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....They are terms of venery, which means that they are quite likely to have been made up just to be a bit funny and act as linguistic curios. Some terms of venery have a long-standing tradition and are actually in use in English (like a pride of lions or a school of fish), but many others, going all the way back to the 15th century and the Book of St. Albans, were/are clearly just made up to be amusing and set you off as someone who knows an awful lot about which specific collective noun to use for which specific animal.
Using a streak/ambush of tigers in an actual, normal English context would most likely just get you odd looks or blank stares. A few here and there may realize that you’re talking terms of venery, and they may even think that you just made it up yourself to be funny; but I would wager very, very few people would recognize them as ‘accepted’ collective nouns.
If you’re looking for a term that just makes your intention clear without sounding strange or abstruse, just use a generic collective noun, like a group of tigers. This is quite commonly used—it gives about 93,000 Google hits. Streak and ambush both give less than 5,000 hits, and most of the first ones are pages listing terms of venery.
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