Nachusa Grasslands Blog

Bumble Bees: A Familiar Face

8/2/2020

By Chandler Dolan
Bumble Bee Technician

Yellow coneflower (Ratibida pinnata) and wild bergamot (Monarda fistulosa) provide great nectaring habitat for bumble bees in mid-summer.

Introduction

The scene: It’s a classically humid, July afternoon. A gaze across the prairie shows patches of yellows and pinks, suggesting the presence of yellow coneflower and wild bergamot. As the heat intensifies, the birds and bison seem to slow. You stand quietly, intently listening to the sounds the grassland offers. Suddenly, a loud buzz tears through the patterns of bird melodies and katydid song. A familiar yellow and black face emerges from under a canopy of partridge pea: a bumble bee.

Bumble bees are familiar insects. The shaggy combination of yellow and black (and sometimes orange) hairs with a plump, round build makes these insects nearly unmistakable. Their role of pollinating beautiful wildflowers and food plants alike is an important ecosystem service they provide us, free of charge. Their friendly buzz and frantic foraging suggest a healthy ecological system. Unfortunately, bumble bees face an uncertain future. Through habitat loss, pesticide use, and disease, many bumble species have experienced significant decline and are becoming increasingly rare.

One of the largest bumble bee species at Nachusa, the black-and-gold bumble bee (Bombus auricomus) can be characterized by its dark wings and low-pitched buzz.

Thankfully, Nachusa gives refuge to three threatened species of bumble bees, including the critically endangered rusty-patched bumble bee (Bombus affinis). In 2017, Bethanne Bruninga-Socolar discovered the presence of the rare bumble bee at Nachusa in the form of a foraging worker. This was a great discovery, as the current distribution of the species is fairly unknown. To know this species was living at Nachusa was special and has given rise to new research opportunities and questions to be answered.

With the new motivation of a federally endangered species in the Grasslands, new projects have begun! The 2020 season is the first season we have boots on the ground (in the form of me!) to monitor bumble bee abundance and diversity across all species of bumble bee at Nachusa. We start with simple questions: What species of bumble bees are here? How many of them are there? What flowers are they using? By answering these questions, we can start to form new questions and learn about the Grasslands. This season is all about exploration, experimentation, and just getting a sense of the bumble bees at Nachusa.

The endangered rusty-patched bumble bee (Bombus affinis) found at Nachusa Grasslands.

Endangered Bumble Bees of Nachusa Grasslands

As mentioned, the rusty-patched bumble bee is a federally recognized endangered species in the United States. In fact, it is the first bumble bee species to be listed on the United States Endangered Species Act. This characteristic bumble bee sports a unique “rusty patch” on its abdomen, which is one of its best identification traits, hence the name. The decline of this species is somewhat mysterious and very sudden. Prior to 1996, this species was abundant throughout much of the Midwest and Northeastern U.S. After 1996, the species tumbled into rapid decline and is now extremely rare in the Northeast. Most records of this species today are sporadically reported in the Midwest, but at very low rates.

To identify the endangered rusty-patched bumble bee (Bombus affinis), look for the distinct rusty-patch of the abdomen surrounded by yellow hairs.

In the seven weeks I have been surveying, I have detected two rusty-patched bumble bee workers at Nachusa. To know this species is still present and not extinct is a great discovery alone. But understanding the way it uses the mosaic and where it chooses to nest is still up for question, and is difficult to answer with such sparse sightings. Our first sighting occurred very early in the field season. In fact, it was the fourth day of surveying! Seeing a single rusty-patched worker busily foraging on beardtongue (Penstemon digitalis) was a great way to start the season. Our second was about a month later on July 17th. Upon my arrival to a hill to do some quick exploration, the very first bee I spotted was the rare but distinct bumble bee methodically feeding on wild bergamot (Monarda fistulosa). I held back tears of joy as I quickly netted the bee for proper identification.

The golden yellow bumble bee (Bombus fervidus) on Culver's root (Veronicastrum virginicum).

Nachusa also houses two other declining bumble bee species: the golden yellow bumble bee (Bombus fervidus) and the American bumble bee (Bombus pensylvanicus). Bombus fervidus has quickly become one of my favorite species, as its striking yellow abdomen and bold, black thorax band are impossible to miss. While these species are not recognized as endangered by the federal government, they have documented declines that warrant them a “vulnerable to extinction” assessment by the IUCN Redlist. I’m happy to report that these species are detected regularly and seem to like certain parts of the Grasslands. One day we hope to answer these questions: What parts of Nachusa are these vulnerable species found, and why? What makes one patch of habitat more suitable than another?

American bumble bee (Bombus pensylvanicus) on wild bergamot (Monarda fistulosa).

