The summer populations of hummingbirds (Mi’kmaq: militaw) should be well established in our Biosphere by now.
Did you know that we only have one species, the Ruby-throated variety? The Bras d’Or Lake Biosphere is near the northern limit of the breeding range of this tiny bird (about 7-9 centimetres long, weighing about 2-6 grams). When the hummers start to trickle in after their long winter in Central America, there are very few flowers here to feed on.
They don’t rely solely on nectar but also dine on insects which provide much-needed protein for these weary travelers. They catch insects in midair, pick them off leaves or steal them out of spider webs. When more flowers bloom, they will feast on the nectar of red or orange tubular flowers such as honeysuckle, jewelweed and bee-balm. They are also fond of sugar water, although that attraction is site-specific.
The Ruby-throated hummingbirds return to the Bras d’Or Lake Biosphere in May. This year the first reported sighting was on Mother’s Day. The numbers in your yard will vary significantly over the summer. That is partly because of the beautiful but extremely territorial adult males. They are the individuals with the iridescent red throats. These beautiful bullies may drive the younger male hummingbirds away during the spring nesting season. The acrobatics of Ruby-throats are an entertaining sight as you sit on your deck nursing your summer Marguerita.
All hummingbirds are precision flyers. As the males aggressively defend flowers and feeders you can witness impressive chases and occasional beak stabs. They provide an aerial courtship dance for females that enter their territory. You have probably seen that looping, U-shaped dive starting very high above the female.
If the males are successful in hooking up, the females build their nests about 3 to 12 metres above ground on top of a slender branch of trees like oak or birch. Some females, however, are not so picky and will build nests on loops of chain or wire. The thimble-sized nest is made of thistle or dandelion down held together with strands of spider silk or pine resin and camouflaged with lichen and moss.
The female lays one to three tiny eggs and incubates them for 12 to 14 days. The chicks stay in the nest for 18 to 22 days and mother may have two broods during particularly nice summers. After the deed is done and the young chicks rejoin the grouping, you will see a greater number out and about.
In late summer or early fall, numbers fluctuate as the southerly migration begins. They don’t all leave at once. The first group to leave is mainly made up of male hummingbirds, followed by the females and young. As the diminishing daylight cuts short our beach activities, hummingbirds get restless and start to head south. When we have moved inside and started up our furnaces, they are settling in their winter home, the tropical forests of Central America.
The wintering range of the Ruby-throated Hummingbird has expanded dramatically in the last several decades, shifting nearly 320 kilometres northward up to South Carolina. Researchers predict that wintering Ruby-throated hummingbirds will continue to move further north as the climate continues to warm. This change means that breeding can start sooner and shorter migrations will probably lead to increased survival rates. We (or our descendants) will probably see more summer migrants coming to our Biosphere to breed. However, we won’t see overwintering Ruby-throats until a warmer climate allows insects and flowers to thrive during that cold season.
I have noticed that Ruby-throats swarm my feeders in the woods near my bungalow but I am unable to attract any in my city yard. There they target the many blossoms in the garden, ignoring my carefully-prepared sugar water. To attract the Ruby-throats you should plant some pretty red, tubular flowers. However, if you have hummingbird feeders, heed the advice from the Cornell University ornithologists: use one-quarter cup sugar per cup of water; honey spoils rapidly so don’t use it; real nectar is colourless so don’t add red food colouring; change sugar water every 3 to 5 days and more often in hot weather; clean feeders with hot water and a bottle brush (no soap or detergent). A mild bleach solution can be used if thoroughly rinsed; if wasps are causing problems, move the feeder around. Do not put oil or sticky substances around feeding ports. These contaminate the bird’s feathers; and if your efforts result in bird battles, use several small feeders in different areas rather than one large one.
Enjoy these energetic little summer visitors!
Dr. Annamarie Hatcher is a consulting ecologist and a board member of the Bras d’Or Lake Biosphere Reserve Association.