Fall Bird Migration - Identification in Flight

An important part of phenology is migration.  As birds begin to migrate south in the fall, it is fun to learn to identify them in the air.  You can learn to identify some easy species by reading the post at http://baypoll.blogspot.com/2011/08/birds-in-flight-easy-ones.html.

If you go back to August and September 2010 from the Baypoll Blog, you can also learn to identify other migrants in flight.

Then after Hurricane Irene blows through the region, go out an practice!

The First Signs of Fall?

It is not even mid-August, but I have already noticed a murmuration of starlings (actually I have seen a few).  Witnessing these roving bands is to me one of the earliest signs that summer is beginning to wane.  I suspect that this is, in part, because the observation coincides with the time that I begin working on (or at least thinking about) the syllabi for my fall courses.  Fall is my favorite season, but I always experience a touch of melancholy when I notice signs of summer’s end.

Meteorological summer ends with the month of August, although many people associate the season's passing with Labor Day weekend since beaches and pools typically close.  Our days have been getting shorter for some time now, and the third week of July that is typically the hottest in eastern PA is long gone.  You can feel the fresher, cooler air if you are an early riser and it is refreshing to open the windows in the evening.  And there are other signs that things in nature are starting to change. The complementary colors of fall-blooming flowers—purple and gold—are already visible in the Joe Pye Weed, Ironweed, and the species of Goldenrod that are already blooming.  And any birders out there know that the hawk watch seasons at Bake Oven Knob (http://lgnc.org/research/bok-hawk-watch) and Hawk Mountain (http://www.hawkmountain.org/Raptor_Migration.php) commence in just a few days on August 15^th.

What do all of these seasonal notes tell us?  That it is time to think about fall phenology and to contribute new data to the Eastern PA Phenology Project (http://lgnc.org/research/phenology)! 

 
There are a number of raptors that will begin to migrate early including Bald Eagles and Ospreys.  Songbirds that are early fall migrants include Louisiana Waterthrush, Yellow-billed Cuckoos, and flycatchers--especially Eastern Kingbird, Olive-sided Flycatcher, and Empidonax species (the ones I can’t typically distinguish without hearing their spring songs).  In fact, late this afternoon, a Least Flycatcher was spotted by my son in an apple tree by our house.

You should begin to see Monarch caterpillars and chrysalises soon.  This past week, I have been seeing more Monarchs nectaring on plants, but, as of yet, they aren’t showing migration behavior.  These butterflies will likely lay eggs and you may soon begin to see the caterpillars munching on milkweed.

Yesterday we began seeing the dark form of the female Eastern Tiger Swallowtail that mimics the Pipevine Swallowtail—both being late season butterflies in this region.

Below is a list of some other fall seasonal signs to be looking for.  Don’t forget to report your observations of seasonal changes to the Eastern PA Phenology Project at phenology@lgnc.org.

Goldenrod (Solidago sp.; photo by D. Husic)

Aromatic Aster (Symphyotrichum oblongifolius; photo by D. Husic)

-         First blooms on goldenrod (Solidago sp.) and asters (typically Symphyotrichum sp. in this region);

-         Chipmunks collecting and storing food;

-         Milkweed seed pods opening and dispersal of the seeds;

-         Last sightings of Barn and Tree Swallows (see fact sheets on project website for identification);

-         First sightings of Dark-eyed Juncos returning – often at feeders;

-         Loss of bright yellow color on male American Goldfinches or of the brilliant blue of Indigo Buntings;

-         The date of the first frost;

-         Tree leaves beginning to change color (note species, first color changes, timing of tree at peak color).  The Red Maple is one of our species of particular interest, but we will take reports on any and all trees that are common to eastern PA (see fact sheet on project website);

-         The timing of when leaves begin to fall and when a tree is completely bare; 

-         The timing of sumac leaves changing color and loosing leaves; 

-         Starting this fall, we are particularly interested comparing the timing of when native vs. invasive shrubs lose all of their leaves.  Some examples include native viburnums, dogwoods, and blueberries, vs. the invasive Autumn Olive, Multiflora Rose, Japanese Honeysuckle, and Japanese Barberry.

