A telemetry-based study of bushbuck (Tragelaphus scriptus) home range in Valley Bushveld

With the aid of radio‐telemetry, bushbuck home range was investigated to determine total home range size, home range utilization and home range overlap for the summer season. Estimates of total home range size for males using minimum convex polygons (MCPs) and fixed kernels (FKs) were 33.9 and 32.1 ha, respectively. Estimates of total home range size for females using MCPs and FKs were 12.0 and 13.5 ha, respectively. A significant difference between total home range sizes for male and female was found but there was no significant difference for age (adult and subadult). Female bushbuck home range size was compared to that expected from the published allometric relationship for the scaling of home range area on body mass, where the study animals appeared to have home ranges of half of that predicted. Bushbuck typically utilized one core area within their home ranges in which 50% of their time was spent in approximately 17.0% and 11.7% of their total home range for males and females, respectively. A substantial overlap in total home range and core areas between animals was found.     

Diurnal and nocturnal strategies of the bushbuck Tragelaphus scriptus (Pallas)

Bushbuck density, activity cycles, and ranging patterns on the Mweya Peninsula have been determined by continuous observation of individually recognizable animals. Individuals were followed for periods of 2 to 12 h, and observations were continued at night with the aid of a Starlight Scope image intensifier. The density of this population of bushbuck is very high compared to those reported using more standard censusing techniques. Home range size is larger (15-3-35-2 ha) for adult and subadult males than for females and immatures. Sex ratios show a preponderance of adult females, as has been reported for other populations. Contrary to most published accounts, these bushbuck are no more active at night than during the day; rather, they exhibit cycles of activity with a periodicity of 2–5 h. A crepuscular peak of movement is, however, apparent. Examination of individual home ranges and of ranging patterns indicates that this crepuscular activity peak is connected with a complete disjunction of areas utilized at night and during the day. Bushbuck move out of thickets into patches of grassland at dusk, returning to thickets before dawn. Other differences between nocturnal and diurnal activity include an increase in the relative amount of grazing at night. Possible reasons for these phenomena, in particular the probable role of predation, are discussed.     

Scent marking and resource defence by male coypus (Myocastor coypus)

The alternative ideas that scent marking functions mainly in intrasexual competition or for attracting or stimulating mates were tested using data from a 16-year study of coypus, Myocastor coypus . Male coypus have a large anal gland, specialized for marking. Despite year-round breeding, the anal gland shows regular seasonal variation with marked enlargement in OctobeDecember. The analysis supported the hypothesis that this seasonal increase in glandular activity was linked to intrasexual competition: the size of the autumn peak was correlated with the increase in male numbers from the previous season and with the frequency of fighting scars. There were no relationships between gland size and any measures of the availability of mates. Increased scent marking may have been part of the response by resource-holding males to male recruits as these competed for existing territories. The timing of the autumn peak in marking and fighting may have been a response to the accumulation of non-resource-holding males over the summer (when recruitment exceeded mortality in the population) and to increasing accessibility within previously dense wetland habitats; together, these factors may cause a switch from scramble to despotic competition and an increase in scent marking to help keep the costs of resource defence within economic limits.     

Scent marking within and between groups of wild banded mongooses

Scent marking is commonly described as a territorial behaviour, and scent marks might deter potential intruders from entering occupied areas. Conspecific neighbours present both a reproductive and a territorial threat, thus, determining which, if any, of these threats shapes scent-marking behaviour is difficult. Banded mongooses Mungos mungo provide a rare clear separation between reproductive rivals (found within groups) and territorial rivals (neighbouring groups), because immigration into social groups is extremely rare, and mating occurs almost exclusively within groups. This situation offers an opportunity to assess the relative importance of territorial defence and intra-group competition for mates in shaping scent-marking behaviour. We combined detailed behavioural observations of scent marking, chemical analyses of scent composition and discrimination experiments in the field, and found little evidence for higher rates of scent marking in overlapping areas, a lack of group specificity of scents and a failure of individuals to discriminate between the scents of different groups. Although scent may fulfill some role in territorial demarcation and defence, these results suggest that scent marks and scent-marking patterns are also involved in communicating within social groups.     

Scent marking and social relationships in pine martens (Martes martes)

Scent marking was studied in pine martens (Martes martes) in female-female and male-female pairs. Results show that agonistically dominant individuals generally had higher scent marking frequencies. However, environmental familiarity can modify the social relationship, whatever the previous social experiences, and, consequently, marking activity. Despite important intra-and interindividual variations, the subjects appeared to react to physical and social modifications by an increased marking rate. One factor affecting marking activity in both novel and established pairs was the activity level of the conspecific partner. the data support the hypothesis that pine martens react in the same way to physical and social modifications, but with different response levels. The discussion focuses on possible functions of scent marking. © 1993 Wiley-Liss, Inc.     

Parasites reduce territorial behaviour in red grouse (Lagopus lagopus scoticus)

Hypotheses for the cause of population cycles have focused on the role of intrinsic mechanisms such as spacing behaviour and extrinsic mechanisms such as parasitism and predation. This paper examines the interaction between the two dominant hypotheses in the cycles of red grouse, parasitism and spacing behaviour. The influence of the caecal nematode, Trichostrongylus tenuis, on male aggressiveness was investigated using two approaches. First, the territorial behaviour of a group of male grouse experimentally treated with an anthelmintic to reduce parasite intensities was compared with a control group with natural intensities of infection. Second, the response of treated and control males to a novel conspecific territorial intruder were recorded using playback tests. Treated males, with reduced levels of parasitism, won significantly more territorial contests than control males and produced more aggressive behaviour in response to the playback recordings. These results show that parasite removal enhanced aggressive behaviour. Implications of these results on red grouse population dynamics are discussed.     

Resource control by territorial male cichlid fish in Lake Malawi

1. The rocky habitat communities of Lake Malawi contain a high diversity of ecologically similar, predominantly herbivorous, cichlid fish species. How so many species can coexist is still unknown.
2. Adult males of the majority of these species hold permanent territories which form dense multispecies mosaics across the shores.
3. The study examined six coexisting species of cichlids from the rocky habitat where males are known to control access to the algal food resources within their territorial space. These included four sibling species of the Pseudotropheus ( Tropheops ) species complex, which are specialized epilithic algal herbivores, and two sibling species of the trophically more generalist P . ( Maylandia ) species complex which feed upon both epilithic algae and plankton.
4. The hypotheses that both intraspecific and interspecific territoriality occur in these communities and that interspecific aggression initiated by territorial males is preferentially directed at species with the most similar diets to their own were tested.
5. It was found that males preferred to exclude conspecific intruders, while they tolerated intruders with different diets to their own. Also, male P . ( Tropheops ) preferentially excluded similar heterospecific dietary specialists, while male P. ( Maylandia ) tolerated similar heterospecific dietary generalists.
6. Based on this study, it is proposed that interspecific territoriality may be reducing competition between species with different diets and promoting their coexistence, while it may be enhancing competition between species with the same diet. Furthermore, it suggests that ecological generalism may be reducing the intensity of interspecific competition, while specializations for the same resources may be increasing competition.     

Colony-specific territorial marking with the metapleural gland secretion in the ant Solenopsis geminata (Fabr)

S. geminata workers mark the areas they explore with a secretion from the metapleural gland. The territorial mark lasts for more than 6 h. Territories without the chemical mark induce the workers to initiate recruitment to that territory. Ants on their own territory or on territories impregnated with metapleural gland extract from workers of their colony, initiate more intraspecific combats than ants on territories of a different colony or on territories without the chemical mark.