Remember when you could remember everything?
. . . Certain hours of the day give you better results depending on the number of satellites that occupy the area at that time.
GPS satellites are in so-called geosynchronous orbits - their position about 24,000 miles above us is stationary relative to the earth. There are 24 US GPS satellites, one for each time zone. So on flat, unobstructed land, at least several are in 'view' at any given time. Mountains and trees can block receivers from getting the signals sent by satellites, especially from those further towards the horizon in either direction. Most receivers require signals from at least 3 satellites in order to triangulate position. Fewer than 3 sets of signals means no triangulation, thus the receiver isn't able to indicate its position.
That's why receivers with more-sensitive and powerful antennas are more accurate. Some receivers like the Garmin 60 and 62 series actually have jacks that allow separate antennas to be attached, vastly improving their accuracy.
BTW, GPS-calculated distances can be pretty accurate in X and Y axes (down to as fine as 2-3 meters). But the Z axis or elevation, is much less accurate which is why most units still rely on a barometer to calculate altitude.
My notes don't indicate how flocks of birds might influence signal accuracy!