Hummingbirds court in the air but, contrary to common myth, mate on a perch. Males arrive first to establish a territory and food supply. They fly a courtship display when the females arrive, calling with a chirping sound and displaying his brightly colored gorget. Many species perform a flying dance to impress the female.
Once mated, the male takes no part in building the nest or raising the brood. The female lays a clutch of usually 2 eggs over a day or two, some as small as a coffee bean. The hatchlings are blind and have only a little down and a short bill.
A female may have more than one nest and may be building a new nest while still caring for an early brood. A third brood is not unheard of. Fewer females will be seen at the feeder while the hatchlings are in the nest as she feeds them insects she catches on plants or while flying (hawking).
The Rufous and Calliope hummingbirds have been observed to build a new nest on top of one from the year before. As many as four nests stacked up have been seen.
A hummingbird nest is about the size of a golf ball and about 1-inch deep. Spiderwebs are used to attach the nests to tree limbs.
Grooming
Hummingbirds care for their feathers using their bills and claws. They obtain oil from a gland near their tail and groom each feather. Head and neck are groomed by using their claws like a comb or by rubbing against a twig.
Hummers sunbathe by facing the sun and fluffing their feathers out. They may also spread their neck and tail or spread one wing and then the other to catch the sun. Water baths are also a favorite of hummers and they will bathe in shallow pools, dipping their chins and bellies, splashing with their wings, or tossing water with their bills onto their backs. Hummers will also fly though a sprinkler, or fluff out in the rain to catch the water. They will perch and groom after bathing.
Traplining
Hummers feed by sight and will generally check out anything to see if it is a source of food. Our hummers seem determined that our wind chimes will someday be edible. Many birds follow a regular route through their territory checking out the food sources several times daily. This behavior is called traplining. Having a constant source of food on the route, either a hummingbird garden with successively flowering plants or reliable nectar sources, will go a long way in keeping hummers at your house all season.
Torpor
Torpor is a state in which a hummer's metabolic rate is only one-fifteenth that of normal sleep. Body temperature may drop by 20 to 50 degrees F and breathing may stop for a time. The bird's heart rate may drop from over 1000 beats per minute to as few as 50. Hummers go into torpor to conserve energy, generally overnight, and in cooler temperatures as a survival mechanism. Often hummers which may appear to be dead are merely in torpor and will readily "recover" if disturbed.
Predators
Hummingbird nests are raided for eggs and chicks by snakes, large birds, and some mammals but adult hummingbirds are not regular prey. The most common danger is the family pet that gets lucky enough to ambush one. Birds, such as owls, hawks, roadrunners, and other large birds have been known to take hummers as have frogs, spiders, and preying mantises.
Spider webs also pose a hazard. Webs are very strong and sticky and the bird may become entangled and may actually be wrapped by the spider as just another large "insect".
Bees and wasps may attack a hummer and a single sting may be enough to kill the bird because of its small body.
There are reports of frogs capturing a hummingbird and one source reports a case of a hummingbird being taken by a BASS!
Though one would not consider plant burrs to be predators, there are three known cases of hummingbirds in Washington, DC, being fatally snared by burdock burrs in Rock Creek Park when they were not strong enough to pull the burrs from the plant.
Migration
Hummingbirds are solitary travelers and the migration is separated by age and gender. Males begin moving north about three weeks before the females and depart the summer range before the females and juveniles. Some reasons are offered by experts for this behavior but the reason is more guesswork that solid fact.
One reason for the later departure north for the females is that a later trip will help insure that more food sources will be available. Hummers do not pair up and the loss of a few males will be less damaging to the species survival than the loss of females.
Conversely, the early departure of the males opens up the feeding area, usually highly protected by the males, for the new brood. The juveniles are the last to leave and migrate to the winter area without adult guides.
It is generally believed Ruby-throated hummingbirds fly non-stop across the Gulf of Mexico in the spring and possibly in both directions. This trip is believed to take a hummer 18 to 20 hours. This is a remarkable journey and certainly the trip carries the extra danger of adverse winds with little margin of error for the tiny travelers. Birds lose a quarter to half their body weight during migration. Scientists suspect the birds navigate by stars when traveling at night.
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