Scent marking in a territorial African antelope: I. The maintenance of borders between male oribi

Scent marking is ubiquitous among the dwarf antelope and gazelles of Africa, but its function has been the subject of debate. This study examined preorbital gland scent marking in the oribi, Ourebia ourebi, a territorial African antelope. Several hypotheses for the function of scent marking by territorial antelope were tested with observational data. Of these, the hypotheses that scent marking is driven by intrasexual competition between neighbouring males, and that marks serve as an honest advertisement of a male's ability to defend his territory from rivals, were supported best. Thirty-three territorial male oribi on 23 territories marked most at borders shared with other territorial males, and territorial males marked more often at borders shared with multimale groups than at borders shared with a single male. This suggests that males perceived neighbouring male groups as a greater threat to territory ownership than neighbouring males that defended their territories without the aid of adult subordinates. Marking rate was unrelated to territory size or the number of females on adjacent territories, but males with many male neighbours marked at higher rates than those with fewer male neighbours. These results suggest that the presence of male neighbours has a greater effect on the scent marking behaviour of territorial antelope than has been considered previously. Copyright 1999 The Association for the Study of Animal Behaviour.     

Effect of auxiliary males on territory ownership in the oribi and the attributes of multimale groups

I observed free-ranging oribi, Ourebia ourebi, in Serengeti National Park, Tanzania, to determine whether group formation by males provides evidence for cooperative territory defence, a behaviour that is rare among male vertebrates. Socially dominant males that shared territories with subordinate auxiliary males were replaced by rivals less often than males that defended territories without auxiliary males. Auxiliary males marked territories with preorbital glands, dung and urine, and territories defended by male groups were marked more thoroughly than those defended by single males. Fifteen of 24 (62.5%) auxiliary males whose histories were known were born on territories defended by males that probably were their fathers. But 37.5% of auxiliary males probably were unrelated to dominant males, because male groups also formed when territory owners accepted adult male immigrants as subordinates, and when owners allowed young males to remain philopatric after evicting a male likely to have been the young male's father. All males in groups probably had some mating access to females, but dominant males may have minimized matings of auxiliary males by guarding fertile females. These results suggest that auxiliary male oribi aided dominant males in territory defence, and that dominants traded off the risks of losing matings to auxiliaries, or being overthrown by them, in exchange for a reduction in their chance of being evicted by rival neighbours or immigrants. Copyright 1999 The Association for the Study of Animal Behaviour.     

Temporal and Spatial Distribution of Male Scent Marks in the Polygynous Greater Sac-Winged Bat

Scent marks are relatively long-lived signals that can be perceived by conspecifics when the producer is absent. Therefore, it is often not obvious to whom the signal is directed. In daytime roosts of the polygynous greater sac-winged bat, males scent mark territories with facial gland secretions. Territories are a valuable resource for males, as they offer exclusive courtship opportunities, which results in increased male reproductive success and, consequently, increased male–male competition over territories. The information encoded in male scent marks could, therefore, be either directed at females as part of an olfactory courtship display or at male competitors as part of territorial behaviour. We expected territorial males to scent mark in the morning, shortly before females return to the territory and close to female roosting sites, if scent marks are directed at females as part of the courtship display. And we expected harem males to scent mark at the territory boundaries, where male–male encounters are most likely to occur, if scent marks are directed at male competitors. We found that males marked more frequently in the afternoon, at a time when all females have already left the territory, and harem males marked at the territory boundaries and not inside their territory in the area where females roost. At boundaries males fan volatiles from specialised wing sacs towards competitors outside the territory. Scent marking of male Saccopteryx bilineata might therefore be congruent with the assessment-hypothesis, which states that scent marks offer intruders the possibility to make an olfactory assessment of the territory owner without direct physical interaction. Thus, scent marks of male S. bilineata are most likely influenced by male–male competition and not by female choice.     

