Fur is biodegradable
Real fur is an organic material. « Faux fur » (fake fur) and most synthetics are made from petrochemicals. Like other plastics, these materials do not break down easily and will remain in landfills for centuries. The “dressing”process (tanning) helps to preserve the pelts for some time, but after many years of use they will eventually dry out and begin to deteriorate (i.e., biodegrade), returning to nature. Old fur apparel can even be composted for your garden!
See also, in Biodegradable and Sustainable Fibers, Edited by R.S. Blackburn: “While vegetable (plant-based) and animal fibers are fully biodegradable, mineral fibers are not.” (“Biodegradable Natural Fiber Composites,” by A.N. Netravalli, Cornell University, pg. 274.) And: “Of even more concern is the ability of (synthetic) polymeric fibres to remain unchanged in the environment as polymers do not degrade very readily, which has exacerbated the already existing ecological and environmental problems of waste building; the volume in waste disposal and landfill is very high. (R.S. Blackburn, Page xv.) And: “…natural fibers like wool and cotton are broken down through biotic process. Microorganisms have evolved enzymes that attack key bonds in these natural polymers, thereby releasing monomers that can be used as carbon and energy sources for microbial growth. In contrast, microorganisms lack enzymes to break down many synthetic fibers, thus these materials persist and accumulate in the environment. “Microbial Processes in the Degradation of Fibers”, P.M. Fedorak, University of Alberta, pg.1.