My Daily Visitor

Last spring I was filling my feeder daily, for the flock of hummingbirds coming constantly.

For whatever reason, as the summer progressed the herd thinned to a trickle and now only a few come by for a daily drink.

Now I fill the feeder once a week.  Are my friends leaving us for warmer climates?  Are they tired of my sugar water mix?

Is this normal, seeing them less frequently? 

If you know anything about hummingbirds and their travel plans, please let me know!