2. The second reason could be they are simply just very much in need of energy.
When their migration journey has ended, or when they are along route, or before they begin migration, they are in great need of extra food.
For male birds fighting for territory, attracting a mate with their aerial dance, protecting a mate from other suitors and for the females building a nest and raising babies, are all very taxing activities which require extra energy, which can only be derived from food.
3. You might need to simply purchase another feeder, which will provide twice as much food for the little birds and make your nectar last longer.
But do remember that keeping fresh nectar out for your Hummers is very important.
If the sugary solution sits too many days outside, especially in intense heat, it will develop mold or go rancid.
Putting fresh syrup out every couple of days is never a bad thing!
Ready Made Hummingbird Food
It is very important to use the correct mixture ratio.
Follow the directions on the ready-to-mix package carefully.
You should never add fresh nectar to what has been in the feeders already.
When the feeders need refilling you should wash them and rinse them well.
Then refill with fresh nectar mixture.
And never mix it stronger than the directions say on your package.
Making Your Own Hummingbird Food
Or if you are making your own Hummingbird food follow a 1 to 4 ratio of one part white sugar to 4 parts water.
There are times when it is better to use different strengths of nectar mixture. You can learn more about that here at How to Mix Hummingbird Food?.
You can boil the water first before adding the sugar, but you do not have to.
Just make sure the homemade nectar is cooled down before re-filling the bottle if you do boil it or the hot syrup will make the feeder leak.
You will want your feeders clean and fresh for the arrival of young birds.
Some Hummingbird females can raise 2 to 3 broods in one summer in the more southerly regions of North America!