Monday, January 30, 2017

Robber Flies

I took this series of photos one afternoon about six months ago during a time when I was experiencing internet connectivity problems.  The file has been stuck in my blog folder since then, along with several others.  I deleted the others, but I am such a fan of Robber Flies that I just had to make this post.  Resting on a leaf about half way down into the canopy of an herbaceous border sits this Diogmites species. 

Robber Flies are predators.  They spend much of their time sitting where they can watch for passing flying insects. I enjoy watching this species because its head is so mobile. It swivels its head in the direction of even the slightest bit of movement, which at some point always includes the photographer.

This slightly larger member of the Robber Fly group is a representative of the genus Efferia.  It came to rest on my hand while I was working in the field, which I hope does not give anyone the impression that I move so slowly while working that animals find me a convenient perch.  The end of the abdomen tapers down into an almost sword like appendage. Although it looks to be a formidable weapon, it is used as a tool for laying eggs deep into flower heads or other locations deemed suitable for growth of the larvae.

This is Promachus hinei.  Although it’s not the most common in terms of total Robber Fly numbers at Blue Jay Barrens, it is the most commonly encountered species of Robber Fly. Because of their large size and noisy flight, they are hard to miss when you happen upon them in the field. On this particular day, almost every individual I found was busily feeding, and several were feeding on somewhat unusual items like this paper wasp. When hunting, Robber Flies launch from a perch, grab an insect from the air, and return to a perch to consume their prey. The Robber Fly’s first action after a catch is to insert its piercing mouthparts into the body of the captured insect and inject a chemical relaxant that attacks the nerves and calms the prey. Along with the nerve agent is an enzyme that liquefies the internal body of the insect, so the robber fly can drink its meal.

To some, this may look like a love embrace. Unfortunately, that fly giving the big hug is not moving in for a friendly cuddle. 

These big flies will take any prey they can handle, even if it’s their own species.  That’s a male of the species making a meal of a female.  You can see his piercing mouthparts just below his front leg in a direct line with the grass stem beside his head. I hope next summer is another bumper season for Robber Flies.

Monday, January 23, 2017

Salamander Eggs

So far this month we’ve had 5.8 inches of rain, with rain falling more days than not since January 1.  Temperatures have remained above average.  High temperatures in the 50’s and 60’s Fahrenheit have been the norm so far this year.  It’s been a tough year for pinpointing when salamanders began showing up in the pond for their annual breeding frenzy.  All I can say for certain is that the pond was free of salamanders three weeks ago, and now the pond is full of salamander eggs. 

The frequent rains have kept the water level high and visibility slightly clouded, but it’s easy to see the masses of egg clusters clinging to plant stems scattered across the bottom of the pond.

I found this Jefferson Salamander during a break in the rain a couple of nights ago. 

This is the most common pond breeding salamander at Blue Jay Barrens, and the only one here that produces egg masses this early in the year.  In a month or two, Spottted Salamanders will enter the pond and leave their own egg masses.

Attached to the underside of a floating plank were these eggs of the Streamside Salamander.  This species typically places its eggs on the undersides of flat rocks in small headwater streams.  In situations where they utilize temporary pools, the eggs are placed on the undersides of any available surface.  Once it became apparent that Streamside salamanders were breeding in this pond, I adorned the deepest part of the pond with a variety of items suitable for receiving eggs.    I am assuming that these items are now sporting a nice covering of Streamside Salamander eggs. I’ll find out for sure when the water clears enough for me to see though to the pond bottom.

The Streamside Salamander eggs seem to be developing rapidly.  I suspect that warmer water temperatures have increased the rate of egg development.  This may increase the chances of the salamander larvae reaching their land dwelling stage before the pond water disappears for the summer.

Monday, January 16, 2017

Status of Girdled Trees Project

Back in May 2015 I girdled and applied herbicide to the large trees in this area in an attempt to create a grassland corridor between two areas of healthy prairie.  I thought it would be a few years before any of the killed trees began to fall.  Things are progressing much more quickly than I imagined.

In only a year and a half, about a third of the girdled trees have already fallen.  With one exception, all of the fallen trees have been Tuliptrees. 

