In BTD4, this upgrade allows detection of Camo Bloons for any tower in the radius. It is good for those early rounds with Camo Bloons if players don't have any other tower or upgrade that is able to detect them. In Bloons TD 5, this upgrade only allows the Monkey Buccaneer itself to detect Camo Bloons unless a Tier 3 Pirate Cove is active. In BTD6, it is very similar to BTD5.
In BTD6, this upgrade is the 2nd upgrade of Path 3 for the Buccaneer. It is now succeeds the Long Range upgrade and now is on a separate path to Cannon Ship and Grape Shot. Like most other upgrades in BTD5 and later, it only gives the Buccaneer itself camo detection. The Crow's Nest is now also more expensive than it used to be, costing $340 on Easy, $400 on Medium, $430 on Hard, and $500 on Impoppable.
In BTD5 and BTD5 Deluxe this upgrade does not allow Camo detection for all towers, unless a level 3 Pirate Cove is active. This is because upgrades in Bloons TD 5 and Bloons Tower Defense 5 Deluxe that allow Camo detection have changed to only let the tower who bought it be able to detect Camo.
Due to this, if players have a Tier 3 Pirate Cove and a 4-2 Aircraft Carrier, every tower on screen gets Camo detection due to the infinite range of the Aircraft Carrier.