Johnston Island of Johnston Atoll is the station of the Crazy Ant Strike Team’s effort to eradicate the Yellow Crazy Ants that were initially found on Johnston in 2010. Photo credit: Susan White/USFWS

By Danielle Lampe, AmeriCorps Intern, Pacific Remote Islands NWR

Situated in the central Pacific Ocean between the Hawaiian and Line Islands, Johnston Atoll National Wildlife Refuge is one of the most isolated atolls in the world. Likewise, the Johnston Atoll field camp, staffed by Crazy Ant Strike Team crews, is one of the most remote in the National Wildlife Refuge System. The strike team’s mission is to control and eradicate the invasive yellow crazy ants, which are harmful to the seabirds that nest on Johnston Island. The ants spray formic acid which causes severe damage to the birds’ eyes ranging from swelling to blindness. Strike team crews have been going to Johnston Atoll Refuge since 2010 and even reduced ant populations by 90 percent.

Ground nesting birds such as Red-tailed Tropicbirds are particularly susceptible to the effects of the ants, which release formic acid causing damage to the birds’ eyes. Photo Credit: Stefan Kropidlowski/USFWS

To eradicate the ants, the crews use squirt guns to distribute insecticide, mixed with cat food, corn syrup, and water, to the 150 acre infestation area. Worker ants then collect and bring the bait back to the queens and the young to kill the nest. The sixth strike team crew was stationed on the refuge from June 2013 to December 2013. Known as CAST Six, the crew was led by Sam Edmonds and included volunteers Dan Orlando, Greg Francois, Molly Reingold, and Ashton Mieritz. Leading a project with distinct goals and distant oversight was a challenge embraced by Edmonds and his crew. The crew’s key accomplishments include improving the effectiveness of baiting procedures and developing a standard operating procedure for building ant farms to study yellow crazy ant life cycles. The information gathered will help future strike teams to design increasingly effective ways to eradicate the ants from the refuge.

One of the bait stations from 2010 shows how dense the colonies used to be. The efforts of the CAST crews have reduced the populations by 95% and are currently working on eradicating the final 5% of the population. Photo Credit: Stefan Kropidlowski/USFWS

Mieritz and Francois took the lead for the ant farm project. Keeping the ant farms alive in a field setting makes the project more of a challenge than operating in a controlled laboratory setting. Reingold’s knowledge of working in remote field locations in Alaska was beneficial to the crew and the ant farm project. The crew helped with more than just yellow crazy ant-related tasks, Orlando for instance, enjoyed completing surveys for other wildlife as well. On one occasion, he observed a group of spotted eagle rays in a turtle survey area.

After successfully building on the work completed by the first five CAST crews, CAST Six was ready to welcome their replacements, CAST Seven. CAST Six led a five day instructional period during which they taught the proper experimental techniques, to the seventh crew who were ready to take over. Led by Jenny Howard, the crew includes volunteers Kristen Brunk, Jane Sheffer, Allison Griffin, and Ben Donnelly.

At the end of a five day training period, CAST Seven is ready to begin their six month adventure. Jane Sheffer continues to watch the M/V Kahana leave wish CAST Six as Ben Donnelly, Allison Griffin, Kristen Brunk, and Jenny Howard walk back to the Gator to drive back to camp. Photo Credit: Mark Brown/USFWS.

CAST Seven is challenged with monitoring and eradicating the rest of the yellow crazy ant population while also developing a further understanding of the ant’s ecology and how it changes, maintaining and improving the ant farms, continuing to utilize Insect Growth Regulators to prevent the colonies from reproducing in addition to the use of insecticide as part of a new baiting schedule, and monitoring the biology of the entire island.

With Griffin and Brunk at the helm the ant farms continue to be successful, even achieving a 50 percent reproduction rate. The next step will be to conduct bioassays, a scientific experiment, on the workers and queens to see how different concentrations of insecticides affect the colonies. They are looking for the ideal concentration that will allow the ants to take the bait back to the nest to spread the insecticide to the rest of the colony.

To monitor other biological processes on the island, Donnelly initiated a Red-footed booby color morph survey and Sheffer has been a terrific aid in researching unknown plants for a vegetation project.

The hard work and dedication from the volunteers and crew leaders of the CAST program has made the goal of complete eradication of yellow crazy ants to help maintain a healthy ecosystem on Johnston Atoll Refuge an attainable one. Volunteers are an important part of the U.S. Fish and Wildlife Service. The Service is extremely grateful for all of their hard work at Johnston Atoll Refuge and to all of the volunteers who help ensure a future for fish and wildlife.

Learn more about the yellow crazy ant invasion at the refuge.