Hummingbirds and the Seasons
The Annual Cycle of the Ruby-throated Hummingbird
January: Basking in the Tropics During January, the vast majority of Ruby-throated Hummingbirds are on their wintering grounds in the Southern Hemisphere. Hummingbirds aren't the only feisty birds there, so they have to tone it down a bit. They are getting fresh new feathers and molting, but they still need to visit hundreds of flowers every day.
February: Growing Restless By February, Rubythroats get a little restless in response to hormonal changes that are triggered by changing length of daylight. The first birds start migrating north the end of February.
March: Heading North In March migration is underway. Hummingbirds can't afford to be in too much of a hurry when they return to their breeding range in spring. There has to be food all along the way due to their tiny size and high metabolism.
April: Full Speed Ahead - Peak Migration Males arrive first and establish a territory. They look for a place with many flowers and high perches. They show off with flight displays, diving, dipping and looping to attract a female to their territory. Breeding begins in the southern states where flowers are in full bloom, and where the first egg can be laid as early as the second week in April.
May: Getting Down to Nesting In May, hummingbirds are still reaching the northernmost parts of their vast breeding range. Although it takes her 5 or 6 days to build her waterproof, camouflaged, stretchy nest isn't much bigger than a coin. The male has one job, but it's really important: keeping everything else away from the flowers. Females need quick access to food to get back on the nest so the eggs don't chill.
June: Raising Babies In June, a female hummingbird is busy! She does it all: lays and incubates two eggs, broods the babies in the nest, feeds them small insects and spiders, leads them to good flowers after they fledge, and keeps feeding them until they are independent. They fledge the nest at 21 or 22 days. A female may raise 2 or even 3 broods in a summer.
July: A Busy Time July is busy on the breeding grounds. Females are feeding their growing babies. Meanwhile, males are putting on the fat. Fewer hours of sunlight trigger the urge to migrate as fall approaches, and males leave first. Some will start migration in mid-July. Hummingbirds migrate at the time when their food is most plentiful, and they can more than double their weight before migration. By leaving first, males are ensuring more insects and nectar available for the babies.
August: Peak Migration August brings the biggest push south, and hummingbirds are gathering in huge numbers along the Gulf of Mexico. By August you may see no males at your feeders. Juvenile Rubythroats look so much like their mothers that most of us can't tell the difference. The babies have no memory of past migrations. They do not migrate with a parent. They just follow their urge to put on a lot of weight, fly in a southerly direction for a certain amount of time, and find a good place to spend winter.
September: Action Everywhere By late August and early September, the southward migration peaks. By mid-September, the Rubythroats at feeders are migrating through from farther north, and are not the same individuals seen in the summer. Adults are still arriving down at the Gulf Coast. The only Rubythroats still in the northern half of their breeding range are young ones. They must build up fat and flight muscles. These birds have no migration history. They do not migrate with a parent. They just follow their urge to put on a lot of weight, and leave when they are fat.
October: Settling in the Tropics In October, Ruby-throated Hummingbirds are on their wintering grounds. All of the arrivals from the north now face more competition for food. The babies have not been to the tropics before. They must adjust to new dangers they never imagined. Here the young hummers must learn about army ants and many different predatory insects. Snakes lurking in trees or slithering by flowers are their enemies. Some of the other hummingbirds that live in the tropics can be predators, too.
November: Changing the Feathers In November the hummingbirds are molting, a process that may start as early as October. While on the wintering grounds, all Ruby-throated hummingbirds are losing and replacing their flight and body feathers, including wing feathers. They will need fresh new feathers before migrating north. Hummingbirds have fewer feathers than other birds. Even a tiny Ruby-throated Hummingbird has about 940 feathers to keep in order, so it stops flying several times a day to preen. Preening helps keep the feathers clean and aligned.
December: Focusing on Food Hummingbirds on the tropical wintering grounds are focused on feeding and completing their molt. Growing new feathers uses lots of calories, and the tiny hummers need to bulk up again. It's easy when they are surrounded with lush tropical flowers to fuel their insect-catching flights. Meanwhile, some hummingbirds stay along the Gulf coast each winter instead of continuing to Central America. A small population winters in the Outer Banks of North Carolina. No one knows why.
What is the annual cycle of the Ruby-throated Hummingbird?
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