January: Basking in the Tropics
the vast majority of Ruby-throated Hummingbirds are on their wintering grounds in Central America. 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 visit hundreds of flowers every day. Hummingbirds burn energy so fast they often eat 1.5 to 3 times their body weight in food per day. After hovering over a flower long enough to drink a nectar meal, they zip through the air, snatching tiny insects as they go.
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. Hummingbirds follow Yellow-bellied Sapsuckers north because those birds drill holes, called sapsucker wells, in trees as they migrate north. These tiny birds cannot survive a day without food, so sap running from the holes is important for Ruby-throated Hummingbirds in early spring.
April: Full Speed Ahead: Peak Migration
In April people on the Gulf Coast start watching for hummingbirds to arrive. 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. If she likes his display, she will mate with him. If not, she moves on to another 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. Hummingbirds don't mate for life; they don't even stay together to raise the babies.
May: Getting Down to Nesting
In May, hummingbirds are still reaching the northernmost parts of their vast breeding range. A Rubythroat's nest isn't much bigger than a coin, but it takes her 5 or 6 days to build her waterproof, camouflaged, stretchy nest. The male has one job, but it's really important: keeping everything else away from the flowers. He ferociously chases everything from bees to big birds away from his territory's flowers, feeders and food. Females need quick access to food to get back on the nest so the eggs don't chill. A flower-filled territory means Mom uses less energy for flying so she has more energy for incubating. She doesn't have to worry about competition at the feeders or flowers.
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. The babies grow inside the egg for 12-14 days before hatching. They are born naked and have eyes closed until about 9 days of age. At 16 days of age they are 8 times bigger than when they were born. Finally, they fly out of the nest at 21 or 22 days of age. They will start sleeping on a leafy branch, protected from wind and rain. A female may raise two or even three broods in a summer.
July: Preparing for Migration
July is busy on the breeding grounds. 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. Early migrants spread out the migration, resulting in less food competition along the route. Meanwhile, the females, busy with babies, don't need to search for food. Flowers and insects are still abundant. The nestlings' feathers are growing, and the adults are keeping their feathers cared for because they'll be migrating with these same feathers.
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. Hummingbirds migrate at the time when their food is most plentiful, and they leave when they are fat enough. Some follow the coastline of the Gulf of Mexico. Many—but not all—fly 500 miles nonstop across the water to Mexico and other Central American countries. It's a mystery how individual birds make the decision.
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, while others are crossing the Gulf. However, breeding activity may still be happening in Southern Ontario, where eggs may be laid from May 25 to September 2, or in southern states where hummingbirds nest again after babies fledge. 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, leave when they are fat enough, fly in a southerly direction for a certain amount of time, and find a good place to spend winter.
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 adults are molting and getting fresh new feathers. 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. Small wonder our Rubythroats return north in spring to escape all that and breed!
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. Feathers are a bird's most important flight gear. 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. Nectar is sticky so hummers must clean up. Preening helps keep the feathers clean and aligned, making the bird's wings efficient and its body aerodynamic.
December: Focus 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, outliers are hummingbirds that decided to stay along the Gulf coast each winter instead of continuing to Central America, and there are always a few hummers that stay up north. Another small population winters in the Outer Banks of North Carolina. No one knows why. Each individual bird has a lot of choices.
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