The National Park Service is not responsible for damage caused by marmots, so it now recommends using tarps to prevent them from entering cars undercarriages.

marmots are attracted by the smell of engine components and fluids and marmots regularly crawl into undercarriages for exploratory nibbles and that causes damage to radiator hoses and car wiring.

Physically block marmots by driving over a tarp and then wrapping it around your entire vehicle. Cover the wheel wells.

https://unofficialnetworks.com/2024/07/19/national-park-marmot-tarp-wrap-protocol/