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Main research projects:

Large Carnivores and Animal Population Models

A female brown bear and her two cubs in the Cantabrian Mountains in northern Spain

Reconciling large-scale conservation of endangered large carnivore populations with conflicting human activities

Introduction
Europe once offered a wide range of natural habitats for its large carnivore species. Today, however, relict brown bear populations are dangerously small and highly fragmented in Southern, Central and Western Europe. The Iberian lynx has recently been labeled by the IUCN as the most critically endangered felid species world-wide. Wolf populations are under intense human pressure throughout most of their range. The Eurasian lynx has disappeared in much of Europe and even though wolverine numbers in Fennoscandia appear to have stabilized since it became protected, illegal hunting is still a constant threat. There was widespread and bitter opposition to large carnivores in the past but today there is increasing public interest in their conservation. However, the predatory behaviour of large carnivores is often in conflict with local economic activities, especially livestock  farming. 

The role of models in conservation of large carnivores
In the last years we are witnessing the rapid development of advanced new scientific tools in the field of ecological modeling and population biology in the form of individual-based, spatially explicit population models. These models describe population dynamics by simulating the fate of individuals or assemblages of individuals, generally using a geographical information system (GIS) database to compile maps on habitat quality, and apply a population model that relates demographics of the species explicitly to the landscape in which the organism lives. This type of simulation models allow for a direct translation of the biological information into the model. They include the essential biological information in the form of structural realism (rules defining our current knowledge on the biology of the species) rather than simple mathematical equations, and thus avoid problems with deformation or mutilation of information due to mathematical constraints, or problems with abstract compound model parameters that have no direct biological meaning. Especially in more complex problems and applied case studies, this allows for the direct inclusion of data and real-world spatial information. 

Recovery of large carnivores and the expansion of their range may take decades. This long-term duration is due to a mix of factors, including low growth rates of long-lived species, fragmented and isolated habitat, and high mortality rates due to poaching. Therefore models of the dynamics of entire populations can help to better understand the complex process of recovery and expansion. For small and endangered populations, (spatially explicit) demographic models can be used to estimate minimum viable population sizes (PVA). Secure sustainable management of wild populations should give high research priority to the development and evaluation of reliable methods to estimate population size and population trends. Especially pattern-oriented modeling provides means to indirectly assess population sizes from fragmented information. 

Because of several uncertainties and vagueness in model rules, modeling can be used as a conceptual framework that integrate the many pieces of information in a logical and hierarchical way, and models can be developed for “purposeful representation” and understanding. This understanding should provide managers and policy makers with a powerful tool to guide decision making under our best current understanding on the processes involved in population dynamics. Furthermore, this approach facilitates the inclusion of new information (or scenarios) as it becomes available, facilitating the application of adaptative management, which is basic to be able to maximize the information and resources available in any moment. 

Aims of my research plan
My general objective is to develop and evaluate conservation and management strategies able to reconcile conservation needs and human activities in a sustainable compromise by limiting the conflicts. This general objective can be broken down into specific objectives and work steps:

• Development of general species-specific models that summarize the current knowledge on the species. In this step I bring together scientist and experts from different countries to develop appropriate analytical techniques (especially on dispersal movement (Kramer-Schadt et al 2004; Kramer-Schadt et al 2005; Revilla et al 2004) which is of high importance in fragmented landscapes) and tools for the integration of the existing data. A result of the data analyses are a set of rules that describe the essence of the demography, social structure, dispersal, and use of space of selected carnivore species, such as brown bears or lynx.

• Quantifying and understanding the status and demographic trends of selected populations and the impact of human activities. In this step the general species-specific models are applied to selected populations and their specific management problems. Important elements of this adaptation are the development of large-scale cartography, created with the aid of a Geographic Information System (GIS) that describes the important habitat types (e.g., breeding habitat, dispersal habitat, avoided but occasionally used matrix, not used barriers) in an organism-centered way (e.g., Schadt et al. 2002a, Schadt et al. 2002b, Wiegand et al. 2008), as well as maps showing the spatial distribution of suitable areas, and critical areas with high risk of human-induced mortality and high natural suitability (e.g., Naves et al. 2003, Rhodes et al. 2006). Dynamic SEPM models (e.g.,Kramer-Schadt et al 2005; Wiegand et al. 1999, 2004 a, 2004 b) are used (1) to determine critical areas where reintroduction, augmentation and habitat restoration should be directed for increasing population viability and maintaining genetic interchange between subpopulations, and to enhance reestablishment of individuals into new areas, (2) to assess the impact of human activities (e.g., urbanization, road and highway construction, forestry, agricultural development, tourism) on habitat fragmentation and connectivity (Kramer-Schadt et al 2004; Wiegand et al. 2005), and (3) to estimate population sizes and population trends, minimal viable population sizes, the risk of extinction, and the most sensitive management accessible parameters (Kramer-Schadt et al 2005; Wiegand et al 1998).

• Developing conservation strategies for the selected populations. In this step the specific conservation problems of the populations are analyzed and different management scenarios are evaluated in their effectiveness and costs. The conservation problems can be grouped roughly into three classes: (1) problems of expanding populations, (2) problems of species in regression, and (3) problems of re-introduction for locally extinct species. Depending on the specific conservation problems the models are used (i) to test different reintroduction and augmentation scenarios with view on population viability, (ii) to assess the effect of scenarios of habitat restoration on interchange between subpopulations, on reestablishment of individuals into new areas, and on population viability, (iii) to assess the effect of realistic scenarios of landscape design and development and human activities (e.g., urbanization, road and highway construction, forestry, agricultural development, tourism) on habitat connectivity and population viability, and (iv) to ascertain the sustainable harvest threshold for planning the possible removal of animals as a management instrument in particular conflict situations, and for managing hunting.