Female preference for males that have exclusively marked or invaded territories depends on male presence and its identity in the subterranean rodent Ctenomys talarum

Territorial scent‐marking provides chemical records of male competitive interactions that are available to females, who gain valuable information to assess and identify best quality partners. In this context, the solitary subterranean rodent tuco‐tuco (Ctenomys talarum) offers excellent possibilities to evaluate the effects of male exclusive scent‐marking of territories on female assessment. For evaluation, we used wild caught individuals of C. talarum, manipulated their scent marks within the territories in captive conditions and staged preference tests where females were able to choose between exclusive and invaded territories. The evaluation was performed in two scenarios considering the identity of the intruder scent mark: territories invaded by a strange male and territories invaded by a neighbour male. Females investigated the chemical cues deposited on the substrate of the exclusively marked territory more frequently. Next, females displayed equal interest to scent samples of both males presented in a Y‐maze. Finally, when females could gain access to both individually isolated males and their scent‐marked territories, they spent more time within invaded territories despite they visited them with the same frequency. Moreover, females tried to get in contact by scratching the mesh of the owner of the invaded territory more frequently. We found that females of C. talarum evaluate the homogeneity (exclusiveness) of scent marks within a male territory and then show preferences in relation to the identity of the intruder's scent –whether strange or neighbour.     

Sex differences in scent marking in Propithecus edwardsi of Ranomafana National Park, Madagascar

In this study we compared the scent-marking rates of females with those of males. Specifically, we examined the ability of season, dominance status, and natal status to explain the frequency of scent marking in female sifakas living wild in Ranomafana National Park, Madagascar, and compared the results with those published for males [Pochron et al., American Journal of Primatology, in press]. We also sought to determine whether vulnerability to infanticide affects marking frequency in adults of either sex, and whether female reproductive status affects female marking behavior. We found that males marked at twice the rate of females, and like males, females in single-female groups marked at the highest rates. Dominant females and non-natal females marked at higher rates than did subordinate females and natal females, a pattern also seen in males. This suggests that scent marks may convey important information about status. Neither females nor males varied their marking frequency with the presence of vulnerable infants. Females did not alter marking frequency with reproductive state, and like males, they marked at higher rates in the period prior to the mating season than they did in the mating season itself. This implies that females may use scent marks more for intrasexual aggression or territoriality than for mate attraction.     

A comparison of scent marking between a monogamous and promiscuous species of peromyscus: pair bonded males do not advertise to novel females

Scent marking can provide behavioral and physiological information including territory ownership and mate advertisement. It is unknown how mating status and pair cohabitation influence marking by males from different social systems. We compared the highly territorial and monogamous California mouse (Peromyscus californicus) to the less territorial and promiscuous white-footed mouse (P. leucopus). Single and mated males of both species were assigned to one of the following arenas lined with filter paper: control (unscented arena), male scented (previously scent-marked by a male conspecific), or females present (containing females in small cages). As expected, the territorial P. californicus scent marked and overmarked an unfamiliar male conspecific's scent marks more frequently than P. leucopus. Species differences in responses to novel females were also found based on mating status. The presence of unfamiliar females failed to induce changes in scent marking in pair bonded P. californicus even though virgin males increased marking behavior. Pair bonding appears to reduce male advertisement for novel females. This is in contrast to P. leucopus males that continue to advertise regardless of mating status. Our data suggest that communication through scent-marking can diverge significantly between species based on mating system and that there are physiological mechanisms that can inhibit responsiveness of males to female cues.     

Scent‐marking behavior by subordinate Eurasian beavers

Chemical communication by scent‐marking is widespread among mammals and can serve different purposes, such as territory demarcation, mate attraction and self‐advertisement. In this study, we examined scent‐marking behavior by subordinate Eurasian beavers (Castor fiber) in a population in southeast Norway. We conducted scent experiments in 18 family groups, simulating a territory intruder using experimental scent mounds (ESM). In total, we recorded 196 territorial reactions (destroying and/or overmarking of scent mounds). Subordinates contributed 14% of all territorial reactions and first overmarked 12% of the ESM, and the number of subordinates in the family group did not increase the total number of territorial reactions. This suggests that the contribution by subordinates plays a minor role in territorial defense. The number of territorial reactions by subordinates was positively related to the age of their parents, suggesting that subordinates might take over territorial duties with increasing parental senescence, likely because they have increased chances of inheriting the territory. Increased experience in territorial activities possibly helps subordinates to successfully gain and defend a territory of their own.     

The scent-marking behaviour of the spotted hyaena Crocuta crocuta in the southern Kalahari

All hyaenas scent mark their territories by smearing grass stems with paste from their subcaudal scent glands and by depositing faeces at latrines, but they adopt different strategies in terms of how they disperse these scent marks in their territories. For example, brown hyaenas living in the southern Kalahari deposit pastes and latrines throughout the whole of their territory, while spotted hyaenas living in the Ngorongoro Crater of East Africa place their scent marks strictly along the territorial borders. We have argued elsewhere (Gorman & Mills, 1984) that these different strategies are not species-specific but are instead adaptive responses to local conditions. Here, we use data from a population of spotted hyaenas, living in small clans and large territories in the Kalahari, to test the hypothesis that hinterland marking is a response to the problem of marking a very large territory with a limited amount of scent and within a limited time budget.     

