Rocky Knob Migration Watch, Fall 2010: Report # 1

American Copper (Lycaena phlaeas), nectaring on white clover bloom.

Sunday 29 August 2010

Bruce Grimes & I arrived at Rocky Knob at Noon and stayed till 4 p.m. We were playing hooky from a lot of tasks that we both need to get done, but the hours of migration watch were worth it.

First, some background:

Rocky Knob Hawk Watch occurs at milepost 168 on the Blue Ridge Parkway. We watch from the Saddle Overlook sometimes, which gives us a fairly good view of Rock Castle Gorge to the east, and Buffalo Mountain westward. Mostly we watch from a large pasture just to the north of the Saddle Overlook parking lot. We affectionately call this location the Cow Pie Palace.

The hawk watch is occasional, mostly on weekends, and even then we seem to steal time from other activities. I wish that it could be closer to more daily monitoring of migration.

There are other hawk migration watch sites on the Parkway, and these are monitored far more frequently than our migration watch site at Rocky Knob:

Rockfish Gap (aka Afton Mountain)
Harvey's Knob
Mahogany Rock

If you are in this part of the universe, stop by and take a look for yourself: hawks are circling, gliding, soaring, flapping, hurrying or easing southward. So are many other species of birds: ruby-throated hummingbirds, chimney swifts, swallows, thrushes, warblers, tanagers, orioles, and many other kinds. And other creatures are pushing south also: several kinds of dragonflies, mostly common green darners, black saddlebags, wandering gliders, and twelve-spotted skimmers; and several species of butterflies too: besides monarchs, these include, Cloudless Sulphurs, Sleepy Orange Sulphurs, Little Yellows, Variegated Fritillaries, Eastern Commas, Mourning Cloaks, Painted Ladies, American Ladies, Red Admirals, and Common Buckeyes.

As soon as we got there yesterday, we noticed that Common Buckeyes, and Common Green Darners were flying by. We stayed busy trying to watch high and low for species that were on the move. The buckeyes mostly flew low just above grass blade and cow pie, but a few of them were actually fairly high up--one even buzzed a black saddlebags dragonfly, then flew on south. Some of the monarchs and buckeyes, the two most common insect migrants yesterday, would stop a while and refuel at thistle blossoms.


Tally for the 29th:

Raptors:

Osprey 1
American Kestrel 1

Other migrating birds:

Chimney Swift 16
Ruby-throated Hummingbird 5 (two were adult males)
Barn Swallow 5
Scarlet Tanager 2

Migrating butterflies:

Variegated Fritillary 1
American Lady 1
Painted Lady 1
unidentified Vanessa sp. 2
Common Buckeye 34
Monarch 31

Migrating Dragonflies:

Common Green Darner 20
Spot-winged Glider 2
Wandering Glider 1
Black Saddlebags 23
Carolina Saddlebags 1

Great Spangled Fritillary (Speyeria cybele), nectaring on thistle.

There were many other species of butterflies nectaring on thistles and other flowers in the fields: seemed to be gazillions of Pipevine and Eastern Tiger Swallowtails, one female Black Swallowtail, a few Spicebush Swallowtails, lots of Great Spangled Fritillaries (probably close to 100) and three Aphrodite Fritillaries, and one male Diana Fritillary. There were a few American Coppers, and a small horde of Peck's Skippers and Sachems!

The one Painted Lady that migrated through the field, stopped a couple of times for a portrait pose while it nectared on some flowers. Bruce got some pictures of this critter, plus some of the other butterfly species.

Hopefully there will be a few more migration reports during September. Please do stop by and check out the migration scene at Rocky Knob.


Painted Lady (Vanessa cardui), nectaring on a thistle flower. Thistles are also host plants for the caterpillars. Painted Ladies have nearly worldwide distribution, and are one of the most common migrating butterflies in the world.

The Summer "horn of plenty"

In walking around our farm in this late Summer period I am struck by the exuberant production of Nature including flowers, fruits, seeds, green vegetation, etc. I especially notice the fruits of the hackberry (likely Celtis occidentalis), which grows along one of our fence lines. This is not a species I see often although it is touted as a bird-friendly plant because of its fruits. We have tried planting it and its more southern relative the sugarberry, without a great deal of success. I think it requires a richer soil and more moisture than our sites generally provide.

Another beautiful and bird-friendly plant is the relatively rare cardinal flower (Lobelia cardinalis) which is highly specialized for pollination by hummingbirds. It has a very interesting ecology since it is a poor competitor with grasses and thus is found most often along streams, disturbed by occasional floods, or in wet areas of pastures where competition is reduced by grazing. It appears to be poisonous, as is ironweed, and is thus not eaten by horses. Ironweed is also one of our favorites due to its wonderful flowers and attraction to butterflies, and later to seed eating sparrows, such as the white crowned which spends Winters here on the farm.

Of course we should not ignore the growth of grasses and their abundant seeds which provide food for many animals. Indeed some herbaceous plants that farmers may consider weedy and less than desirable can be highly beneficial for wildlife. For example consider the foxtail (various Setaria species), grasses that flourish in Summer if the competition from cold-season grasses such as fescue is removed by cutting in mid-June. If you allow this to grow (we have a patch next to our garden) it will attract resident indigo buntings and even migrating bobolinks to harvest its seeds.

In contrast to this late Summer explosion of plant growth, most birds are past their breeding periods and are relatively quiet, many have begun migration, or are filling their bellies with the "horn of plenty" available all around them from the natural foods that have sustained them for eons. Given the luxury of such natural foods, it is very hard to justify artificial feeding of birds in the Summer. Let's try to balance our desire to enjoy birds in a backyard setting at feeders, with the best interests of the birds themselves. There is an alternative that can serve both the best interests of birds and their human watchers, namely the planting of appropriate native and exotic plants around our houses that provide foods in a manner consistent with natural patterns of behavior.

