It was Bill Moore who peaked my interest in estimating total hummingbird numbers to my feeders. He uses a caloric intake calculation which would be a quite accurate method. In Googling his method & others, I've also found another calculation. Take most hummer numbers seen at feeders at one time & multiply by 6.
I've been checking both methods the past week & found that each gives results within 2-3 birds of one another. Yesterday, at most, by each calculation would have had 36 hummers. This AM, 18. This AM, seeing juv Black-chinned & Calliope only. Makes me wish I had watched real-time Doppler last night (as previously discussed with Robert) to look for an outgoing rush of "biologics". As seeing much fewer BH Grosbeak numbers this AM, as well.
In any case, appears fall movement to the south of songbirds has started in earnest. Not surprising, with recent onset of heat wave, wildfires & cool mornings.