Field Notes from Pennsylvania Mountain Natural Area
from MALT Research Interns Emelyn Piotter and Maya Rayle.
from MALT Research Interns Emelyn Piotter and Maya Rayle.
“Hello! I’m Emelyn. I just graduated from the University of Missouri in Columbia Missouri (which also happens to be my home town) where I majored in Biological Science and minored in Captive Wild Animal Management. For the last two years I have worked in Dr. Candace Galen’s lab studying pollination ecology. Last summer I was able to join Dr. Galen’s graduate students and the MALT interns in Colorado and had the opportunity to conduct some research of my own on Pennsylvania Mountain. I studied how the hair structure of different insects affects their ability to collect pollen. After spending the last two semesters counting and measuring pollen grains and insect hairs I still have a couple of unanswered questions that I will be following up on this summer.”
2019 Field Notes
At each of the three bee box sites at different altitudes, we pollen-swab workers. The purpose is to find out which flowers they’re visiting throughout the season. To catch the bumblebee workers, we sit a meter or two from the bee box with a butterfly net placed underneath the entryhole. When a worker bee flies into the colony, we catch it in the net, then transfer it to a falcon tube, then place it in a cold lunch box. Once the bee has cooled off, it won’t be able to fly away so it’s much easier to handle. Then, we use a small cube of jelly (made out of gelatin) that’s just a few millimeters wide in order to swipe the bee’s body. We’ll then store the gelatin cube in a labelled microcentrifuge tube to make slides with back at the house.
We’ve also been collecting pollen from different families of flowers in the area so we can identify pollen from the bees -- a pollen library of sorts. We’ve been collecting pollen off of workers once every two weeks at each site. This will provide useful information about what flowers workers are foraging from, and how this changes throughout the season. Maya 08-11-19
Acoustics of Flower Visits
Every Friday, we set out microphones to do acoustic monitoring of bee activity on flowers. In the flower plots that have all of the flowers we monitor (there are eight or so flower species that we’re interested in), we visit each plot to set up microphones. Right now, we to to three flower plots.
For the past few Fridays, Zack and I have gotten up early then hiked up Penn Mountain. We first go to a flower plot above the second slope, then one near the false summit, then one near the true summit. In each flower plot, we check which flowers are blooming. Even though these flower plots have all of the flower species at some point in the season, not all of the species bloom at once. Last week, the plots had trifolium nanum, polemonium viscosum, and mertenzia.
Once we check which species are blooming, we pick out the patch of flowers from each species with the most flowers blooming to set up a microphone. This involves bending a wire into a twist to hold the microphone, leaving the microphone suspended above the plants. It’s best to place the microphone a little ways away from the flowers so it doesn’t physically interfere with bee activity. We also place a muffler on the end of the microphone to reduce wind sounds. You can see the setup in the photograph.
We then leave the microphones out for 6 hours or longer before Emelyn and Mackenzie go to pick them up. After that, we’ll send the audio to a collaborator who’s come up with an algorithm that subtracts the audio from a nearby control microphone where there are no flowers from the microphones at each flower species. This gets rid of background noise such as airplanes, wind, and any other odd sound that isn’t a localized buzz.
The purpose of this microphone experiment is to listen to bees foraging on flowers. Our microphones will pick up bee buzzes within a range of one meter, so we can tell when the bees are foraging on the chosen species of flower. We can learn about bee preferences, what sounds they make when they forage, and we can hear arrivals, departures, and visitation buzzes.
One of the most important pieces of information we get out of this is to measure if peak bee activity matches peak flowering. We get our flower data from flower phenology (counting flowers in plots each week), and bee activity comes partially from this. Since last year was so dry, there was a large mismatch between peak flowering and peak bee activity, such that the flowers peaked long before the bees did. This can be really hard on colonies because they rely on flowers for food. Studies suggest climate change can exacerbate mismatches because plants and bees use slightly different biological indicators for when to begin flowering or to come out from their dormancy period. Our work with microphones will help to measure mismatches in the short term, season to season. A mismatch caused by last year’s drought is not necessarily climate change related, but since climate change is predicted to cause more frequent droughts and warmer temperatures on average, a comparison between a drought year and a normal or even snowier-than-average year like this year is useful for studying the effects of climate change on bee flower mutualisms. - Maya
The Life of a Bumblebee
Since our work focuses so much on bumblebees, I thought it would be worthwhile to take the time to explain the bumblebee life cycle and a little about bumblebee behavior.