Conclusion

Bumble bees are interesting. Their familiarity provides a calming energy, as their small wings effortlessly lift their seemingly oversized bodies and loads of pollen to provide for the nest and its offspring. But despite how recognizable they may be, there is still much to learn about them. Simple things such as their habitat and favorite flowers are yet to be fully understood. A closer look into the world of bumble bees reveals a world of individual decision-making by our hairy friends that we are working hard to better understand. One of the first steps to conserving a species is to better our understanding of them. With the first long-term bumble bee surveying season at Nachusa underway, we hope to better understand our bumble bees and to one day provide them the best habitat we can. To lose a species is to lose a piece of a puzzle. Once gone, the picture will never be the same, with a hole no other piece can fill.

*** UPDATE: On July 29th and 30th, two more rusty-patched bumble bees were observed at Nachusa! That makes a total of 4 observations this season! ***

Dr. Bethanne Bruninga-Socolar's ongoing research on Nachusa's bumble bees is supported with a Scientific Research Grant from the Friends of Nachusa Grasslands.

If you would like to play a part in helping the bees at Nachusa Grasslands, consider joining our Thursday or Saturday Workdays or giving a donation to the Friends of Nachusa Grasslands. Donations to Friends can be designated to Scientific Research Grants.

Chandler Dolan graduated from the University of Northern Iowa in December of 2019. Throughout Chandler's career as a young biologist, they have been continually drawn to endangered species ranging from the rusty-patched bumble bee to neotropical parrots and migratory songbirds. As Chandler dives deeper into the world of bumble bees, they hope to pursue bumble bee conservation as a long-term goal for graduate school.

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Without Violets, There Would Be No Fritillary Butterfly!

2/8/2020

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By Jess Fliginger

At first glance, it’s easy to mistake a fritillary butterfly for the well-known monarch; both can be seen fluttering across the prairie during the summer months, are similarly-sized, and are orange with black markings.

In 2017 I spent the summer surveying for butterflies, particularly regal fritillaries and monarchs, in remnant prairies across the Loess Hills of Iowa. From my experience, the only way to get close enough to identify, or be fortunate to snap a photo of a butterfly is to move slowly and cautiously towards it as it’s fixed atop a flower, busily sipping nectar. Be prepared to pursue a fidgety butterfly for several yards as it swiftly drifts from one flower to the next. It took a great deal of practice and patience before I was able to become a stealthy butterfly ninja. Upon closer observation, the difference between a monarch and a fritillary butterfly becomes more apparent.

Great spangled fritillary (Speyeria cybele)

There are 14 species of greater fritillaries (genus Speyeria) and 16 species of lesser fritillaries (genus Boloria). Both have a widespread range and can be found across the northern half of the United States into Canada, in some southern states, and parts of Mexico. Greater fritillaries inhabit woodland openings, meadows, prairies, and other open habitats where violets are present, while lesser fritillaries primarily live in wet meadows and bogs. Although greater fritillaries are much larger than lesser fritillaries, it can still be difficult to tell them apart while in flight.

Meadow fritillary (Boloria bellona)

In total, there are 6 species of fritillaries that call Nachusa Grasslands home: great spangled fritillary (Speyeria cybele), regal fritillary (Speyeria idalia), aphrodite fritillary (Speyeria aphrodite), silver-bordered fritillary (Boloria selene), meadow fritillary (Boloria bellona), and variegated fritillary (Euptoieta claudia). The most common, and easiest to approach, is the great spangled fritillary. Of these, the regal fritillary is the only state-threatened species.

Regal fritillary (Speyeria idalia)

Regal fritillary, a state-threatened species

A prairie-specialist species, regal fritillaries have drastically diminished throughout the Midwest, with only two localized populations remaining east of Illinois and several small isolated populations east of the Great Plains states and western Missouri.

Birdsfoot violet (Viola pedata lineariloba), an uncommon native flower and fritillary butterfly food.

Typically, fritillaries have one brood and one flight period from June to August. Females lay their eggs near violets (Viola spp.), the caterpillar’s main food plant, in shady areas on the underside of dead vegetation. Soon after, the larvae hatch, crawl into nearby leaf litter, and sleep through the winter without feeding. During late winter to spring, the caterpillars begin munching on newly-sprouted violets and mature rapidly. Once fully grown, they pupate for several weeks until an adult fritillary butterfly emerges. Clearly, without violets there would be no fritillaries! Luckily for fritillaries, Nachusa has 7 species of violets throughout the preserve, as well as plenty of nectar sources to choose from.

Equally as important to their survival, adult fritillaries require a large variety of nectar sources from native and non-native plants. I usually see them on coneflowers, goldenrods, ironweed, blazing-stars, milkweeds, mints, clovers, thistles – just to name a few. Plant any of these, along with violets, in your butterfly garden, and maybe a beautiful fritillary will pay you a visit.

Jess Fliginger worked for Nachusa as a restoration technician during the summer of 2016. She has continued to be involved at the preserve, helping researchers conduct fieldwork and gather data. Working alongside Dr. Rich King in 2018 and 2019, she has collected data on Nachusa’s Blanding’s turtles . In addition, she has been volunteering with small mammal research since 2015, and worked for Dr. Holly Jones as a small mammal field technician in 2019. Lately, she has worked and volunteered in land restoration to enhance her skill set. She plans on assisting with prescribed burns at Nachusa this upcoming spring.

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