https://phys.org/news/2018-10-hidden-disease-greater-yellowstone-elk.html

Utah State University researchers Gavin Cotterill and Johan du Toit report that by mid-winter, elk that test positive for brucellosis are less likely to be pregnant than healthy elk, independent from the abortions caused by that disease later in the year. Cotterill and du Toit, along with colleagues from the Wyoming Game and Fish Department, US Geological Survey Northern Rocky Mountain Science Center, and University of California Berkeley, discuss their findings in Ecology and Evolution published 28 October 2018.

"Mid-winter elk pregnancy rates are often seen as an indicator of an elk herd's health and viability," says Cotterill, a Ph.D. candidate at USU and lead author of the paper. "If we're interested in figuring out the effect that predators or climate are having on elk we need to also account for disease."