The details from the text which best supports the author's purpose to inform the reader that the islands are amazing to him are:-
The plenty of giraffes, wild boars were really big as buffaloes with tusks of 14lbs, Gryphon bird are terrifically huge in size and these are the wild asses on the islands.
There are basic three purposes of an author, which are:- to inform, to persuade, and to entertain the reader.
It is so because the author travelled and so he shared the facts that he comes to discover on the islands, in a way he was depicting the island through his words.
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