Blogs from our Scientific Researchers

Carnegie Museum of Natural History is home to active research and vast scientific collections. Our scientific researchers regularly contribute to the blog at the museum.

July 14, 2020 by wpengine

How to catch 311 amphibians in 10 days

Step 1: Deploy pitfall traps across Powdermill Nature Reserve

Step 2: Get out of the way and let nature do the rest

Over the course of 10 days in June of this year, I captured 311 amphibians of 12 different species. Every day, rain or shine, I spent over four hours checking 132 pitfall traps and several more hours identifying, measuring, and weighing the day’s amphibian haul. I did a rinse and repeat of this cycle for 10 days straight. Why would anyone do all of this for what Carl Linnaeus, the father of modern taxonomy, once described as “vile animals” with “a foul odor” (Wahlgren, 2011)? Although this sentiment might still ring true for some people today, I did this because amphibians are in serious trouble—more than 30% of species are facing extinction. The threats to amphibians range from habitat losses to disease epidemics, but these are merely symptoms of the underlying cause: unnatural changes brought about by the Anthropocene. Human-induced alterations to nature are irrevocably modifying biodiversity so rapidly that species we learned about in grade school are now extinct and, if we view amphibians as sentinel organisms, then the worst is yet to come.

The Powdermill Nature Reserve is a protected site in Pennsylvania’s Allegheny Mountains where, since 1956—the year it was established by a forward-thinking herpetologist— the property has functioned in a similar way as forests did before human settlement swept across the region. In the early 1980s, scientists at the Carnegie Museum of Natural History studied the amphibian community at the Powdermill Nature Reserve and, serendipitously, established the empirical baseline necessary to study how environmental changes have affected amphibian biodiversity in the Alleghenies (Meshaka, 2009).

close up photo fo orange salamander with black stripes

Examining the results of amphibian trapping during two long ago Junes offers insight into the reserve’s value. In June 1982, 78 traps captured 262 amphibians of 11 species. In June 1983, 54 traps captured 174 amphibians of 11 species. While the species richness has not changed much since the 1980s, there has been species turnover and shifts in abundance, with some species becoming more common in the community. The Two-lined Salamander (Eurycea bislineata), for example, went from 0 captures in June of 1982 and 1983 to 7 captures this June. In terms of standardized trap nights in June (i.e., the number of traps multiplied the number of days opened), a combined rate of 0.11 amphibians per trap was detected across the two years in the 1980s, compared to a rate of 0.24 amphibians per trap this year. What could the ecological scenario be that has led to such an apparent increase in the amphibian capture rate over this 40-year period? Could trophic cascades be involved? Perhaps the protection of habitats in 1956 helped forest regeneration, and this change led to improved stream health and greater water retention later into the season via increased canopy cover. By providing better habitat and more resources for the streamside invertebrates that makeup the main prey base of forest-dwelling amphibians, such a transformed system might benefit amphibian communities indirectly. It’s also possible that some entirely different mechanism produced this result.

The species that dominated captures historically and today was the Allegheny Dusky Salamander (Desmognathus ochrophaeus), which went from 0.048 individuals per trap in June from the 1980s to a slightly increased rate this June of 0.052 individuals per trap. Interestingly, the average body size of female Allegheny Dusky Salamanders has not changed over the 40-year study period, suggesting stability in morphology despite other studies reporting salamander species either shrinking (Caruso et al., 2014) or growing (McCarthy et al., 2017) in response to warmer temperatures brought about by recent climate change. Without the founding of the Powdermill Nature Reserve and the herculean efforts of historical and modern scientists from the Carnegie Museum of Natural History, we would not be able to understand the extent that humans have impacted biodiversity, let alone the data needed to solve mysteries of the modern world.

photo of black salamander with white spots

So, when I look at a Spring Salamander (Gyrinophilus porphyriticus) or a Slimy Salamander (Plethodon glutinosis) or a Four-toed Salamander (Hemidactylus scutatum) from the Powdermill Nature Reserve, I don’t see Linnaeus’s “terrible animal” with a “ghastly color”, rather, I see profound resiliency in the face of tremendous pressure, and the power that natural history collections and protected areas hold for improving our relationship with biodiversity.

Daniel F. Hughes is the Rea Post-doctoral Fellow in the Herpetology Section at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

References:

Caruso, N.M., Sears, M.W., Adams, D.C. and Lips, K.R., 2014. Widespread rapid reductions in body size of adult salamanders in response to climate change. Global Change Biology, 20: 1751–1759.

