Migratory livestock grazing significantly impacts rangeland vegetation and wild-ungulate population in the Indian Trans-Himalaya

Intenselivestock grazing outcompetes wild-ungulates in low-productivity rangelands.This is a long-standing and highly debated conservation problem globally. We examinedimpacts of migratory livestock grazing on Trans-Himalayan rangeland and Asiaticibex, a wild-ungulate and primary prey of the endangered snow leopard. Vegetationand ibex were sampled in an intensely grazed (livestock density 63 sheep-goat/km²)and ungrazed areas, during spring (before-grazing), summer (during-grazing) andautumn (after-grazing). Proportionate to vegetated area, independent randomlylaid 1mX1m plots were sampled for vegetation cover and biomass estimation (Cover:N_Ungrazed=237; N_Grazed=127; Biomass: N_Ungrazed=119;N_Grazed=64). Ibex density and young:adult-female ratios were estimatedby repeatedly sampling 17 trails using double-observer method across bothtreatments for the three time periods and two consecutive years. Graminoid and herb biomass were significantly higherin ungrazed than grazed area (ANOVA; Graminoid: F_Treatment=16.05; P=<0.001;Herb: F_Treatment=22.75; P=< 0.001). Overall vegetationcomposition was dissimilar across ungrazed and grazed area (Morisita Index 0.18),however, palatable species composition was similar (Morisita Index 0.70). Biomassof palatable species was 2.25 times higher in ungrazed than grazed area. Totaloff-take of dry forage by migratory livestock from grazed pastures (61 km²)was 10,658 kgs km^-2 over two months of grazing. Ibex density was 1.80-7.0times higher in ungrazed than grazed area in 2015, while 2.45-4.7 times higherin ungrazed than grazed area during 2016. Ibex yearling:adult-female ratio was sixtimes higher in ungrazed than grazed area. Significantreduction in forageavailability lowered ibex density and yearling:adult-female ratios in grazedarea, suggesting migratory livestock outcompetes ibex through exploitativecompetition.