serious menace to birds during migration and some are killed nearly 

 every fall. 



When the torch on the Statue of Liberty in New York Harbor was 

 kept lighted, it caused an enormous destruction of bird life, tabulations 

 showing as many as 700 birds killed in a single month. 



In September 1948, bird students were startled by news of the whole- 

 sale destruction of Maryland yellowthroats, redstarts, ovenbirds, and 

 others that were dashed against the 1,250-foot high Empire State Build- 

 ing in New York City, the 491-foot high Philadelphia Saving Fund 

 Society Building in Philadelphia, and the 450-foot high WBAL radio 

 tower in Baltimore. In New York the birds continued to crash into 

 the Empire State Building over a 6-hour period and their bodies were 

 scattered over a four-block area. The mortality was so heavy in Phila- 

 delphia that it was impossible to use the sidewalk below the sky- 

 scraper until the birds had been gathered. A study of the weather 

 conditions prevailing at this time in the Atlantic coastal region sug- 

 gests the probable cause of this catastrophe. By early morning on 

 September 11 a mass of cold, southward-flowing air had just reached 

 New York City where it was forcing upward and was being over- 

 ridden by a mass of warm, northward-flowing air. Presumably the 

 migrants were riding the upper levels of the southbound current which, 

 in the contact zone with the northbound current, was being deflected 

 earthward, thus causing the birds to fly lower and lower until they 

 were below the tower of the Empire State Building. Clouds and gusty 

 winds in the zone of contact between the two air masses reduced visi- 

 bility and disrupted avian navigation with the result that the confused 

 travelers crashed into the stone and steel obstruction. As the cold air 

 mass continued to move southward, the situation was repeated at 

 Philadelphia and at Baltimore. 



Exhaustion 



Although it would seem that the exertion incident to the long flights 

 of many species of migratory birds would result in their arrival at their 

 destination in a state bordering on exhaustion, this is contrary to the 

 truth. Both the soaring and the sailing of birds show them to be 

 proficient in the use of factors employed in aerial transportation that 

 only recently have become understood and imitated by aeronautical 

 engineers. The use of ascending currents of air, employed by all soar- 

 ing birds, and easily demonstrated by observing the gulls that glide 



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