Uganda kob prefer high-visibility leks and territories

In lekking species, where males provide estrous females withlittle more than sperm, it has been widely supposed that theonly possible benefits to females of mate choice are genetic.We studied female choice of leks and territories in a reduncineantelope, the Uganda kob (Kobus kob thomasi), and found thatfemales consistently preferred high-visibility mating sites.Leks were elevated and had shorter grass and fewer thicketsthan the surrounding areas. Changes in the number of male andfemale kob on 10 leks were correlated with changes in surroundinggrass height, and both females and males preferred leks withexperimentally reduced grass height over neighboring controls.Within a lek, territory popularity was the primary determinantof male daily mating success, and females preferred territoriesrelatively far from thickets, but removal of thickets did notaffect female territory preferences. Because lion hunting successon kob increases with grass height and thicket density, femalesmay benefit directly from these preferences by reducing therisk of predation.     

The territorial system of the kob antelope (Kobus kob kob) in the Comoé National Park, Côte d'Ivoire

The territorial system of kob antelopes in the Comoé National Park, Côte d'Ivoire, was studied from March 1993 until April 1997. Whereas size and shape of territories remained constant between 1993 and 1994, the number of territories decreased from 1994 onwards. A decline of the population density probably led to the decline in territory numbers and also to variations in size and shape of the remaining territories. The decline of kob numbers is the result of heavy poaching in the study area. Whereas a lekking system was present in the study area prior to 1975 when the population density was approximately 14.4 kobs/km², males switched to the resource defence territorial system present today after the population density decreased to 12.5/km² in 1993 and finally to 2.3/km² in 1997. Compared to other research areas with higher population densities, territories in the Comoé National Park are larger, almost all adult males are capable to defend a territory, fights over territories are rare and loss of territory tenureship is almost exclusively due to the death of the territorial male. We suggest that those differences can all be related to the low population density in the study area.     

Phylogeography, hybridization and Pleistocene refugia of the kob antelope (Kobus kob)

Mitochondrial DNA control region sequences and seven microsatellites were used to estimate the genetic structuring, evolutionary history and historic migration patterns of the kob antelope (Kobus kob). Ten populations were analysed, representing the three recognized K. kob subspecies: K. k. kob in west Africa, K. k. thomasi in Uganda and K. k. leucotis in Sudan and Ethiopia. Despite being classified as K. k. thomasi and being phenotypically identical to the kob in Queen Elizabeth National Park (NP), the Murchison Falls population in Uganda showed high genetic similarity with the phenotypically distinct K. k. leucotis populations in Sudan and Ethiopia. This was regardless of marker type. Pairwise comparisons and genetic distances between populations grouped Murchison with K. k. leucotis, as did the Bayesian analysis, which failed to find any genetic structuring within the group. We propose that the divergent phenotype and life-history adaptations of K. k. leucotis reflect the isolation of kob populations in refugia in west and east Africa during the Pleistocene. Subsequent dispersal has led to secondary contact and hybridization in northern Uganda between lineages, which was supported by high levels of genetic diversity in Murchison. The reduced variability observed in Queen Elizabeth NP reflects a small founder population from west Africa and in part the decimation of Uganda's wildlife during the country's political turmoil in the 1970s. Due to similarities in phenotype and ecology, and the joint evolutionary history of their mtDNA sequences, the taxonomic status of K. k. kob and K. k. thomasi as separate subspecies is called into question.     

The Lek System in Uganda Kob Antelope

The tradition with which both male and female Uganda kob returnto permanently located territorial breeding grounds (TG's orleks), along with the dispersion of individuals in relationshipto a home TG and morphological variation between individualsassociated with different TG's, indicates that the total populationof kob in the Toro Game Reserve and its vicinity is subdividedinto relatively closed breeding units. Mathematical analysesof linear body measurements show significant differences inmorphological features between three demes, not only in averagesbut also in the inter-relatedness of body characteristics, suggestingan underlying genetic integrity within demes. Interdemic geneflow through individuals appears to be inconsequential, butthere may be significant gene flow through the formation oftemporary TG's. Altruistic behavior among territorial males may contribute tokinship selection, and the individual kob behavior in responseto predation suggests that altruism may have a bearing on theregulation of predation. The lek system of social organizationmay be significant in maintaining genetic heterogeneity in thekob antelope, which lives in geographically isolated populationsthroughout its range.     