Bumblebee queens are born the previous summer, and spend the winter underground. They generally burrow six inches or so into the dirt, and live off of fat reserves. Alpine bumblebee queens face extreme winter conditions, and are often buried deep under the snow. Queens are much larger than workers, which helps them survive the cold. There’s a rule in ecology called Bergmann’s Rule, which states that across geographic regions and across different species, colder climates tend to have larger animals, and warmer climates tend to have smaller animals. This is because a larger body means a lower surface to volume ratio, which helps an animal to conserve heat. Bumblebees are generally large and queens are especially large which allows them to survive in colder environments.
In the spring, when the temperature warms sufficiently, the queens emerge to feed off of nectar. Then, they begin to hunt for a nest site. We’ve seen a lot of queen bees hunting -- they fly low to the ground, moving along methodically as they search for holes in the ground. We’ve been placing wooden boxes with an entrance and exit hole and a thick layer of cotton inside to provide a good artificial nest site similar to a natural site.
Once a queen finds a nest, she makes frequent trips all day, each trip lasting 30 minutes or so to collect pollen and nectar. She’ll bring this back to the nest to either save it or consume it. She builds a wax mound (she can secrete wax from her body), and then lays her first round of eggs. It takes about three weeks for them to mature into larvae and then into worker bees. During this time, the queen sits on the wax mound to keep the larvae warm by shivering her body. Bumblebees are excellent thermoregulators.
After the first workers are matured, the queen will hardly leave the nest. She’ll spend most of her time laying and incubating eggs. Worker bees either forage or guard or clean the nest. Worker bumblebees that forage split into three working groups: nectar gathering, pollen gathering, and a group that does both and fills in where needed.
Later on in the summer, the colony produces male bees, which go out to attempt to mate and do not return to the nest, and new queens. When the new queens mature, they leave the nest to find males to mate with, then they spend the rest of the summer feeding on nectar and pollen to store up for their winter underground. Queens only live one year, so the old queen and the rest of the colony dies, with only the new queen surviving. Sometime in the fall, the new queens will burrow, and the cycle starts again. - Maya
A snowy start: So far this field season has been quite different from last years. The summer of 2018 was an extremely dry year and this summer is much wetter than usual. At this time last year virtually all the snow on Pennsylvania Mountain had already melted, flowers were in peak bloom, and pollinators were out all over the mountain. Because of all this winter’s snow the plants and pollinators are getting a much slower start. Right now on Pennsylvania Mtn. bumblebee queens have just started emerging from their winter hideaways underground and only a couple of wildflowers have started to bloom. We even need snow shoes to access many areas. A lot of the research we do on Pennsylvania Mtn. involves studies that span multiple years so the extreme difference in the conditions between last year and this year allow us see how plants and pollinators are impacted by different temperature patterns.
Because dandelions, bumblebee workers, and bee flies aren’t out yet I can’t do much work on the research I have planned for the summer other than writing up methods for how we plan to conduct different studies and making sure we have all the materials we need. It will likely be two more weeks before the native dandelion species starts to bloom. The slow start isn’t unwelcome though as it’s giving us ample time to adjust to the altitude. Until the dandelions start blooming I will primarily be helping Zack, one of Dr. Galen’s graduate students, with his work on bumblebee acoustics. I have spent the last couple of days setting up bee boxes (which are essentially bird houses but for bumblebees), monitoring them for activity, and taking note of what flowers are blooming in the area. I also helped analyze some of last year’s bumblebee acoustic data and got to learn the basics of software program called “Audacity” that we use to look at audio files. - Emelyn. 06-26-19
A Snowy Start!