Meshaka, Jr., W.E., 2009. The terrestrial ecology of an Allegheny amphibian community: Implications for land management. The Maryland Naturalist, 50: 30–56.

McCarthy, T., Masson, P., Thieme, A., Leimgruber, P. and Gratwicke, B., 2017. The relationship between climate and adult body size in redback salamanders (Plethodon cinereus). Geo: Geography and Environment, 4: e00031.

Wahlgren, R., 2011. Carl Linnaeus and the Amphibia. Bibliotheca Herpetologica, 9: 5–37.

Relevance and the Spirit of Research at Powdermill

three people collecting specimens from a stream

When people think of scientists doing research, they tend to think of a laboratory with microscopes, technical machinery, exotic chemicals, and a person in a white coat doing “experiments” to invent a miraculous new compound, or maybe cure a disease. We have a technical laboratory with microscopes, machines, and chemicals at Powdermill, and we enjoy that kind of work. In reality, most of our research is done outside, with living plants and animals in the field. Usually we are in muddy boots, and we are more likely to be wearing rain gear and backpacks than white coats.

Our research comes in several flavors. Because we own the land, we can invest in long-term studies that require strong continuity. Examples of this would be our studies of birds that migrate in spring and autumn along the Appalachian ridges, traversing routes from the Caribbean and South America to Pennsylvania, Canada, and the Arctic. Since these studies were initiated in 1961, we have compiled the longest continuous data set of this type for any American research institute. Another example would be our forest succession research, initiated in 2012, and intended to last several decades. These long-term studies are not likely to be undertaken by the college professor who must show results promptly for promotion and tenure, so it is important that places like Powdermill commit to them.

two people doing field research in the woods

On the flip side, we support student researchers to use Powdermill for their projects that have to be completed in a short time, between one summer and three years, depending on whether the research is for a senior thesis or a PhD. Together, the students embrace many topics across the entire diversity of biological systems: What do trout eat? How effective are birds at dispersing seeds? The work of the long-term studies can be thought of as composing a careful symphony, where student projects represent the catchy tunes coming from a dance club: each centered on a good riff, immediate and focused; then another tune, and another. Both the symphony and the dance band are important to our scientific culture, and together they demonstrate the relevance of the nature reserve.

Field stations necessarily focus on topics that occur on their landscape. Most of our work has a strong relevance to Pennsylvania in particular, but also to Appalachia and eastern North America in general. Sometimes our work in Pennsylvania connects us to a much broader audience, as the migrating birds that spend the winter in South America do. We often host researchers from other countries who view Powdermill as an exotic locale. Every year we host a series of workshops to train the next generation of scientists, and every year we have far more applicants than spaces. In the last decade, an award-winning program that sponsors Latin American guests (so that the actual cost of the program is not a barrier to applicants) has trained about 120 scientists from 10 nations who came to Powdermill to learn our research techniques. When they return to their home countries to resume their scientific careers, some of our Powdermill culture goes with them.

The visitor traffic through Powdermill presents a learning opportunity for us. Getting to know our visitors sometimes introduces us to new methods or entirely new fields of research. We expand our research interests and capacity, too.

A pleasing and unique aspect of a research career at a field station is being in tune with the pulse of the natural world. You care about when it rained last, how cold it was the previous night, and why you have seen so many porcupines this year. The late freeze hurt the beeches and spice bush, but the maples and oaks are okay. Observing a small wildflower where you did not see it last year is like finding a gemstone. Training your eye to notice when certain plants bloom or when certain animals appear becomes rewarding, like playing a favorite game. We expect hummingbirds to arrive from Mexico on April 30. On May 1, they appear at our feeders. All of these observations make each day an experience with its own reward and mystery. And being connected to the natural world makes you feel very much alive.

John Wenzel is the Director at Powdermill Nature Reserve, Carnegie Museum of Natural History’s environmental research center. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

Bird Banding with a Crew of One

This year, spring migration was different. Cold weather early in the season (one night during peak migration saw a low of 23 degrees and was accompanied by snow) seemed to delay the arrival of many species. The paucity of insects resulting from the low temperatures seemed to drive many birds like Baltimore Orioles to find food at feeders, which delighted socially distancing observers. Then, when warm winds from the south brought the bulk of migrants north, there were a few days of really great birding until those birds either settled into local breeding territories or continued to trickle north.

One gauge of “really great birding” is seeing more than 20 species of warblers in one day, and this eye-pleasing event happened at Powdermill more than once this spring!

