Differential long-term impacts of a management control program of axis deer and wild boar in a protected area of north-eastern Argentina.

GÜRTLER R.E; RODRÍGUEZ-PLANES L.I.; GIL G.; IZQUIERDO VM; CAVICCHIA M; MARANTE A

BIOLOGICAL INVASIONS

SPRINGER

Lugar: Berlin; Año: 2018 vol. 20 p. 1431 - 1447

1387-3547

Exotic ungulates are among the top global invasive mammals and a threat to biodiversity. Axis deer (Axis axis) and wild boar (Sus scrofa) are of increasingconcerninmultipleregions. Amanagement program reduced wild boar abundance and soil damage below target levels through controlled still shooting from watchtowers and dog-hunting performed by recreational hunters at El Palmar National Park, Argentina. Here we assess program impacts on axis deer over a 10-year period in which 2380 deer were dispatched, and document two largely unexpected outcomes: increasing axis deer abundance toward a plateau, and a strong inverse correlation betweendeer andwild boarnumbers. Unlikethe initial steep decline and subsequent stabilization of wild boar, deer abundance indexed by standardized catchper-unit-effort increased at 37.6% per year over 0?5 years post-intervention (YPI) and stabilized from 7 YPI on when still-shooting effort averaged 948 hunting party-hours per quarter. Deer catch was nonlinearly related to still-shooting effort. Timing of deer and boar catches did not differ significantly regardless of sex, season and YPI. Catch-per-unit-effort indices and nightly spotlight deer counts showed similarly increasing trends. The fraction of older adult deer declined over 0?4 YPI and remained stable thereafter. Sex ratios were consistently skewed toward males only among older adults. Failure to reduce deer abundance may be explained by several major processes: protracted exponential growth of the deer population after park invasion; deer regional expansion with increasing immigration; insufficientsex- and stage-biased hunting mortality, and competitor (and perhaps predator) release from wild boar.