Bill Dunson
Galax, Va & Englewood, FL

Cacti, Lobelias, Swallowtails, and Horsemint

It's been hot.
My solution?...go west...and up.... aahhh ... the Blue Ridge.

We really needed to get out of the house, and so I took the girls on a field trip to visit some fun habitats...and cool air.

We started with what we thought would remind us of a desert...inspired by the heat: Eastern prickly pear cacti (Opuntia humifusa) habitat. This community of native plants thrives in cracks of an exposed sheet of granite in the Ragged Mountains of Albemarle County. (To date, I am aware of only four other sites in the county.) My five year old (Norah) could not resist "petting" the prickly pear pads. Well the nearly invisible teeny tiny needles (glochids) made her pay dearly...and yes, I gave her a firm warning in advance, reminding her of what happened the last time she caressed a prickly pear (in Tucson).

With needles and a renewed sense of respect in tow, we planned our next destination to a softer and cooler place.
We are budding butterfly watchers. The swallowtails currently have my attention, and the dark ones continue to mystify me. So, off we went again, this time to the land of butterflies...a Blue Ridge meadow. We soon arrived at Humpback Rocks, up along the Blue Ridge Parkway. The specific destination in mind was a meadow of milkweeds and campions. Immediately upon arrival, we were pleasantly surprised. Lobelia cardinalis was in full bloom in a nearby woodland understory, and the tiger swallowtails were taking full advantage of the nectar:

In our "target" field, the common milkweed was nearing the end of its bloom, but the butterflies were still sipping from campion flowers. Dominating the activity were spicebush swallowtail, monarch, and eastern tiger swallowtail. ...and a few milkweed tussuck moth caterpillars were trying to cross the road (see photo to right)!

As the milkweeds and dogbanes move into seed production, butterflies shift attention. This was made evident by the clouds of fluttering wings in a meadow we had previously overlooked...one dominated by Joe Pye weed, ironweed, Helianthus sp. and emerging goldenrod and thistle. This was the jackpot, but we had to watch from afar, as the patch of activity had a dense thicket of blackberry between us and it.After spending a couple of hours on the mountain, and with the evening approaching, we descended. The final destination was Ivy Creek Natural Area, for a look at the unfoldings in a lower elevation meadow. We opted for a single go-around on the field loop trail, and did it rather quickly...lightning was quickly approaching. In our rapid trot we hurdled a black rat snake, exchanged glances with an osprey , and spooked several deer....which spooked us. We also happened upon one of the more interesting wildflowers of late summer...Spotted horsemint, also known as spotted beebalm (Monarda punctata):

Marvelous milkweeds

I am a huge fan of milkweeds due to their special attraction not only to monarch butterflies but also to a considerable list of other insects that are milkweed specialists, and some generalists who use milkweeds as a community to forage in. But the problem is that those of us that own hay fields will cut the grass including the milkweeds once or usually more per year, slaughtering the marvelous milkweeds. However I have come up with a compromise that I think both feeds the cows, and preserves the milkweed community. See what you think of my solution.

My plan is to cut the grasslands only once per year and that is in mid to late June in our location here in the SW Virginia mountains. This serves not only to harvest the grass for use in fodder but removes woody vegetation that invades the grasslands, and removes a layer of cold-season grasses (such as fescue) that are primarily exotic to this area. This releases the warm-season grasses and allows them to grow and produce a crop of seeds by Fall for use by native birds. But you may ask what about the milkweeds and their fate? It appears to me that this regime may actually be beneficial to the milkweed community in the following way. I retain a certain number of fields that are not cut except very occasionally (they are burned every three years in late Winter) and which have natural populations of milkweeds (in this case mainly the common milkweed, Asclepias syriaca). The fields that were cut this year on June 17 began about seven weeks later in early August to produce a wonderful crop of milkweed flowers, while the uncut milkweeds are setting seed and are no longer blooming. The leaves of the uncut milkweeds are old and tough whereas the cut and regrown milkweeds have young tender leaves. Thus my single-cut method of harvesting hay fields stretches out the milkweed season but does not obliterate it, as would happen if the fields were to be harvested a second time, a common practice among farmers to maximize hay production. Also I have noticed that the monarchs often do not arrive in this area in time to fully utilize the naturally cycling milkweeds, and indeed seem to use the "second crop" milkweeds extensively.

Some illustrations of the re-grown milkweeds are shown in photos of an adult monarch gathering nectar from a "second crop" flower, of a female yellow morph tiger swallowtail also nectaring on a re-grown plant, and a monarch caterpillar feeding on a re-grown leaf. Surely there is much yet to learn about the characteristics of milkweeds that are cut and then sprout again- do they provide proper food at tolerable levels of toxins, and in a timetable that is appropriate? Certainly it appears from my observations that this is a win-win situation that can preserve the habitat of many species that depend on milkweeds while also providing some income for the farmer. Of course subsequent hay cuttings must be sacrificed for the pleasure of observing and fostering the milkweed animal community, and providing enhanced food and cover for birds in Fall and Winter.

One of the other lesser known insects that I encounter among our milkweeds is a bit sinister- the famous assassin or wheel bug (see photo)! It is a predator with a wicked beak, a poisonous bite and a reputation for delivering a painful zap with its tubular mouth. It eats insects that come to the milkweeds and it would be interesting to observe whether it is capable of devouring those that are protected by the milkweed toxins, in contrast to others such as tiger swallowtails that are not.

So many puzzles and so little time! So get out there and check out the milkweeds and their fascinating inhabitants.

Bill Dunson

Galax, VA

Englewood, FL