Just as spring migration was a bit different for the birds, it was quite different for those who study birds. Across the continent, field seasons were cancelled and research projects redesigned or postponed due to the Covid-19 pandemic. For the first time in nearly 60 years, Powdermill’s bird banding program was unable to be run as normal. A banding operation of this magnitude requires many staff and volunteers working as a team to safely and efficiently extract, band, and process birds each day. Because bird banders’ priorities place bird safety and well-being along with human health ahead of dataset continuity, the difficult decision was made to cancel the banding season.

Despite the pandemic, there were many bright spots this spring. Although a lot of research was put on hold, projects that could be run solo or by people in the same germ pool were given approval to proceed. As part of my dissertation work, I conducted a research project that is a collaboration between Powdermill and the University of Toledo to investigate the distance migratory songbirds fly between stopover locations. This project uses a novel method, sampling subcutaneous fat deposits to infer the geographic location of previous stopover areas using the data generated by stable-hydrogen isotope analysis. This first phase of the larger project was a success: I sampled 39 individuals of two species! I had mixed emotions about operating the mist nets at Powdermill alone. It was certainly lonely, but it was also peaceful and rewarding. Because the focus was on banding only a few study species, I released all other birds that I caught at the net. This meant that there were a few extra moments to marvel at the beauty of spring birds in their fresh and brightly colored breeding plumage, and to reflect on the incredible migratory journeys these relatively tiny birds make each year. There were even a few surprises in the nets, including a Prairie Warbler that stayed in the Powdermill banding area for a few weeks, and Powdermill’ s fifth ever capture of a Least Bittern, a secretive marsh bird that many yearn to see! Despite the pandemic and shutdown, spring banding with a crew of one was successful and productive.

Annie Lindsay is the Bird Banding Program Manager at Carnegie Museum of Natural History’s Powdermill Nature Reserve. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

Behind the Scenes with the Baron de Bayet and L. W. Stilwell Collection, Part 4: Buying and Selling Fossils in the 19th Century

Figure 1: Letter from Stilwell to Bayet, June 29, 1897 (Carnegie Museum of Natural History, Section of Invertebrate Paleontology)

In this, our fourth and final installment, we will look at the Stilwell-Bayet letters. Because letter writing was the central form of communication in the late 19^th century, this correspondence documents past collecting practices. Although the Carnegie Museum’s Bayet archive retains only Stilwell’s part of the correspondence, the letters provide insight into their business relationship.

Procuring Fossils Was Time Consuming and Expensive

In June of 1897 (Figure 1), Lucien W. Stilwell wrote, “In reply, I am glad you are pleased with the Fossils. As to their getting there a little late, I did all on my part and cannot be made to suffer in any way for lateness. Had you ordered earlier and hand [sic] not correspondence been necessary previous to my shipment, I would have sent them earlier.” Shipping was labor intensive and costly in the late 1800’s. Additionally, the risk of breakage was high. The trip from South Dakota to Brussels required multiple carriers and involved wagons, trains and ships. From start to finish the trip could take months. One Stilwell receipt dated January 12, 1889, shows the cost of shipping two boxes from New York to Brussels at $5.05, or about $141 today. Keep in mind, this figure does not include the cost of shipping from the Dakota Territories to New York.

Negotiating Was as Wild as the West

Deal making was a delicate dance. Stilwell wanted to maximize profit. Bayet wanted the best price. In March 1889 Stilwell states “I do not know what new animal you spoke of. I sent the new ammonite. As to shipping and getting them away across the ocean, before we agree on price, that is a rather indefinite way and might be an expensive thing. I can say now, that if people do not want to give what I ask for these heads [Cenozoic mammal heads], I do not care to collect them for when I base my prices on the cost of finding and cleaning them and the cash expense and place them as reasonable as anyone can afford to do the work then I would cease to collect them.”

Let the Buyer Beware

Sometimes, lines were crossed. In addition to invertebrates, Stilwell sold Bayet Cenozoic mammal fossils from the Badlands. Stilwell references a mammal skull in the quote above. In 2004, Spencer Lucas of the New Mexico Museum of Natural History and Science, wrote a paper titled “O.C. Marsh and the Eocene Brontothere Teleodus: A Paleontological Hoax. In it he describes negotiations between paleontologist O.C. Marsh and Lucien W. Stilwell. Lucas concludes that Stilwell, or someone in his employ, added extra teeth to a brontotherium skull in order to induce Marsh into paying a higher price. At that time, Marsh did not notice that the teeth were doctored. According to Lucas, Marsh was determined to have the skull at the lowest possible price. He convinced Stilwell that the skull was not a new species and Stilwell eventually sold him the skull for a reduced figure. The altered teeth were not discovered until 1982 by Lucas and Schoch. Lucas concluded in 2004 that, “The Teleodus avus hoax is yet another example of the authenticity problems inherent to the commercial purchase of fossils as well as the great capacity all paleontologists have for seeing what they want to see in a fossil, not what actually is there.”

