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The Rubies Return

By Brittany Richards

The pear and cherry trees have bloomed and leafed out. The eastern redbuds are glorious fuschia. Your yard is abuzz with chubby carpenter bees and flying insects of all sorts. But how do you know it’s really spring? The first hummingbird sighting of the season, of course! Our bird of the year, the Ruby-throated Hummingbird, will be returning soon (if you aren’t already one of the lucky few to have welcomed an early visitor). While there is still much unknown about the exact mechanics of their spring migration, what scientists have been able to learn offers a fascinating glimpse at the remarkable feat these tiny birds undertake on their way to our backyards. 

We know from our last blog post that our hummingbirds are preparing for their spring journey by fattening up in their wintering grounds and refreshing their beautiful plumage, and that male birds will leave first to establish their territory. Just as they did last fall, most birds will take an overwater route and fly 500 miles nonstop over the Gulf of Mexico before reaching the Gulf coast states to refuel while making their way to the North Carolina piedmont and beyond (and smaller numbers will hug the coast to migrate over land). It is believed that their overwater flight largely takes place at night, while their migration over land happens during the day and near ground level to take advantage of food sources for frequent feeding. 

But why do they leave their tropical paradise at all? Ruby-throated Hummingbirds evolved to take advantage of the seasonally available flowers in their two habitats, and that adaptation is now a hardwired instinct. Their northern summer breeding territory is six times larger than their winter territory (25 million square miles versus four million square miles), so when nectar-producing flowers bloom in abundance across eastern North America, hummingbirds migrate to feast on the bounty. They likely know when it is time to migrate because they are sensitive to changes in the photoperiod, or the amount of daylight hours in a 24-hour timeframe. So as spring days grow longer, hormonal signals trigger the instinct to head back north. 

When the Ruby-throats reach the southeastern United States, they will fan out across the summer range, as far west as Texas and as far north as Canada. Studies of banded Ruby-throats shows that birds will take astoundingly consistent routes: flying the same route in spring and fall and the same route each year, and even stopping over at the same places along the way, and in some cases stopping on the same day, until they return to their own birthplace where they hatched. So the birds you see return to your feeder are indeed likely the same birds you saw last year. With an average lifespan of three to four years, you can enjoy seeing the same birds for several summers. Scientists do not know precisely how they accomplish this amazing precision, especially considering Ruby-throats migrate alone without a parent or flock to guide them. Along with instinct, they may use some combination of sensing the Earth’s magnetic field, using the sun as a compass, and noticing landmarks to remember their favorite layovers and find their final destination. 

As we all anxiously await a familiar fluttering at our feeders, the National Audubon Society has a handy list of hummingbird feeder FAQ to help us prepare a tasty meal for our hungry migrants. Some general tips to keep in mind:

• Not only is red-dyed nectar unnecessary, it’s actually harmful. A simple homemade recipe is one part white sugar to four parts water (and never honey, molasses, brown sugar, or artificial sweeteners). 
• The hotter the weather, the more frequently the feeder needs to be cleaned. Placing your feeder in the shade is a good way to keep it from spoiling as quickly. Early in the season you also won’t need as much, so you can use less (and waste less!) at the start. 
• In addition to your nectar feeder, native plants are a great way to attract and feed hummingbirds (and other pollinators). The National Audubon Society also provides tips for creating a hummingbird-friendly yard and a database of native plants based on your zipcode. 

Hopefully you’ll mark the true start of your spring season with a Ruby-throated visitor or two very soon. After their long journey north, your birds will be very grateful for your nourishing nectar!