Every year when I start to see hummingbirds migrating south, it seems like it's far too early, but in reality they are leaving right within the times of many migrant birds. It's been a steady flow of birds from the North and it'll continue for weeks to come.
My last hummingbird of 2017 was on August 25th, and as of today, August 27th, 2018, I still have at least 5 hummingbirds hanging around, 2 being mothers ready to bring young. These late mothers wouldn't have anything to do with late arrivals in Spring because the 50 day brood cycle of the Ruby-throat would put their arrival time at July 7th, if the young arrived today, which is far beyond the Spring migration times. Could it be an unlikely second brood of a Ruby, or an incomplete brood, forcing the mother to start again? Every year I've noticed that Ziggy or any past males have stuck around until mid-July with breeding behavior. It's only once that mid-July point has passed that they go into a different type of behavior, not resembling breeding. If Ziggy or any male found a mate in mid-July, the possibility of a late brood happening in my garden or anyones in my region would be quite possible, therefore young showing up in late August.
I've had recent hummingbird sightings reported to me still in Alberta, including as far north as Peace River, a region not commonly known for many hummingbird sightings. Now for those wondering how long to continue with changing their feeders, this is important. Those N.W. of you are still seeing hummingbirds, and for myself, I have 2 mothers still to bring young to my garden. This tells me that my potential for hummingbirds will be at least 7 more days with my birds alone, and not including those 5 or more days N.W. of me, which means everyone south of me has many more possible days of hummingbirds. Just because your local birds have gone, does not mean the migration is finished. The intense migration forces these tiny birds to travel 50km/day(30 miles), and food is essential to these calorie burning missiles. My suggestion is to leave feeders up a MINIMUM of 7 days after your last birds have left, and 14 -21 days would be even better for the possibility of migrants.
This young Ruby sits and protects its own little basket of flowers. N.E. of Edmonton, Alberta, Canada. Mid-August, 2018