on such insects as they caught by their 

 own exertions. Early in August I found many lying 

 dead, both in the burrowings and at the foot of the 

 cliff. Examination proved that all were old birds. 

 In autumn, about October 1, the main body of the 

 colony largely frequent the weedy marshes, and seem 

 to be for ever on the wing, insect-catching, as they 

 move in an endless labyrinth of curves over the quiet 

 waters. I have seen thousands of them thus engaged, 

 and far from their nesting haunts. ' Occasionally they 

 would alight upon tall reeds and objects projecting 

 above the water, and twitter without ceasing. Theri 

 as by a signal, these thousands would rise together 

 from their resting places, and rising to an unusual 

 elevation fly away, to' return no more that season. 

 These birds were associated colonies on the southern 

 migration; but were' the sunny cliffs that so lately 

 were' teeming' with : happy swallow-life now wholly 

 deserted? Was there no trace of 'the many families 

 that had here' spent a joyous, gleesome summer V 

 Yes! There were' still a few. The lame, the weak, 

 the blind, and the unburied dead of that avian city 

 still remained ; and what a mournful spectacle they 

 offered ! painfully so in themselves,' and the more' 

 impressive when the thoughtless, glittering throng of 

 a few days past was vividly recalled. 



Cheered for the time by the mellow sunlight that 

 beamed upon them, the aged, half-helpless swallows, 

 whose wing still responded to the will of their owners, 

 languidly chased the few remaining insects flitting 



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