Hummingbirds crowd backyard feeders in July

Hummingbirds are familiar to almost everyone – especially those of us who maintain wildlife-friendly gardens.

Ruby-throated hummingbirds alone number more than 7.3 million in the Eastern U.S, having rebounded hardily from the dent made in the 1800s by collectors who hunted them for their brilliant feathers.

For many years, hummingbirds have been the beneficiary of a multinational treaty of protection and are no longer considered endangered. Yet the tiny, tropical birds retain an exotic quality and are perennial favorites of birdwatchers and gardeners alike.

The attention is well due. Beneath the bird’s ephemeral beauty and cachet as an international traveler, you’ll find a tough, down-to-earth creature that defies long odds in following nature’s call to reproduce.

Ruby-throateds are the only hummers to regularly breed east of the Mississippi River, said Susan Campbell, a research affiliate with the N.C. Museum of Natural Sciences. To do so, they must fly from Mexico, the Caribbean, Central or South America across the Gulf of Mexico, typically in a nonstop 500-mile trek that takes about 20 hours.

“From early April to mid-October is when we see the migrants,” said Campbell, who tracks hummingbirds across the state.

Some of the 15 Western hummingbird species also may be spotted in North Carolina in the summer, having ventured over the Rocky Mountains before heading south for the winter, she explained.

By late July, when a second round of ruby-throated fledglings emerge from their nests, North Carolina’s hummingbird population is at its annual peak, which lasts about a month before the males, “no longer in breeding mode,” begin migrating south, Campbell added.

Males migrate ahead of females because they are territorial and eager to stake out their space for the winter season. Similarly, in spring, males are the first to return to North America, with the females 10 days or more behind them.

Key to understanding hummingbird behavior is realizing that they are primarily carnivores, subsisting on insects, with nectar as a side dish.

When the temperature drops in North Carolina, and with it insect populations, hummingbirds flee south to look for spiders, ants and beetles. In a small number of places, including N.C.’s Outer Banks, ruby-throated hummingbirds sometimes stay put in the winter, especially older birds or those that very recently left the nest, according to hummingbirds.net, a website run by licensed hummingbird bander Lanny Chambers.

Gardeners who wish to support hummingbirds in North Carolina should also be considerate of beneficial insects and arachnids, such as beetles and spiders. That usually means avoiding pesticides and including a variety of plant species in your yard.

“Nectar is just a pick-me-up this time of year,” Campbell said. “At migration time, they will need it to increase their body weight rapidly. But most of the year, they eat insects and feed their young mainly insects.”

Hummingbirds have a special relationship with spiders, in particular, she added.

They eat smaller spiders and feed them to their young, but they also need the larger ones – which produce lots of webbing – to build nests in May, June and July.

Hummers build their tidy homes by weaving together bits of plants, leaves and twigs with spider silk, so “you don’t want to go whole hog in your efforts to remove spider webs,” Campbell said.

Each nest usually contains two eggs that hatch after two to three weeks.

Preparing for the flight back across the Gulf of Mexico, ruby-throated hummingbirds will add a gram or more to their body weight, with the average male topping out at just below 5 grams total. Nectar offers a quick way to gain energy.

Nectar from plants is the best source, because it contains nutrients that sugar-water solutions do not, Campbell said. Some plants have even evolved to be solely pollinated by hummingbirds, such as trumpet creeper (Campsis radicans).

But nectar feeders are not verboten. In fact, they provide a quick calorie boost to busy hummingbirds, which have the world’s fastest metabolism and eat up to three times their weight each day.

“Feeders are wonderful for entertainment, but it’s important to keep them clean,” Campbell advised. “With our humidity and heat, they should be emptied out and cleaned every three to four days. If you don’t have that dedication, it’s better to just plant for hummingbirds.”

Plants enjoyed by hummingbirds include Carolina Jessamine (Gelsemium sempervirens), native goldenrod (Solidago), columbine (Aquilegia) and bee balm (Monarda). Sun-loving options include lantana (Lantana camara), particularly the “Miss Huff” variety, along with salvia and sages, which are deer and rabbit resistant, too, Campbell said.

For more information on hummingbirds and the N.C. Natural Science Museum’s hummingbird tracking and banding operations, visit http://bit.ly/1Jk9olF.

This story was originally published July 25, 2015 at 9:39 AM with the headline "Hummingbirds crowd backyard feeders in July."