KDWP study finds low eye-worm infection rates in Kansas bobwhite and pheasant samples

Jeff Prendergast, a staff member who presented KDWP's quail eye-worm sampling results to the Kansas Wildlife and Parks Commission, said the agency found lower infection rates than reported from parts of Texas and described management implications.

"Out of our 283 bobwhites, we only had 12 positives for eye worm infections, which was about a 4.2 infection rate," Prendergast told the commission, adding that pheasant samples showed a 12.5 percent infection rate. He said most infected birds carried a single worm; only one bobwhite had an exceptionally high count of 28 worms.

Prendergast described the eye worm as a parasitic nematode that lives in the bird's orbital cavity, requires an arthropod intermediate host, and is not known to infect mammals or people. Kansas sampling, collected in 2018 from roughly half the state's counties, included 283 bobwhite and 218 pheasant heads that were frozen, dissected and analyzed in KDWP's lab following methods from Texas researchers.

The KDWP presenter noted that the Texas Rolling Plains work that drew attention to eye worms found very high infection rates there, and that Texas researchers recently received FDA approval for a medicated feed (fenbendazole) intended to reduce infection when placed in feeders. But Prendergast and commission members emphasized that existing Kansas data do not show eye worms are driving population declines.

"There hasn't been really any strong scientific evidence to show that the eye worm has had any negative impact on individual fitness or that treating for the parasite has resulted in any population-level increase," Prendergast said, adding that bobwhite population dynamics are driven primarily by production of young rather than adult survival.

Prendergast and commissioners recommended Habitat First management as the priority response. He described several concerns about broad use of medicated feed on public or private lands: feeders concentrate birds and can elevate predation, medicated feed in open environments risks exposure of non-target animals, and logistics and scale make meaningful statewide treatment difficult (recommended use is one feeder per 200 acres for 21-day treatments twice per year).

Commissioners and KDWP staff said KDWP will continue surveillance and noted the department will post Prendergast's slides and include the results in the meeting materials. The commission did not take formal action on the item; KDWP said current public recommendations remain focused on habitat conservation rather than medical treatment programs.

The presentation and subsequent discussion also noted knowledge gaps: long-term trends are uncertain because Kansas samples provide a single baseline year for comparison, and small sample sizes for some species (scaled quail, prairie-chicken) prevent reliable infection-rate estimates for those species.

Prendergast told commissioners the agency will keep monitoring the issue but urged landowners and managers to prioritize habitat creation and maintenance over feeding as a long-term approach.

Ending: KDWP staff recommended continued monitoring and public information; no regulatory change or agency treatment program was proposed based on this sampling.