Some of the trees dropped into the neighboring prairie.  Since this area is still being treated to eliminate invasive shrubs, I’ll remove the fallen trees to make it easier to find and destroy any invading sprouts.

The trees broke just above the girdle ring.  The girdling was done high enough on the trunk that a tall stump remains.  It’s best to leave the stump tall enough to be visible in the grass.  This way you are less likely to fall over or run your mower up onto the stump.

It looks as though the dead trees hosted quite a few wood boring insects.  I was surprised to see the extent to which the wood had been penetrated.

Woodpeckers appear to be taking advantage of the insect laden tree trunks.  I thought some of the trees were large enough to serve as woodpecker nesting sites, but I don’t think they are going to be standing long enough to serve that purpose.  I’m expecting this tree to fall soon.

In June 2016, about a year after being girdled, the Tuliptrees were still producing leaves on a few branches.  I was having some doubts that I had successfully killed the trees.

The trunks themselves gave some positive evidence that I was getting the desired results.  Impressive fungus growths suggested that decomposition was occurring beneath the bark.

A variety of fungus species were present.

I was impressed by the number of fungus species that were able to so quickly take advantage of the recently killed trees.

This area will soon be dominated by tall grass, but it won’t be without a few trees.  I have left several young Blackjack Oaks, Quercus marilandica, to grow among the grass.  Blackjack Oaks have a special relationship with several prairie invertebrates, and are well worth saving.  There won’t be enough trees left to hinder the growth of the prairie grasses, but there will be enough to enhance the quality of this small area.

You can read about the original girdling project by clicking HERE.  

Wednesday, January 11, 2017

2017 Blue Jay Status

January weather typically includes a bout of cold temperatures and snow cover. These conditions bring an increase in activity at the Blue Jay Barrens birdfeeders and give me an opportunity to assess the local Blue Jay population.

Blue Jay numbers are running at about their normal level this year. Except for one or two birds that have a distinctive marking or unique behavioral trait, I can’t tell the individual birds apart, so I don’t know for certain how many are year-round residents of Blue Jay Barrens and how many have just moved in for the winter. The general behavior of the flock makes me think that the majority of individuals are here all 12 months of the year. In particular, I don’t believe that a new arrival would automatically know to sit in the apple tree and yell when the feeder goes empty.

As always, the almost constant movement between the feeding area and the nearby trees makes it nearly impossible to get an accurate count. I spotted 29 Blue Jays in the previous photo, including the one in the air. I know there were at least 47 here at one time, but at that same time I could see several more moving in the trees at the edge of the field a few hundred feet away.

The feeder on the post contains black oil sunflower seed. The area at the base of the tree in the upper right-hand corner of the photo gets a few cups of cracked corn scattered out each morning.

Second to the Blue Jays in producing consistently high numbers in the feeder area are the Cardinals. In between trips to the feeder, the Cardinals tend to hang out in the dry stalks of Giant Ragweed and Wingstem adjacent to the feeder.  The smaller feeder visitors also seem to prefer this area for feeding and loafing. The large crop of seeds produced by these plants has now been nearly consumed.

The tall plant stalks have been battered by rain, wind, and snow, but they continue to remain upright.

It’s not uncommon to count 30 or 40 Cardinals in the feeder area at one time. Most take their seed from the ground instead of directly from the feeder.

Mourning Doves typically arrive a couple hours after sunrise. There are usually 25 or 30 individuals in this flock.

Most of the doves in the area spend the winter gleaning seed from nearby harvested crop fields. A deep snow can make that source of food inaccessible, and the result is a substantial increase in Mourning Doves at the feeder.

These two Blue Jays demonstrate how so much sunflower seed gets on the ground beneath the feeder. They scrape seed up and over the edge of the feeder tray until they find just the seed they want. This also explains why my feeder sometimes so rapidly runs out of feed. I thought for a while that they were searching for the few shelled seeds that could be found in the mix, but that didn’t turn out to be the case. When they start to load up with seed, it’s just the standard seed in a shell. Maybe they just want to be sure that their friends down below have plenty to eat.