Ecologist's Notebook

Over the past month Deborah and I have been closely watching the spring wildflowers in Harrison Hills Park. So far we have seen 40 different flowering species (a mix of native and introduced plants) and expect to see another 20 or so through the late spring and early summer. The "usual suspects" dominate almost every trail in the park: spring beauty, Jack-in-the-pulpit (left), Solomon's Seal (both "true" and "false"), violets (at least 5 or 6 species of these!), mayapple, and skunk cabbage. There are also, though, some surprises like a large patch of Virginia bluebells (on the Pond Loop Trail), and red trillium ("wake robin") in unexpected clusters along the woodland trails. We also saw many of our spring favorites including bloodroot, pepperroot, bluets, Canada mayflower and bellwort.

We have also watched many types of fern unfold from fiddle-head to expanded frond. Sensitive fern and New York fern joined the overwintering fronds of evergreen wood fern and Christmas fern, and both of these species began to grow their new fronds for the season. Large, circular bare patches between the trees filled in with thin fern stalks that will branch and thicken into a continuous, green cover over the coming weeks.



Mayapple is very abundant along almost all of the park trails. The distinctive "parasol" plant has thick, shiny green leaves and a partially hidden, nodding white flower. This perennial plant grows from expanding rhizomes and often forms large, interconnected patches of dozens to hundreds of genetically identical plants. Mayapple relies on soil fungi (mycorrhizae) to assist their uptake of soil nutrients. Competition with plants that inhibit these soil fungi (like garlic mustard) can be very harmful to mayapple. Reproduction in mayapple is via both vegetative growth (the expanding rhizomes) and via sexual reproduction (flowers that form fruit after pollination). There is a steep physiological cost involved in making flowers and fruit, and this cost can significantly drain the energy reserves from the colonial rhizome. This energy loss may even be sufficient to kill the large, clonal colony. Dispersal, though, of the species via the fruit, and the genetic mixing and variation that arises from sexual reproduction are advantages well paid for by this stress. In the masses of clonal  mayapple along the park trails no more than 20 or 30% of the plants had the double leaf stalks with the forming flowers. The colonies seem to hedging their reproductive bets a bit!

This week Deborah and I saw our first ticks of the season. One was an engorged tick that came off of one of our pets (we have since treated our cats and dog with a topical flea and tick repellant), and the two others were deer ticks that we found on ourselves following a walk in a nearby woods. My guess is that along with everything else that is bursting into activity with our "sudden" conversion into spring, the ticks are also going to start to be both plentiful and active.

Pasted below is a species page I wrote for the Virtual Nature Trail about deer ticks. I also came across an interesting article (2001 in The New England Journal of Medicine) concerning prophylactic treatment of  tick bite patients with doxycycline to lower the incidence of Lyme Disease. Incidence of the development of the "bull's eye" pattern of erythema and the progression into Lyme Disease went from 3.2% to 0.4% in patients given a single antibiotic dose. As always, talk to your doctor if you encounter a tick! Tick removal suggestions are included at the end of the species page.

The Deer Tick
 
(Information for this species page was gathered in part by Brittany Wetzel for Spring 2006, Biology 220W at Penn State New Kensington)
 

Deer ticks (Ixodes scapularis) are small, relatively hard-bodied, chelicerate arthropods that are found in some abundance in the northeast, midwest, and southeast sections of the United States. Adult deer ticks are approximately 3 mm in length and are dark brown to black in color (another common name for this species is the "black legged tick"). Immature life stages (larvae and nymphs) are even smaller than the adults and were at one time thought to comprise a separate tick species ("Ixodes dammini"). These life stages now, however, have been clearly shown to be part of the developmental sequence of I. scapularis.
 
The deer tick's life cycle represents a repeating pattern of blood feeding, growth and moulting, and the selection of ever larger vertebrate host species. Eggs laid in the leaf litter early in the spring hatch in mid to late July into 6-legged larvae. These larvae quickly attach themselves to small vertebrate host species (like white footed mice or chipmunks) and feed on these hosts for 3 to 5 days. Dropping off of these hosts and falling back into the forest leaf litter, the engorged, larval ticks either directly moult into the larger nymphal life stage or delay moulting and overwinter until the next May. The nymphs have the characteristic 8 legs of chelicerate arthropods. They seek out larger hosts (like squirrels or opossums) for their next blood meal. These nymphal life stages are very commonly the form of the deer tick that opportunistically attach to and feed on humans. After a 3 or 4 day feeding period, the nymphs drop back into the forest litter and moult into the adult life forms. These adult deer ticks become active starting in October and may remain active through the winter if non-freezing microhabitats are available (see discussion of the "subnivia"). The adult ticks attach to white tailed deer (hence the name "deer tick") and females feed on the deer for 5 to 7 days becoming massively engorged. The males only feed slightly on the deer but may use their attachment time to seek out females. Mating may occur on the deer host or in the leaf litter immediately following release from the host. Females lay between 1000 and 3000 eggs in the leaf litter typically in May. Both males and females die soon after mating and egg laying.
 
