Patterns of movement of radioactive carabid beetles

Abstract

Tracking of individual Ir-labeled ground beetles released in the field revealed that both the day-active and night-active species studied showed periods of small distances covered per day in random directions, alternating with periods of directed movement with large distances covered per day. This pattern occurred not only in the reproductive period but outside the breeding season as well in juvenile Pterostichus versicolor and spent Calathus melanocephalus. Although mean locomotory activity increased with temperature, great daily differences occurred between individuals, pointing to asynchronous behavior. In an unfavorable habitat directed movement occurred both more frequently and more extremely, sometimes resulting in escape to more favorable areas. Most of the radioactive beetles died within 7 weeks due to radiation effects, but independent field experiments and simulations showed that the recorded patterns were valid. Simulated individuals of P. versicolor living on 1 ha spread over 49 ha, whereas simulated C. melanocephalus covered only 9 ha after one activity season. Normal locomotory activities lead to both exchange of individuals between subpopulations and dispersal out of the habitat. The significance of these phenomena for population stability and for the survival of the species is discussed.

Connectivity measures: a review

“…Consequently, functional connectivity covers situations where organisms venture into non-habitat (matrix), where they may (1) face higher mortality risks (e.g., Gaines and McGlenaghan 1980;Henein and Merriam 1990;Poole 1997;Sakai and Noon 1997), (2) express different movement patterns (e.g., Baars 1979;Wallin and Ekbom 1988;Wegner and Merriam 1990;Hansson 1991;Johnson et al 1992a;Andreassen et al 1996b;FitzGibbon et al 2007), and (3) cross boundaries (e.g., Mader 1984;Wiens et al 1985;Duelli et al 1990;Mader et al 1990;Mauremooto et al 1995;Sakai and Noon 1997;Walker et al 2007). Goodwin (2003) subdivides these two basic groups further into 10 subcategories, which are: presence or absence of corridors, distances, amount of habitat, contagion or percolation, dispersal success, graph theory, movement probability, searching time for a new habitat, reobservation of displaced individuals, immigration rate.…”

“…The rest of landscape after exclusion of habitat patches is usually called ''matrix''. The matrix thus consists of patches of non-habitat elements and its composition can also influence movement behavior (Baars 1979;Johnson et al 1992a, b;Matthysen et al 1995;Pither and Taylor 1998;Jonsen and Taylor 2000;Goodwin and Fahrig 2002a) and movement risk (Sakai and Noon 1997;Zollner and Lima 1999;Hanski et al 2000). Landscapes dominated by matrix patches that facilitate movement will have high connectivity while landscapes dominated by matrix patches that impede movement will have low connectivity.…”

The impact of local spatial resistance on the movement behaviour of Tenebrio molitor L.

“…In terms of the totally covered distances LSR leads to a reduction of 1/2 of the control-distances. This can not be explained by putative panic behaviour of beetles that are seeking cover in the open control habitat by moving more directly towards border structures [47,48], because it does not explain the significant differences between LSR1 and LSR2. Rather, one can argue that exactly this qualitiy is the effect of habitats with active LSR: the animals cover less longer distances because they have to make more and shorter steps around the obstacles, which leads to a reduction of the average covered distances respectively to a reduction of the average maximum speed (from 36.1 in the control to 20.4 [mm*step −1 ] in LSR2).…”

“…In the factor move step length the autocorrelation is hardly expressed as it is known from other studies [33,39], and only in the setup control autocorrelation is slightly detectable. The reason for this can be the fact that the beetles performed in the control much more directed walk sensu Baars [47] with higher speed to reach the borders of the EMS which they favored over staying in the open space of the arena. In such a case, it is known from other studies [38], that when the animals disperse longer ways rather directly with high speed and when the observation intervals are relatively close, then the distribution of move step lengths can be equidistant.…”

Beetles in fragmented woodlands: a formal framework for dynamics of movement in ecological landscapes

“…Given that a movement event occurs, the probability m(x H Àx) that an individual moves from location x to location x H is determined only by the distance between the two locations. The model presented here uses a movement kernel having an exponential probability density function for distance (Baars 1979;Charrier, Petit & Burel 1997;Thomas, Parkinson & Marshall 1998), with a mean daily movement distance of 10Á8 m (Baars 1979), and a rectangular probability density function from 0 to 2p for direction, implying no directionality in movement. The assumptions about the speci®c form of M(x, x H , p e ) are among the simplest that can be made, and are used so that the basic argument is not obscured by algebra; the formal structure would allow many alternative assumptions corresponding to the detailed behaviour of particular organisms.…”