Large sequence divergence of mitochondrial DNA genotypes of the control region within populations of the african antelope, kob (Kobus kob)

The genetic differentiation among kob populations (Kobus kob) representing two recognized subspecies was examined using mitochondrial control region sequences. Two distinct lineages (estimated sequence divergence of 9.8%) exhibited different geographical distributions and do not coincide with previously recognized ranges of subspecies. The presence of the two lineages was further supported with sequences of mitochondrial cytochrome b gene. One lineage was predominant in the west and southern ranges of the populations studied and the other was commonly found in a more northern distribution (Murchison populations) in Uganda. Murchison and the geographically intermediate Toro populations (Uganda) represented the area of overlap. The existence of the two lineages in the area of overlap is hypothesized to have resulted from a range expansion and secondary contact of the two lineages of kob that evolved in allopatry. The existence of the kob during the Pleistocene offers a plausible explanation for the observed biogeographic pattern. Our mitochondrial data reveal two examples of discordance between a gene tree and presumed species tree as: (i) the two lineages co-occur in the kob subspecies, Kobus kob thomasi (Uganda kob); and (ii) the puku, which was included in the analysis because of its controversial taxonomic status (currently recognized as a distinct species from the kob), is paraphyletic with respect to the kob. Significant degrees of heterogeneity were detected between populations. Relatively high genetic variation was observed in the populations, however, the inclusion of distinct lineages influences the population structure and nucleotide diversity of the kob populations.     

The status and population dynamic of Buffon’s kob (Kobus kob kob,ERXLEBEN 1777) in the Faro National Park,Northern Cameroon

Assessing the population status of wildlife is useful for enhancing biodiversity management strategies in protected areas. This study was carried out within the framework of the Faro National Park (FNP) management plan. The objective was to provide baseline data on the status and population dynamics of the Buffon's kob (Kobus kob kob). The surveys were conducted in the month of June at the beginning of the rainy season. Data were collected along 145 line transects of 2.5 km apart and analysed using Distance 7.2 and Quantum GIS 3.4 software. The Buffon's kob population was estimated to comprise around 4,094 ± 1,303 individuals, with an overall density of 1.24 individuals/km². When compared to results from a study conducted in the year 2000, the concentration of Buffon's kob was higher in the northern part of the national park as opposed to the southern part, as was previously recorded. The population trend shows an extensive decline of approximately 80% compared to records of the year 2000. There was also a weak negative correlation between Buffon's kob density and human activities in the FNP.     

Spatial and temporal habitat use of kob antelopes (Kobus kob kob, Erxleben 1777) in the Comoé National Park, Ivory Coast as revealed by radio tracking

Spatial and temporal habitat use of kob antelopes (Kobus kob kob) have been investigated in the Comoé National Park (Ivory Coast, West Africa) by use of radio telemetry. A total of 23 kob were equipped with radio collars and radio tracked for up to 15 months. Home ranges of males were smaller and those of females larger than expected from theoretical models. Adult males used smaller areas than adult females and did not show seasonal home range shifts. Daily distances travelled did not differ between sexes. Kob walked less during the night than by day and covered shorter distances in the wet season. Whereas an increase in home range overlap between females resulted in higher rates of association among individuals, association of adults of mixed sexes was not correlated with the degree of home range overlap. Territorial behaviour of males and predator avoidance by females are suggested to explain the sex‐specific differences in home range size of adults and the deviation from the predicted sizes. Predator avoidance is presumed as the main reason for the reduced walking distances at night as well as in the wet season. Reproductive behaviour and feeding ecology are assumed to determine the degree of association of conspecifics.     

Correlates of male mating success and female choice in a lek-breeding antelope

We investigated factors underlying variation in male matingsuccess in Uganda kob (Kobus kob thomasi), a lek-breeding antelope.We found that only heavy (and, possibly, relatively old) malesheld lek territories and that female choice was an importantdeterminant of nonrandom mating patterns at leks. Our measureof male mating success was closely related to the historicalpopularity of the territory that a male defended, and individualfemales showed consistent preferences for particular lek territories,despite changes in territory ownership. Male success increasedwith body weight and declined independently of territory effectsduring each bout of lek territory tenure. We also found someevidence that female kob copied one another's choice of matesbecause females arriving at a lek tended to join territoriesthat already had relatively large harems on them. When comparedacross leks, average male mating success increased with leksize. Our results suggest that female kob may use a suite ofmale- and territory-based cues in mate choice at leks and, asa result, mate with particularly large males. However, we wereunable to determine whether female kob gain any direct or indirectbenefits through mate choice at leks.     

