Dogs Sniff Out Good News for Seabirds at Johnston Atoll National Wildlife Refuge
By Ivan Vicente, Public Affairs Officer, U.S. Fish and Wildlife Service
For the past three years Johnston Atoll National Wildlife Refuge (NWR) has been a happy place for the tens of thousands of seabirds that live there. December 2017 was the last sighting of seabird enemy number one — the yellow crazy ant. First detected in 2010, the yellow crazy ants quickly took over about half of Johnston Atoll NWR, nearly extirpating the red-tailed tropic bird colony in just a few years.
The U.S. Fish and Wildlife Service (Service) has had great success in its yellow crazy ants eradication efforts at Johnston Atoll, deploying twenty Crazy Ant Strike Teams to remove the ants. These teams have been extremely effective — no ants have been detected on the atoll since 2017. However, to help the Service assess how many ants remain, the Service recently brought to Johnston Atoll NWR a different kind of intelligence — detection dogs — to help sniff out if the ants have been exterminated.
Johnston Atoll is one of the most isolated and oldest atoll formations in the world, providing a haven for feeding, nesting, and resting to tens of thousands of seabirds who for nearly a decade have been threatened by the notorious yellow crazy ant. More invasive ants have been accidentally transported to the Pacific Islands than any other biogeographic region in the entire planet. From 12 total introduced ant species to Johnston Atoll NWR, only the yellow crazy ants have presented major threats to the seabird nesting colonies.
Since the invasion was first detected back in 2009, the yellow crazy ants have had a negative impact on the survival of the 15 species of seabird nesting at Johnston Atoll NWR, with red-tailed tropic birds affected the most. Other seabirds that rely on the refuge for nesting include three species of boobies, sooty terns, greyback terns, white-tailed tropic birds, great frigatebirds, fairy terns, Hawaiian short-eared owl, and several species of shorebirds.
Yellow crazy ants spray formic acid that can irritate the skin around the eyes, bill, and feet causing severe injuries ranging from swelling to deformities. These injuries can lead to death. Additionally, invasion by yellow crazy ants eliminates suitable nesting habitat in invaded areas. Since seabirds exhibit high nest site fidelity, meaning they return to the same nest site each year, it is likely that they will not pick others areas in which to nest. This eliminates their ability to reproduce for an unknown number of years.
Between 2010 and 2021, over 80 Service staff and volunteers from 20 separate yellow crazy ant strike teams spent six months living on Johnston Atoll NWR while working to eradicate the yellow crazy ants. To eradicate the ants, crews used different hand baiting methods of applying insecticide to a mapped treatment areas. Worker ants then collect and bring the bait back to the queens and the young to kill the nest. The eradication efforts have entailed many on-the-ground experiments to improve management efforts, including improving the effectiveness of baiting procedures, building ant farms to study yellow crazy ant life cycles and ecology, and developing optimal control protocols.
To declare an invasive ant population as eradicated is no easy task — partly because they are so hard to find due to the fact that their colonies are found underground. For the first time on any Pacific Remote Islands, the Service brought two conservation detection dogs to Johnston Atoll in December 2020. The two dogs, Guinness and Solo, were trained to detect the scent of yellow crazy ants. Combining human visual surveys and canine olfactory surveys yields a higher detection rate than relying on one of them alone. Using detection dogs to detect yellow crazy ants for wildlife conservation had never before taken place in the United States.
After training for most of the year, Guinness and Solo performed yellow crazy ant searches on three separate demonstrations in O’ahu in October and November. They were successful in detecting yellow crazy ants during all three demos. These practice sessions helped prepare them to join the strike team on Johnston Atoll. (Click here to learn more about the ants on O’ahu.)
“The combination of hand searching and use of conservation detection dogs for this project will help determine if the yellow crazy ants are truly eradicated from the Refuge, or if more work needs to be done to exterminate any remaining ants,” said Aisha Rickli-Rahman, Trip Leader and Biological Science Technician with the Pacific Islands Refuges and Monument Office.
After having put their olfactory skills to work at Johnston Atoll NWR for 14 days, Guinness and Solo found no yellow crazy ants within approximately 140 acres. They tracked a combined total of 110 miles! Guinness and Solo returned to O’ahu on December 22, leaving the rest of the search to the humans for the next six months.
The fact that the there were no detections by Guinness and Solo could mean that Johnston Atoll is yellow crazy ant free, thanks to the collective eradication efforts that have taken place since 2010 by the Service’s 19 previous strike teams. While Guinness, Solo, and their handlers headed back to Honolulu after two weeks, the five members of the strike team will remain on the island for six months, searching for any remaining yellow crazy ants and conducting habitat restoration.
“Invasive species have detrimental impacts on our iconic Pacific Islands wildlife and places,” said Kate Toniolo, Superintendent, Pacific Remote Islands Marine National Monument. “Hopefully, when the Crazy Ant Strike Team returns to Honolulu, the U.S. Fish and Wildlife Service will be one step closer to declaring Johnston Atoll National Wildlife Refuge free of invasive yellow crazy ants.”
The U.S. Fish and Wildlife Service works with others to conserve, protect, and enhance fish, wildlife, plants, and their habitats for the continuing benefit of the American people. For more information, connect with us through any of these social media channels at https://www.facebook.com/PacificIslandsFWS, www.flickr.com/photos/usfwspacific/, or www.twitter.com/USFWSPacific.