Defence, intrusion and the evolutionary stability of territoriality

Territorial behaviour can only be adaptive if its costs are outweighed by its benefits. Territorial individuals incur costs by defending their territories against intruders. Usually these intruders are assumed to be non-territorial floaters attempting to take over the whole territory or neighbours trying to extend the borders of their own territory. We instead investigate how costs and benefits of territorial behaviour are affected by neighbours which invade to steal resources on a territory.We show analytically that in the absence of defence intrusion into neighbouring territories always pays and that even if territories are defended intrusion levels can still be high. Using a more detailed simulation model we find that territory defence usually disappears from the population even if owners have a strong advantage over intruders in terms of fighting costs or foraging efficiency. Defence and thus territoriality can only be evolutionarily stable if fighting costs for the intruder relative to the productivity of the territory are very high or if crossing the borders between territories carries additional costs.Our results show that stealing of resources by neighbours can have a considerable effect on the evolutionary stability of territory defence and thus territoriality itself. A more mechanistic model of territorial behaviour is needed to incorporate these kinds of mechanisms into a general theory on the evolution of territoriality.     

The long shadow of senescence: age impacts survival and territory defense in loons

Senescence, increased mortality that occurs among animals of advanced age, impacts behavior and ecology in many avian species. We investigated actuarial, reproductive, and behavioral senescence using capture, marking, and resighting data from a 26‐year study of common loons Gavia immer. Territorial residents of both sexes exhibited high annual survival (0.94) until their mid 20s, at which point survival fell to 0.76 and 0.77 in males and females, respectively. Sexual symmetry in actuarial senescence is somewhat surprising in this species, because males make a substantially greater investment in territory defense and chick‐rearing and because males engage in lethal contests for territory ownership. Survival of displaced breeders (0.80) was lower than that of territorial residents in both young and old individuals. Old males and females also experienced slightly higher annual probability of eviction (0.16 for males; 0.17 for females) than prime‐aged breeders (0.13 for both sexes), indicating senescence in territory defense. Prime‐aged males reclaimed territories at a high rate (0.49), in contrast to females of the same age (0.33). However, old males resettled with success (0.35) similar to old females (0.31), suggesting that males decline in competitive ability as they age. Nonetheless males, but not females, showed an apparent increase in breeding success over the entire lifetime, a possible indication that very old males make a terminal investment in reproductive output at the cost of survival.     

Mate-locating behavior of the butterfly Lethe diana (Lepidoptera: Satyridae): do males diurnally or seasonally change their mating strategy?

The mate-locating behavior of male butterflies has been classified into two major types, territorial and patrolling. Territorial males defend a specific site, whereas patrolling males fly around a wider area without having to defend a site. In this study, I investigated the use of these tactics by males of the satyrine butterfly, Lethe diana. A previous study suggested that the males of L. diana change their mate-locating behavior during the day (they patrol in the morning and defend territories in the afternoon) and that patrolling is the primary mating strategy, whereas defending territories is a supplementary one. In the present study, I found that the daily activity pattern of the males of L. diana was similar to that described in the previous study: males often flew around in the morning and competed for territories in the afternoon. However, contrary to the previous study, all courtships and copulations were performed within male territories during their territorial activity. Closer observations revealed that copulations found in male territories were achieved by the owner of the territory. Males tended to feed in the morning, suggesting that the males flying in the morning searched for food rather than females. I conclude that territory holding is the primary male matelocating tactic in L. diana. I further found that, in summer, males exhibited territorial behavior later than in spring or autumn, which may be a strategy for preventing heat stress.     

An Extreme Case of Interspecific Territoriality: Male Anthidium manicatum (Hymenoptera,Megachilidae) Wound and Kill Intruders

Anthidium manicatum males defend patches of flowering plants as mating territories and copulate with females that enter the territory to obtain nectar or pollen. Territorial males defend their territories not only against conspecific males but also against many other insect species that attempt to utilize the flowers inside the territory. In our study area, a territorial male defended its territory against conspecific males on average only twice per h but it attacked other species of insects on average 70 times per h. Territorial males distinguished between different species of intruders and attacked them unequally. During the hour following experimental removal of the territory holder the number of intruders of some insect species tripled but the number of intruders of those species that were rarely attacked remained approximately the same. A. manicatum males, but not females, bear long spines on the last two segments of the abdomen. Territorial males rammed intruding insects at high speed and shortly before the moment of impact they curved the abdomen forward to hit with the spines. Intruders could be seriously damaged or killed by these attacks. Abdominal spines of A. manicatum males may have evolved as weapons to increase the effectiveness of interspecific territoriality.     