-         Last sightings of Bumblebee, Cabbage Whites or Ruby-throated Hummingbird (see fact sheets on project website for identification); 

-         First sighting of a Milbert’s Tortoiseshell butterfly; 

Milbert's Tortoiseshell (Aglais milberti; photo by Corey Husic)

-         The timing of the emergence of the yellow flowers on Witch-hazel (picture on fact sheet on project website). 

These are just some of the fall seasonal signs.  If you observe other phenological events, we would love to know about your observations.  Remember that you can report your observations at phenology@lgnc.org.  Periodic summaries of what our project contributors are observing will be posted on this blog.

Katydids

Every year, around the last two weeks of July, the Common True Katydids begin singing here around my house in southern Monroe County.  This loud, chattering species is quiet up until this point, then incessantly sings throughout the warm nights of late summer and early autumn.  Often living in the canopy of deciduous forests, the Common True Katydid is very rarely seen, but is frequently heard singing katy-did, katy-didn't.  Both sexes of this species sing, unlike many of the related katydid and cricket species.  The Common True Katydid almost always starts singing after sunset, with only an occasional chatter during the daylight hours.

Common True Katydid (Pterophylla camellifolia)

The broad, rounded wings are unique among the local Tettigonids (members of the katydid family).  This species is also one of the loudest due to its sound-producing wing mechanism, but this ability renders the Common True Katydid flightless, except for weak gliding abilities.  Although this species is primarily found in the upper levels of the forest, it can occasionally be found in shrubs and small trees closer to the ground.  The individual photographed above was sitting in a small birch tree about four feet off the ground, but was not singing.

While the Common True Katydid may be the loudest and the most well-known of the katydids, it is not the only species that inhabits our region.  The Common True Katydid is our only "true katydid" (subfamily Pseudophyllinae), but there are several species of false katydids, meadow katydids, conehead katydids, and shield-backed katydids.  Below are small accounts of a few of the other katydid groups with detailed information about a locally common species or two from each group.

The first major group of these false katydids is the round-headed katydids.  This group is similar to the Common True Katydid because they tend to have broad, somewhat rounded wings, but the wings are still more pointed than the true katydids.  I often find these species around eye-level at forest edges and hedgerows.  Many of the round-headed katydids begin singing around the middle of July, often a week or two before the Common True Katydids begin their full chorus.

One very common round-headed katydid is the Rattler Round-winged Katydid.  This species is commonly found sitting in shrubs at or below eye level singing its rattle-like song.  This particular species seems to frequently sit in the open, so they are easy to find unlike many other katydids.  This species usually sings only at night.  

Rattler Round-winged Katydid (Amblycorypha rotundifolia)

The meadow katydids are another group of very common katydids this time of year.  A meadow katydid is unusual for a katydid, for it looks more like a grasshopper than closely-related katydid species.  Compared to the previously mentioned katydid groups, meadow katydids are small and more brightly-colored.  Meadow katydids also tend to have more intricate songs.  I usually start hearing the first meadow katydids, usually the Short-winged Meadow Katydids, around the beginning of August.  Meadow katydids will sing during the day as well as into the night.

The Short-winged Meadow Katydid is a small, but common meadow katydid species.  This species tends to sit right-side-up on grass blades, whereas other katydids tend to either sit upside-down or vertical on the blades of grass.  The call of this species is a high-pitched buzz interrupted by small ticks.  One song variation of this insect resembles that of the Grasshopper Sparrow.

Short-winged Meadow Katydid (Conocephalus brevipennis)

The conehead katydids, which are very closely related to the meadow katydids, are common denizens of grassy and weedy areas.  In eastern Pennsylvania, almost every weedy field seems to have a population of these abundant, yet secretive katydids.  The coneheads begin singing just as the Common True Katydids start, which is usually around the end of July.  Members of this genus can be heard during both the day and night, but they are excellent ventriloquists, making them difficult to find among grass blades and weeds.  Coneheads sing most frequently at night, but are also commonly heard during the daylight hours.

One of the most common species in eastern Pennsylvania is the Sword-bearing Conehead.  This species is common in weedy fields where it often sits vertically on a blade of grass or the stem of a plant such as goldenrod.  This species can be either green or brown.

