Hello Alex,
I dont know, how reliable the Merlin app is, and I agree with Butty, there are several wrongly identified cases here on BF. But as it identified the call as a Little RP, I agree with you that its ok to use the answer as a feature.
I must admit, that my first gut-feeling was a Common RP too, I agree with JWN, Dave, Jogresh, Butty and Clark. 2cy birds can have a dark bill and I am not sure, an orange bill-base would be visible here, the picture seems slightly colourless to me (no offence you know).
Assuming, that a Little RP isnt a massive rarity (can you give exact location please?) and bearing AI in mind, I struggled to find a pro Little RP feature. And a hard biased look revealed what can be interpreteted as a smallish black/dark mask with the right corner (not rounded) at the lower border. Yes its easy and true, that this is wishful thinking next level. Yes, I try to defeat Merlin here (personal reason, no offence)....