The flowers are blooming early on Pennsylvania Mountain this year, so we are already constantly surrounded by explosions of color! Our team has had multiple conversations about how as far as jobs go, it doesn’t get much better than hiking and spending time with bees and flowers in a beautiful place every day. I am thrilled to be back and eager to start another fascinating, fun, and productive research season!
One of the several studies that I will be helping with this summer will involve acoustically monitoring bumblebees as they pollinate plants. By listening to their buzzes while they visit flowers, we can learn how often different types of plants are being pollinated, and we can also get an idea of how many bees are present at different times of the season. These findings can help us see how the relationship between plants and pollinators may be changing as changes in climate are shifting the timing of important life history events for these species. To perform this study, we are placing small microphones next to plants at different designated places in the mountain. By doing this on a weekly basis, we can compare plant/pollinator interactions at different times of the season (and hopefully in the future, different years). Yesterday was a warm and sunny day on the mountain (perfect foraging weather for bumblebees and perfect researching weather for scientists). We set up our microphones for several hours before collecting them again. We are excited to listen to what we recorded– hopefully there are lots of bees pollinating all of these flowers!
Weather. Views. Work.
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.
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!
A New Project
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!
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!
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!
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!
An Intriguing Season
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!