What evidence do you feel I am ignoring?

@Kindamany The evidence that researchers have collected and documented for over 80 years now. When beings are sighted, they're diminutive, described as child like only 3 to 4 ft tall. So what have we discovered with Kepler? Kepler discovered these large rocky planets that are larger than earth. There dubbed "Super Earths." And while you're wondering if there life out there, I'm wondering why are most alien sightings are 3 to 4ft tall. Well I apparently have gotten my answer.
But lets put ufo sightings aside. You see, what would the color of earth be if we were to reduce the atmosphere to the pressure found on Mars and removed all of earths oceans? The answer to that question is red. Well what color is Mars?
So when you ask your silly questions, the question that I'm asking, are you similar person to a christian conservative believing that the earth is 6,000 yrs old and flat?

@sirbikesalot06 I am simply asking if, since we have no definitive evidence for having been visited by extraterrestrials, it is because there may not be flying creatures on other planets that advanced species would be able to emulate. Are you similar to some sort of conspiracy believer that thinks the governments are holding onto evidence we have been visited by other world beings?
I fail to see how any of what you stated pertains to answering the possibility presented. I am not wondering if there is life out there, because I think with all the planets out there the likelihood is high that some other planet has developed life, but I am wondering if an intelligent species exists on another world that simply has not made machines that fly because the lifeforms they inhabit their world with do not have flight capabilities like birds do. If our planet was not all that much bigger it is many biologists estimation that birds would not have evolved to be able to fly. Also, if a planet reaches sufficient mass the rocket equation would not work for them to escape their planet's gravity, they would have to find a different way. Those planets may have intelligent life, but they simply may have no way of knowing how to "get off the ground."

No doubt there. Though there are several species here that have a lot of brain power.

Maybe not next door, but perhaps within our own galaxy.

Also, planet gravity can inhibit certain traits from evolving.