Oct 6, 2010

End of the Little War

The war is over…for this year. Although the skirmishes were big, the combatants were small. It started in the spring, when the first ruby-throated hummingbird (Archilochus colubris) showed up around the deck in back of the house I rent.

Living in Rappahannock County, at the base of the Blue Ridge Mountains, I bring in any bird feeders every night to avoid attracting the neighborhood bears, who are particularly hungry in the spring. To make it easier, I put putting out the hummingbird feeders until I hear that first hum of wings or catch the first glimpse of these little hovering dynamos.

While some parts of the United States, particularly in the south, enjoy having several species of hummingbirds migrate in to breed in the summer, only the ruby throated comes to the Mid-Atlantic and further north in the east. It measures about 3.5 inches in length. The males have a bright, iridescent red patch on their throats that gives them their name. It actually only appears red when the sun catches the feathers.

The pattern at the feeder is pretty much the same every year once I put it out. At first I see one or two hummingbirds. Eventually usually at least two pairs show up. The males start the war by trying to keep each other away from the feeder, but the females are pretty much left alone to feed and do just that. After all, they need all the nutrition they can get to make baby hummers.

By early summer, the wars begin in earnest, with the babies now grown enough to come to the feeder, and the adults of both genders becoming more aggressive about defending the food source as they start layering on fat for the long flight back to Central America for the winter. Once the wars start in earnest, I put out a second feeder, so that I have two about twenty feet from each other on my long, south-facing deck.

While this year putting out a second feeder dialed down the skirmishes a bit, I found my morning coffee often interrupted with an aerial battle in front of my face that sometimes ended with one bird knocked to the deck. Beyond that, the birds don’t really do much damage to each other, although they are arguably fiercer, ounce for ounce (weighing an average of 1/8 ounce), than any other species of bird in our native ecosystem.

Since I take the feeders in at night, I’m also often approached when I go out in the morning by one of the tiny combatants, who seems to be urging me to get the food out, darn it. I keep both feeders where they are—relatively close to each other–because they’re sheltered by the deck roof, which runs about half the length of the deck, and because it’s easier to get the feeders in each night to avoid ursine visitors.

A lone bald-faced hornet (Dolichovespula maculate) is lured
from a hummingbird feeder with a dish of nectar
At other houses I’ve rented in the county, this scenario has been played out over and over. However, this year, at the new house, the war was stepped up a notch. A couple of weeks after I put the second feeder out, a bald-faced hornet (Dolichovespula maculate) showed up at it. This is a beautiful, tough little (three-quarters of an inch) hornet in the yellowjacket genus, black with a bright white face. It’s called a hornet in the United States because it builds a hanging paper nest, but it is not considered the “true” hornet (of the Vespa genus) native to Europe and Asia.

I watched as the bald-faced hornet worked the area around the little plastic blossoms through which the hummingbirds can insert their beaks to get the nectar. He also checked underneath for any drips that might serve as a meal. This one insect probably wouldn’t have been too much of a problem if he’d been content to scavenge the hummers’ leftovers quietly and leave the birds alone. However, he was a bald-faced hornet, and the bright mask on his face telegraphed his personality.

Hummingbirds, as tough as they are with each other, generally avoid any insects—ants, bees, wasps, or hornets—that are also attracted to nectar feeders. They’ll still try to get at the nectar while carefully keeping away from the smaller critters. However, the white-faced hornet is no shy, retiring bug. Its fierce mask gives fair warning, as war masks do on humans. It’s ready, willing, and able to defend treasure that it finds. Females are known to sting repeatedly if their nest is disturbed.

I watched as, over and over, a hummingbird would approach the feeder. As it did, the little hornet would turn around to face the bird, then launch itself like a rocket at the feathered intruder, driving it off. Of course, at this point there were at least eight hummers, including their offspring, vying for a turn at the feeder, so as one would be driven off another would attempt to sneak in to get a slurp of the nectar before it, too, was driven off—either by the hornet or by one of the bird’s feathered cohorts.

More bald-faced hornets arrive
From one lone white-faced sentry, the skirmishes expanded to inter- and intraspecies ongoing combat as more white-faced hornets were attracted to the feeder. At this point, I decided to use a carrot-and-stick approach to try to at least separate insect and bird competitors. I put a shallow dish with the nectar a few feet from the feeder, on the railing of the fence inclosing the deck, while spraying the feeder with Naturapel, a pepper-based, ecofriendly insect repellent made by Cutter.