Demography of a West African kob (Kobus kob kob) population

The kob (Kobus kob kob) population studied in the Comoé National Park, Ivory Coast, suffered unsustainable losses to poaching before and during the investigation. This in turn did not only lead to low densities but also changed the population composition, resulting in a strong female bias in all age classes except juveniles. The relative rarity of adult males probably had negative effects on the population recruitment. Although mating occurred throughout the year and birth intervals were short, at least in some females, annual birth‐rate was low compared to earlier studies in the same area. Effective conservation measures are urgently needed to ensure the future existence of the studied population.     

Food limitation and demography of a migratory antelope,the white-eared kob

Summary Although it is commonly presumed that many populations of large-herbivores are limited by food availability, supporting evidence is scarce. This hypothesis was investigated in a population of over 800,000 white-eared kob in the Boma National Park region of the southern Sudan. Food availability, body condition, and mortality rates of adults and calves were measured during the dry seasons of 1982 and 1983. Sampled age distributions from both the live population and carcasses were used to calculate age-specific rates of mortality. In 1982, food supplies during the dry season were augmented by substantial rainfall, which produced regrowth of grass in areas that ordinarily had little green forage. As a result, fat reserves declined little, and rates of adult mortality showed no increasing trend. Total adult mortality was 5%. In 1983, there was no rainfall during the dry season and food intake was insufficient to meet the estimated energy requirements of kob. As a result, fat reserves declined and adult mortality rates increased fourfold. Total adult mortality was 10% (equivalent to the recruitment rate of yearling into the population). Calf mortality during the dry season was similar in both years (50%), based on field estimates of mortality rates and calf/female ratios. Lactation throughout the dry season possibly provided a buffer for calves against variations in food availability. The age structure of the live population in 1983 suggests that a drought in 1980 reduced kob numbers by 40%. These results suggest that adult survival is influenced strongly by the availability of food during the dry season. However, the duration of the dry season also plays an important role. During the dry season, declining fat reserves make an increasing proportion of the population vulnerable to mortality. As a result, even moderate droughts may lead to substantial changes in population numbers.     

The Role of Agonistic Sounds in Male Nest Defence in the Painted Goby Pomatoschistus pictus

Animals often vocalize during territorial challenges as acoustic signals may indicate motivation and fighting ability and contribute to reduce aggressive escalation. Here, we tested the function of agonistic sounds in territorial defence in the painted goby. Pomatoschistus pictus, a small vocal marine fish that defends nests during the breeding season. We first measured the number of times a male approached, avoided, explored, entered and exited two unattended nests associated with either conspecific agonistic sounds or a control: silence or white noise. Acoustic stimuli were played back when the male approached a nest. In a second experimental set, we added visual stimuli, consisting of a conspecific male in a small confinement aquarium near each nest. Even though we found no effect of the visual stimuli, the sound playbacks induced similar effects in both experimental conditions. In the sound vs. silence treatment, we found that when males approached a nest, the playback of conspecific sounds usually triggered avoidance. However, this behaviour did not last as in longer periods males visited nests associated with agonistic sounds more often than silent ones. When the control was white noise, we found no significant effect of the playback treatment in male behaviour. Although we cannot exclude the possibility that other sounds may dissuade nest occupation, our results suggest that agonistic sounds act as territorial intrusion deterrents but are insufficient to prevent nest intrusion on their own. Further studies are needed to test the significance of sound production rate, spectral content and temporal patterns to deter territorial intrusion in fish.     

Do male roe deer clump together during the rut?

