Ting, here they are using obliged to express a kind accommodation. It is true that the word "Oblige" means "to force;" however, it is also used as an idiom in English to express one's moral accommodation. In other words, the people who saw the puma obliged the experts, so the experts "felt obliged." The experts are expressing thanks to the people who saw the puma by investigating its presence somewhere. Or think of it like this: The people did the Zoo Experts a favor by providing the descriptions of the puma, and the experts are investigating as a way of giving thanks to the people for reporting that the puma is running about town.

This is a useful explanation: From Merriam-Webster's Dictionary of English Usage page 675 "obligated" remains in Scottish and American use, but has dropped out of British English. Both "obliged" and "obligated" mean "being constrained legally or morally". When the constraint is applied by physical force or circumstances, "obliged" is used. Thus, in your specific example, the experts are doing the investigation because of the circumstances: people claimed to have seen the puma and the descriptions by the people were extraordinarily similar. http://www.merriam-webster.com/dictionary/oblige : to constrain by physical, moral, or legal force or by the exigencies of circumstance <obliged to find a job> vs ob·li·gate : to make (a person or organization) do something because the law requires it or because it is the right thing to do Thus, major subtlety, and oblige is the winner for that specific example.

obliged or obligated both would work fine here. Obliged means under moral obligation to investigate in this case. obliged= duty bound. English people use these words often also :)

obliged or obligated both would work fine here. Obliged means under moral obligation to investigate in this case. obliged= duty bound.