Scavengers protect livestock from infectious disease

Brucellosis is an infectious bacterial disease that causes female bison, elk, and cattle to abort their calves. In the Yellowstone region, both wild animals and livestock can contract this highly contagious disease by coming into contact with the fetal remains, which can stay infectious for weeks or even months.

A new study led by the Northern Rocky Mountain Science Center has found that scavengers such as coyotes, foxes, eagles, or vultures are unwittingly helping both wildlife and cattle by rapidly consuming abortion materials and thus keeping brucellosis epidemics at bay.

“Terrestrial and avian scavengers provide an important yet understudied ecosystem function by removing carcasses from the landscape,” wrote the study authors. “In the Greater Yellowstone Ecosystem scavengers are likely to reduce the transmission and subsequent spread of brucellosis within and between livestock and elk by consuming infectious abortion materials, thereby removing the infectious agent from the landscape.”

The researchers used remote cameras to monitor the time to removal of simulated abortion materials by scavengers at 264 sites in the Yellowstone region from February to June in 2017 and 2018. The scientists have found that there was a 90 percent probability that abortion materials will be removed within 16 days across all sites by scavengers such as coyotes, red foxes, golden and bald eagles, and turkey vultures.

The findings also suggested that the time to removal of fetal materials decreased in grassland habitats in contrast to sagebrush or forest habitats, and that there was an 88 percent probability that time to removal of abortion materials was slower at sites where scavengers were actively reduced compared to sites with no scavenger reduction.

This study shows the importance of scavengers in the mitigation of infectious diseases and points towards the need for increased conservation efforts to protect them from extinction. “Actions to maintain the breadth and diversity of scavengers on the landscape are potential management options that could reduce disease transmission risk to livestock in a system where the wildlife reservoir is difficult to address,” the authors concluded.

The study is published in the journal Ecosphere.

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