DO SWALLOWS HIBERNATE? 175 



of swallows. But I find that not more than one third of 

 the available space is utilized. At this rate, there would 

 be one hundred and forty pairs of swallows occupying 

 the chimney at one time. Now, this may seem like a fish 

 story, but it is an inconsiderable fraction of the truth. I 

 have carefully timed by my watch an unbroken line of 

 entering and out-going swallows, and seen them in these 

 processions steadily enter and reappear for five and a half 

 minutes, without a break, each bird followed by another 

 so closely that intervening spaces were scarcely discern- 

 ible. The downward and upward series were of course 

 different birds to a certain extent, and it is a fair estimate 

 to say that fully one thousand swallows were making a 

 nesting and roosting place of this one chimney at the one 

 time. 



Not the least curious feature of these large colonies is 

 the evident fact that but a small proportion of these birds 

 are nesting at this time ; and we are lost in amazement 

 when considering that the fragile eggs and tender fledg- 

 lings should escape destruction, surrounded as they are by 

 such a crowd of jostling, climbing, crawling, tireless swal- 

 lows. Nor is it at all easy to reach any definite conclu- 

 sion concerning the object of these non-nesting birds, in 

 thus continuously through the day entering their roosting 

 place the chimney. 



Now, these particulars are mentioned in this connec- 

 tion to show that many hundreds of these birds often 

 roost in the one place, and must be very closely packed 

 together when all are at home. For a portion of every 

 twenty-four hours they are well able to withstand the de- 

 pressing influences of a crowded condition, with certainly 

 a minimum of fresh air to breathe. The same conditions 

 would prove fatal to most other birds, if indeed not to all 

 others. 



12 



