Field Research is Rigged
Drowning in pesky Murkrow, soon as "Catch 3 Pidgey or Murkrow" is spun up not one to be seen, even in their popular spots. Same with other tasks like Oddish etc. Do you find the same?
Answers
Some times it does seem to happen like that. It happened to me earlier today. I received the catch 3 Oddish/Bellsprout task, and up until that point in the day I was seeing both pretty frequently. After receiving the task I stayed out playing for another hour maybe and came across 1 Oddish in that time. I live in a grass biome and see both of those Pokemon any time I move 50 feet in any direction
What;s crazier? The idea that the game's spawn mechanics would change based on what a player receives for a field research task or that you would even ask this question in the first place.
Just give up. They're on to you. Once they learn you've figured out their elaborate scheme they'll soft ban your account anyway.
Kinda just the opposite. I tend to see Mewoth right after getting the "Catch 3 Mouth or Skitty" task. Never see them otherwise. Takes a day or so to complete the challenge and then they disappear completely. Same with Mudkip. The only Mudkip I have seen in my area have come right after getting the "Catch 3 Treecko or Mudkip."
Imagine the programming that would go into "rigging" the system to affect each individual player depending on what research quests they had in their inventory, up to and including the lowly "catch 3 pidgey" quest. It would mean that if you had this quest up, everywhere you walked, pidgey would be swept from the playing field around you and everyone else near you.
No, the reason this quest seemed "rigged" was that pidgey and murkrow spawn were relatively rare (especially murkrow) during the earth day event.