Modeling (spatial) population dynamics of endangered animal populations

• Endangered brown bears (Ursus arctos) in northern Spain (with Javier Naves)

• Expansion of brown bears (Ursus arctos) into the eastern Alps (with Felix Knauer)


The expansion of brown bears in Austria is a great challenge for wildlife managers and conservation biologists because they envisage a viable population while reducing the conflicts that the species may generate to a minimum. We developed a spatially explicit population model with the aim to obtain an understanding of the dynamics of brown bears in the eastern Alps after the reintroduction program. More specifically we use current knowledge on bear observations (a 11 yr time series of females with cubs in Central Austria, and 1989-1999 bear observations throughout the eastern Alps) to indirectly assess current key variables of population dynamics, such as population sizes and growth rates, dispersal distances, or mortality rates within different population nuclei. Hence, we aim to study the past to be able to better manage the present and the future. (Wiegand et. al 2004 a, 2004 b).

• Individual-based spatially explicit models applied to the conservation of the endangered Iberian lynx (Eloy Revilla)


Iberian lynx (Lynx pardinus) is the most threatened carnivore in Europe, and the most endangered felid in the world. It only inhabits the Iberian Peninsula, and thus the challenge of its future conservation and that of the Mediterranean habitats the lynx occupies depends solely on Europe. Habitat degradation and fragmentation are the main threats of the Iberian lynx. These deterministic processes are produced by development of the areas inhabited by the species. Activities such as afforestation, intensive agriculture, linear infrastructures, water dams, urbanisation, fires etc. had and will continue reducing the range of the species. Nowadays, lynx lives in nine isolated populations, each of which has a metapopulation structure. Future survival of the Iberian lynx depends on our ability in understanding the dynamic and trends of its metapopulations and their relationship with landscape design, management and development. (Revilla et al, in 2004)

• Scenarios for viable lynx populations in Germany (Stephanie Schadt)


Reintroductions of lynx (Lynx lynx) into Germany have been discussed  controversially and partially undertaken within the last thirty years. Of special interest were questions such as that of suitable habitat patches and connectivity among the populations. In spite of those many initiatives to reintroduce lynx and the natural settlement of lynx in the Bavarian Forest, no spatially explicit model has yet been developed to answer not only the question of enough suitable habitat, but that also simulates the population dynamics for estimating dispersal of individuals and expansion of the population. This would be an approach for assessing the future of the lynx in Germany. (Schadt et al. 2002a, Schadt et al. 2002b , Kramer-Schadt et al. 2004; Kramer-Schadt et al 2005). 

• Conservation Planning for the Koala (Phascolarctos cinereus) (Jonathan Rhodes)


Koala populations in eastern Australia are being threatened by continued habitat loss, degradation and fragmentation. Other threats include, growing urbanisation (causing increased dog predation and road deaths), fire, disease and drought. In order to develop appropriate management strategies to conserve koalas we need to understand and quantify these processes, especially with respect to changes in land use through time. The development of the spatially explicit population models will allow a better understanding of the processes of koala population responses to changes in landscape structure and other aspects of their conservation biology. Further, the project will also enable us to develop objective methods for choosing between management options for koala conservation (Rhodes et al. 2006). Models will largely be developed using landscape and population data from the Port Stephens area, New South Wales. However, they will also be tested, validated and applied at other study sites in eastern Australia.. 

• Conservation of the Cantabrian Capercaille (Tetrao urogallus cantabricus) (Adan Abajo)
  Adan is PhD Student of Moncho Obeso at the Ecology Unit at the University of Oviedo, Spain. He came several times to Leipzig to develop a spatially-explicit and individual-based population model for the Cantabrian Capercaille.  The objective of his PhD is to obtain a better understanding of habitat use and the extinction dynamics of the Cantabrian Capercaillie (Tetrao urogallus cantabricus) in the Cantabrian Mountains (in the NW of Spain) and to assess the viability of the highly endangered (meta)population. His PhD consists in three steps: (1) development of a model of habitat suitability, (2) an inverse-pattern-oriented analysis of individual-based dispersal models to assess connectivity among leks and to reveal dispersal rules of Capercaillie which agree with the observed extinction pattern of leks, and (3) a full spatially-explicit population model to reconstruct the past extinction dynamics and to assess the viability of the (meta)population

• Conservation of the Red-Cockaded Woodpecker (Picoides borealis) (Doug Bruggeman)
  The recent work of Doug involves approaches for trading patches within metapopulations. Such a biodiversity credit system for trading endangered species habitat may be designed to minimize and reverse the negative effects of habitat loss and fragmentation. The idea of the project is to apply the pattern-oriented modeling approach to population genetic and demographic data for the Red-Cockaded Woodpecker.  Patterns of genetic markers may be an effective "filter" for reducing parameter uncertainty in SEPMs. This is a crucial element for patch trading which allows to determine the value of patches for a metapopulation with less uncertainty than possible with conventional approaches.
   

• Evaluating landscape connectivity for tiger (Panthera tigris) (Rajapandian K) 
  As a result of conquest of malaria, establishment of numerous settlements and increase in human population, the Indian portion of Terai Arc Landscape (TAL) landscape has become over the decades highly fragmented and degraded. The project of Raja involves development of habitat models for predicting habitat occupancy of tiger (Panthera tigris) and its prey species in TAL and and to evaluate landscape connectivity using a spatially-explicit and individual-based approach. Further objectives are to evaluate the previously identified corridors in respect to their ability to connect habitat patches, to assess the interaction between landscape structure and dispersing individuals among subpopulations, and to provide conservation and management implications for the long-term survival of tiger and other wildlife species in this landscape.