To successfully complete their life cycles, then, I. scapularis requires the presence of white tailed deer. It is not surprising, therefore, that any area with substantial populations of white tailed deer also frequently has high densities of I. scapularis. White tailed deer are also important dispersal agents in the spread of I. scapularis up and down the eastern seaboard, into the midwest, and across the southern sections of the United States. Within a forest ecosystem, I. scapularis is most abundantly found along deer trails and in feeding and bedding areas frequented by white tailed deer.
 
Ixodes scapularis is especially found in forested ecosystems but is also frequently abundant in shrub lands, leaf piles, and even in mowed fields and lawns. Ixodes scapularis is especially common in small forest plots (which by their geometry have a high percentage of edge ecotones which are typically rich in browse vegetation for white tailed deer).  These ticks also seem to prefer mixed hardwood forests (especially mixes containing hickory, poplar, maple, and beech) and are also positively correlated with the presence of greenbrier, blueberries, pepperbush, snakeroot, and sassafras and with the abundance of the exotic, invasive plants like barberry and Japanese honeysuckle. The accumulation of leaf litter and brush is positively correlated with the presence and abundance of I. scapularis undoubtedly due to its contribution to the quality of the tick's "off-host" habitat. Moderate temperatures and high humidity also favor the survival and abundance of I. scapularis. 
 
An interesting behavior called "questing" has been observed in all three life stages of I. scapularis. When an individual is ready to find a host for a blood meal it climbs to the top of the surrounding vegetation (typically the herbaceous plants of the forest floor) and remains in place on the tips of these plants with its forelegs extended up from the plant's surface. When a potential host brushes past the plant, the tick clamps onto it with its front legs and then quickly moves up and over the host to find a suitable feeding spot.
 
One of the significant human related problems associated with I. scapularis concerns the tick's role in the transmission of the bacterium Borrelia burgdorferi.  This bacterium is pathogen that causes Lyme disease in humans. The bacterium is picked up by I. scapularis when it takes a blood meal from an infected host. Inside the tick the bacterium goes into an inactive state until the tick begins to feed on its next life-cycle host. It takes 12 to 48 hours for the bacterium to become active enough to be transmitted by a feeding tick. This information is extremely important to anyone who picks up an I. scapularis. Prompt removal of the tick (and this is best accomplished by using forceps to gently pull the entire feeding structure ("head") of the tick out from the skin) greatly reduces the possibility that the Lyme disease pathogen, if present, will be transmitted. It is vital, then, to do a careful "tick check" on anyone who has been out in the woods or in areas known to have I. scapularis populations.   Of course, an even better way to prevent the possibility of getting Lyme disease is to prevent the tick attachment in the first place. Long sleeves and long pants, use of insect repellants with high concentrations of DEET, and avoidance of deer frequented areas are all excellent strategies by which one can deal with this species and still go out and enjoy hiking and exploring in our natural ecosystems.  

Deborah and I have been out hiking on quite a few woodland trails this spring. One of the generalized observations we have made concerns the preponderance of alien, invasive plant species that make their ecological presence known long before most of the native species. Early leafing and early flowering are excellent strategies for an invasive plant to gain a "foothold" in our deciduous forest ecosystems. Add the ability to make abundant seeds and an absence of co-evolved biological controls and these exotic, invasive plant species can truly come to dominate an ecosystem!  

Most of the trails we have been walking on have been lined by multiflora rose (Rosa multiflora). Multiflora rose is one of the first understory plants to sprout leaves in the early spring, and its fresh leafed appearance makes entire wooded hillsides glow green. I had mentioned previously seeing this plant's just unfolding leaf buds out on the Campus Nature Trail three weeks ago. This is time of year to appreciate how much multiflora rose there is in our Western Pennsylvania ecosystems! Unfortunately, the story about this plant is both good and bad. It is an extremely aggressive and rapidly growing exotic invasive (from Asia, brought to this country as an ornamental plant) that has choked out many native plant species. It also, though, generates very favorable habitats for many species of small mammals and birds.

Spring is happening all around us! It's very hard to keep up with the pace of change.The daffodils are are in full bloom, and the forsythia are in various stages of flowering. Entire neighborhoods and forest hollows are turning yellow overnight. The lilacs are leafing out along with the willows and the plum trees, and, yes, alas, the grass is continuing to grow.


