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.

Hornworms or hummers?

My wife and I have devoted a lot of effort to providing plants for wildlife to utilize for food and shelter. I greatly prefer to have a plant provide nectar for hummingbirds than to put out a feeder with sugar water. Coral or trumpet honeysuckle (Lonicera sempervirens) is a native species that provides a beautiful red flower with abundant nectar for hummingbirds (see photo above). This seems to be an unequivocal win for the garden since it is beautiful, hardy, and highly attractive to hummingbirds. But today I discovered the "rest of the story" as it pertains to the biology of this wonderful honeysuckle.

As I sat rocking on our porch without a care in the world, I suddenly noticed something troubling- there were bare spots on our two honeysuckle vines and tell-tale small dark pellets on the ground underneath. The pellets seemed to be "frass" or caterpillar poop and this indicated something was eating our valuable vines! A quick search and about 10 minutes picking produced the haul shown in the photograph of a group of caterpillars, mostly green but a few brown. A close-up of one of the more common green ones (see photo below right) indicated that this was clearly a hornworm with a terminal harmless spine. I checked this out in the "bible" of caterpillar identification (Wagner's "Caterpillars of Eastern North America") and found a match with the snowberry clearwing sphinx moth. This moth in fact resembles a hummingbird in its flight characteristics and feeding on nectar, but mimics a bumblebee as a means of protection from avian predators.

So here I had a conundrum- some very interesting caterpillars of a species that I value were competing with both hummingbirds and their own adult stage by eating the plant that produces their nectar. My solution for the moment is to pick off all the caterpillars that I can find (far from an easy chore since they are VERY well camouflaged- green and subtly counter-shaded to blend in extremely well with the foliage) and put them in a container where I will feed them on less valuable honeysuckles until they get ready to pupate, when I will release them.

So what have we learned- that once again Nature is more complex than our simple mindsets, and that manipulation of plants for our purposes is often diverted to other ends? This provides an education for us to remain open to new ideas and to value this complexity and not to find it frustrating. Indeed it is exciting that the unexpected can break out and astound us- we have only to be observant and find wonder in the events as they unfold. I also learned that I can sometimes learn more while rocking on the porch and contemplating Nature from that perspective than hiking in the woods and fields!

Bill Dunson

Galax, VA & Englewood, FL