Movement s an d habitat use of 7 male and 7 female roe deerCapreolus capreolus (Linnaeus, 1758) were studied by radioteleme try from March 1999 to February 2001. Annual and bimonthly home ranges of males were small (ca 10 ha, 95% kernel), with large overlap among individuals throughout the year. Exclusive core areas (ca 0.4 ha, 25% kernel) were concentrated in the forest, a limited and sought-after resource in the study area. The difference in overlap between male exclusive core areas and female home ranges in the pre-rut and rut periods suggested that females made excursions to search for territorial males during the rut Our results support the mating strategy hypothesis of territorial behaviour Different space use patterns occurred between the sexes, with females apparently playing an active role in mate choice by visiting males at clumps of core areas in the forest.     

Observations on the growth rate and development of some East African antelopes

Linear body measurements are presented for two dik-diks, two Uganda kob and three topi calves. Age-weight curves are presented for the dik-diks. Development of characteristics markings is recorded.     

Circulating steroid hormones during rapid aggressive responses of territorial male mountain spiny lizards, Sceloporus jarrovi

Levels of aggression and circulating steroid hormones were monitored simultaneously in free-living male lizards following a staged territorial aggressive encounter with another male. In the first 15 min following the aggressive encounter, the frequency of territorial patroling and the frequency of agonistic and advertisement displays increased four- to fivefold in resident males. In most cases these increases persisted for at least 90 min after withdrawal of the intruder male and probably persisted for the entire day of the encounter. Blood samples collected at 15-min intervals revealed no changes in circulating levels of testosterone or corticosterone while this behavioral change was occurring. Thus, the increase in aggressive behavior that follows a male-male territorial encounter in this species does not appear to be mediated by simultaneous changes in circulating levels of these hormones. Interspecific comparisons suggest that interspecific variation in steroid hormone involvement in rapid aggressive responses may depend on the mating system and the extent of male parental care.     

Short-term changes in plasma levels of hormones during establishment and defense of a breeding territory in male song sparrows, Melospiza melodia

When territorial male song sparrows are captured and removed from their territories, previously unmated and nonterritorial males will take over those vacant territories within 12-72 hr. Plasma levels of testosterone are elevated in these replacement males as well as in their neighbors. Since the latter already have territories, it is suggested that the agonistic interactions over territory boundaries, or behavioral stimuli from challenging males, rather than ownership of a territory per se, stimulates secretion of testosterone. To test this hypothesis further, male song sparrows were challenged by experimental simulation of a territorial intrusion. This procedure involved placing a caged male song sparrow in the center of the subject's territory and playing tape recorded conspecific song through an adjacent speaker. Responding males were then captured at intervals after onset of the intrusion. Plasma levels of testosterone were significantly higher in males exposed to experimental territorial intrusion than they were in controls, supporting the hypothesis that behavioral stimuli emanating from an intruding male can act as supplementary information stimulating secretion of testosterone.     

Effects of Keishi-bukuryo-gan on vascular function and hemorheological factors in spontaneously diabetic (WBN/kob) rats.

Keishi-bukuryo-gan (Gui-zhi-fu-ling-wan) is a formula used for the improvement of blood circulation. Recently it has often also been used for arteriosclerosis. One of the mechanisms involved is thought to be the improvement of endothelial dysfunction, but the details are still unclear. In this study, the effect of Keishi-bukuryo-gan on vascular function and hemorheological factors in spontaneously diabetic (WBN/kob) rats was studied. Rats were given Keishi-bukuryo-gan in chow for 30 weeks. Body weight, blood glucose, endothelium-dependent/-independent relaxation, vasocontraction by free radical-induced and contractive prostanoids, triglyceride, advanced glycation endproduct, lipid peroxides, serum NO2-/NO3- and blood viscosity were measured. The results indicated that Keishi-bukuryo-gan caused a decrease in endothelium-dependent relaxation by acetylcholine to become significantly increased, and vasocontraction induced by free radicals and contractive prostanoids was significantly decreased. Furthermore, serum NO2-/NO3- and blood viscosity were significantly decreased. From these results, it was supposed that Keishi-bukuryo-gan exerted a protective effect on the endothelium. The WBN/kob rat is a useful study model for the complications of human diabetes, and Keishi-bukuryo-gan showed a protective effect against vascular injury in the susceptible rat.     

