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.     

Scent marking in a territorial African antelope: II. The economics of marking with faeces

Faeces may be ideal substances for scent marking because they have a minimal energetic cost to the signaller. However, marking with faeces is also constrained by the animal's ability to produce faeces. This study examined whether limits on the volume of faeces produced by oribi Ourebia ourebi, in Serengeti National Park, Tanzania, caused territorial males to regulate their output and prioritize the placement of faecal marks. Territorial males marked with faeces more often, and with a smaller volume per defecation, than did juvenile males and females. Territorial males also defecated only on established dung middens along borders shared with other territorial males or on top of a female's urine and faeces. In contrast, juvenile males and females defecated randomly with regard to their location in territories. Territorial males with larger harems marked with faeces at higher rates and less volume than males with few or no females. This difference suggests that when males overmark female excretions they reduce the amount of faeces available for marking other preferred sites, such as along territory borders shared with other males. Dominant males with adult subordinates marked with faeces less often, and with a greater volume per mark, than males that defended territories without the aid of subordinates. Dominant males also reduced the volume of marks less as the number of females on their territory increased than did males without subordinates. Territories occupied by more than one adult male also were marked with faeces at higher rates, and with marks of greater volume, than territories held by single males. These results suggest that the presence of subordinate males reduced the demand on dominant males to regulate the volume and placement of faecal marks. Overall, these results suggest that territorial male oribi regulate their faecal marking behaviour in response to a limited supply of faeces. Copyright 1999 The Association for the Study of Animal Behaviour.     

The social organization of feral peafowl

Peafowl are usually reported to have a mating system based on harem defence by adult males. In a small feral population near Oxford, males defended small (<1 ha) territories while females remained in one flock that ignored male territory boundaries. After mating, females become solitary. At no time did a female associate selectively with one male or remain within his territory, nor did males attempt to follow or guard female groups. Two out of four males were seen to mate. These differed from the other two in being neither very old nor very young; they held territories smaller than that of the young male and were no larger or longer-tailed. However, they spent more time displaying. We suggest that peafowl have a mating system similar to a lek: males defending small, clumped territories visited by females for mating.     

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.     

Dispersal and philopatry in the European badger, Meles meles

In comparison with other carnivores, European badgers, Meles meles L., show an unusually high degree of natal philopatry. In this paper, we present data on temporary and permanent movements between groups, in both male and female badgers, in a moderately high density population. A relatively small proportion of males dispersed, alone, to neighbouring territories. Dispersing males were larger than those remaining in their natal groups, and following dispersal they had higher testosterone titres and maintained testicular activity for a greater part of the year. Circumstantial evidence suggests that immigrants were the principal breeding males in their new territories. Dispersal was slightly more common in females, which dispersed away from large groups, where their chances of breeding were relatively low. Females dispersed in coalitions of 2–3, over longer distances, to territories occupied by single females. Resident females disappeared following the arrival of the immigrants, suggesting that territory 'takeovers' may have occurred. Members of both sexes also made temporary 'visits' to neighbouring territories, probably to obtain extra-group matings. Comparison with other badger populations suggests that the frequency of male dispersal declines at high population densities. In contrast, there is no effect of density on female dispersal, which occurs only rarely in some other populations. We suggest that the pattern of female/female competition is too complex to be explained solely in terms of variation in population density.     

Determinants of territory size in the pomacentrid reef fish,Parma victoriae

Summary Factors governing the size of territories defended by the pomacentrid reef fish, Parma victoriae, were investigated, prompted by contradictory predictions in the literature concerning the effects of food supply and competitors. Observations were carried out over the non-breeding period (March–October) on a medium density population in which territories were partially contiguous. The territory size of adult fish varied between 3 and 26 m², and was inversely correlated with local densities of conspecifics. The same range in territory size was found for both males and females, which did not differ in the time they spent on territory defence and foraging activities. No correlation existed between territory size and the abundance of algal food, body size, age or time spent on territory defence. Also, there was little variation in territory size over time, despite seasonal changes in the abundance of food algae.Experimental reduction of food supplies on isolated territories of males and females had no effect on territory size. In a higher density habitat an experiment was carried out in which population density and food abundance were simultaneously manipulated. This showed that territory size was primarily determined by intraspecific interactions, as territories exhibited considerable increases in size upon removal of neighbours. No changes in the size of defended areas resulted from either artificial increases or decreases of food levels. There were also no changes in the time spent on defence of territories, foraging time or feeding rates associated with food manipulations or territory expansion, which suggested that food was not a limited resource. This conflicted with current theories proposed to explain territory defence and expansion. It is hypothesized that intraspecific interactions constrain territory size well below the optimum in terms of the abundance of preferred food algal species.     

