Wednesday, June 10, 2009
Life as a Little: Hummingbirds
Have you ever wondered what it would be like to be the smallest being in a land of giants? A place where even insects prey on your kind? Welcome to the world of hummingbirds, where reports abound of hummies being snatched in mid-air by the likes of roadrunners, jays, flycatchers, and your favorite pet feline. There’s even a report of a hummingbird snatch by an alert mountain lion in Arizona’s Sonoran Desert Museum. Even the praying mantis, that slow motion insect, sometimes dines on the most diminutive of birds. Lest you wonder if I am filling your head with grisly stories worthy of Snopes, check it out yourself. Just Google “hummingbird eaten by praying mantis” and see what turns up, some 4,130 hits including a YouTube video.
One might wonder just how the little guys are faring since most everything views them as a snack. Not much to worry about here though, because the top predator on the planet has a special fondness for the tiniest of North American birds, but not as a diet supplement. Yes, it is we, the two-legged, land-locked of this planet, that are enmeshed in a love affair with hummingbirds. We watch over, photograph, feed, and protect the little fellows, sometimes to the tune of many thousands of dollars annually per household. Some individuals report usage of up to 50 pounds of sugar a week.
What this means in scientific terms is that the introduction of exotic plants and feeders has produced a widespread energy subsidy that may maintain unnaturally large populations in times of flower scarcity, or when the natural nectar supply is reduced due to drought, insects, or weather. Our stocked feeders have helped increase populations in urban and suburban settings, leading to an overall increase in the species, as evidenced by range expansion and previously unoccupied habitats that are now occupied. Some hummingbirds now overwinter far north of their former range, including a handful that survive Albuquerque winters, almost entirely due to well-maintained feeders.
The two most common nesting hummingbirds in New Mexico are the Black-chinned and Broad-tailed. Both are present in the state, although the Black-chinned is often found at lower elevations, in riparian woodlands. In high quality habitat along rivers, black-chins might be found every 100 meters (33 feet), and this birder can tell you from personal experience that it happens. In the Middle Rio Grande bosque, the Black-chinned Hummingbird is the most common nesting bird, and it’s all-out war as males battle over the rights to sire offspring. Did you know that you actually can distinguish the different hummingbirds by calls?
Surveys here produce not single entries, but 2-3 birds at a time, often locked in combat or issuing battle cries of tiny warriors as they zoom past your head at warp speed.
Hummingbirds have many unique and interesting adaptations too, all necessary for survival. A hummingbird tongue has 2 grooves. Nectar moves through these grooves via capillary actions and the bird squeezes nectar into its mouth when it retracts its tongue. It drinks by extending its the tongue through a nearly closed bill at a rate of about 13-17 licks per second and consumes an average of 1/5 fluid ounce in a single meal. In cold weather, a hummingbird might eat 3 times its weight in food a day, a whopping ½ ounce for a bird that weights 1/10 - 1/5 ounce! However, natural nectar and sugar water alone are not adequate sustenance. Insects comprise a large portion of their diet, and the young are fed insects almost exclusively. Just watch hummies hovering above a slow moving stream. They are hawking insects, the no-see-ums that are a plague on all outdoor-loving people.
Their resting heartbeat is 480 beats and their resting breathing rate is 245 breaths per minute when it is 91 degrees – makes one hyperventilate just thinking about all that hyper-speed. At 55 degrees, their breathing rate increases to 420 breaths per minute! Hummingbirds survive cold nights by going into torpor. This is a state in which the bird’s heartbeat and breathing slow to such a degree that movement is impossible. A torpid hummingbird can be picked up easily, and has no power to move. However, warm it in your hand for just a little while, and the little fellow will spring to life and zoom away.
So for now, in mid-June, we should maintain our feeders by regularly cleaning them with a bleach solution to control mold, mildew, and bacteria. They should be filled with a solution of 1 part sugar to 4 parts water that has been boiled and cooled.
But, soon, probably about July 1, another hummie will arrive, the tiny Rufous Hummingbird, the little red dude. I call him Attila the Hum, for his fearsome guarding of all the hummingbird feeders on your property. He sits in wait for any unsuspecting local species to attempt to drink and then immediately dives upon them to drive them away from ‘his’ feeder. To help reduce the aggression, provide him with one feeder that contains a stronger elixir, a mix of 1 part sugar to 3 parts water. He might just decide to keep that one and leave the other, lesser quality feeders alone.
At any rate, it is important to keep feeders clean and filled until two weeks after your last hummingbird observation of the year and to put them out again in the spring about two weeks before their normal arrival, about April 1 in central New Mexico. You just never know. Perhaps your feeder will be the one that sustains a little throughout the long New Mexico winter.