Orange Newt

Corvid Mobsters—Part 2

I have wondered why it is that hawks allow themselves to be shoved around by a bunch of smaller birds (or the same for a crow being mobbed by songbirds). Sure, it may be outnumbered, but in short order a hawk could easily dispatch an overly aggressive and foolish crow—sending the others fleeing through the trees. I’ve watched a hawk try to ignore the mobbing flock, but subsequently choose to flee, with the crows diving and swooping from behind. The hawk doesn’t seem to be inclined to retaliate. Why not?

A little research told me that even though a hawk could easily kill a crow, the act may require an expenditure of too much energy. Food is not always plentiful for flying carnivores. Crows are agile aerial acrobats, and a hawk would likely have to work hard to catch one. It maybe just ain’t worth the effort, so it vacates the scene. Besides, a hawk is not all that territorial. If it just happens to be sallying through, it has no investment in the area, so it allows itself to be driven off. If the hawk has its own babies to protect, however, it’s a very different story. In this case the crows know it and don’t push their luck. Just a little mobbing noise to warrant their awesome reputation and then move on to easier targets.

This crew of crows that I heard the other evening kept up their raucous chorus for about a half hour, as the scene of the action floated through the woods. It suggested to me that they had themselves a real target and were not just playing or bluffing. In time, they calmed down, and quiet once again reigned in the woods. Then, after a while, I could hear one lone hawk plaintively calling out from the direction of where the mobbing had ended. It sounded weak or defeated. I tried to guess whether it was crying out of pain, or a dented ego, or just sassing back. It was not a happy or triumphant call. I think that crows prevailed on that one.

Dropped Blue Jay Feather

Left click for larger image.

Corvid Mobsters--Part 1

I recently listened to a horde of crows noisily and persistently squawking, cawing, and bellowing off in the woods. I could not see them to know who or what they were hassling, but it seemed to be a case of what is called “mobbing”: when a group of birds surrounds and attacks a larger predator or threat. I’ve watched a group of songbirds mob a crow that posed a threat to their babies. I’ve watched a band of crows mob a hawk, although I couldn’t figure out quite why the hawk was being targeted.

Maybe that’s what I was hearing the other day: crows mobbing a hawk? (They also mob owls and even raccoons, foxes, and house cats.) After nearly half an hour, the ruckus moved several hundred feet down the hill, toward the creek. This suggested to me that the crows were mobbing a bird that flew that way, rather than a mammal, since they remained in the trees and moved rather quickly. But what was really going on? I don’t think the crows were defending their babies—it’s late enough in the season that all youngsters would be fledged and pretty much on their own by now. Could the youngsters be playing some kind of game among themselves?

Crows tend to hang together in colonies, so when a threat is spied, they can depend on a group to quickly form, to harass and drive off the menace. They have several possible motivations for mobbing a larger bird: They may be defending their nests of eggs or nestlings. They may be protecting their food supply—crows are also predators of songbirds and other small critters. They may be teaching youngsters how to mob. Earlier in the season they may be showing off to potential mates. (“Hey, sweetie, see how brave I am? Want to hook up with me?”) Or maybe they’re just playing. Sometimes crows—especially young ones—will play a game of hide and seek, wherein the “it” crow tries to hide and the others fly about and shout at the hider, once he’s been spotted.

When crows mob, they are either trying to drive away a predator or simply alerting all birds in the vicinity that a pariah has entered the neighborhood. A hawk or owl may simply be passing through and resting on a branch for a few minutes—unaware that it has violated corvid territory. The crows’ frenzy is an ambivalent mixture of fear and aggression—fear for their individual safety and a boldness engendered by the need to appear formidable. If you watch crows mobbing a larger bird, you can see a fascinating dance, wherein each one tries to do it from a safe distance, while seeming to be fierce and intimidating. Like teenage urban boys bluffing, they sound as if they’re calling out, “Hold me back, boys, before I pound his ass into the pavement!”

