warrant

Reader's Digestには動物の記事が必ずありますが、次の引用文は6月号の亀の話からです。
Our neighbour's tortoise, Harold, would constantly escape from their garden, often warranting a large search party to find him. My father, who was a scientific engineer, offered to build a tracking device.
"warrant" と言うと、「保証する」と「認可する」の意味しか覚えていないので、上記の文脈には合いません。別の意味もあるに違いありません。辞書を見ます。
・Oxford English Dictionary: Justify or necessitate (a certain course of action): ‘that offense is serious enough to warrant a court marshal’
・Macmillan Dictionary: to make an action seem reasonable or necessary: What he did was serious enough to warrant punishment.
・Vocabulary.com: It's a noun! It's a verb! It's a word that warrants our attention! As a noun, it's the piece of paper they show you through the keyhole during an investigation. It's also a reason for doing something, or a promise (think of the warranty on your new car, the promise that it'll work for a certain amount of time). As a verb, it means to make something seem reasonable or necessary, such when the ticking suitcase warrants bringing in the bomb squad, or when the teenager's sneaking in late again warrants a stricter curfew.
"warrant" のこの意味も覚える必要があるのは当然の事ですね。