Habitat use and behavioural ecology of the juveniles of two sympatric damselfishes (Actinopterygii: Pomacentridae) in the south-western Atlantic Ocean

Spatial distribution, microhabitat use and territorial and feeding behaviours were compared between the juveniles of two sympatric territorial damselfishes Stegastes variabilis and Stegastes fuscus on a small tropical reef in the south-western Atlantic Ocean. Juvenile S. variabilis were most abundant at sites subject to stronger hydrodynamics and with mixed benthic cover, whereas juvenile S. fuscus were most abundant at sheltered sites with dense turf algae cover. No differences regarding feeding habits were detected, with both species preferentially feeding on turf algae. Also, despite similarities in territory area and agonistic encounter rates, the identity and proportion of intruders involved in agonistic interactions differed significantly between species. These interdependent traits suggest strong asymmetric competition, with juvenile S. fuscus dominating high-quality sites and evicting juvenile S. variabilis to low quality, marginal areas of the reef.     

Artificial rearing of some East African antelopes

Six topi ( Damaliscus korrigum ), five Uganda kob ( Adenota kob thomasi ) and two kirk's dik-dik ( Rhynchotragus kirkii ) were artificially reared from a few days of age.
Foue kob and four topi were fed first on a humanized milk powder "Lactogen"; all four developed intestinal disorders which in two cases were fatal. The survivors recovered on a diet of pasteurized cows' milk on which they were satisfactorily reared. Two topi were satisfactorily reared on cows' milk from the time of capture.
One dik-dik was reared from two weeks on cows' milk enriched with egg yolk to the composition of eland ( Taurotragus oryx ) milk. weight gain was not significantly different to that of a second dik-dik reared on cows' milk alone.
Causes of ill health and death were: ( a ) dehydration during the first three days of captivity; ( b intestinal disorders during the milk-feeding period; and ( c ) heavy intestinal parasitic infections during the post-weaning period.     

Seasonal dynamics of agonistic displays in territorial and non-territorial males of goitered gazelle

Aggression serves a great variety of social functions, one of which is protection of individual territories from intruders. Territorial males of many antelope species show aggressive noncontact displays, and only rarely fight. It has been suggested that ungulate males tend to have more frequent and longer aggressive interactions with rivals of similar age or social status than with males of dissimilar status. In the present paper, we test whether territorial and non-territorial males behave in a similar manner and avoid fights, and whether or not they preferentially direct aggressive and longer agonistic interactions towards males of similar age or social status, rather than towards other classes of males. We found that territorial males usually avoided straight fights with peers, and instead mainly used noncontact displays in aggressive interactions. In contrast, non-territorial males used fights considerably more often, especially during the onset of territoriality in April to May, when these males had their most frequent aggressive interactions. Territorial bucks aggressively interacted most frequently with non-territorial males and significantly less often with other territorial males, but agonistic noncontact displays between territorial males lasted the longest. In contrast, non-territorial males addressed their aggressive noncontact displays and fights most often to peers and less frequently to sub-adults. Asymmetry in the social status of territorial vs. non-territorial males was likely responsible for the distinctively different agonistic behaviors shown by the two types of males, which in turn are likely due to the different costs and benefits each male can accrue from these aggressive interactions.     

Fire induced changes in the foraging behaviour of impala Aepyceros melampus in Lake Mburo National Park, Uganda

The impact of fire on the foraging behaviour of impala (Aepyceros melampus), was studied in the Lake Mburo National Park, Uganda. Two indices of foraging efficiency were used to establish differences in feeding behaviour in burnt and unburnt control areas. These are acceptable grass/browse abundance (AGA/ABA), expressed in terms of feeding time achieved per 50 steps and food ingestion rate (FIR), expressed as the cumulative percentage. Accumulation of above ground grass biomass was also measured in burnt and control areas. After burning, the grazing efficiency remains constant throughout the dry season, while the browsing time achieved per 50 steps decreases drastically. In the control areas AGA decreased with increasing length of the dry season while ABA increased. When expressed in terms of cumulative percentage (FIR), the results show a significant increase of 31% in foraging time spent grazing and a 24% decrease in foraging time spent browsing, in burnt areas. The results confirm the classification of impalas as intermediate or mixed feeders with a distinct preference for grass. Impala foraging patterns after burning are discussed and compared with investigations on the effect of burning on the behaviour of impalas and Buffon's kob (Kobus kob kob) in other areas of Africa.