The objective of mobbing may be to engage the intruder in multiple dive bombings and buzzings, to prevent the larger bird from being able to focus on one target. Keeping him distracted, they swarm around and cause the hawk to leave, just to get a little peace for itself. Or the crows may be attempting to teach a young hawk or owl to give crows a wide berth in the future: If they get one of their band to act as a decoy—causing the hawk to focus forward, as the others attack from behind—the young hawk might conclude that a crow is one of those magical critters that will fly in your face, as it simultaneously pecks at your butt. If that impressionable young hawk spreads the news by telling its buddies what happened, the crows will have achieved a great coup. The crows may even top off the humiliation by defecating on the hawk.

More on mobbing next time…

Concrete Block Makes a Solid Toad Abode

Granddaddy Red—Part 2

One of these harvestmen visited me the other evening, as I soaked in the outdoor tub. He had an attractive red body (most of them are gray or brown, so that caught my attention right away). I’ll call this guy “he,” because he was rather small, and male harvestmen are more diminutive than “harvest women.” Males are also more colorful, and this guy was pretty snazzy looking. So I’ll call him Granddaddy Red, or just Red for short.

I have a wooden paddle laid across the top of the tub, with which I occasionally stir the water, to even its temperature. (On winter nights, the water near the bottom of the tub cools quite quickly and needs to be stirred often, lest my butt get cold.) I first spotted Red as he sauntered down the paddle, towards me. When he reached the end, less than a foot from me, he stopped, waved a couple of legs out into space, and seemed confused that his plank road had come to an abrupt end. He stood still, lifting first one leg then another—appearing to be testing the solidity of air. Since I don’t wear my reading glasses in the tub and dusk was rapidly approaching, I was left wondering what he was up to. Guess I’ll have to live with the mystery.

I soon lost track of Red, as I sunk back into my soaking reverie. Darkness began to descend. A few minutes later, I absent mindedly picked up the paddle, stirred the water, and set it back down again. Something tickled the back of my hand. It was Red! My hand had apparently given him a way to continue his stroll forward. Not wishing to drown him. I tried to urge him back on the paddle, but he was having none of that. “Been there, done that… I’m moving on!” So I held my hand out to the wall next to the tub and Red promptly stepped off, climbed up the wall, went over the top, and was gone into the night. He’d found a way to keep heading south, using my hand to boost him along. Farewell, Red! May the road rise to meet you.

There is an urban legend that, although daddy longlegs are very poisonous, their fangs are too small to puncture human skin. As is the case with most urban legends, neither of these beliefs is true. First, they have no venom. Second, their fanglike mouthparts are able to take a harmless bite out of you, but why do so when you may get squashed in the process by the two-legged monster? No, they are innocuous.

In fact, harvestmen are quite beneficial to our world. They are scavengers, chowing down on decaying plant and animal detritus. They are also helpers in the garden, since the other half of their diet consists of aphids, flies, mites, wee slugs, and other tiny pests. They are mostly active at night, so we don’t get to watch what they are up to.

American Indians called them “Grandfather Graybeard.” I find it fascinating that different cultures often have such similar names for nature’s critters. So why is a dragonfly called an “eye-poker” in Sweden and an “adder’s servant” in Wales?

Daddy Red Taking a Drink From the Tub

Granddaddy Red--Part 1

One of the more intriguing insects that we have around here is really not an insect at all: the daddy longlegs or granddaddy longlegs spider. But then it’s not a spider either. So, is it a bug? No. Then, what the hell is it? The best and entomologically correct description is “harvestman.”

Let’s back up a little. An insect is defined as a little critter that has six legs, three segmented body parts, antennae, and wings. OK? A spider has eight legs, eight eyes, only two body parts, no antennae or wings, but has spinnerets (their silk-producing organ). OK? A harvestman is similar to a spider, but does not make a web (has no spinneret), has only one body part, and only two eyes. The harvestman is more closely related to a scorpion than a spider—though it has neither venom nor fangs. OK? So, what’s a bug? Well, it’s an insect (so it does has six legs) but is distinguished from an insect by having sucking, beaklike mouthparts. OK? Confused? So am I. It’s no wonder that we common folk have a struggle understanding entomologists.

