Population Densitiy, Interspecific Territoriality and Philopatry of Shrikes (Lanidae) and Bush‐Shrikes (Malaconotidae) in a Mosaic of Natural and Human Modified Acacia Savanna

In avian behavioural and spacial ecology especially important are issues related to population density, territoriality and philopatry. These are often interrelated. To aim of this study was to analyse these behaviours in shrikes inhabiting an acacia savanna in northern Namibia (400 ha). Population densities of one shrike and four bush-shrike species were studied by means of the territory mapping method About half of the study area was modified by man into cultivated fields, orchards, sport fields and human settlements. The study was conducted in 2012, 2017 and 2020. The most common was the Black-backed Puffback (2.5 pairs / 100 ha) and Crimson-breasted Shrike (1.9); the least common: Southern White-crowned Shrike (0.8) and Brubru (1.0). The Brown-crowned Tchagra reached a density of 1.5 pairs / 100 ha. While the density of the Brown-crowned Tchagra and Brubru remained stable over the years, the population densities of the Black-backed Shrike, Crimson-breasted Shrike and Southern White-crowned Shrike showed a remarkably increase over the years 2012-2020. All bush-shrike species showed a preference for patches of natural savanna vegetation. This was especially evident in the Crimson-breasted Shrike and the Brubru. The presented studies shown marked interspecific differences in territoriality and philopatry. Furthermore, even within the same species, marked temporal differences were shown in population density and probably also in the philopatry. Within families, these behaviours may shape both resource competition or mate competition, while between families – only resource competition.