Sunday, May 28, 2017

Edwards' Hairstsreak Larvae - Night Feeding

Within the Blue Jay Barrens prairie openings are a scattering of medium to small sized Blackjack Oaks.  Some of these trees are decades old, but various environmental factors keep them from getting very large.  Dry site conditions limit water available to the tree, White-tail Deer find them to be the perfect choice for rubbing antlers, Periodical Cicadas cause a dramatic die-back every 17 years and a wide variety of insects find the leaves extremely palatable.  I make several close examinations of these trees each spring as I follow the development of the Edwards’ Hairstreak butterfly larvae, one of those species with a dietary preference for Blackjack Oak.

Edwards’ Hairstreak eggs hatch just as the oak buds begin to swell in early spring.  The larvae feed on the buds and newly developing leaves.  On May 8, temperatures dropped to 29°F causing frost and freeze damage to many plants.  Damage to Blackjack Oaks varied between individual trees, but all suffered the loss of some new growth.  This was a setback for both the trees and the Edwards’ Hairstreak larvae.  Fortunately, buds were not affected and regrowth was rapid.

When I checked the Blackjack Oaks three days ago, the leaves were showing signs of heavy predation by the Edwards’ Hairstreak larvae.  When this magnitude of damage occurs to the leaves it is a good indicator that the larvae have reached their final instar stage and will soon be pupating.  At this point it does no good to search the tree for larvae, because they do not spend the day in the open.

Young Edwards’ Hairstreak larvae remain in the open feeding through the day.  When they become older, they feed only at night and spend the day at the base of the oaks, hidden in cavities constructed by Allegheny Mound Ants. 

Near sundown, the larvae leave their shelter and begin climbing the tree.

Each larva is accompanied by its own cadre of ants. From the time they hatch until emergence as adults, the Edwards’ Hairstreaks are accompanied by ants.  The larvae achieve a degree of protection from the ants and the ants receive a sugary Honeydew solution excreted by the larvae.

The larvae on the first tree went too high to be easily observed, so I switched my attention to a smaller tree that displayed feeding activity.  This tree was less than three feet high and struggling to regrow leaves killed by the freeze.

The larva’s head is located near the top of this photo.  As the larva eats, an ant visits honeydew producing glands near the larva’s tail.

It’s fortunate that pupation is near.  This tree was loaded with larvae.  At the rate they’re eating, the tree may soon be stripped bare of leaves.

The above video is a compilation of several shots of moving and feeding Edwards' Hairstreak Larvae.  Make sure your sound is on, so you can enjoy the call of the Chuck-will's-widow while you watch.  This video, in a possibly clearer form, may also be viewed on YouTube by clicking HERE.

Wednesday, May 24, 2017

Toad Pool Success - Part 2

Blue Jay Barrens is experiencing an influx of thousands of young Eastern American Toads emerging from the still under construction Toad Pool 2. This little guy has fully absorbed his tail and, looking every bit like the adult version of his species, is moving away from the pool towards the open fields.

The pool experienced no shortage of water this spring. Frequent rains provided above average rainfall totals causing the water to regularly be at a level higher than intended.

Toad eggs appeared in the pond on March 29 and began hatching on April 2. By April 5 the eggs had completed hatching, but the tadpoles were not yet mobile and their pattern on the bottom of the pool continued to match the strings of eggs that had been laid out a week before.

After exiting the egg membrane, the tadpoles remain stationary for several days as they absorb their yolk sacs and mature into a more traditional tadpole form. Their first food will be the algae seen growing on the empty jelly strings and pool bottom.

Once they become mobile, with tadpoles migrate upslope to shallower water where the generally warmer temperatures will aid in their growth and development. Their initial efforts cause them to congregate atop the slightly higher mounds on the pool bottom.

A few days later their improved swimming ability allows them to reach the shallow water at the edge of the pool.

The unfinished condition of the toad pool caused an unintended broad expanse of shallow water to become available to the tadpoles.

The shallow area, which had been left smooth when construction was halted last fall, had become pocked with depressions caused by deer visiting the pool.

As water levels receded during uncharacteristic hot periods between rainfalls, the depressions became isolated pockets that rapidly dried after their connection to the main body of water was severed. Tadpoles caught in these depressions quickly perished.

Fortunately, I still retained the mud puddle engineering skills that I had honed as a child and was able to make periodic adjustments in the way of dams and channels to ameliorate the desiccation threat to the tadpoles. If weather conditions allow me to complete my construction activities is fall, the hazard should not exist next year.

Transformation from tadpole to terrestrial toad form began a week ago and is now proceeding at a rapid pace.

Once all four legs appear, the tail quickly shrinks and the young toad pushes himself free of the water.

It spends a day or two near the water’s edge before heading off to begin a terrestrial lifestyle.

The little toads are so numerous in the vicinity of the pool but I can’t walk in that area without stepping on a few, so I’m waiting until they’ve had a chance to disperse before checking the pool again. I’m looking forward to encountering these little guys through the summer. It will be two or three years before this year’s hatch is mature enough to return here to breed. By that time Toad Pool 2 will be completed and, with any luck, there should also be a Toad Pool 3.

Wednesday, May 10, 2017

Storm Damaged Orchid

The lone Blue Jay Barrens Yellow Lady’s Slipper Orchid sent up two stalks this year and managed to produce three full blooms.

It’s hard to consider a population as being stable when there is just a single individual involved.  As in the past, I’ve been searching to discover another of this species somewhere on the property.  No luck so far.

This plant manages to send up at least one flowering stalk each year.  Unfortunately, it seems a normal occurrence for disaster to befall the plant before it can develop a seed pod.  The flowers and top of plant have been eaten on several occasions, a large limb fell and crushed the single flower that developed that year, a strange wilting disease shriveled up the flowers another year.  It always seems to be something.  This year it was a particularly violent wind storm.

This flower lost its slipper completely.

A neatly storm cleaved slipper makes it easy to view the interior pattern.

Only one of the three flowers was unscathed.  So far, the plants have only had to contend with a single disaster per year.  Though that doesn’t mean they are now really safe.

Friday, May 5, 2017

Number 544 - Virginia Bluebells

Virginia Bluebells, Mertensia virginica, has been added to the flora list as the 544th plant species known to reside within the borders of Blue Jay Barrens.  This is a rather common native species for this area that I knew was to be found growing in the floodplains downstream of my property.  Since the seeds of floodplain plants are generally moved by flood waters in a downstream direction, I thought it unlikely that Virginia Bluebells would show up here.  Four individual plants were discovered, but only one produced blooms this year.

The other three plants exist as only a few leaves.

To the West, Blue Jay Barrens tapers to a long narrow point which contains a short segment of Creek bounded on both sides by extremely steep slopes. I refer to this area as Farpoint because, at a distance of six tenths of a mile, it is the farthest point away from my back door. The length of the Creek from property line to property line is only about 160 feet. The thing that makes Farpoint interesting is the fact that the Creek is fed by a different watershed than that which maintains the Creek on the east side of the property. Several the plants on the Blue Jay Barrens flora list exist only at Farpoint and I credit the Farpoint watershed as being a major cause of that fact.

I would guess these plants to be two or three years old. If they survive, I would not be surprised to see them flowering next year or the year after.

All of the plants are growing in that precarious gravel bar area within the actual creek banks. A major flash flood event could easily remove both vegetation and gravel from the site. If I find that the flowering individual produces viable seed, I will probably take the liberty of scattering some of that seed in the more stable area about the creek bank. Perhaps in a few years, Farpoint will display a few nice clumps of Virginia Bluebells.