id	author	title	date	pages	extension	mime	words	sentence	flesch	summary	cache	txt
flmnh-184	Brodkorb, Pierce	How Many Species of Birds Have Existed?	1960	16	.pdf	application/pdf	5238	372	67	TABLE 1 LONGEVITY OF AvIAN SPECIES Estimated Years average Locality and stage before Total Extinct Percent longevity present species species extinct in years Florida, mid-IV glacial 1 17,000- 63 6 9.5 89,474 California, IV glacial ' 25,000 121 22 18.2 68,681. Lowered temperatures during the glacial ages of the Pleistocene and elevated temperatures during the interglacial ages undoubtedly caused some shifting of the ranges of bird species, either directly or, more probably, indirectly through changes in vegetational zones.	cache/flmnh-184.pdf	txt/flmnh-184.txt