Let me get back to the one particular critter I started with: the daddy longlegs… the harvestman. From any perspective, they are an odd-looking creature, with their small, round, one-part body, supported by incredibly long skinny legs. If its body size were as big as a human, each of those legs would be some 50 feet long!

Harvestmen are one of the most ancient animals on the planet—dating to some 400 million years ago. That predates the dinosaurs by a long shot! There are over 200 species of harvestman in North America alone. They come in many different sizes and colors, but all of them possess those ungainly long legs. And speaking of those legs, one of them can easily detach, if a predator attacks them and grabs a leg (which is likely to happen, given that they are mostly all leg). What’s more, the lost leg continues to twitch on its own for several minutes, which is Mother Nature’s way of confusing the attacker and giving the daddy longlegs a chance to run (seven-legged) away to safety… sans one leg for the rest of its life, but alive.

There are a few other peculiarities of harvestmen, but we’ll leave it at that for now. Well, OK… one more. Even though it has eyes (just two of them, remember?), they can’t see much at all, so its other sensory capabilities must make up for that loss. Mother Nature has compensated by allowing its second pair of legs to act sort of like the eyes, nose, and tongue on humans. Weird, eh? But remember, they have been around for nearly half a billion years, so they’ve gotta be doing something right.

More on Granddaddy Red next time…

Curiosity Has Landed!!

Almost exactly 41 years ago NASA landed Apollo 11 on the moon. This is the next big landing in its history. What wonders will be forthcoming?

Clarion Call--Part 2

The first English colonists to land in Virginia in the early 1600s were enchanted by the flashy trumpet vine blooms. They sent seeds back to England—presumably earning the enduring enmity of the fussier British gardeners. The vine is native to southeast United States, but like kudzu, it happily and obnoxiously thrives in many foreign sites. When I surfed the web for information on the vine, nearly as many websites offered suggestions for eradicating it, as described its attraction for hummingbirds. I like it because it masks the view of the ugly outbuildings, but also looks very attractive—to say nothing of the enjoyment I get watching pollinators come for a nectar sip.

Nectar is a sugar-rich liquid that many blossoms secrete, to attract hummers, bees, butterflies, and other pollinators. It is much more than the bland sugar water that we fill our hummingbird feeders with. The plants have evolved a clever technique of adding smelly chemicals to the nectar that emit attracting aromas to flying critters who have a sweet tooth. But nectar has even more goodies: a complex blend of many amino acids that constitute protein. So a hummer not only gets a sugar high, but ingests crucial protein. When a hummer’s sweet diet consists primarily of human offerings of sugar water in a feeder, the bird must supplement this diet by finding tiny spiders and insects for its protein. I doubt that I could come up a balanced diet as good as nectar, even if I were to try to find some way to add a pinch of amino acids to my feeder.

Of course, the flower’s sweet gift is not solely a generous gesture to pollinators. It requires some energy on the part of the plant to manufacture nectar—something it really doesn’t need for itself. But it does need to have its pollen transported from bloom to bloom, in order to inseminate its reproductive structures, and it hasn't yet evolved to fly. The (humming) birds and the bees do that for it. When the hummer ducks its head into a blossom, it withdraws it coated with pollen. When a bee waddles down inside, it must brush against the flower’s reproductive organs, coating itself with pollen in the process. It’s a wonderful example of one of nature’s symbiotic relationships—an interaction between two different organisms, to the advantage of both.

The bloom time for the trumpet vine is just a few weeks in late July. There is no other nectar-offering plant close to my outdoor tub. I think I’ll want a bath more often at this time of year, just so I can get more of the aerial pollination show.

Female Hummingbird

This is a female ruby-throated hummingbird. she was in jured and later died, despite my attempt to care for her.