An analysis and review of models of the sociobiology of the Mustelidae

JOHNSON, D.D.P.; MACDONALD, D.W.; DICKMAN, A.J. 2000. An analysis and review of models of the sociobiology of the Mustelidae. Mammal Review 30(3-4):171-196.

Abstract. Classical models of social organization in mustelids suggest that female ranging patterns are determined by the dispersion of resources, whereas those of males are determined by the dispersion of females. However, mating systems and social spacing patterns vary widely both between and withing species. For example, European Badgers exhibit a continuum from the classical mustelid model of intra-sexual territoriality and inter-sexual overlap to very large, mixed-sex, promiscuous groups. We evaluated hypotheses and existing data to explain this variation, using comparative analyses and Principal Components Analysis of life history and ecological variables. In addition, we applied a null model of allometric scaling to test for associations between group mass and residual home range size. We found that: (1) the degree of social behaviour and breeding group size increased with life history variables indicative of K-selected strategies of parental investment. (2) Absolute home range size and residual home range size (derived from allometric home range scalling) decreased, paradoxically, with breeding group size and group mass, respectively. These results provide support for ecological theories of social grouping in general and, in particular, for the importance of dispersed resource-rich patches as developed in the Resource Dispersion Hypothesis.

Factors affecting home range size and overlap in Akodon azarae (Muridae: Sigmodontinae) in natural pasture of Argentina

PRIOTTO, J.W.; STEINMANN, A.R. 1999. Factors affecting home range size and overlap in Akodon azarae (Muridae: Sigmodontinae) in natural pasture of Argentina. Acta Theriologica 44(1):37-44.

Abstract. Differences in home range size in relation to sex, age, breeding and non-breeding periods were studied. Home range size and overlap were examined at different densities values in populations of Akodon azarae (Fischer, 1829) on railway banks in southern Córdoba Province (Argentina). The sampling was carried out between October 1994, and February 1997, using the capture-mark-recapture method. Home range size in A. azarae was determined by sex and breeding period, and it was independent of the observed density values. Home range size of males was always larger than that of females. Increase of population density during the breeding period affected the degree of intersexual overlap of home range.

A radio tracking study of home range and movements of the marsupial Micoureus demerarae (Thomas) (Mammalia, Didelphidae) in the Atlantic forest of south-eastern Brazil

JUNIOR, E.A.M.; CHIARELLO, A.G. 2005. A radio tracking study of home range and movements of the marsupial Micoureus demerarae (Thomas) (Mammalia, Didelphidae) in the Atlantic forest of south-eastern Brazil. Revista Brasileira de Zoologia 22(1):85-91.

Abstract. From August 2001 to July 2002 the home range and movements of seven Micoureus demerarae (Thomas, 1905) (three males and four females) were investigated using radio tracking in the União Biological Reserve, state of Rio de Janeiro, south-eastern Brazil. A total of 436 locations was obtained and home range estimated with fixed Kernel (95% of data points), and minimum convex polygon (MCP) methods, with 100 and 95% of data points. Male home ranges estimated by MCP (100%) ranged from 5.4-24.2 ha and females from 0.3-10.7 ha. Corresponding figures calculated with Kernel (95%) were 4-10.9 ha for males and 1.3-5.9 ha for females. Animals travelled on average 423 m/night, with males travelling significantly further (582.8 m/night) than females (335.1 m/night) (t test, t = 3.609, p = 0.001). We concluded that radio tracking produced much larger home ranges than those estimated with traditional live-trapping techniques, suggesting that the latter might underestimate ranging when the area covered with traps is relatively small (ca. 1 ha or less). Radio tracking also indicated that M. demerarae, although predominantly arboreal and weighting only ca. 130 g., has movements similar in magnitude to larger-sized terrestrial didelphimorph marsupials, such as Didelphis Linnaeus, 1758, Philander Linnaeus, 1758 and Metachirus (Desmarest, 1817).

A demo-genetic analysis of a small reintroduced carnivore population: the otter (Lutra lutra) in the Netherlands

SEIGNOBOSC, M.; HEMERIK, L.; KOELEWIJN, H.P. 2011. A demo-genetic analysis of a small reintroduced carnivore population: the otter (Lutra lutra) in the Netherlands. International Journal of Ecology, v. 2011, Article ID 870853, 11 pages. doi: 10.1155/2011/870853.

Abstract. Assessing the viability of reintroduced animal populations is a complicated task. Reintroductions are usually carried out with a small number of individuals, thereby, limiting the possibilities for monitoring because of the possible negative effects of intensive monitoring on survival and reproduction. Moreover, reintroduction studies are part of a socioeconomic interplay of forces, thereby, also limiting monitoring possibilities. Also, knowledge of population demography and abundance can be incomplete or unattainable. Here, we illustrate how we combined traditional telemetry and novel non-invasive genetic methodology to construct a detailed life table of a small reintroduced otter population in The Netherlands. Combining an appropriate capture-mark-recapture framework with a matrix modelling approach provides, in general, useful insights for such populations. The data indicated that (i) male survival is lower than female survival, (ii) the reintroduced population is currently growing (estimated λ = 1.26: range [1.06, 1.42]) and seems viable, (iii) increasing adult survival is currently the critical stage at which efforts of field managers should concentrate, and (iv) the modelling framework allowed us to determine the boundary conditions for the vital rates under which the population would go extinct. The applied approach directs at measurements that help field managers to implement the right conservation strategy after reintroductions.