Albert Kollar notes that to his knowledge there is no indication that any of Bayet’s invertebrate specimens were fabricated or distorted.

The Stilwell-Bayet Correspondence is a fascinating look at collecting and negotiating in the “Wild West” a century ago. Preparation of fossils for shipping was time consuming and risky. Rarity and preservation quality often dictated price and it was a “buyer beware” marketplace. The items in the Carnegie Museum of Natural History collections give a glimpse into the mores, history and values of a past business climate. Stories, such as this one, also provide an opportunity to think about the future. One wonders what collecting adventures, conducted by museum scientists today, will resonate with future generations and what conclusions they may draw.

Joann Wilson is an Interpreter for the Department of Education and a volunteer with the Section of Invertebrate Paleontology and Albert Kollar is Collections Manager for the Section of Invertebrate Paleontology. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

Fourth of July and the Firefly

drawing of firefly that says World Firefly Day July 4-5, 2020

Although many fireworks shows are cancelled this Fourth of July, this is a great opportunity to get out over the holiday weekend and enjoy nature’s very own light show during World Firefly Day, on July 4^th and 5^th!

Fireflies, AKA lightning bugs, are neither flies nor bugs. They are actually a type of beetle with soft wings and the ability to bioluminesce (light up).

There’s a good chance you will see (or have already started seeing) firefly light displays this summer. There are six genera of fireflies that you are likely to encounter in Pennsylvania. Three are diurnal and don’t light up as adults (Ellychnia, Pyropyga, and Lucidota). Their light organs are absent or reduced in the adult stage. The remaining three genera are nocturnal and use light displays as adults. One is Pyractomena, which is a spring-active firefly that has already finished displaying for the year. That leaves Photinus and Photuris as the hosts of nature’s fireworks this Fourth of July. If you pay close attention to the flash patterns you’re seeing in your yard or get a chance to see one up close, you’ll probably be able to tell which one it is!

Photinus fireflies (top) are flattened in appearance and their heads are usually concealed from above, whereas Photuris fireflies (bottom) are hump-backed and you can often see their heads from above.

firefly on a leaf during the day — Creative Commons © David Cappaert, Bugwood.org

firefly on gray fabric — Photo credit: Andrea Kautz

Flash patterns vary by species, as do the timing and location of the display. Some species display low to the ground, while others display high in trees. Some are active at dusk, and others after dark. The most common firefly in the eastern U.S. is Photinus pyralis which has a lazy J-shaped flash pattern. Other flash patterns you may have seen are single or multiple rapid blinks. The displays you see are male fireflies advertising to females, who respond inconspicuously with their own flash pattern from a lower perched position. Some “femme fatales” in the genus Photuris will actually hunt by flashing in response to males of other species to lure them in, and then eat them!

Speaking of hunting, firefly larvae (below) are predators that live in moist soils, feeding on slugs and snails, which is a great method of pest control! Adults of some species are predators, but others drink nectar from flowers or simply do not eat at all.

The light-producing behavior has its origins in the larvae, which use the glow as a warning to predators that they are toxic. Other animals use bright colors to achieve this, but this wouldn’t be effective for nocturnal species in darkness. Adult fireflies light up to warn predators, but also to communicate with members of their own species, specifically potential mates. The distress signal is different from the mating signal, which you may notice if you capture a firefly in your hand and it starts to blink repeatedly.

We hope you get a chance to celebrate both the Fourth of July and World Firefly Day this year by witnessing some natural firework displays in your own back yard! We encourage you to share your experiences on the Fireflyers International Network Facebook page.

Andrea Kautz is a Research Entomologist at Carnegie Museum of Natural History’s Powdermill Nature Reserve. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

Mesozoic Monthly: Protostega

June 20^th was the first day of summer! The weather here in Pittsburgh is already beautiful. It’s enough to make one dream of a socially distant beach! Summer, of course, is sea turtle nesting season: during the next several weeks, female sea turtles all across our planet’s Northern Hemisphere will return to the beach where they hatched, drag themselves onto land, and lay their eggs in the sand. It would have been an incredible sight to see Protostega gigas, one of the largest sea turtles of all time, hauling itself onto the beach to lay its eggs! For June’s Mesozoic Monthly, we’re going to “dive in” to the paleontology of this giant reptile.

