Differences in Feeder Visitation by Invasive Rose-Ringed Parakeets (Psittacula krameri) Between Hawaiian Islands

Authors

Steven C. Hess, USDA APHIS Wildlife Services, National Wildlife Research Center, Hawai‘i Field StationFollow
Jane Anderson, Texas A&M University – Kingsville
Eric A. Tillman, USDA APHIS Wildlife Services, National Wildlife Research Center, Florida Field Station
William P. Bukoski, USDA APHIS Wildlife Services, 3901 Mokulele Loop Unit 20, Lihue, HI
Aaron B. Shiels, USDA APHIS Wildlife Services, National Wildlife Research Center, Ft Collins, CO
Page Klug, USDA APHIS Wildlife Services, National Wildlife Research CenterFollow
Shane R. Siers, USDA, APHIS, WS, National Wildlife Research CenterFollow
Bryan M. Kluever, NWRC, GainesvilleFollow

Date of this Version

2023

Citation

Pacific Science (2023), vol. 77, no. 1:111–123 doi:10.2984/77.1.7

Comments

U.S. government work

Abstract

Rose-ringed parakeets (Psittacula krameri; parakeets) are among the most invasive bird species worldwide. In their introduced range, populations of this species have caused negative effects on native species, natural environments, economies, and human safety. Lethal population management has been complicated by the intelligence of the birds, as they quickly alter behavior to avoid risks. Further, lethal control programs have been halted due to public opposition, as parakeets are considered to be charismatic by animal welfare advocates. The contraceptive DiazaCon has been demonstrated to effectively reduce fertility in captive parakeets. In field applications, any chemical control agents (e.g., toxicants or contraceptives) must be delivered in a manner that prohibits access by non-target species. Parakeets are known to feed from bird feeders throughout their native and introduced range, suggesting contraceptivetreated bait may be a useful management strategy. However, our 24-week trials with free-ranging parakeets using platform, hopper, and tube feeders on the island of Kaua‘i did not result in any parakeet visitation and thus precluded further testing of using feeders to selectively deliver fertility control products. Nonetheless, multiple citizen science reports and other documentation indicate parakeets using feeders on the island of O‘ahu over a period of >10 years, and recently on the island of Maui. Our findings suggest the chemical control of nonnative parakeet populations is a promising technique, but implementation success will likely vary by target population acceptance, location, local faunal diversity, and availability of alternative forage.