Diet and impacts of non-native fallow deer (Dama dama) on pastoral properties during severe drought

Context There is concern about potential competition between non-native fallow deer (Dama dama) and livestock for food, particularly during times of low rainfall when pasture scarce.Aims We aimed to estimate the extent which a high-density population (~37deerperkm2) competed with food severe drought on pastoral properties Liverpool Plains, New South Wales, Australia.Methods collected rumen contents from 125 shot helicopters control operations in June August 2018, used microhistology quantify their diets. then diet data adjust published estimates stock unit equivalence farmed deer. Fallow sex age class abundances equivalences were multiplied grazing pressure pre- post-control relative recommended sheep cattle stocking rates. Finally, we estimated density–impact relationships deer.Key results was dominated by monocots (primarily grasses), but some individuals consumed large amounts dicots (commonly Eucalyptus). grazers intermediate mixed feeders. dry-sheep equivalents (DSEs, based 50-kg merino wether) varied 1.01 (juveniles) 1.85 (adult females adult males). Assuming complete overlap, pre-control equivalent approximately 60.3 DSEs per km2 reduced rate domestic 50.2%. Discounting amount browse resulted 45.7DSEsperkm2. The helicopter-based shooting 26%, increasing natural 22.0% (complete overlap) or 13.8% (discounting browse).Conclusions When limiting, at high density can exert strong competitive livestock, reducing carrying capacity. Browsing, including Eucalyptus, likely helped persist densities had destocked.Implications Helicopter-based effects our study area only small extent, more intensive would have led greater reduction. received positively landholders time stress, suggesting that agricultural areas other important benefits.