Mate choice by marsh wrens: the influence of male and territory quality

If females choose breeding situations to maximize their fitness, then those features of the male and/or territory that are important in mate selection by females should affect female fitness, be assessable prior to mating, and vary among males. The purpose of this study was to identify characteristics of male quality and territory quality that fit these criteria for marsh wrens Cistothorus palustris. The male's contribution to nest defence appeared not to affect female success or choice. However, females that received male assistance with feeding young produced more and heavier fledglings than females without assistance. Males that fed young did not attract more mates. Few males in this population fed young, and no relationship was found between feeding effort and physical or behavioural features of the male. Results of multivariate analyses suggest that, within sites, the measures of territory quality used here cannot explain the variance in the number of young fledged per female or male harem size. The examination of arbitrary territories showed that male pairing success, female settlement order and predation patterns were not significantly correlated between years. The results suggest that territory quality does not influence female success or choice. These results are discussed in the light of earlier attempts to relate features of males and territories to mate selection by female passerines.     

The influence of age and experience with conspecifics on territorial behavior inDrosophila melanogaster

Drosophila melanogastermales initiated aggressive behavior toward other males and defended territories several hours after they were able to court and mate females. Males that were 3 days or more posteclosion were more successful at holding territories than younger males. Three-day-old males established territories more readily and escalated more often against territory residents than males that were 1 day old. Residents did not usually force young males from territories until they were a few hours posteclosion. The development of territorial behavior was not affected by familiarity or prior exposure to females. Males held in isolation established territories more quickly and behaved more aggressively than males held in groups. Males that previously held territories were more likely to reestablish them after a disturbance.     

Reproductive parasitism: male and female responses to conspecific and heterospecific intrusions at spawning in a mouth‐brooding cichlid Ophthalmotilapia ventralis

A rare form of alternative reproductive behaviour without simultaneous parasitic spawning was observed in Ophthalmotilapia ventralis, a lekking mouth‐brooding cichlid from Lake Tanganyika. Floater males attempted to sneak opportunistically into the territory to actively court the female, while the owner (bourgeois male) defended the territory against other potential intruders. Floater males had more body fat than territory owners and generally higher condition factors. In field experiments, the response of bourgeois males and courted females was tested towards floaters and egg predators (a catfish Synodontis multipunctatus) present in the territories. Territory owners responded aggressively particularly to floaters, and female responsiveness to bourgeois male courtship tended to decline when floaters were present. The potential influence of reproductive parasitism on sexual selection in mouth‐brooding cichlids is discussed.     

Effects of Exogenous Androgen and Antiandrogen on Territorial and Nonterritorial Red-winged Blackbirds (Aves: Icterinae)

We investigated the role of testosterone (T) in territory establishment and maintenance in male red-winged blackbirds (Agelaius phoeniceus) by implanting exogenous T or pharmacological agents that block the action of T in nonterritorial floaters and territory owners. Floaters with artificially elevated plasma T levels were unable to obtain territories. Territory owners implanted with T did not expand their territories, although they engaged in more aggressive behavior than did control males. Flutamide, which binds to T receptors in target areas, had no effect on territoriality. However, most territory owners given a combination of flutamide and ATD, an aromatization blocker, lost portions of their territories even though they actively defended them. Our results 1) suggest that, although T influences aggressive behavior, elevated plasma levels alone are insufficient to overcome previously-established social relationships between territory owners or between owners and floaters; 2) indicate that impairing the action of T leads to reduced abilities of territory owners to maintain territories against vigorous challenges: and 3) support recent findings that T acts on reproductive behavior in birds through both androgenic and estrogenic metabolites.     

The role of territory settlement,individual quality,and nesting initiation on productivity of Bell's vireos Vireo bellii bellii

Variation in habitat quality among territories within a heterogeneous patch should influence reproductive success of territory owners. Further, territory settlement order following an ideal despotic distribution (IDD) should predict the fitness of occupants if territory selection is adaptive. We recorded settlement order and monitored nests in territories occupied by individually marked Bell's vireos Vireo bellii bellii across a range of shrubland habitats in central Missouri, USA. We used an information theoretic approach to evaluate multiple hypotheses regarding the relationship between territory settlement order and seasonal territory productivity (productivity), which we define as the number of young fledged from all nest attempts in a territory. Territory settlement order and arrival date were not analogous and later arriving males displaced early settlers in 13 of 49 territories. Settlement order and lay date together were the best predictors of a territory's productivity; productivity decreased 2.08 young from earliest to latest settlement rank and lay date. Males that defended the same territory in successive years occupied territories with earlier settlement dates, but we found little evidence that age or prior ownership influenced productivity. Territory selection by male Bell's vireos was adaptive because males preferred to settle in territories that had high seasonal offspring production, but even though settlement rank was linked to territory quality, high productivity was only realized on high quality territory when also linked to early nest initiation date. While settlement rank was related to territory quality, obtaining a high quality territory had to be combined with early nest initiation to maximize productivity. We found support for the IDD hypothesis because the highest quality territories, (i.e. most productive), were settled earlier. Research that identifies high quality habitat by linking individual fitness with habitat characteristics may elucidate the importance of habitat quality, individual experience and temporal factors to productivity of Bell's vireos.     

