While I guess using large calibers to hunt birds with looks cool on camera, it's completely unnecessary and in most cases dangerous. Large bird Pesting situations on a more professional level do not require large calibers, especially when shooting up in the air. Now that slugs have become the new fad I see little discussion on safety. Those slugs travel much further than most realize and carry so much energy with them. The goal is to eliminate as many birds as possible and as safely as we can without causing damage to property and other animals (and people). Most of the large permissions I hunt do have livestock, this makes using large calibers something of a liability. Using a .177 is not unethical at all, especially on the level of shooting birds that require very little energy to ethically kill. Get within reach of that caliber, we aren't playing military sniper here but doing a job that needs to be done. Whomever told you this obviously has no experience with hunting large commercial properties.