  

Sword-bearing Conehead (Neoconocephalus ensiger) - green form

Sword-bearing Conehead (Neoconocephalus ensiger) - brown form

Another group of katydids that resemble grasshoppers are the shield-backed katydids.  Shield-backs are named for the large plate that covers the thorax and part of the abdomen and wings.  This group contains several native species, most of which are relatively uncommon and challenging to find.  However, there is one non-native species that is extremely common and abundant in this area, the Roesel's Katydid (also spelled Rösel's Katydid).  The Roesel's begin singing in late June, before many of the other katydid species.  This species can be found singing its sustained buzz song in any field with tall grass, wildflowers, or small shrubs.

Roesel's Katydid (Metrioptera roeselii)

Although Common True Katydids are now starting to sing their loud, obvious song, and the Sword-bearing Coneheads can be easily heard in any field, my favorite katydids are the bush katydids in the genus Scudderia.  The members of this group are all fairly skinny-winged, and sing weak songs.  Members of this genus are difficult to discern from each other by appearance, but the songs are unique, making identification easier at night, when these katydids sing.  

The Northern Bush Katydid is the species that is currently dominating the forest and forest edge understory chorus at night.  The "song" of this species is a series of clicks followed by a series of tsits.  I first heard this species singing during the first week of July.  This species is often attracted to lights at night.  I often find several sitting on the walls of the porch if the porch light is left on.

 

Northern Bush Katydid (Scudderia septentrionalis)

Another species of bush katydid that is common right now is the Curve-tailed Bush Katydid.  This species prefers open fields over woods.  Although extremely similar in appearance to the Northern Bush Katydid, the song of lisping sits rising in volume is distinct.  I have seen these in the field near my house since early July, but they did not start singing until the middle of the month.

Curve-tailed Bush Katydid (Scudderia curvicauda)

For more information about these species and other singing wildlife, visit the Lehigh Gap Nature Center's Sound Field Guide.

Phenology Note: July 15, 2011

While on a walk today, I noticed several small toads crossing the path.  These tiny toads probably emerged from the nearby pond earlier today.  Toads start out as an egg, which is laid under water, then live in these ponds as a tadpole for several months.  Once the tadpole grows, develops legs, and loses its tail, it is ready to leave the pond.  This time of year, these toads seem to be everywhere as they spread out from the place where they were born.

While on the walk, I also noticed a small, bluish flower along the side of the path.  The tiny flower belonged to an Indian-tobacco (Lobelia inflata) plant, a mid-summer flower of woodland edges.  The species name, "inflata," comes from the shape of the swollen ovaries (seed pods) once the flower is done blooming.  This photo is from last year, so the flowers and seed pods are visible.  Here in Kunkletown, today was the first day I noticed flowers on this species this summer.

Summer Phenology

Many phenology observers get excited about spring and fall phenological events but neglect summer. In spring, returning birds, emerging butterflies, leaves unfurling, and spring flowers blooming signal rebirth. Autumn gets lots of attention for autumn foliage here in Pennsylvania, and once again migration takes center stage. But summer is just more of the same -- everything is green, the birds are breeding (nothing new is arriving) and bees and butterflies are about visiting flowers but not much changes from day to day. Unless you look a bit more closely.

Mountain Laurel blooms at the beginning of June and gets lots of attention, but its cousin Rhododendron maximum (or Great Laurel) blooms at the beginning of July in hollows and hillsides, especially in cool, damp places.It has big, showy flower clusters and I saw the first blooms here on June 19 this year -- quite early in my recollection. The peak bloom was the last week of June and first week of July. Lots of bumblebees visited these blooms.
















Rhododendron/Great Laurel

Many other flowers also bloom at various times throughout the summer. Scarlet Beebalm (Monarda didyma) and Wild Bergamot (Monarda fistulosa) bloomed in mid- to late-June this year as well. Lots of native bees, butterflies, and Ruby-throated Hummingbirds have been visiting these flowers.


















Wild Bergamot (top) and Scarlet Beebalm

Speaking of bees and butterflies, some of these have fairly brief seasons as well. The diversity of insect probably peaks in mid-summer but the cast of characters changes. We are now beginning to see Monarch Butterflies (which will become abundant later in August), but their mimics, Viceroys are also out and about. You can tell the smaller Viceroy from the Monarch by the line across the rear wing of the Viceroy.














