Indicators of ecological change: new tools for managing populations of large herbivores

Abstract

Summary1. High-density populations of large herbivores are now widespread. Wildlife managers commonly attempt to control large herbivores through hunting to meet specific management objectives, considering population density as the minimal key source of information. Here, we review the problems of censusing populations of large herbivores and describe an alternative approach, employing indicators of ecological change. 2. Estimating density of large herbivores with high precision and accuracy is difficult, especially over large areas, and requires considerable investment of time, people and money. Management decisions are often made on an annual basis, informed by population changes over the previous year. However, estimating year-to-year changes in density is not a realistic goal for most large herbivores. Furthermore, population density per se provides no information on the relationship between the population and its habitat. 3. For successful management of large herbivores, we need to consider not only the fate of the population, but rather changes in both population and habitat features, as well as their interaction. Managers require information on trends in both the animal population and habitat quality in order to interpret changes in the interaction between these two compartments. 4. We propose that a set of indicators of animal performance, population abundance, habitat quality and/or herbivore habitat impact provides relevant information on the populationhabitat system. Monitoring temporal changes in these indicators provides a new basis for setting hunting quotas to achieve specific management objectives. This sort of adaptive management is employed widely in France for managing roe deer Capreolus capreolus . 5. Synthesis and applications . The management of large herbivores would be improved by investing fewer resources in trying to estimate the absolute abundance of ungulates, and more resources in collecting additional data to inform understanding of the ecological status of the ungulate-habitat system being managed. This paper presents a set of indicators of ecological change for monitoring the interaction between a population and its habitat as a basis for adaptive management to attain explicit goals and to improve knowledge of the system. This approach could improve management for a variety of large herbivores, by harmonizing actions at wide spatial scales.

Long-term effects of supplementary feeding of moose on browsing impact at a landscape scale

“…Whilst supplementary feeding intuitively seems a promising tool to mitigate such conflicts, our results suggest that in the long term, site specific relationships between forage availability and herbivore population density may determine whether supplementary feeding has the desired diversionary effect. The application of feeding as a diversionary tool requires knowledge of preferences by the herbivore, and continuous monitoring of herbivore density, forage availability and damage to the resources to be protected (Morellet et al, 2007). Our study also shows that the extent and effects of supplementary feeding systems may change over time, which highlights the need for longterm planning when feeding programs are initiated.…”

Achieving landscape‐scale deer management for biodiversity conservation: The need to consider sources and sinks

“…Although thermal imaging distance sampling now offers a technique to quantify deer numbers across different contiguous landscape units (Gill et al 1997, Hemami et al 2007, estimating deer density is often considered prohibitively difficult , Zannèse et al 2006. Management, therefore, is based on subjective perceptions of abundance, deer condition, or on impact levels (e.g., Morellet et al 2007, Mysterud et al 2010. However, as impacts are context-dependent and nonlinearly related to densities (Koda and Fujita 2011, Putman et al 2011, their assessment does not translate readily into cull targets.…”

Situación de las poblaciones de corzo andaluz (Capreolus capreolus) en las sierras occidentales de Málaga

“…Incluso la utilización de métodos que corrigen la detectabilidad, como el Distance Sampling, requiere de una serie de asunciones básicas que a veces no se cumplen en ambientes forestales con reducida penetrabilidad visual . De hecho, para ungulados y en el caso concreto del corzo se ha propuesto que el uso de índices de abundancia (IKA) e índices de cambio ecológico relacionados con el estado del hábitat y las poblaciones (Morellet et al 2007) permiten obtener estimas más veraces y precisas, así como tomar decisiones más acertadas de cara a la gestión. Sin embargo, muchos de estos índices siguen requiriendo de la observación directa de los animales (caso del IKA o del conteo de unidades reproductoras) e incluso del manejo directo de animales para tomar medidas biométricas.…”