Nature Trail Tour - July, 2008
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On July 1st, volunteer Zach Reynolds ventured out along the trail with camera in hand a few minutes after a twenty-four hour rain of an inch and a half. The slow drizzly rain was the first measurable rain since three inches fell in December 2007. The spring wildflowers had long since faded, not one blade of grass was green, and several weeks of over 100-degree temperature had blasted the landscape. The rain was a blessing! Zach discovered something we believe unknown to science (that happened because of the rain!).
Also, please read the related essay.
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The winter crop of tasajillo berries had not been completely eaten by the mockingbirds and curved-bill thrashers. Some of the berries had turned brown from rot. Some of the branches of the cactus had died and turned yellow. Flower buds were beginning to appear.
Horsecrippler cactus shrink when it is dry as its moisture is used up. The ribs become closer together and dirt often blows to cover the shrunken cactus. The roots of this one must have been damaged, for it had not swollen with the rain...
...like this one. The fruit is edible, but the tiny glochids (thorns) on it have to be carefully removed. It is rare to find the fruit untouched by the birds, skunks, turtles and other creatures that find them as soon as they ripen.
What in the world is going on here? When Zach brought in this picture, the Sibley staff immediately send him back out to further investigate. The green is cryptogamic soil, but the gelatinous syrup was something new. The beetles were quickly identified as dung beetles, but what were they doing? The butterfly was imbibing the liquid of the syrup. Does the fungal component of the cryptogamic soil sometimes put out the liquid? Some mushrooms have sticky liquid ooze (full of spores) out of them that attracts flies, thereby transporting the spores to new locations. The brown mass in the center was a mystery as well - was it merely soil, an small animal dropping, or yet something else? Tiny Crematogaster ants were also present - but why?
As Zach watched, more and more Crematogaster ants appeared. They usually feed on aphid honeydew, and even herd the aphids. They also may have a relationship with the caterpillars of some of the "blues" including the Reakirt's blue. Some species of honeydew feeding ants herd the caterpillars to the correct food plant and allow them to overwinter in the ant nest. Notice that one beetle is partially buried in the soil to the left. Zach did not notice any beetles arriving (either on foot, or by flying in).
Several harvester ants appeared, and the Crematogaster ants swarmed around them, as well as beginning clamber on the beetles. In the lower center of the picture a small larvae (possibly of some species of beetle) is visible. All of this action is occurring within an inch of the gooey mass.
One of the beetles created a ball out of the goo. It appears another ball had been partially formed, but look closely at it (it is just above the obvious ball). There appears to be a tiny invertebrate somewhat shaped like a worm curling out of it. Did its presence cause a beetle to stop working on creating that ball? Several ants attended each beetle along the edge of the goo. Those beetles did not seem to be creating balls.
More butterflies appeared and even used the beetles as perches to stand on as they fed on the goo. More and more beetles began making balls. The gooey mass began drying out within 45 minutes of the rain.
A red rainbug came and remained on the goo for a few minutes. They feed on termites, so was it drinking the liquid? A small fly with the appearance of a housefly (but much smaller) came to the goo, as well.
When it stopped rolling the ball it began digging. The first chunk of dirt was "large" and merely pushed aside. Did the beetle find a small crevice in the soil that it just pushed against to flip it? One ant has come to investigate. A few seeds lay half buried at the top of the picture.
The beetle had been digging at an angle, going under the ball, for suddenly the ball rolled and was centered in the disturbed dirt. (The first chunk of soil can be used as a reference to see how far it rolled.)
An Aphanogaster ant carried an oyster scale by the site of the pulpy mass. Normally the dome shaped scale insect is attached to a woody twig (such as a mesquite). Had the ant pried it loose, or had the rain loosened it?
More winged ants appeared. The cluster of the ants had been part of the emergence of the winged virgin queens and male ants. Up to 100 winged ants emerge from the nest. The ants will fly some distance where they will join other ants of the same species but from a different nest. There, mating will occur. Because Zach was recording the activity of the beetles, we did not try to record the activities of the ant swarm.
Red harvester ants were also clustered around the entrance to their nest. Normally this species forms a pile of loose soil shaped like half of a volcano on one side of its nest, but the loose soil had all washed away with the rain.
A rainbug wandered by. (To learn more about rainbugs visit this photoessay.)