Monarch on Buttrerfly Milkweed (left); Viceroy (right)

Perhaps the most beneficial group of plants for attracting and helping insects is the milkweeds. We have Common (Asclepias syriaca), Butterfly, (A. tuberosa), Swamp ((A. incarnata), and Horsetail (A. verticillata) milkweeds in our habitat gardens and they bloom in June and July. The common and butterfly milkweeds bloomed first this year with the first blossoms opening on June 14. Swamp and horsetail have been blooming in the past week. Watch your milkweeds for lots of bees and butterflies, bugs and beetles. And also watch for beautiful Monarch butterfly caterpillars.














Common Milkweed and Bumblebee



There is lots more to record during the summer. Keep an eye on your gardens and backyards and let us know what you are seeing out there.

Azure Phenology and the Appalachian Azure

Within the last twenty years, researchers have made several discoveries involving the butterfly genus Celastrina, the azures. Several years ago, there was only one recognized species in the eastern United States, the Spring Azure (Celastrina ladon). Now that scientists can look at DNA sequences, it has become clear that there are several distinct species in this region. As I have mentioned in previous posts, there are five species that are commonly found in eastern Pennsylvania. The Northern Spring (Lucia) Azure (Celastrina lucia) is the first azure to appear in spring. This species is most common in the mountains from the Kittatinny Ridge and north from there. The Northern Spring Azure primarily eats the leaves and stems of blueberries (Vaccinium) as caterpillar.

Northern Spring Azure, Celastrina lucia

The second species to emerge in spring, often in the first week of May, is the Spring Azure (Celastrina ladon). Almost identical to the previous species, the Spring Azure is the common azure for the first few weeks of May. In the Lehigh Valley, which is located south of the Kittatinny Ridge, this seems to be the predominant azure species. The Spring Azure's primary caterpillar food plant is flowering dogwood (Cornus florida), a common tree of deciduous forests.

Spring Azure, Celastrina ladon

Beginning around the third week of May, a new batch of azures can be found in the woods and forest edges. At this point, many Spring Azures are worn and dull, as they have been flying for a few weeks, so they can be separated from these new Cherry Gall Azures (Celastrina serotina). This species uses Wild Black Cherry (Prunus serotina).

The longest-lasting of the azures is the Summer Azure (Celastrina neglecta). This species is the most distinct of any of the species already mentioned. The spring species are usually well-marked with dark spots, but Summer Azures are often very very pale and chalky white rather than blueish gray. As a caterpillar, the Summer Azure may use several shrub species including silky dogwood (Cornus amomum) and meadowsweet (Spiraea latifolia). Since these plants are commonly found along woodland edges and brushy fields, this butterfly is often found in these habitats rather than woodlands.

Summer Azure, Celastrina neglecta

The fifth and rarest species is the Appalachian Azure (Celastrina neglectamajor). This large, pale azure flies at the same time as the Summer Azure, but only feeds on black cohosh (Actaea racemosa; syn. Cimicifuga racemosa). The female Appalachian Azure lays her eggs on the unopened flower spikes of this cohosh. Once the caterpillar hatches, it feeds on the flower buds and stems (Pavulaan & Wright, 2000).

Appalachian Azure (Celastrina neglectamajor) on the host plant

In Pennsylvania, this species is primarily found in the southern half of the state. A few years ago, I learned that this species had never been found in my home county. After learning this, and after finding a large patch of the host plant, I kept an eye out for any azures in that area. In 2009 and 2010, I checked the plants for eggs and caterpillars, but was unsuccessful. This year was different. While I was in the woods, I spotted an azure flying just above my head. I followed the azure in an attempt to get a better look. I followed the blue speck until it led me to the patch of black cohosh and finally landed--on the host plant for the Appalachian Azure. Until this point, I had assumed that this was another one of the ubiquitous Summer Azures. I immediately checked the flower spike of the closest cohosh plant. Sure enough, I found two azure eggs situated between the flower buds! This was the first sighting and documented record of Appalachian Azure in Monroe County, which could be a sign of range expansion since these butterflies were not observed at this location in previous years. In the next week or so, I hope to return to the patch of cohosh and count the number of eggs present and hopefully get photos of adults and caterpillars.

Appalachian Azure eggs on buds of Actaea racemosa

Pavulaan, Harry and David M. Wright. "The Biology, Life History, History, and Taxonomy of Celastrina neglectamajor (Lycaenidae: Polyommatinae)." The Taxonomic Report. 2.5 (2000): 1-19. pdf.