Deborah and I went up to Harrison Hills Park on Wednesday afternoon to take a walk on their Wetlands Trail. The Wetlands Trail loops around and over a set of small streams that run through the north part of the park. In all of the creek-side low spots large numbers of the distinctive, striped, reddish-purple spathes of skunk cabbage were visible. The spathe houses the skunk cabbage flower and as I previously discussed is able to generate its own heat and survive and attract pollinators even in early February. Most of the spathes were still intact although a few were starting to crumble away. Almost all were surrounded by 8 or 10 inch long, bright green leaves. These leaves will grow rapidly in the coming weeks to make an interconnected mass of vegetation.(all images: D. Sillman)

The Worm Moon (the full moon in March) has come and gone. I didn't see the usual, nighttime, mass emergence of earthworms from their warming soil burrows. Nor did I see the sad array of sluggish, straggler worms in the morning laying half-frozen on the driveway and sidewalks, but, over the past week, I have watched robins more and more frequently snagging nightcrawlers out in the short grass of my field. A quiet, more controlled Worm Moon this year, I guess.

Some of the bird migrants have returned! Lisa Meyerhuber spotted a pair of Baltimore orioles down on the Roaring Run Trail, and red-winged blackbirds have started to visit my bird feeders. The cowbirds are back, too (not all signs of spring are good!). The male goldfinches are getting increasingly yellow, and as I have mentioned in previous postings, the chorus of the morning bird songs is stunning.

Donald Bruckner reported that he heard spring peepers last Sunday, and Kay Balderose heard them at Harrison Hills Park. Deborah and I heard tree frogs trilling yesterday. My guess is that we need one or two more warm days to get our local wetlands charged up with calling peepers. The expected rain tonight should be just the stimulant they need!

Our deer are looking scruffy and unkempt as they shed their winter coats. Last year's fawns are only slightly smaller than the other individuals in the herd. I can tell the two fawns from the older deer, though, by their stunningly brazen behavior in my front yard. Neither leave the sunflower feeders even when I open the front door, step out on the sidewalk, and yell at them. Only Kozmo charging around (and through) my legs is sufficient to chase them off.  

The crows have been carefully snapping twigs off of our red maple tree and flying off with them into the surrounding woods, and robins and blue jays have been gathering up beaks-full of the straw I had spread on the low, muddy spots in the front yard. Someone has also been collecting the handfuls of dog hair I have tossed in the yard from Kozmo's regular brushing (he's losing his winter coat, too), and I am sure that many birds are finding the shed deer hair, too. Such great materials to use in all of the new spring and summer nests!

But, the biggest sign of spring here in southern Armstrong County is right in the corner of my dining room. Spider, my box turtle, has come out of his winter torpor. So far he has eaten four, large strawberries and seven nightcrawlers (he likes sweet with his savory!) and is even starting to thump impatiently on the sides of his terrarium. The sight of the sun coming in the front window is definitely a stimulant for him. On the next warm afternoon I will put him out in his outdoor pen so that he can enjoy the sunshine and fresh air. I may even join him!

Crocuses are blooming, and the daffodils are just starting to show color around my house but are blooming gloriously (as of this morning!) along Route 780 near our campus. Our red and silver maples are in flower (and my eyes are itchy and my nose is running), and the multiflora rose bushes are sprouting leaves. And, the cruelest sign of spring of all, the grass is starting to grow. I actually think that I heard a lawn mower being started up yesterday. We have to take the bad along with the good, I guess.
 
Enjoy the sunshine and warmth! We deserve it!
   

There have been a number of signs of spring wedged in between the cold and the snows. For the past two weeks the mornings have been greeted by a chorus of bird songs no matter what the temperature or type of on-going precipitation. The male cardinals, titmice, Carolina wrens, mourning doves, and robins are all showing off their individual energies and potential reproductive fitnesses by shaking off their cold night's sleep with loud, echoing songs. Also, the common grackles have returned to my front yard. The male grackles in between beaks-full of shelled corn and long drinks from my bird bath, dance slowly around each other (and the smaller, more drab colored females) with ruffed out neck feathers and sky-pointed beaks. I have been making sure that my bird feeder area is well stocked early in the morning for all of the day's action.

The branches of my spruce trees have been lively, too, with pairs (and even trios!) of titmice and cardinals chasing each other about trying to be noticed. The gray and red squirrels have been running up and down the tree trunks, too, much to the joy of my still mostly house-bound cats.

But the biggest sign of spring to date was something that Deborah, Rob, Michele and I saw Saturday on our hike around Ferncliff Peninsula down at Ohiopyle. Not only did we see colt's foot flowers (at last!) scattered about in the warmer areas of the trail and a comma butterfly fluttering around under the rhododendrons, but we also saw eastern wood frogs gathering in loud, chirping numbers in most of the vernal pools along the trail.  