Territorial behavior of both sexes in the water striderMetrocoris histrio (Hemiptera: Gerridae) during the mating season

Territorial behavior of overwintered individuals of Metrocoris histriowas observed in an upstream area. Adults of both sexes held territories, but male territories were larger than those of females. Severe competition occurred among males for territories which give them access to receptive females. The effects of male body length and midleg length on establishment of territories were not significant. The effect of female midleg length on activity of females entering preferred foraging sites was equally not significant. Instead, territorial behavior increased with male age and males stayed longer at prime sites. Females of intermediate age were likely to occupy prime sites. Females had longer territory residence time than males. The sexes were dimorphic with respect to midleg length, and dimorphism in M. histriomay be related to a difference in life history, in that sexual selection may be relaxed due to asynchronous adult emergence patterns.     

The adaptive significance of non-contact mate guarding by males of the dragonfly,Nannophya pygmaea Rambur (Odonata: Libellulidae)

InNannophya pygmaea, ovipositing females were frequently disturbed by conspecific males. Disturbed females often copulated with one of these males or flew away from the pool. Females which flew away from the pool due to male disturbance often returned later the same day and mated with different males. A territorial male would guard his ovipositing mate by hovering above her, presumably trying to prevent her from moving out of his territory. A non-territorial male would also guard his mate in a similar way, both at a vacant water area which was not occupied by any territorial males, or within the territory of a resident male. In addition, both territorial and non-territorial males chased intruding males in an attempt to prevent their mates from being stolen. Territorial males defended their mates better than non-territorial males. Both males and females often mated more than once in the course of a single day. Some territorial males copulated with a new female while another mate oviposited in their territories. This observation supported the “multiple mating hypothesis” proposed by Alcock (1979) and Uéda (1979) but other evidence suggested that this is an inadequate explanation for the non-contact guarding ofN. pygmaea.     

Long-range call use in dominance-structured Crested Tit Parus cristatus winter groups

In this study on free-ranging Crested Tits Parus cristatus , I examine the relationship between social dominance and the frequency of use of long-range communication calls. Calling rates of trills were highest among socially dominant individuals and they gave more calls when close to the boundary of their territories. Dominant females uttered fewer calls than their mates. However, they gave significantly more calls than subordinate males and subordinate females, the latter calling least. A removal and playback experiment revealed a relationship between the utterance of trilled calls and the defence of the winter territory in the Crested Tit. Although territorial vocalizations could incur costs, territorial individuals may gain from improved winter survival by decreasing the risk of food stealing by Crested Tits from adjacent territories.     

The Behavioral Significance of Male Body Size in the Tarantula Hawk Wasp Hemipepsis ustulata (Hymenoptera: Pompilidae)

Large males of the tarantula hawk wasp Hemipepsis ustulata appear to have an advantage in the competition for mates. Large males are more likely to acquire perch territories used to scan for incoming receptive females and territorial males appear more likely to mate than non‐territorial males. In addition, among the males that do secure a mate, those that intercept a female on a territory are larger than those that do so elsewhere. Despite the mating advantages apparently enjoyed by larger males of this species, average male size has remained essentially constant over the last 25 yr. Moreover, larger males are not seen to employ certain competitive tactics that might otherwise enhance their reproductive success. Thus, larger males did not preferentially visit the most popular landmark territory compared to a site that attracted fewer visitors overall. Nor were larger males more likely to return to potential territories after marking, capture, and release, either immediately or on a subsequent day. Finally, although large males made up a significantly greater proportion of the males captured at two territories as the 2005 flight season progressed, over all the years of the study, receptive females have not been concentrated in the latter part of the flight seasons.     

Why are Male Columbian Ground Squirrels Territorial?