Late Spring Butterflies

Summer is known as the best time of year for butterfly diversity.  With warm temperatures and blooming flowers (e.g. joe-pye-weed, beebalm, and milkweeds), butterflies can be extremely abundant.  During this time, the species diversity of butterflies is very high.  In mid-July, it is not uncommon to easily find 20-30 butterfly species in a single meadow.  As a result of this high diversity and abundance of brightly-colored species, many "butterfliers" wait until this prime time to go looking for these insects.

Although summer is often considered the best season for butterflies, many unique species show up around late spring.  Many of these species only fly for a short time period, so by the time the summer butterflies emerge, these interesting spring species are no longer around.  Unlike summer, where large, flower-filled meadows and gardens seem to be hotspots, spring butterflies prefer woodlands and grassy meadows or shrubby areas.

A meadow with warm-season grasses, greenbrier (Smilax), and meadowsweet (Spiraea) is perfect for spring butterfles.

The only downside to finding butterflies during the spring is that they rarely sit still.  Since there are few flowers blooming for the butterflies to get nectar, the butterflies do not sit still for very long.  However, if flowers such as northern dewberry (Rubus flagellaris), the butterflies may congregate around the flowers.

Here are some interesting late spring butterfly species that are currently are flying or will be emerging very soon.  If you see these species, please report them to the Eastern Pennsylvania Phenology Project.

Many of the common spring butterflies are classified as "skippers" a group of small, plain butterflies that are commonly found in grassy areas.  The butterfly pictured above is a duskywing, which is a type of skipper.  This species is most likely a Wild Indigo Duskywing, a common species of open areas.  However, there is the possibility that this is a Columbine Duskywing, a little-known species that is virtually identical to the Wild Indigo.  Due to the fact that these species are so similar, it is possible that the Columbine Duskywing, although considered rare now, may be more common than researchers currently know.  These Wild Indigo-type Duskywings are just beginning to emerge in northeastern Pennsylvania.

This butterfly, a Dreamy Duskywing, is a common butterfly of late spring and early summer.  As a caterpillar, Dreamy Duskywings eat the leaves of birches, aspens, and willows.  The adults are commonly found in open meadows or fields near forests where these trees grow.  Unlike Wild Indigo Duskywings, a fairly large skipper, Dreamy Duskywings are very small and often avoid detection due to this size as well as their quick flight.  This species is very similar to the Sleepy Duskywing, a species that flies a few weeks earlier and is mostly gone by the time Dreamy Duskywings emerge.

Another "large" skipper is the Northern Cloudywing.  The cloudywing is similar to the duskywings, but has a different shape, often sits with its wings partway open (whereas duskywings often sit with wings fully opened), and does not have as much patterning on the wings.  This species can be found in woodlands or open areas.  Although this species will begin to emerge during the coming weeks, it will stick around throughout part of the summer.

 Yet another brown skipper, the Cobweb Skipper is a very interesting late-spring species.  Unlike the previously mentioned species, the Cobweb Skipper belongs to a group of skippers known as grass skippers, a large group of small butterflies.  While many of these species are found throughout the summer, some species (including the Cobweb) only occur for a few weeks in late May and early June.  The Cobweb Skipper relies on bluestem grasses (Andropogon and Schizachyrium), so it is almost always found in fields or meadows where these plants grow.  Unfortunately, good meadows with these necessary grasses are being lost to development, and the butterfly population is falling as well.  Although this species can be quite common at a good location, such locations can be difficult to find.

Indian Skippers are often found in the same places as Cobweb Skippers: upland meadows with bluestem grasses.  The Indian Skipper also only occurs for a few weeks around the end of May and the beginning of June.  This species is also declining due to a loss of habitat, so finding stable populations is extremely important.  Since this and the previous species have such short flight periods and are very dependent on rainfall amounts and other meteorological patterns, they are important indicators of climate change and varying weather patterns.  

A final butterfly of late spring is the ubiquitous Little Wood-Satyr.  These medium-sized brown butterflies are commonly found along wooded edges, fields, yards, and roadsides.  The wood-satyr is not a skipper like the previous species and behaves differently.  Little Wood-Satyrs often sit on a sunny perch and allow close observation.  Wood-satyrs also fly much slower than skippers, making them easy to follow and observe.  This species is currently very abundant in many habitats and can number in the hundreds over a small area in suitable habitat.