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Territory Holders (territory + holder)

Distribution by Scientific Domains

Life Sciences	100%

Selected Abstracts

Home-range overlap and spatial organization as indicators for territoriality among male bushbuck (Tragelaphus scriptus)

JOURNAL OF ZOOLOGY, Issue 3 2005
Torsten Wronski
Abstract Many studies have concluded that territoriality is absent in male bushbuck Tragelaphus scriptus but a minority has suggested that some exclusive mechanisms act between adult males. This study provides indirect evidence for the existence of territorial structures between adult male bushbuck by comparing home-range overlap between adult and sub-adult males. The spatial organization of individuals in relation to each other was established by using numerical classification. Location fixes of 52 males, each individual distinguished by a characteristic coat pattern, were taken over a period of 3 years. Home ranges were estimated using the fixed kernel density estimator. Two indices (coefficient of overlap, index of overlap) were applied to compare home-range overlap between the different male age classes. There was a strong home-range overlap up to the 30% home-range core between sub-adult as well as between adult and sub-adult males, while adult male home ranges overlapped up to the 50% home-range core only. It could be shown that home ranges of adult males overlapped significantly less than those of sub-adult males and those between sub-adult and adult males indicating an exclusive use of central core areas (home sites). Sub-adult males form bachelor pools without being permanently associated. With increasing age, sub-adult males challenge territory holders and replace them in order to take over their exclusive areas. These maturing sub-adult males (young adults), often focused on a particular territory holder denoting the young adults as prospects or candidates. [source]

Absence of a dominance hierarchy confirms territorial organization in male bushbuck (Tragelaphus scriptus Pallas, 1766)

AFRICAN JOURNAL OF ECOLOGY, Issue 3 2009
Torsten Wronski
Abstract It has been suggested that all species of spiral-horned antelopes (Tragelaphini) lack territoriality. Furthermore, some authors suggested that bushbuck (Tragelpahus scriptus) males form dominance hierarchies. In this study, we investigated the dominance relationships in two groups of free-ranging bushbuck males in Queen Elizabeth National Park, Uganda. Adult males dominated young-adult bachelors and subadult males, but no distinct dominance relationships were found among adult males. Landau,s index of linearity revealed no linear dominance hierarchy in the study populations. Our results support the idea that adult males are territorial, and overt aggression is directed almost exclusively towards bachelors that challenge territory holders. Résumé On a suggéré que toutes les espèces d'antilopes à cornes spiralées (Tragelaphineae) ne montraient pas de territorialité. Qui plus est, certains auteurs ont suggéré que les mâles Guib harnaché (Tragelaphus scriptus) formaient des hiérarchies par dominance. Dans cette étude, nous avons cherché les relations de dominance dans deux groupes de mâles Guib harnaché vivant en liberté dans le Parc National Queen Elizabeth, en Ouganda. Les mâles adultes dominaient les jeunes mâles célibataires et les mâles sub-adultes, mais on n'a trouvé aucune relation de dominance distincte entre les mâles adultes. L'index de linéarité de Landau n'a révélé aucune hiérarchie linéaire de dominance dans les populations de l'étude. Nos résultats soutiennent l'idée que les mâles adultes sont territoriaux, et toute agression manifeste est dirigée presque exclusivement vers les jeunes célibataires qui défient ceux qui détiennent un territoire. [source]

Home-range overlap and spatial organization as indicators for territoriality among male bushbuck (Tragelaphus scriptus)

Movement patterns and study area boundaries: influences on survival estimation in capture,mark,recapture studies

OIKOS, Issue 8 2008
Gregg E. Horton
The inability to account for the availability of individuals in the study area during capture,mark,recapture (CMR) studies and the resultant confounding of parameter estimates can make correct interpretation of CMR model parameter estimates difficult. Although important advances based on the Cormack,Jolly,Seber (CJS) model have resulted in estimators of true survival that work by unconfounding either death or recapture probability from availability for capture in the study area, these methods rely on the researcher's ability to select a method that is correctly matched to emigration patterns in the population. If incorrect assumptions regarding site fidelity (non-movement) are made, it may be difficult or impossible as well as costly to change the study design once the incorrect assumption is discovered. Subtleties in characteristics of movement (e.g. life history-dependent emigration, nomads vs territory holders) can lead to mixtures in the probability of being available for capture among members of the same population. The result of these mixtures may be only a partial unconfounding of emigration from other CMR model parameters. Biologically-based differences in individual movement can combine with constraints on study design to further complicate the problem. Because of the intricacies of movement and its interaction with other parameters in CMR models, quantification of and solutions to these problems are needed. Based on our work with stream-dwelling populations of Atlantic salmon Salmo salar, we used a simulation approach to evaluate existing CMR models under various mixtures of movement probabilities. The Barker joint data model provided unbiased estimates of true survival under all conditions tested. The CJS and robust design models provided similarly unbiased estimates of true survival but only when emigration information could be incorporated directly into individual encounter histories. For the robust design model, Markovian emigration (future availability for capture depends on an individual's current location) was a difficult emigration pattern to detect unless survival and especially recapture probability were high. Additionally, when local movement was high relative to study area boundaries and movement became more diffuse (e.g. a random walk), local movement and permanent emigration were difficult to distinguish and had consequences for correctly interpreting the survival parameter being estimated (apparent survival vs true survival). [source]