American Bullfrog - Invasive Predator

American bullfrog, adult - Photo by Russ Ottens; University of Georgia

Native to the eastern United States, the American bullfrog (Rana catesbeianus; formerly known as Rana catesbeiana) is a highly invasive species in the western U.S., Asia, Europe, and South America. A female bullfrog can lay up to 20,000 eggs at one time, compared to native frogs, which only lay 2,000 to 5,000 eggs. Bullfrogs will eat anything they can fit in their mouths, including their own young. They also aid in the spread of Ranavirus that is infecting native frogs internationally, as well as the chytrid fungus (Batrachochytrium dendrobatidis) which threatens native amphibians worldwide.

To see the current distribution of the American bullfrog in the United States, check out the USGS Nonindigenous Aquatic Species Database Point Map for the American Bullfrog.

Identification

• Egg masses: Black on top and white underneath. They start as a round, basketball-size mass that flattens over time.

• Tadpoles: Dark green with black dots, have orange or bronze eyes and opaque yellow underbellies. Up to 6 inches long.

• Juveniles: Green to brown with small black spots, orange or bronze eyes, and a fold of skin from the eye around the eardrum.

• Adults: 7-8 inches, with large, exposed eardrums the size of their eyes. Green, tan, or dark brown with dark spots and gold eyes.

In order to distinguish the American bullfrog from native frogs, be sure to look up the physical characteristics of our native species (Pacific treefrog, red-legged frog, Columbia spotted frog, Oregon spotted frog, Cascade frog, and others). A good place to start is on the Oregon Department of Fish & Wildlife’s Frogs and Toads webpage.

What should you do if you think you’ve seen an American Bullfrog?

Positively identify and eradicate bullfrogs when found in the wild. One of the most important aspects of control is to kill adult females as early in the spring as possible (when they first emerge from hibernation) to prevent the large number of eggs that they disperse. It is advised to destroy eggs when they are discovered which are easily identifiable by their large size.

In Oregon, Washington, and California, bullfrogs are classified as a controlled species and people are allowed to trap and kill bullfrogs found in these states without obtaining a permit.

Oregon: Report sightings online or call our hotline: 1-866-468-2337

Washington: Report sightings online

Additional Resources:

• Invasive Species Video - Bullfrogs (Statesman Journal) 

• Don’t Let it Loose OISC campaign page

• Fishing for Bullfrogs OISC News Channel post featuring a video from the Oregon Department of Fish & Wildlife

• Invasive Species Factsheet - Bullfrog from Oregon Department of Fish & Wildlife

• Aquatic Invasions! A Menace to the West - American Bullfrog Species at a Glance from Oregon Sea Grant

• Stop the Invasion - Bullfrog Factsheet from Washington Invasive Species Council

• American Bullfrogs as Invasive Species: A Review of the Introduction, Subsequent Problems, Management Options, and Future Directions (Snow & Witmer 2010)

The information above was compiled from the USDA National Invasive Species Information Center webpage on bullfrogs, the Washington Invasive Species Council bullfrog webpage, and the Aquatic Invasions! A Menace to the West - American Bullfrog Species at a Glance from Oregon Sea Grant.

Upcoming 2020 OISC Meetings & Milestones

Below is a list of upcoming OISC meetings and milestones. You can find these and other important dates on the OISC Events page. Detailed information on OISC Business Meetings is posted on the OISC Meetings page as it becomes available.

• September 9 (1-4 pm): OISC Virtual Business Meeting - draft agenda available here.

• September 14: Deadline for 2021 OISC member nominations! https://www.oregoninvasivespeciescouncil.org/nominations

• OISC Strategic Plan Working Group Session focused on key topics. The intent of these working sessions is to review strategies & document actions that have occurred 2017-2020. Proposed dates are below:

  • Sept 16 (10a-12p): Forests & Watersheds

  • Sept 18 (10a-12p): Aquatics & Animals

  • October 14 (10a -12p): Agriculture 

• Week of September 21 (scheduling in progress): Ex-Officio voting members review nominations and appoint 2021 members

• September 23 (1-3pm): OISC Communications & Education Committees Joint Meeting 

• September 23-25: Oregon Legislative Days

• Week of September 28: Expected announcement of 2021 membership & 2021 officer (Chair & Vice-Chair) nomination period begins

• December 9 (1-4 pm): OISC Virtual Business Meeting - agenda and conference details coming soon. 

If you would like to participate in any of the Committee or Working Group meetings mentioned above, please email the Coordinator (coordinator@oregoninvasivespeciescouncil.org).

Western Forester Invasive Species-Themed Issue

The Western Forester invasive species-themed issue (April-June 2020) is now available! Click here to view/download.

Issue highlights include:

• Looking to the Past and Future When Managing Invasives

• Alaska’s Chokecherry Trees: From Ornamental to Invasive

• The Cooperative Agriculture Pest Survey: Collaborative Nationwide Monitoring

• A Proactive Approach to Manage False Brome

• Thwarting Invasives in the Pacific Northwest: Success Stories from the Field

• Herbicides are Part of the Forest Manager’s Toolkit

• The Latest News on Invasives in the Pacific Northwest

• Invasives on the Horizon

The Western Forester is a publication prepared approximately quarterly for members of the Society of American Foresters and non-industrial private forest landowners in the Pacific NW (AK, WA, ID, western MT, OR, northern CA).

USDA Declares August Tree Check Month

August is Tree Check Month! Everyone is encouraged to take 10 minutes to check their trees for signs of invasive pests, such as the Asian longhorned beetle. August is the best time to spot the Asian longhorned beetle as adults emerge from trees. The Asian longhorned beetle feeds on a wide variety of popular hardwood trees, including maple, birch, elm, willow, ash, and poplar. For more information about the Asian longhorned beetle, please visit www.AsianLonghornedBeetle.com.

If you are interested in learning more about how you can get involved in protecting our forests from invasive species, please visit the Oregon Forest Pest Detector program website. Oregon Forest Pest Detectors are volunteers that help prevent the damaging impacts of invasive forest pests by monitoring for and reporting potential infestations. The Oregon Forest Pest Detector program currently focuses on detection of the emerald ash borer (EAB), Asian longhorn beetle (ALB), and goldspotted oak borer (GSOB).

Always remember to report any potential sightings of invasive species and Don’t Move Firewood!

Asian Giant Hornet Update from WSDA

On July 24th, the Washington State Department of Agriculture (WSDA) released an Asian giant hornet stakeholder update. Below are a few important takeaways from the update:

• Volunteers have put up over 1300 traps, which is in addition to the hundreds of traps managed by WSDA!

• The Washington Invasive Species Council contributed $3,000 toward the cost of billboards in Whatcom County, WA to help raise awareness and encourage reporting of Asian giant hornets.

• WSDA is partnering with the Washington State University Master Gardeners to provide a training (August 11 at 10 a.m.) for Master Gardeners who might be answering questions or receiving suspected Asian giant hornet specimens from clients. Master gardeners who are interested in participating in this webinar should contact their program coordinator for  information on how to attend the training.

All Asian giant hornet stakeholder updates from WSDA can be found here. If you would like to receive updates from WSDA’s Pest Program on Asian giant hornet (and other topics), click here. The OISC’s original Asian giant hornet News Channel post can be viewed here.