Long‐Term Population Development of a Reintroduced Beaver (Castor fiber) Population in Sweden

Abstract

Deliberate reintroductions of locally extermi. hated animal species to areas within their former ranges is an increasingly important conservation tool Most reintroductions are fairly recent and still in an initial phase of population development There are few long-term studies of reintroduced population~ The aim of this study was to see if the population development of the reintroduced European beaver (Castor fiber)population in Sumden exhibits the same pattern of population development as other introduction~ in accordance with general theorie~ and to discuss possible management consequence£ Since the European beaver was reintroduced to Sweden 70 years ago, the population has developed in a way predicted by the Riney-Caughley model for introduced ungulate~ exhibiting an irruption and a subsequent decline. In two study area~ the rate of population increase (r) turned negative after 34 and 25 years and at densities of 0.25 and 0.20 colonies/km 2, respectively. The data suggest that management policy for an irruptive species should allow hunting during the rapid-increase phase thus maintaining food resources and avoiding uncontrolled pop. ulation decline DesarroUo a largo plazo de unq pobaci6n reintroducida de Castor (Castor fiber) en Suecia Resumen: Las reintroducciones deliberadas de especies de animales exterratnados en forma local en dreas dentro de st, antigua zona de distribuci6n es una manera de conserva. ci6n de tmportancia crecient¢ La mayor parte de las reintroducciones son bastante recienteg y todavta estdn en una fase iniclal del desarrollo poblacionaL Ya que estudios realizados durante una larga temporada son escaso~ no se sabe si se comportardn del mismo modo que otras especies reintroducidax El prop6sito de este estudio fue comprobar si el desarrollo poblacional de la poblaci6n de castor europeo (Castor fiber) reintroducido en Suecla exhibe el mismo pa-tr6n de desarrollo poblacional de otras introduccione~ de acuerdo con teorias generale~ y tambi~n discutir las posibies consecuencias para el manejo de especlas reintrodacidax E1 castor europeo rue reintroducido en Suecia hace 70 aao~ En este estudio mostramos que la poblaci6n se ha desarrollado segt~n la predicci6n del modelo Riney-Caughley para ungulados inroducido~ mostrando una irrupct6n y rods tarde una disminuci~ Si se pone r observa~ de dos areas estudlada~ en relaci6n con la temporada despu~s de ia colonizaci6n y se ajustan las curvas a los dato~ se obtienen modelos donde r pasa a set negativa despuds de 34 y 25 a~o~ y con densidades de 0.25 y 0.20 colonias/km 2. Los datos sugieren que la$ estratg]las de manejo de especie irruptivas deberlan permitir la caza durante la fase del crecieraento rdpido para mantener los recursos alimentario~ y tratar de evitar una declinacion problacional descontrolada 713

Distribution and patterns of spread of recolonising Eurasian beavers (Castor fiber Linnaeus 1758) in fragmented habitat, Agdenes peninsula, Norway

“…Single groups are relatively recently established on two more watersheds, and these have both selected high quality habitat patches. This pattern is in accordance with other studies, which show a pattern of rapid colonization within watersheds, strong selection for the highest quality unoccupied habitat available, progressive lowering of the quality of habitat on which settlement occurs as a watershed population grows, and a strong barrier effect of watershed divides on dispersal (Hartman 1994(Hartman , 1995Fustec et al 2001;John et al 2010;Halley et al 2002 for review). Beavers are known to have colonised site 2, on Skjenaldelva watershed, within 5 years of the initial release on Ingdalselva.…”

Use of linear and areal habitat models to establish and distribute beaver Castor fiber harvest quotas in Norway

“…Natural predation is minimal as wolves (Canis lupus Linnaeus, 1758), the only major predator on beaver (Novak 1987;Andersone 1999), were not present. Mean density of occupied sites for all area below tree line (242 km 2 ) was 0.26/km 2 in 1995 (Parker et al 2002a), which is typical for Scandinavian landscapes (Hartman 1994;Parker et al 2002b;Parker & Rosell 2012).…”

“…Beaver-utilized shoreline lengths were marked in the field on maps scaled 1:10,000 (Norwegian "Økonomisk kartverk" series) and measured to the nearest 100 m. Our goal was to reconstruct the original beaver territorial boundaries established as best possible, often defined by the remains of exploited vegetation and scent mounds (Nolet & Rosell 1994). Beaver occupy shoreline habitat on a rotational basis, apparently deserting an area when vegetation for food and building material becomes insufficient, returning some years later following sufficient regrowth (Hartman 1994;Parker et al 2001b). Since the remains of beaver cutting and building activity normally remain visible in the landscape for decades, and most sites are reoccupied before old sign disappears, we were able to map most past and present beaverutilized shoreline in the township.…”

“…Since the remains of beaver cutting and building activity normally remain visible in the landscape for decades, and most sites are reoccupied before old sign disappears, we were able to map most past and present beaverutilized shoreline in the township. This was possible since most potential sites within the municipality presumably had been occupied at least once following the beaver's return 55 years previous (Hartman 1994;Parker et al 2002a). Knowing the proportion of previously utilized sites that were occupied in any They occupy riparian landscapes in a linear fashion, i.e.…”

Hábitos alimenticios de Lagidium viscacia y Abrocoma cinerea: roedores sintópicos en ambientes altoandinos del norte de Chile

“…Una extensión de lo anterior es que los estudios dietarios de animales silvestres han cobrado importancia en los planes de conservación de especies y planificación de reservas naturales (Cole et al 1995), reintroducción de especies exterminadas a sus hábitats naturales (Lundie-Jenkins et al 1993, Renssen & Vogel 1993, Bright & Morris 1994, Hartman 1994 y en el desarrollo de técni-cas de control biológico (Beg et al 1994, Jiménez et al 1994, Tobin et al 1994.…”