Assessing red deer hunting management in the Iberian Peninsula: the importance of longitudinal studies

Abstract

Understanding the dynamics of a wildlife population in relation to hunting strategies is essential to achieve sustainable management. We used monitoring data over 25 years from two red deer (Cervus elaphus) populations with different management (with and without supplemental feeding) in South Central Spain to: (i) characterise the density dependence of population dynamics under contrasted management, and (ii) provide the basis for sustainable extraction by considering the theoretical maximum sustainable yield (MSYt) as the reference. The red deer population displayed a typical management reactive culling approach ('saw-tooth-like' curves), with occasional strong annual harvests but not occurring on a regular basis. Interestingly, we found reduced population growth at high densities in both populations, indicating that density-mediated factors determined population growth even when artificial feeding was provided. However, no effects of sex not age class of the extracted population on the population growth rate were determined. The total number of animals hunted was only slightly above those predicted by MSYt (i.e. K _50%) in both populations, despite high densities close to theoretical K, being consistent throughout the study period. The extraction rates (30.3 and 34.0%, for supplemented and unsupplemented populations, respectively) were 13.3% and 10.2% lower compared to the MSYt situation in the unsupplemented and supplemented populations, respectively. Long term population monitoring data provided feasible and suitable baseline values to optimise the sustainable exploitation of red deer populations in the Mediterranean ecosystem under these contrasting management scenarios. Adaptive management, involving objective-driven decision making informed by data on red deer population dynamic, can contribute (i) to maximising the total extraction over the long term while (ii) reducing the ecological impact of high population densities.

Keywords: Artificial feeding; Cervus elaphus; Management; Population dynamics; Population growth; Recruitment rate.

Figure 1. Annual population density (black line, ind/km²) and annual harvest (grey line, % of harvested population) for (A) supplemented and (B) unsupplemented populations, during the study period.

Figure 2. Tests of statistical density dependence.

The tests of statistical density dependence derived from the logistic growth model, separately for each study population (supplemented = red and unsupplemented = blue).

Figure 3. (A) Annual number of animals harvested depending on the surface area (n° ind/km²) and (B) proportion of extraction with respect to the total population for the supplemented (grey line) and unsupplemented estates (black line).

For comparison, horizontal lines indicate the predicted value in a situation of MSYt (dashed lines).