The role of male territories in the mating system of the Yellow-shouldered Widowbird Euplectes macrourus

The territorial system and breeding biology of the Yellow-shouldered Widowbird Euplectes macrourus (Ploceidae) was investigated in western Kenya. Yellow-shouldered Widowbirds had a resource-defence polygynous mating system: males defended large (mean = 0.95 ha) territories and built the coarse framing for the nests in tall grass. Males had up to five females nesting per territory. Females provided nearly all parental care except for a territorial male seen feeding a fledgling: the first observation of paternal care in the wild for this genus. There was considerable variation in territory size, but the cause of this variation remains unknown: territory size was not related to potential indicators of territory quality, such as grass height and abundance, did not relate to male morphology (mass, size and ornament size) or territorial behaviour (boundary displays and singing) and did not affect female preferences. Although resources (territories and nests) were defended by the males, observations that males frequently fed outside their territories and formed communal roosts during the breeding season suggest that this species represents a transitional stage between typical resource-defence polygyny and lek breeding.     

Access to mates in a territorial ungulate is determined by the size of a male's territory, but not by its habitat quality

1. Territoriality is commonly associated with resource defence polygyny, where males are expected to gain access to females by anticipating how resources will influence female distribution and competing for resource-rich sites to establish their zone of dominance. 2. We tested this hypothesis in European roe deer (Capreolus capreolus) by simultaneously assessing the influence of resources on female distribution and the influence of female distribution on male distribution and breeding success using paternity analyses. 3. Females did not fully distribute themselves among male territories in relation to resources. As a result, relative female abundance in a male's territory depended on territory size, but not on its habitat quality. In turn, relative female abundance in a male's territory determined, at least partially, his breeding success. 4. Interestingly, male territory size, and hence access to females, was partly determined by male body mass (all males) and by residual antler size (subadults only). The latter result suggests that large antlers may be important to young males for establishing their first territory, which is then usually retained for all subsequent reproductive seasons. 5. To conclude, although territoriality of male roe deer has certainly evolved as a tactic for ensuring access to mates, our results suggest that it does not really conform to a conventional resource defence polygyny strategy, as males seem to gain no obvious benefit from defending a territory in an area of high habitat quality in terms of enhanced access to mates. 6. This may explain the stability of male territories between years, suggesting that male territoriality conforms to an 'always stay' and 'low risk-low gain' mating strategy in roe deer.     

Increased energy investment in testes following territory acquisition in a maternal mouthbrooding cichlid

Underwater observations conducted in Lake Tanganyika showed that males of a maternal mouthbrooding cichlid, Petrochromis fasciolatus, defended a mating territory for at least several months, but left at approximately noon every day. After the experimental removal of males from their territories, new owners occupied the vacated territories within several days. New owners exhibited higher body-condition factors and fat indices than the original owners. These results suggest that the new owners had not previously occupied a territory, considering the physical exhaustion of owners owing to the energy expenditure on territory maintenance and mating behaviors and a limited time for feeding. Original owners had heavier testes than new owners, despite similar body sizes. This disparity in testis weight suggests that energy investment in testes increases following territory acquisition. Among males that newly occupied a territory during the observation period, larger individuals occupied territories sooner, suggesting that large body size facilitates competition for territory. It is concluded that energy investment in testes is delayed for somatic growth until territory acquisition.     

Male dimorphism, territoriality and mating success in the tropical damselfly, Paraphlebia zoe Selys (Odonata: Megapodagrionidae)