So far this field season has been quite different from last years. The summer of 2018 was an extremely dry year and this summer is much wetter than usual. At this time last year virtually all the snow on Pennsylvania Mountain had already melted, flowers were in peak bloom, and pollinators were out all over the mountain. Because of all this winter’s snow the plants and pollinators are getting a much slower start. Right now on Pennsylvania Mtn. bumblebee queens have just started emerging from their winter hideaways underground and only a couple of wildflowers have started to bloom. We even need snow shoes to access many areas. A lot of the research we do on Pennsylvania Mtn. involves studies that span multiple years so the extreme difference in the conditions between last year and this year allow us see how plants and pollinators are impacted by different temperature patterns.
Because dandelions, bumblebee workers, and bee flies aren’t out yet I can’t do much work on the research I have planned for the summer other than writing up methods for how we plan to conduct different studies and making sure we have all the materials we need. It will likely be two more weeks before the native dandelion species starts to bloom. The slow start isn’t unwelcome though as it’s giving us ample time to adjust to the altitude. Until the dandelions start blooming I will primarily be helping Zack, one of Dr. Galen’s graduate students, with his work on bumblebee acoustics. I have spent the last couple of days setting up bee boxes (which are essentially bird houses but for bumblebees), monitoring them for activity, and taking note of what flowers are blooming in the area. I also helped analyze some of last year’s bumblebee acoustic data and got to learn the basics of software program called “Audacity” that we use to look at audio files. - Emelyn 06-24-19
2018 Field Notes
The summer of 2018 has been an intriguing season for alpine ecology on Pennsylvania Mountain. Between the early snowmelt, higher than average temperatures, and the wildfire directly south of us, I’m surprised any of the plants we were working with survived to set seed! I am used to arriving to the field site in early June and having to trek through feet of snow just to be able to hike up the mountain a bit. This year however, early June looked like early July! This was true not only for the snow levels, but also the flowers, because as soon as the snow melted some flowers had already started to bloom. One possible drawback here is that there could be a disconnect between the flowering time and the timing of pollinators. This could make it more difficult for flowers to reproduce if their animal partner is not present when they put on their colorful display, and it could also make it more difficult for pollinators to survive late in the season when the flowers are no longer blooming as much. Part of my colleague Ellie’s research this summer will hopefully shed light on whether that happened.
Overall for the purposes of my experiment with dandelions, the weather seems to have been in our favor. During the drought conditions in late June, I was very worried that the dandelions would fail to set their seeds. However, in early July a mild monsoon season rolled through the area, dampening the wildfire and giving the wildflowers much a needed boost. While we don’t know the overall effects of this early and drought-ridden year, it is important to monitor things like flower abundance and bee activity (both projects of our field crew) so that we have a better idea of how the changing climate will affect ecosystems in the future.
That said, many plants and insects are still active at this time of year. For example, I recently found this cool insect on the top of Horseshoe Mountain. At first it appears to be a bumble bee, standard for the habitat. However, upon closer inspection this is definitely a fly! The colors may fool you, but look at the eyes and wings and you will see that they are fly-like instead of bee-like. One of the big clues here is that this creature has two wings -a fly trait- while all bees have four wings. The fly likely evolved to look like a bee for defense, as mimicking a bee with a stinger is likely to dissuade predators from bothering the fly.
Another type of organism still persisting in the late summer alpine is the dandelion. However, the one pictured here is not just a common dandelion, rather this is a type of dwarf alpine dandelion! In addition to the size and habitat differences (the dwarf grows in high alpine habitats, while the common dandelion grows along low alpine trails and down in towns), there are physical differences evident even in this close-up photo. Specifically, notice the black-grey seeds of this dwarf dandelion. In Colorado, this is a trait specific to just a couple species of high alpine dwarf dandelions. If you look at dandelion seeds from your yard or near a lower elevation trail, you are likely to see brown-straw colored or red seeds, but not these striking black ones. This is just one trait of many that can be used to distinguish between different types of dandelions, and if you are really interested in learning more about identifying dandelions, check out the Flora of Colorado book!
Austin Lynn 08-13-18
A PUFF OF CO2?
