Concepting a trap design

Let's look at the design statement and goals.

No native bird trappings

100% trap rate

design to normal feeding behavior - foraging on ground or flat surface

Low key - professional looking - do not attract attention - attractive to birds

Ability for user to dispatch (if they choose) without handling the birds.

Low to ground. High traps scare birds.

Go ahead and add others...

That would be the magic unicorn of traps! Ease of use and simple adjustments ought to be on that list too. Not sure if there are many more goals.