City Nature Challenge Meets Emergence of Brood X Cicadas

Defenders of Wildlife
May 1 · 5 min read

This weekend, two nature phenomena are colliding. The first is that April 30 marked the start of the City Nature Challenge (CNC), an international community science competition motivating people around the world to get outside and participate in science. The second is the emergence of Brood X cicadas, when billions of cicada nymphs arise from the soil and take to the trees across the East Coast and Midwest. The opportunity to track and observe Brood X only comes once every 17 years (13 for some other periodical broods) and the next brood to come to the DMV won’t emerge until 2025.

cicada on wood
© Lindsay Rosa/Defenders of Wildlife

The City Nature Challenge is a global bioblitz — an attempt to record all the species living in an area and measure how biodiverse our cities are. It is also a friendly competition “to see not only what can be accomplished when we all work toward a common goal, but also which city can gather the most observations of nature, find the most species and engage the most people in the event.” Since we are still in the wake of the COVID-19 pandemic, the 2021 City Nature Challenge will focus more on the healing power of nature and the people all around the world appreciating their local biodiversity.

This year, my family and have eagerly mapped out our route along our city’s local trails and parks. Our wooded trails pass over creeks and through fields leaving us hoping to find pickerel frogs, eastern tiger swallowtails, pileated woodpeckers and our neighborhood fox. I have been an active community science participant for some time now, but this will be the first year that my daughter — now three — can truly appreciate what all the buzz is about. And this year, there will be plenty of BUZZ!

Lindsay Rosa/Defenders of Wildlife
Lindsay Rosa/Defenders of Wildlife
Lindsay Rosa/Defenders of Wildlife
© Lindsay Rosa/Defenders of Wildlife

We’ve already begun to see some signs of the Brood X cicadas in our neighborhood. The last time this brood emerged, John Kerry was running for president, Michael Phelps won his first Olympic gold medal and Phish was touring for the final time. Females lay 200 to 400 eggs(!) in holes in branches. Once the eggs hatch, the nymphs fall to the ground and burrow into the soil, attaching to roots to nurse on tree sap. After 17 years, when the soil temperature reaches 64º F and is soaked after a rain, they emerge, climb a tree and shed their skin. As adults, they search for mates. The males fill the air with buzzing sounds and females click with their wings if they like the song. If you have cicadas in your area, you will know — it is quite the chorus! Their adult life lasts for about five weeks — male and females die soon after they lay their eggs.

© Lindsay Rosa/Defenders of Wildlife

Cicadas play an important role in the ecosystems they emerge. Scientists believe their mass emergence is strategic. The goal is to produce so many offspring so that even after predators (birds and small mammals) have gotten their fill, there are still plenty of cicadas to mate and lay eggs that will become the next generation. They will be an important nutrient source, positively impacting the survivorship and reproductive success of local bird populations for years to come. And once the cicadas mate and die, their carcasses fertilize the soil, allowing plants to grow bigger and stronger.

While it’s exciting to observe foxes and eagles in our area, it’s important to remember the small creatures are just as important. (A lesson that doesn’t need to be explained to a three year old!) Urban areas like cities can serve as hotspots for bees and other pollinators, particularly when more green space is available. Unfortunately, insect biodiversity is threatened worldwide: over 40% of insect species are threatened with extinction, in part due to the spread and intensification of agriculture and to the changing climate. These declines have already been linked to declines in insect-eating bird and animal-pollinated plants, reminding us of just how pivotal their role truly is to our environments, our food sources and our overall wellbeing.

© Foster Lea

You can make a difference by providing even the smallest spaces for pollinators and other insects to thrive. Grow native plants, mow your lawn less frequently (my husband’s favorite!), and avoid using pesticides. Join me in contributing to community science! Get involved in the City Nature Challenge:

Even though the 2020 CNC was subdued because of pandemic precautions, over 815,000 observations of over 32,000 species were made by more than 41,000 participants! That’s a lot of data! At Defenders’ Center for Conservation Innovation, we use these observations and similar datasets to help inform species conservation. Knowing where the species are helps us to understand which places need stronger protections.

© Lindsay Rosa/Defenders of Wildlife

I am fortunate that I get to work in science every day. But anyone can do science from anywhere! Call up your kids, mom, grandpa, best friend or friendly neighbor and tell them to head to the nearest window for some nature viewing.

And please remember to science safely! Anyone going outside should follow current CDC guidelines and practice social distancing — with both humans and wildlife.


Lindsay Rosa

Senior Conservation Scientist

Lindsay works with our interdisciplinary team of scientists to help develop new tools and ideas for strategically using spatial data to improve biodiversity conservation policies and practices.

Wild Without End

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