The ploy worked. The hornet, while occasionally cruising the feeder first, quickly figured out that accessing the nectar was much easier on the dish. The war settled back into a relative peace at the feeder, broken up occasionally by competition among the hummers.

This more-or-less calm in which I could sit in my comfy deck chair a few feet from the feeder and have my coffee in the morning didn’t last. The little bald-faced hornet I was seeing pretty regularly was not the only one in the area, and others soon started to arrive at the nectar-filled dish, along with a few smaller, less-aggressive wasps. Even then, the relative peace reigned as long as each of these pollinators kept a decent distance from the others.

European hornets compete for nectar
with much smaller native ant and wasp species
Soon the dynamic at the nectar dish was further thrown off by an even more aggressive intruder–the European, or “giant” hornet (Vespa crabro). This large (about an inch long), yellow-and-brown beast is an invasive competitor to our native wasps.

Skirmishes once again broke out at the dish and the feeder as all the nectar eaters jockeyed for control of the food. With birds and hornets, small and large, duking it out so near where I was trying to enjoy the calm of the morning, I’d had it.

I moved the dish way down the deck railing, beyond the two hummingbird feeders. The insects followed, thankfully, and for the most part kept away from the feeders, as long as I kept dousing the feeders with repellent. I could once more sip my coffee in peace and enjoy the view of the forest unfolding down the slope behind the house. Butterflies, woodpeckers, the song of the wood thrush—it was great.

As the summer stretched on, and it got drier and drier, more insects came to the deck to seek nectar and their predators followed them. Spiders, small and extremely large, were omnipresent. A couple of species of nonagressive paper wasps built nests under the deck roof and carefully visited the dish of nectar, avoiding their more aggressive cousins. Harvestmen (an arachnid of the Opiliones order, commonly called "daddy longlegs," along with many other species) were everywhere. All the predators, combined with the effect of the dry ridge on which my house was built, made the deck relatively mosquito free, so evenings on the deck were also a joy. I sometimes took my laptop out there to watch a ballgame while enjoying the animal activity between pitches.

The hummingbird males still seemed to spend most of their time trying to drive off other hummers instead of feeding. Eventually, I found these little battles, with the constant humming and dive-bombing, still too disruptive and removed the feeder closest to my chair, letting the birds duke it out at the other feeder. As long as I kept the feeder and the dish full of nectar, the feeding frenzies at the other end of the deck were low in intensity. Every day there was at least a brief detente where all four feeding stations on the feeder were occupied by hummers—albeit usually by females.

Then another insect showed up to disrupt this relative calm—large black ants. I’m not sure which of the many species of ant these were, but they were big and plentiful, ate night and day, and didn’t seem to mind the repellent much. Being a big fan of E. O. Wilson, who coined the word “biodiversity” and focused his studies as a biologist on ants, I have a huge respect for this insect family, Formicidae. Their social behavior and skills, including “farming” other insects, are fascinating to observe. However, the numbers and size of this particular species were too daunting for the hummers. The only strategy I could figure out was to move the feeder, which I did. Every few days, when the ants had found its new location, I’d move it a few feet up or down the deck.

This went on until last week. The hummers had slowly been disappearing, dwindling from at least eight to just a couple who occasionally visited the feeder. The rest had undoubtedly left for their long flight south for the winter. Now they’re all gone, and I’ve brought the remaining feeder in. The insects, which don’t migrate, are still enjoying the dish full of nectar and, so I’ll continue to put refill the dish for a while.

Having coffee on the deck is a more peaceful experience now. I can watch the leaves slowly turning from green to various warmer shades and dropping to the ground. The quiet is somewhat disrupted by the steady drop of acorns and hickory nuts from the bumper crop the trees are producing this year (good for our mast-crop eaters, such as turkeys and bears). The sun is shifting more to the south but staying lower, and the mornings are definitely cooling off. It won’t be long before I won’t want to keep the door into the kitchen open to listen to the morning programs on NPR for fear of letting too much cold air in.

Soon the view will open up on the deck to reveal the Blue Ridge Mountains to the west and the small outlier hills and low mountains to the south. I’ll start watching admiring the view over coffee from inside the kitchen, where it will be cozier on the deck. The songs of insects will disappear and those of birds will become less diverse and more intermittent, dying into the quiet of winter. At that point, I’ll miss the frenzied little war on my deck and look forward to putting the hummingbird feeder out again next spring.

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