Carnegie Museum of Natural History’s spectacular skeleton of Protostega gigas is a composite made from the fossilized bones of two different individuals. Come see it on display in our Dinosaurs in Their Time exhibition when the museum reopens at the end of this month. But don’t forget to purchase your timed ticket in advance!

All turtles, including sea turtles like Protostega and tortoises like the Galápagos giant tortoise, belong to the group Testudines. This group originated during the Triassic Period, the first of the three time periods of the Mesozoic Era (aka the Age of Dinosaurs). Turtles split from other reptiles to form their own group before crocodiles and dinosaurs evolved! This means that turtles are not descended from dinosaurs, no matter how primordial some tortoises may look. Turtles differ from other reptiles in many ways, the most noticeable being their iconic shells.

A turtle shell is formed of two main parts: the carapace, or top shell, and the plastron, or bottom shell. The shell is made of bone fused directly to the spine and ribcage, so a turtle cannot crawl out of its shell without leaving its skeleton behind! Another major difference between turtles and other modern reptiles involves skull anatomy. Turtles have anapsid skulls: the bony case that protects their brain lacks any external openings behind their eyes (known as temporal openings). All other extant reptiles plus birds are diapsids, meaning their skulls have two holes behind their eyes. Mammals differ from both conditions because we have only one temporal opening, making us synapsids. Traditionally, the anapsid condition of turtle skulls has been taken to indicate that they are the most primitive of living reptiles. More recently, however, many paleontologists and biologists have uncovered evidence that turtles are in fact diapsids whose evolutionary course led, for some reason, to a secondary closure of their temporal openings. According to these scientists, the closest relatives of turtles among today’s diapsids are either lepidosaurs (lizards, snakes, and kin) or archosaurs (crocodilians and birds).

A bird’s (or pterosaur’s!) eye view of Protostega gigas (left) swimming past two long-necked elasmosaurid plesiosaurs in shallow waters of North America’s Western Interior Seaway roughly 85 million years ago. (This scene is set in what’s now Kansas!) Art by Julio Lacerda; see more of his beautiful work here.

Reptiles, mammals, and birds all belong to a group called Amniota, and the key defining feature of amniotes is a protective layer around their eggs that allows this vulnerable life stage to survive on land. Having eggs that did not have to be laid in water meant that animals could move to less-wet habitats, a significant step in evolution! Unfortunately for sea turtles, which spend most of their lives at sea, this means they must return to land to lay their eggs. An amniotic egg would “drown” in water because the embryo still needs access to air. As a sea turtle, Protostega would have faced these same reproductive challenges, plus one more: it was huge!The largest modern turtle, the leatherback sea turtle, can grow over seven feet (2.1 meters) long; Protostega dwarfs it at 9.8 feet (3 meters)! If you’ve ever seen video of a sea turtle crawling onto the beach to nest, you know that it’s an awkward process. Imagine seeing a turtle that weighs at least a ton try to do the same! Although surely clumsy on land, Protostega was a graceful swimmer, using its four rigid flippers like wings to “fly” through the water.

Protostega lived in the Western Interior Seaway, an inland sea that stretched across much of North America during the Cretaceous Period (the third and final period of the Mesozoic Era). The seaway was warm, shallow, and teeming with all kinds of aquatic life: the perfect habitat for an omnivorous sea turtle. Because sea turtles are ectothermic (sometimes erroneously called “cold-blooded”), they cannot regulate their own body temperature. Instead, Protostega relied on warm water temperatures and sunlight hitting its back to keep warm. Although we don’t have a fossil record of the coloration of Protostega, we know that today’s large sea turtles are counter-shaded, with heat-absorbing, dark-colored backs and pale undersides. In an ocean environment where both predator and prey shift positions in the water column, this combination aids concealment. From below, a light-colored underside blends with light-saturated water. From above, a dark back blends with dark water. Camouflage in the water was an important feature when living alongside so many sizable predators. Protostega fossils have been found with bite marks from the large shark Cretoxyrhina mantelli, and it almost certainly was also on the menu for the mighty mosasaurs as well. Fortunately for us, we humans can enjoy the ocean knowing that few creatures are interested in eating us!

Lindsay Kastroll is a volunteer and paleontology student working in the Section of Vertebrate Paleontology at Carnegie Museum of Natural History. Museum staff, volunteers, and interns are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

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