61884
In Sri Lanka , for example , vocal mimicry by the greater racket-tailed drongo might have a key role in the initiation of mixed-species foraging flocks , while in parts of the American tropics noisy packs of foraging golden-crowned warblers might play the same role .
 Sri Lanka
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Sri Lanka