Volcanoes are not a part of our Western Pennsylvania landscape, so the opportunity to go and hike around three of them was not something we could pass up. It was a beautiful afternoon with high, blue skies and lots of sunshine. I brought along a light jacket in case the wind picked up but ended up just carrying it under my arm. There was enough sun to give us each the start of a sunburn after a couple of hours of walking, and I am still amazed at how dry the air is here. Two bottles of water were barely enough for the three mile hike. (photo by D. Sillman)

We drove about a half an hour west of the city to a slightly more distant section of the same Petroglyph National Monument that we hiked around on the day before. There are several new, four and six lane divided highways radiating out into the open desert along the cardinal points of the Albuquerque compass, and a spread of houses and strip malls follows each one. We crossed a bridge over the narrow trickle of the Rio Grande and after several more minutes abruptly passed the edge of the city. The highway with all of its active widening and new off ramp construction was now surrounded by empty (at least for now), brown sagebrush expanses domed over by the seemingly infinite, deep blue sky.

Albuquerque sits in a broad valley that runs from Colorado all the way down to El Paso, Texas. The valley has been spreading out both to the east and to the west over geological time, and the Rio Grande runs down the middle of it. This Rio Grande Rift Valley like the Great Rift Valley in East Africa may have been a major highway for human migrations. It is also the reason we have volcanoes so close by!    

Sunday started out in a very spring-like manner and just kept getting warmer and sunnier all day. In the afternoon, Deborah and I took some of the just arrived daylight savings time to go down to the nearby Rock Furnace Trail. There were several "signs of spring" that we wanted to look for.

A couple of hundred yards down the trail from the parking area is the McInerney #6 gas well. Just opposite of the well is a tall, concave, south-facing shale cliff that acts as a natural solar collector. Spring wildflowers bloom around this warming rock face weeks before they show up anywhere else in the area (see this previous March blog entry). Since my crocuses had started to bloom around my house I thought that there was a chance that the first wild, yellow blooms of spring, colt's foot (Tussilago farfara), might be up. I poked through the dry stems and leaves at the base of the cliff but didn't find any flowers. Maybe they'll be up next week!   .     
 

One of the more welcome signs of spring arrived last week: Penn State's week-long Spring Break. Deborah and I headed 1600 miles west and south to sunny, but not yet quite warm Albuquerque, New Mexico to visit our daughter and to do some hiking in the high deserts.(photo by D. Sillman).

Our first morning was cool and gloriously sunny. We walked east from our daughter's apartment toward the campus of the University of New Mexico. Our nature observations began immediately upon stepping out the front door: in the London Planetree across the street were my first two robins of spring! They chirped and called to each other for several minutes and flew off to grace some other street corner and some other observer.

We walked several blocks past the typical Albuquerque houses: low, adobe-style homes painted in varying shades of tan. Many of the houses had small, front "lawn" squares that were mostly bare soil or carefully raked gravel. Some of the yards had honey locust or London Planetree growing in them. There were a few with some unknown (to me) thorny shrubs, too. There was very little grass, and what was there was dry and winter-brown and well covered by dry, brown tree and shrub leaves.

This all changed when we got to the campus. Apparently, the University of New Mexico has its own aquifer and, so, is not bound by the logical water restrictions that the rest of Albuquerque has to adhere to. Stepping into the campus grounds was like walking into a different climate zone. There was no bare soil or gravel or stones. Instead there was a continuous carpet of winter-brown grass and dozens and dozens of trees some of which should not have been growing within a thousand miles of here!

Last Wednesday I went for a noon-time walk down to the Campus Nature Trail. I had two "signs of spring" goals for this walk: I wanted to check for arriving flocks of robins (they often cluster on the wet soil of the soccer field next to the Nature Trail to feast on earthworms), and I wanted to see if the skunk cabbage flowers had come up down in the small wetland alongside the stream.  (Image: D. Sillman)

There were no robins on the soccer field. Maybe they are lingering in their more sheltered and fruit-filled habitats down in Pittsburgh and the close-in suburbs. So, I walked past the quiet soccer field and stepped into the dense woods of the Nature Trail.

The week before the trail had been buried under several inches of snow, but our recent (but short-lived) warming spell had done a good job melting it. Even well shaded spots under the black pines were snow-free. There was an even, brown, ground litter cover all through the woods that was broken only by scattered green fronds of evergreen wood fern and Christmas fern. I made my way down the Oak Trail and Spice Bush Trail all the way to the bottom of the ravine. The stream was low but flowing steadily. I splashed across it (water-proof boots!) and walked downstream in the soft, mucky soil of the far bank for about 30 yards. There I spotted the red and white striped metal stakes that we had put out several years ago to mark the skunk cabbage plot. Looking very carefully, I saw seven, striped, reddish-purple skunk cabbage spathes (the cone of tough, modified leaves that encase the flower structures of the spadix) standing up about two inches above the surface of the cold, wet soil.