Factors affecting the use of space by two rodent species in Brazilian Atlantic forest

BERGALLO, H.G.; MAGNUSSON, W.E. 2004. Factors affecting the use of space by two rodent species in Brazilian Atlantic forest. Mammalia 68(2-3):121-132.

Abstract. The main purpose of this study was to determine whether the maximum distance traveled and home range are of Nectomys squamipes and Oryzomys russatus differ between sexes, breeding seasons and species. We also evaluated whether rainfall and food availability influenced the maximum distance traveled. Rats were trapped monthly from February 1993 to January 1995 in an area of Atlantic forest, Brazil. Maximum distance traveled by N. squamipes was not related to mass and was longer during the breeding season for males. There were not differences between seasons in the distances traveled by O. russatus, but larger males traveled further. Food availability and rainfall had no effect on the distance traveled by each species. Home ranges of male N. squamipes were larger than those of females during the breeding season, but home ranges did not differ between the sexes in O. russatus. Differences between the two species in movement may be related to differences in mating systems, which are probably promiscuous in N. squamipes and monogamous in O. russatus.

Area de acción, actividad y uso de hábitat del zorro patas negras, Cerdocyon thous, en un bosque seco

MAFFEI, L.; TABER, A.B. 2003. Area de acción, actividad y uso de hábitat del zorro patas negras, Cerdocyon thous, en un bosque seco. Mastozoologia Neotropical 10(1):154-160.

Abstract. Home range, activity, and habitat use of the crab-eating fox (Cerdocyon thous) in a dry forest. The ranging behaviour of three crab-eating foxes in a dry forest in Santa Cruz, Bolivia was studied using radiotracking. Animals occupied an area between 110 and 280 ha estimated with Minimum Convex Polygon and has a small overlap (27 ha) between ranges. The foxes were principally active at night between 17:00 and 08:00 hours. They preferred riparian forest over chacoan and montane forest habitats, althought the former was less available than the others.

Where have all the cavies gone? Causes and consequences of predation by minor grison on a wild cavy population

KRAUS, C.; RÖDEL, H.G. 2004. Where have all the cavies gone? Causes and consequences of predation by minor grison on a wild cavy population. Oikos 105:489-500.

Abstract. We investigated whether predation by the minor grison (Galictis cuja , a small mustelid) played a key role in limiting a wild cavy population (Cavia magna), ultimately leading to its local extinction. Radio-telemetry and capture-mark-recapture techniques were used to estimate grison predation rates (kill rates), time-specific probabilities of apparent mortality (population loss rate), overall mortality and grison predation for the cavy population. Additionally, we present data on alternative prey species, grison diet and reproduction to show potential proximate mechanisms of grison predation on wild cavies. The predictions specified were mostly confirmed: (1) grison predation was responsible for almost 80% of the cavies killed by known predators; (2) grison predation probabilities paralleled those of overall mortality of cavies over time; and (3) also those of the apparent mortality of the population. Thus, the population dynamics and the local extinction of the cavy population were not due to emigration processes. (4) Grison predation rates were not density-dependent, but showed pronounced peaks during the austral summer. The grison mainly preyed on small mammals: two water-rat species and the wild cavies. When the availability of alternative prey decreased in summer, the grison appeared to specialise on cavies. The onset of grison reproduction was somewhat delayed in relation to the onset of cavy reproduction. The lack of alternative prey coincided with high grison food demands due to reproduction, leading to a very high predation pressure ultimately resulting in the local extinction of the cavy population. We conclude that grison predation was indeed the main factor driving changes of the cavy population studied and speculate why caviomorph rodents might be especially susceptible to local extinction processes.

Movement distances and density estimation of small mammals using the spool-and-line technique

MENDEL, S.M.; VIEIRA, M.V. 2003. Movement distances and density estimation of small mammals using the spoll-and-line technique. Acta Theriologica 48(3):289-300.

Abstract. Edge effect is an inherent problem when using trapping grids to estimate density of small mammals, resulting in a sampling area larger than the area of the grid. Distances between captures of individuals are used to estimate A(W), the effective sampling area of a trapping grid, but grid size sets a limit for the largest detectable distance. The spool-and-line technique is proposed here as a new method to estimate A(W). Movement distances based on the spool-and-line technique were compared to similar movement distances based on capture-recapture of three spacies of marsupials of the Atlantic Forest of Brazil. Distances based on the two methos were uncorrelated, and only ln-transformed distances based on the spool-and-line were normally distributed. The maximum distance moved (MaxD) estimated by the spool-and-line was chosen as the more accurate and practical distance to estimate edge effect. Estimates of the effective sampling area and densities for the common opossum Didelphis aurita (Wied-Neuwied, 1826), were compared using MaxD based on spool-and-line (MaxDspool), capture-recapture (MaxDcap), and also the distance between traps (DT). MaxDspool reflected more accurately density variation between seasons. Movement distances of small mammals based on the spool-and-line technique permit more accurate estimates of density and its dynamics.