The field season is beginning to wrap up here on Pennsylvania Mountain! We are continuing to run through our experiments and collect as much data as possible in these final weeks. Time flies when you're doing field work!
This week, we are starting one final experiment. We want to see if the bumblebees in our nest boxes will respond to puffs of carbon dioxide entering their nests. We hope to collect some preliminary data to give us a better idea of how we might conduct a longer study next year. As you may know, animals (and plants) release carbon dioxide when they exhale during respiration. Studies have shown that some insects can detect varying levels of CO2 in the air. Bumblebees would experience increased concentrations of CO2 inside their nest if a curious potential predator was to breathe into the nest opening as they were looking for food inside. If the bumblebees are able to detect this, they might also make some kind of audible response to warn the predator to stay away, or to alert the other members of the colony. How do we test this? Although we could act like a predator and breathe into the nests ourselves, we decided not to risk an angry bumblebee encounter and try a different strategy. We are instead using small canisters of CO2, like those used to inflate bike tires, to emit controlled puffs of CO2 into the nest opening. We will pair the CO2 puffs with some different buzz playbacks like the ones we are using for other experiments to see, for example, if the combination of a defensive buzz and this CO2 sends a strong danger signal to the bees inside and elicits a response. As with all these experiments, we will have our small microphones set up inside the nest to hear any potential responses from the bees. We have started so many exciting projects this summer, and we're just beginning to scratch the surface of the many interesting findings that are sure to come!
Ellie Harrison 08-06-18
As a botanist, I don’t typically have to deal with concerns of mortality in the organisms that I study. However, I have continually branched out to study how plants interact with animals that pollinate them, and as such I must undergo one of the typical entomological rituals of lethally collecting insects for science. In order to reduce the amount of insects we must kill for our research, one thing we can do is chill the bumblebees so that they slow down to a manageable speed and then we can collect pollen from their bodies and the identify them by looking with a magnifying glass at the minute features of their bristles. This allows us to release the bee back into its original habitat following our sampling procedure. Just last week I had a wonderful experience with this, where I brought several bumblebee workers back to the field and watched them warm up while replenishing their energy by feasting on dandelions. Because it was a bit cold outside, we had to watch the bees closely and sometimes bring them fresh flowers so they could feed easily even in their weakened state.
Just a bit after this beautiful moment with the bees, an intense and wintry storm rolled up to Pennsylvania mountain to drop around three inches of snow and hail for us on July 5th. I find that field work is typically like this- triumphs and set-backs always seem to follow each other. Either way, now that the storm was upon us, we had to deal with it. This storm was bizarre for several reasons, first it brought snow in the middle of the summer, but also the location of the lightning strikes were concerning to me. All of my life I have heard that thunderstorms in the rockies are dangerous because being above treeline puts you as the tallest thing around and then the lightning will be more likely to go through you as the path of least resistance. So imagine my surprise during this storm as we are running to get below treeline and we see lightning strike in front of us in the forested area that we thought was safe! Needless to say, we eventually made it to cover underneath some willow bushes where we waited out the storm. Overall this intense storm taught me that droughts are typically followed by deluges, and that sometimes nowhere on the mountain is safe from nature’s wrath! Austin Lynn 07-13-18
BUMBLE BEE MOVING DAY!
