Basics of Hummingbird Nesting and Life Cycle

Now that nesting season has begun, we thought everyone following the progress of our project might like to know about what to expect for development of hummingbird nestlings (also called chicks) as they grow.  Teachers might like to share this information with their students!

Nesting Season:  All of the nests we have found are of the species Allen's hummingbird Selasphorus sasin. Some of the birds of this species are year-round residents of Southern California, while others are migratory. The migrants arrive early, starting in January and continuing through February, which is why we are seeing so many nests of this species!  They will remain in the area for breeding season through June to July, with the last remaining few heading south in August.

Incubation Phase:  Once the eggs (avg of 2, about the size of a navy bean!) have been laid a couple of days apart, the female then incubates the eggs 24x7, only leaving the nest briefly to feed.  This is a very vulnerable time for the eggs, due mainly to egg predation and cold temperatures.  The eggs need to maintain a constant temperature of about 96 degrees.  Two of the 5 nests we have found so far on the LMU campus have been predated, which is a common occurrence in nature.  The eggs that do survive will be incubated for an average of 15-18 days by the female hummingbird.  The male plays no role in incubating the eggs or raising the chicks.   Currently we have three active nests:  1 has two nestlings that will likely fledge (leave the nest) within the next week; 1 has 2 eggs that are being incubated; and the third has 1 egg and 1 hatched chick.  The other chick will hopefully be hatching very soon!  

Hatching Phase:  When chicks hatch out of the eggs, they weigh only an avg of 0.62 grams! (url.learner.org)  They are virtually naked, helpless, and blind, and remain in the nest until they are fully feathered, usually within about three weeks in North American species. (Howell, 2002)  Erich's last post included recent pictures of the chicks in Nest 1.  Aren't they adoreable?!

Brooding / Nestling Phase:  The three-week brooding phase is also a very vulnerable time for the nestlings. As they grow, the mother needs to leave the nest to find enough spiders and insects (and some nectar) to feed them (and herself!).  The nestlings need to be fed about once every 20 mins.  It is a constant back-and-forth, which leaves them alone, often for up to 30 minutes at a time.  In the 18-28 day nestling period, the chicks grow rapidly, so that they can fly on their own within a few weeks from hatching.  Extraordinary!

Fledging Phase:  The fledging phase is really fun to watch!  The nestlings begin to flap their wings within the safety of the nest to practice flight, which is often difficult for two of them! There is not much room in that tiny nest!  They end up bumping into each other and hitting each other in the face with their wing flapping or as they are trying to get settled back down.  It really is quite comical to watch!  Once the nestlings are ready to become fledglings (like a rite of passage!), out they go!  Fledglings often stay close to the nest but usually do not fly back into it.  The mother may continue feeding the fledglings for a few days after they leave the nest, but then she chases them out of her territory.  (url: worldofhummingbirds)  Nests are often re-used by other hummingbirds.  What a great natural recycling process! 

Life Cycle:  Many hummingbirds die within their first year, but the ones that do survive, can live an average of about 7 years.