Explaining the decreasing number of hummingbirds

As summer continues, many of our breeding birds are finishing up their reproductive chores for this season. Some are still finishing nesting duties, but young birds may currently be found all around us, some already making their own way in the world beyond their nests, others still learning from their parents the skills they'll need to survive.

A few folks have inquired about a perceived lack of hummingbirds this season. The tiny treasures have not completely forsaken our area, although in some areas their local populations may have declined considerably.

First off, all wild animal populations are dynamic, exhibiting cyclical periods of increase followed by periods of decrease. These cycles would appear to be based primarily on the amount of suitable habitat available. Recall habitat has three components: food, water and shelter. Reduce or remove any one of those components and the animals that use them will be affected. Recent alteration of nearby landscape may reduce the amount of available habitat such that it can no longer support as large a population as it previously did, or may leave an area completely unable to support a population of species who may have very specific habitat requirements.

With regard to the size of an area that may cause such effects, consider we have documented hummingbirds here in South Carolina's coastal plain traveling as far as four miles between feeding sites. In Alabama, hummingbirds have been documented to travel as far as six miles between sites.

Reducing populations of tiny insects has a definite and immediate impact on nesting hummingbirds. The amazing Aves cannot live on nectar or sugar water alone. They require tiny arthropod prey to fulfill their dietary need for fats and protein. Females especially must have continual access to such prey to successfully raise offspring. Male hummingbirds are in search of potential mates, and will seek out females wherever they are.

However, at present we are entering the finishing up period for hummingbird nesting in our area. Adult males that have defended territories since their arrival in early spring will soon be relinquishing those territories and starting their pre-migratory wandering. The numbers of juvenile hummingbirds is on the increase, and hummingbird numbers in our area will continue to increase for the next four to six weeks, with numbers generally peaking during the first two weeks of August as birds from more northern breeding grounds make their way southward through our area.

Remember to keep your feeders clean and maintained with a solution of one part sugar to four parts water with no other additives, and keep an eye out for these avian gems in your backyard.

This story was originally published July 6, 2016 at 5:00 AM with the headline "Explaining the decreasing number of hummingbirds."