Battling the Invaders: Our NISAW 2025 Adventure
National Invasive Species Awareness Week (NISAW) 2025 was our chance to dive headfirst into the wild world of ecological troublemakers, species that don’t belong but have made themselves way too comfortable. Jack and I spent the week learning about, searching for, and (when possible) wrangling some of these notorious invaders in our own backyard. From amphibians to plants to sneaky slugs, we encountered an impressive lineup of unwanted guests.
The Heavyweight Champion of Amphibian Invasions: The American Bullfrog
My first stops was a local wetland, where i was on the lookout for the American bullfrog (Lithobates catesbeianus). Native to the eastern U.S., these massive amphibians have hopped their way across the country, outcompeting native frogs and devouring anything they can fit in their mouths, including birds, fish, and even other frogs. It wasn’t long before I spotted one, a hefty, green beast sitting at the edge of the water. It locked eyes with me, looking entirely unbothered, probably assuming I was too slow to catch it (which was true). I spent some time listening to their deep, unmistakable croaks before moving on, reminded once again of how much these invasive frogs dominate wetlands where they don’t belong.
A Tangle of Trouble: Himalayan Blackberry & Japanese Honeysuckle
Invasive plants might not have the same “wow” factor as a giant frog, but they’re just as destructive. If you’ve ever tried to walk through a patch of Himalayan blackberry (Rubus armeniacus), you know it’s a painful experience, this spiky menace takes over everything. Originally brought to North America for its delicious berries, it quickly escaped cultivation and now chokes out native plants, reducing biodiversity and altering soil composition. I spent a good chunk of time pulling it out, at my place of work this week (with plenty of scratches to show for it).
Right alongside it, reigning as a noxious weed king, we found Japanese honeysuckle (Lonicera japonica), a vine that smothers native shrubs and trees by wrapping around them like some kind of botanical boa constrictor. It might smell sweet, but it’s an ecological nightmare.
Stealthy Spreaders: Herb Robert & Winter Creeper
One of the sneakier invaders encountered was Herb Robert (Geranium robertianum), also known as "stinky Bob" because of its strong, unpleasant smell. This small but aggressive plant spreads rapidly in forests, pushing out native wildflowers. It looks innocent enough with its delicate pink flowers, but don’t be fooled, it’s a fast-spreading problem.
Then there was Winter creeper (Euonymus fortunei), a vine that carpets forest floors and tree trunks, blocking sunlight from reaching native seedlings. This plant doesn’t just spread, it takes over. We spotted entire patches where nothing else could grow because winter creeper had formed a dense mat, starving out everything beneath it. As satisfying as it was to rip up, the battle against this vine is never-ending.
Slug Invasion: Licorice Slugs & Leopard Slugs
No invasive species list would be complete without some slimy invaders. Washington is home to plenty of amazing native slugs (shoutout to the banana slug!), but some unwelcome European imports have slimed their way into local ecosystems.
First up: the licorice (Black) slug (Arion Ater). This little yellow-brown slug has a knack for outcompeting native decomposers, disrupting the balance of the forest floor. While they’re nowhere near as famous as their larger invasive cousins, they’re still trouble.
And speaking of large invasive cousins, enter the leopard slug (Limax maximus). These massive, spotted slugs are expert generalists, capable of eating almost anything, including native slugs. They’ve been spreading across North America for decades, and we found more than a few of them sliming their way through the undergrowth.
The Feline Factor: Domestic Cats as Invasive Predators
One of the biggest, and most controversial, invasive species isn’t a plant, amphibian, or mollusk. It’s the domestic cat (Felis catus). As much as we love our feline friends, outdoor cats are one of the biggest threats to native wildlife. Studies estimate that free-ranging domestic cats kill billions of birds, mammals, and reptiles every year. While hiking, we spotted a couple of feral cats slinking through the underbrush, a stark reminder of how much they impact local ecosystems. While solutions like TNR (trap-neuter-return) programs exist, preventing cat-related wildlife loss remains a massive challenge.
What We Learned (and What We Can Do)
By the end of NISAW 2025, Jack and I were covered in dirt, scratches, and possibly a little bit of slug slime, but we had a deeper appreciation for the complexity of invasive species management. These species aren’t inherently “bad”, most of them were introduced by humans, either intentionally or accidentally. But their impacts on native ecosystems are undeniable, and it’s up to us to help mitigate the damage.
So what can we do?
Remove invasive plants in your own backyard and replace them with native species.
Report invasive species sightings to local conservation groups.
Keep domestic cats indoors or provide safe outdoor enclosures.
Support conservation efforts that focus on habitat restoration and invasive species control.
NISAW is a great reminder that conservation isn’t just about protecting cute and charismatic species, it’s about maintaining balance. Every little effort counts, even if it’s just pulling up a few weeds or spreading awareness about species that don’t belong. And who knows? Maybe next year, we’ll finally catch that bullfrog.