I was outside sitting on a chair at the padio table looking at the incoming storm clouds. i saw a flash in the corber of my eye and looked in the direction of a clear blue patch of sky and spotted and airplane that had reflected the glint of sunlight that flashed. as i was watching the plane disappear over the cloudcover i noticed the thin black oblong object. it resembled the shape of a riverstone if you were looking at it upright and on the thin side. it was headed northwest. i immediately called for my partner inside to come outside. i yelled saying that i was seeing a ufo and to come look. i had this strange intuitive feeling that the object was leaving when i first started following it? in the distance probably a few blocks away, i noticed a large bird in flight flapping that was in the same line of sight at the black thin oblong object. the bird was obviously much closer. this object was at the same height as the white clouds because i could see clouds behind it as well as some fast-moving low clouds that passed that were thin and mostly transparent. i then saw the object slow down and begin changing it's straightline path by curving to the south. i then had the feeling that this object was aware that i was seeing it because it slowed down in speed for a minute after it began heading south. as the object was about to disappear behind the neighbor's roof, i jumped up to continue watching it. it got further away and became smaller as it's speed increased. in effort to keep track i walked backward until i walked into a chair and lost my balance. my partner finally came outside later saying he didn't believe me until he saw me jump up to follow it across the sky. when i looked back up to try and find the object after stumbling into the chair, it was gone. my partner said he didn't see the object. that is understandable because the sky was very bright and the object was small. i was wearing prescription glasses that turn into shades so i was able to follow the object against a backdrop of bright white clouds. my partner went inside. i kept looking for several minutes when my partner asked me to please come inside because he had a bad eery feeling in his stomach. i went inside right away. this object was not a plane, and was not a bird because i had actually seen both examples of those objects over the course of this sighting. it was something else. it was intelligent in its movement. the feeling i got while watching this object at first was that for whatever reason, it was leaving. when it changed direction and then slowed, it can only be compared to how you might feel odd if you were watching a person walking away from you and then after realizing you were starring at the person, they turned around to face you and slowly started walking sideways as if studying you until they walked out of sight.