We make a lot of sleeping bags. And they all have bird names. With so many sleeping bags, the names can get a bit confusing. We still have the Merlin, Osprey, Kestrel and Grouse, but they have been renamed. The Merlin was always the 30 degree version of the Hummingbird 20, so we combined them to the Hummingbird 20/30 Likewise, the Osprey was the 30 degree version of the Swallow 20, so they are also combined into the Swallow 20/30 If you're sensing a pattern, you're totally right. The Kestrel was the 30 degree version of the Swift 20, so they are combined into the Swift 20/30 And finally, the Grouse was the 30 degree version of the Egret 20. They are combined into the Egret 20/30