One of the “super powers” of African Swine Fever virus (ASF) is it’s ability to survive for prolonged periods after the death of the host. When an infected wild boar dies, the virus remains infectious in the carcass and soil for an extended period of time (months). Safe removal and disposal of carcasses from the environment is a very important disease control measure and is critical to ASF eradication from wild boar populations. Vertebrate scavengers provide a benefit to the ecosystem by accelerating carrion decomposition and returning nutrients to the ecosystem. Some scavengers do not consume carcasses on the site where they find the carcass but rather scatter the carcass remains in the immediate surroundings. The movement of entire or partial carcasses can present a risk of increased exposure to additional wild pigs. These German and Norwegian researchers wanted to study the scattering of wild boar carcasses by vertebrate scavengers. They placed 20 carcasses (up to 25 kg) and 21 separate limbs equipped with very high frequency (VHF) transmitters and monitored scavenger activity using camera traps in a mountainous region in southeast Germany.
The researchers found the following:
- All but one of the carcasses or separate limbs experienced some scatter.
- There were 72 scatter distances that could be recorded from 89 scattering events. The mean scatter distance was 232 meters and the maximum recorded distance was 1250 meters.
- Scavengers moved scattered pieces into denser vegetation compared to the half-open vegetation where the carcasses were initially placed by the researchers.
- Red foxes (Vulpes vulpes) were the most common scavenger species and contributed to 72 scattering events and 58 measured scatter distances.
- The first scattering event by a crow occurred within 1 hour and the first scattering event for a fox was within 4 hours although the average was closer to 5 days.
Take Home Messages:
- The researchers commented that these results indicate that scatter distances are greater than those suggested in previous studies.
- Early detection and removal of infected carcasses and carcass parts can help to reduce the potential for exposure of infected carcasses or soil to susceptible wild boar.
- Consider as well that scavengers may bring infectious domestic diseases closer to your pig site if the scavengers have access to infected carcasses that are not disposed of properly on other sites.
Reference: Janine Rietz , Sophia Ischebeck , Franz J Conraths , Carolina Probst , Andreas Zedrosser , Christian Fiderer , Frank Reckel , Christian von Hoermann , Jörg Müller , Marco Heurich Scavenger-induced scattering of wild boar carcasses over large distances and its implications for disease management J Environ Manage . 2024 Jun 20:365:121554. doi: 10.1016/j.jenvman.2024.121554. Online ahead of print.