We had a big event this week in the world of our bumble bees: moving day! At the beginning of the summer, in addition to setting up our nest boxes at Penn, we also set up a few on top of Weston Pass. One of them was successfully occupied by a queen and her colony (we named this queen Winnifred, along the same lines of our other queens: Agnes, Dorothy, Opal, and Ruth). As some of you may know, a wildfire started near Weston Pass at the end of June. Because of this, we were unable to access that nest box for a couple of weeks. Now, thanks to the hard work of many firefighters and a few lucky rain showers, the fire has been contained to a safe level for the time being. However, it was decided that it wouldn’t be a good idea to plan on weekly visits to Weston for our research because of the risk of the fire starting up again. So instead, we made a plan to go out this week and move Winnifred and her colony to Penn Mountain. To do this successfully, we had to go out at sunset when we knew all the bees would be back in the box and likely asleep. The weather was perfect and the views of the sunset from the top of the pass were stunning! When we arrived at the box, we temporarily closed up the entrances and carefully carried the box back to the car. For the bumpy drive down the pass, our field assistant, Claire, had the box wrapped in towels and firmly placed between her feet to give them as smooth of a ride as possible. After the box spent the night on our porch, we took them up to Penn early in the morning and set them up at their new home! There are more flowers blooming at Penn than at Weston, so we hope they’ll be even happier and healthier than they were before— and without the risk of a fire! Good luck and happy pollinating, Winnifred! Ellie Harrison 07-12-18
One of my favorite things about working in the field is training new field scientists and planning and executing a new project with them. This year I am mentoring Emelyn, an undergraduate from the University of Missouri, through her project dealing with dandelion pollination. When working out on Pennsylvania Mountain, we collect any insect we see feeding on the plants and then once we are back at the field station we take a sample of pollen from the insect. One of the initial things we noticed is that some visitors of the dandelions seem to be quite effective, picking up lots of pollen, while other visitors don’t appear to pick up hardly any pollen at all! This observation led to the question of why certain pollinators may be better mutualists than others- is it because of the way they forage or feed from the flower, or is it a function of the hairiness of the pollinator? An exciting example that we just noticed from simple observations of how different insects feed from the flower is that the bee-flies, while covered in hair, do not appear to collect much pollen because they stand on top of the flower to forage. On the other hand, solitary bees such as the megachilidae dig deep into the tubes of the dandelion flowers to get the nectar at the bottom, and in the process they become covered in pollen, meaning they are effective pollinators.
Once we have collected the insects from the field, we take them back to the field station so we can sample pollen from their bodies. This process is shown in the photo below where Emelyn is making slides in the kitchen. To do this we use tiny cubes of gelatin that we brush against the bodies of pollinators. Doing this allows us to look under the microscope at traits of pollen that are successful in adhering to the pollinator, and compare to unsuccessful pollen that remains on the flower. If certain traits are more prevalent in pollen on the pollinator, that could suggest that those traits are evolving for a greater ability of the pollen grain to succeed in transferring to another flower, fertilizing it, and creating seeds! Austin Lynn 07-01-18
We started a new project this week! Although we are primarily using our occupied nest boxes for the study I told you about last week, they also present us with a great opportunity to study other aspects of the bees. We are starting some playback experiments, which involve using a speaker aimed at the nest to play buzzes (which we have previously recorded), then to see if we hear any kind of response from the bees inside the nest. We will play different types of buzzes with different purposes: the buzzes that they make when they fly, when they pollinate, and when they feel threatened. Right now, we are just hoping to hear any kind of reaction to any kind of buzz. It has long been assumed that bees can’t hear sounds. However, if we are able to hear distinct responses from the bees after the playbacks, we might be able to find some evidence to the contrary! This will require a lot more data collection and different kinds of experiments, but we are very excited to be collecting some preliminary data and eager to see what we find! Ellie Harrison, 07-01-18
We have had another week of sunny
weather, beautiful views, and hard work. We are working on several different
projects at once, so we are busy but learning lots! One of our biggest projects
this summer involves acoustically monitoring bumble bee colonies. At the
beginning of the summer, we set up nest boxes (wooden boxes with a small hole
in them) at different sites on the mountain. Our hope was that they would
become homes for the bumble bee queens who had spent the winter underground and
were now looking for a place to start their colonies. Bumble bees usually use
abandoned rodent holes or other similar cavities in the ground for their nests,
but scientists have found that they will sometimes use these nest boxes,
which makes it easier for us to find and study them. Luckily, a few queens
moved in! Now, our goal is to use microphones and environmental sensors (to
record things like temperature and humidity) inside the boxes to track the
growth and development of the colony, which has never been done before. With
luck, we may even hear the bees talking to each other! This past week, the
queens and their eggs were the only bees occupying the boxes. We already heard
the queens making some interesting sounds that we haven’t heard before. I am
excited for their colonies to grow and to see what we will hear when we are
listening to a box full of bees! I will be sure to report back here with any
interesting findings. Ellie Harrison, 06-24-2018