Trying to develop an animatronic owl who's head turns to look at who ever enters its area. Using Audrino Uno and an ultrasonic sensor with 9g servos. Is this possible or should I go a different route?
An ultrasonic sensor only measures distance. If it "detects" an object in front of the back wall then you don't get any information when the object moves - you just see the back wall again.
A Pixy camera can do this very easily although there may be cheaper solutions that don't use a camera.
What has your research found when you googled it? What don't you like about those ideas?
Honestly Im very new to this. Saw that there was a great community on here and figured I'd get other opinions on the best method to achieve the goal I was looking for. Google shows either a motion sensor or camera might be the best course.
In order for the owl to turn its head to face the visitor, it has to know where the visitor is, or at least, the proper direction to point.
That is not a simple problem and unfortunately, all the good solutions that I know of are relatively expensive. The Pixy camera (about $70) has been mentioned, but a scanning laser range finder ($150 plus) would also work.
TymWayne:
Trying to develop an animatronic owl who's head turns to look at who ever enters its area.....
The aim is illusion and I don't think it should be that difficult - but then I am not doing it 
You have not defined what the owl's 'area' is and how a person enters the area.
Can there be more than one sensor, do the sensor/s need to be in the owl itself?
If a person can only approach the owl from the right or left then a couple of ultrasonic sensors in the 'perch' might be able to monitor those e.g. the distance to the wall changes because somebody has approached from that direction. You need to check the range of devices before purchasing, some might be as short as 0.5m. A short range could be an advantage though as it might make it easy to have the owl ignore distant people and only turn towards somebody who gets too close.
As well as ultrasonics you might be able to use infrared. One way would be to have people break the beams between IR transmitters and receivers. Perhaps a better way though would be to have pairs of transmitters and receivers pointing towards surfaces that reflect IR quite well. A person walking in front of the pair would disrupt the signal between them. You might not need to use special reflective surfaces, existing walls might be good enough.
IR would probably be a lot cheaper that ultrasonics, an it would be much easier to hide multiple IR pairs. It is worth remembering though that IR does not go through glass.