The tropical damselfly Paraphlebia zoe has two male morphs: a black-winged (BW) male which is associated with territorial defense of oviposition sites; and a hyaline-winged (HW) male similar in appearance to females, and, compared to the black morph, less frequently found defending territories. In a wild population of this species, we first assessed the relationship between phenotypic traits [male morph, size and territorial status (being territorial or non-territorial)], their role on mating success, and the degree to which a particular territory may contribute to male mating success. Second, to relate a physiological basis of being territorial we compared both morphs in terms of muscular fat reserves and thoracic muscle, two key traits related to territory defense ability. Males of both morphs defended territories although the BW males were more commonly found doing this. BW males were larger than HW males and size predicted being territorial but only within HW males (territorial males were larger) but not in BW males. Male mating success was related to territorial status (territorial males achieved a higher mating success), but not to morph or size. Furthermore, territory identity also explained mating success with some territories producing more matings than others. The BW morph stored more fat reserves which may explain why this morph was more likely to secure and defend a place than the HW morph. However, the HW morph showed higher relative muscle mass which we have interpreted as a flexible strategy to enable males to defend a territory. These results are distant to what has been found in another male dimorphic damselfly, Mnais pruinosa, where the advantage of the non-territorial morph relies on its longevity to compensate in mating benefits compared to the territorial morph.     

Turnover of territorial Scops Owls Otus scops as estimated by spectrographic analyses of male hoots

In this study we assessed territory turnover of the European Scops Owl Otus scops, a migratory nocturnal raptor, using sonagrams of hoots recorded in the same territories in the 1993 and 1994 breeding seasons. Three structural parameters of the hoot (duration, inter-note interval and frequency) varied considerably, and a Discriminant Function Analysis classified >90% of individual calls correctly. In order to investigate yearly turnover and site-fidelity of male Scops Owls, the discriminant functions derived from the hoot sample recorded in 1993 were used to classify hoots of individuals recorded in the same territories in 1994. Apparently, turnover rate of territory owners was high and rapid, because 55–78% of territories censused in 1993 were defended by a different male in 1994. The fast decline of our Scops Owl population, probably due to winter mortality, could be responsible for such a high turnover of territorial owners.     

Male contesis for territories and females in the fly Dryomyza Anilis

Dryomyza anilis males defend the small carcasses on which females oviposit as well as the females themselves during copulation and oviposition. Contests over territories and females, were compared to assess the way different asymmetries affect the outcome of a struggle. In contests over females with a lot of eggs the rate of take-over was lower than in contests over immature females, but the size of the female or her size relative to the owner did not affect the outcome. In territorial disputes and territories was the size difference between the opponents. Fifty-three per cent of the contests over females and 39% of territorial struggles resulted in a take-over. In take-overs, owners were smaller than copulating males or territory owners on average. Take-overs are part of a process in which resource owners continue to change until one is strong enough to defend the resource successfully. Contests over females lasted significantly longer than those over territories, which suggests that for males females are more valuable than territories. This is to be expected as territories are of value because they ultimately increase the probability of obtaining females. A positional advantage or the higher payoff of the owner in disputes over females may be the reason for the lower rate of take-over in female defence than in territorial struggles between opponents of similar size.     

Pair formation in the Mongolian gerbil

This report describes the initial phase of social organization in Mongolian gerbils, Meriones unguiculatus, in large outdoor enclosures. These conditions offer a comparatively free choice for the establishment of bonds and social structure. In five replicate 20-day studies, the only social unit that formed was the male-female pair. The order of events was related to four sequential 5-day periods: (I) males established territories by male-male competition (1st to 2nd period); (II) females visited more than one male initially (1st and 2nd period), but developed a preference for one male or territory (3rd to 4th period); (III) as the females developed a preference, they also challenged other females having a preference for the same male or territory (approximately the 3rd period); (IV) as one female became locally dominant, some territorial males started chasing all but the dominant female. Males remained more active in territorial defence throughout the study. The defence became more intense as the females became strongly attached to one male and/or territory only. However females, after having established themselves in one particular male territory, spent significantly less time in the preferred area during the day of oestrus compared with the days before and after. Copulatory behaviour patterns, where observed, did not occur exclusively in interactions between territorial mates.     

Territoriality and associated behaviour in three species of the genus Cephalopholis (Pisces: Serranidae) in the Gulf of Aqaba, Red Sea

Social structure and behavioural mechanisms enabling sympatry in three species of predatory fish in the Gulf of Aqaba ( Cephalopholis miniata (Forsskål), Cephalopholis argus Bloch and Schneider, and Cephalopholis henistiktos (Rüppell)) were examined in this study. C. miniata and C. argus formed compound interspecific territories in which they occurred in haremic groups consisting of a dominant male and two to 12 females. C. miniata and C. argus groups occupied territories of up to 475 m², and 2000 m² respectively, subdivided into secondary territories, each inhabited by an individual female. Observations of tagged fish disclosed behaviour patterns of patrolling by males, visiting the females, and antiparallel swimming of sexes. C. hemistiktos , in contrast, was monogamous and each pair jointly defended a common territory of up to 62 m². Among the three species the dominance hierarchy was C. argus > C. miniata > C. hemistiktos .     

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.