Male territorial defence is a component of many vertebrate mating systems and is often regarded as a tactic for acquiring mates. Traditionally considered within the context of overt site‐specific defence, territoriality actually may have several components which encompass a variety of behavioural tactics (e.g. post‐copulatory mate‐guarding, defence of resources that females need, defence of area around females) that underlie a mating system. The purpose of our study was to evaluate such influences on the territorial behaviour of male Columbian ground squirrels in southwestern Alberta, Canada. Males were dominant and territorial if they defended a minimum convex polygon activity range by chasing other males more within the activity range than they were chased. Subordinate males had no territory and were chased throughout their ranges, but they competed for mates by increasing chases in their activity range when nearby females were oestrous. Dominant males exhibited conditional breeding tactics, tending to chase other dominant males from their territory when nearby females were oestrous, but travelling outside their activity ranges to chase subordinate males when females were not oestrous. Although females mated first with a dominant male on whose territory they resided (and in order from oldest to youngest if several territories overlapped), mating pairs were not exclusive, as females usually mated with additional males. Males also guarded females after copulation and defended females directly just before oestrus, rather than defending territory per se during those times. Thus, males possess a repertoire of behaviours that complement site‐specific territoriality, and territory ownership serves to facilitate a first mating with females that live on the territory.     

Sex, drugs and mating role: testosterone-induced phenotype-switching in Galapagos marine iguanas

Males of many vertebrate species have flexible reproductivephenotypes and must decide before each mating season whetherto adopt sneaker, satellite, or territorial mating tactics.How do males gauge their abilities against others in the population?We tested experimentally whether hormone–behavior feedbackloops allow Galapagos marine iguana males to activate theirthree behavioral phenotypes as predicted by the relative plasticityhypothesis. Territorial males defended small mating areas andhad significantly higher plasma testosterone (T) levels (75± 11 ng/ml) than did satellite males that roamed aroundterritories (64 ± 8 ng/ml) or sneaker males that behavedlike females within territories (43 ± 11ng/ml). In territorialmales, temporary pharmacological blockade of T slowed head-bobpatrolling, decreased territory size threefold, and reducedthe number of females on territories 20-fold. This supportsprevious data that females may gauge male attractiveness byusing head-bob patrolling, here shown to be a T-dependent trait.Control-treated neighbors reacted to the weakening of T-blockedmales by increasing head-bob rate fivefold and territory size1.6-fold, and female numbers increased 2.5-fold. Unmanipulatedor control-injected males remained unchanged. Behavioral effectswere partly reversed after 7 days. T injections induced satellitemales to establish temporary territories, even at unconventionallocations. Some T-boosted satellite males suffered serious fightinginjuries. T-injected sneakers left female clusters and behavedlike larger satellite males that roam around territories. Thus,territorial and mating tactics are activated by T, but experimental(de-) activation at the wrong ontogenetic stage is costly: manipulatedmales switched phenotype but thereby lowered their access tofemales. We hypothesize that T levels of males that are basedon early-season behavioral interactions influence a males' subsequentphenotypic role.     

Seasonal and sex differences in urine marking rates of wild red foxes Vulpes vulpes

Understanding the role of urine marking in the territorial systems of wild mammals can be difficult, especially for nocturnal cryptic species. Even for common species, such as the red fox Vulpes vulpes, a comprehensive analysis of seasonal and sex differences has not been carried out. Using 6 years of infra-red video monitoring, we compared marking rates between months and between sexes. Urine marking was significantly lower during summer (June–August). Males urine marked significantly more frequently than females during late summer and autumn, but not winter. Males marked more frequently than females also during March. There was no increase during the breeding season for either sex. Our results correlate with previous partial data but demonstrate how urine marking rates vary across the year. They also further support the greater role of males in fox territorial maintenance. Urine marking is lowest during summer when territorial intrusions are least, whilst the higher male urine marking rate in March reflects the period when females are denning. Overall, our results provide the first comprehensive analysis of red fox urine marking rates, contributing to a greater understanding of territoriality and olfactory communication.     

Population density,resource patterning,and territoriality in the Everglades pygmy sunfish

The means by which pygmy sunfish compete for food are influenced by the density of the population and the dispersion of the prey as well as by the sex and dominance status of the individual. At all densities when the prey were predictably located in a central clump, males established territories. When prey were dispersed randomly in both the high and low density population, males abandoned territorial behaviour and, like females, swam freely about the aquaria. Only in the intermediate density populations did the males maintain territories and continue to defend resources. Development of a simple cost-benefit model shows that male territorial behaviour is governed to a large extent by economic considerations. Despite these overall patterns, differences in competitive strategies were observed within populations. Dominant individuals tended to possess territories nearest the central patch of prey, and use the most intense and physiologically exhausting displays. Only under the most stressful conditions did they acquire significantly more food than subordinates, and even then these benefits were not translated into increased growth, largely because dominant fish engaged in disproportionately more energy-consuming contests.