Landmark Territoriality in the Neotropical Paper Wasps Polistes canadensis (L.) and P. carnifex (F.) (Hymenoptera: Vespidae)

Male Polistes canadensis and P. carnifex aggregate along crests of prominent ridges in Santa Rosa National Park, Costa Rica. At these sites males of both species defend territories (trees and shrubs) by chasing conspecific rivals. Territories do not contain nests or resources that are collected by females. Chasing by territorial males reduces the amount of time spent by intruders in a territory. I describe and contrast male territorial behavior of both species. Some male P. canadensis are territorial while others in the same area exhibit patrolling behavior, flying from one occupied territory to another. Males of P. carnifex exhibit territoriality only. Patrolling in P. canadensis is an outcome of relatively high male density along the ridge, rendering territories in short supply, as shown by the observation that experimentally vacated territories are seized rapidly by formerly patrolling males. Due to a high intraspecific intrusion rate, territorial male P. canadensis spend less time perching and more time flying and chasing intruders from their territories than do male P. carnifex. Males of these two species also differ in the placement of their territories along the ridgeline; P. canadensis occupy territories in saddles while P. carnifex occupy those at peaktops. I show that this divergent spatial pattern is not maintained by competitive exclusion of either species by the other, and I discuss alternative explanations for their separate spatial distributions. Comparative data suggest that males are territorial because females restrict matings to within territories, and I discuss alternative hypotheses to explain this bias in female behavior.     

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.     

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.     

Territorial songs indicate male quality in the sac-winged bat Saccopteryx bilineata (Chiroptera, Emballonuridae)

Defense of territories in many animal species involves the advertisementof territory holder quality by acoustic signaling. In the sac-wingedbat Saccopteryx bilineata, males engage in territorial countersingingwhen reoccupying their day-roost territories in the morningand in the evening before abandoning the roost for the night.Females roost mainly in male territories, and territory holdersare reproductively more successful than nonterritorial males.In territorial songs of male S. bilineata, we distinguished6 syllable types and parameterized their acoustic properties.The analysis of 11 microsatellite loci allowed assignments ofjuveniles to their parents. Males had a higher reproductivesuccess both when they uttered more territorial songs per dayand when their long buzz syllables had a lower end frequencyof the fundamental harmonic. Long buzzes had a harsh qualitydue to a pulsation of the fundamental frequency at the syllableonset and also had the highest sound pressure level of all syllabletypes in most territorial songs. Territorial songs and especiallylong buzz syllables are thus likely to advertise territory holderquality and competitive ability.     

Variations of space use in males of the banded demoiselle (<Emphasis Type="Italic">Calopteryx splendens</Emphasis>, Zygoptera,Odonata): Alternative tactics or an age-dependent trend?

Two spatial tactics are usually distinguished in males of Calopteryx damselflies: territorial and nonterritorial. These tactics are believed to underlie two alternative condition-dependent reproductive tactics in these insects, and territorial males are believed to copulate more often. With age, males become weaker, turn nonterritorial, and only occasionally manage to copulate. However, the details of space use by damselflies are poorly known, which hinders the interpretation of the existing empirical data. We describe the space use by individually marked males of the banded demoiselle C. splendens studied during three field seasons in Vladimir Province, Russia. Each male on each day of observations was characterized as either territorial or non-territorial, and the sites of encounter were mapped. The probability of being territorial declined with the male’s age. The spatial tactics (territorial vs. non-territorial) on a given day strongly influenced the tactics used on the following day. We identified the territorial and non-territorial phases in the life of a male damselfly, which occurred consecutively and had a roughly similar duration. During the territorial phase, the male occupied a certain territory and tried to hold it as long as possible. The male abandoned its territory in two cases: (1) when it was driven onto a different territory as the result of competition with other males, or (2) when it was exhausted and became non-territorial. Thus, the space use by the male changed predictably during its life. Therefore, direct comparison of morphological or other characteristics in territorial vs. non-territorial males, frequently made in the literature, makes little sense. Further progress in studying the so-called “alternative reproductive tactics” in damselflies may be more successfully achieved by comparing individual life trajectories of different males (e.g. duration of territorial and non-territorial periods, the number of consecutively occupied territories, etc.). We performed correlation analysis and found that the above parameters did not depend on the wing and abdomen length of the males.     

Changing tactics: dominance, territoriality, and the responses of "primary" males to competition from conditional breeders in the variegated pupfish (Cyprinodon variegatus)

Using variegated pupfish, we examined the flexibility in "primary" male tactics when dealing with the aggressive costs of competition. Analogous to conditional mating strategies, we expected primary males to exhibit one of two interrelated tactics (i.e. dominance or territoriality) in response to different numbers of competitors. In the field, competitors influenced aggression. Primary males defended territories; residents facing more intruders engaged in more chases and obtained fewer spawns per female. In the laboratory, primary males showed dominance at low density, controlling most of the aquarium. With increasing competitor numbers, primary males reduced the area controlled and defended territories. Territories occurred with intermediate to high competitor numbers and only under male-biased sex ratios. During these interactions, aggression was highest and competitors were too many for dominant males to suppress the assertions made by each subordinate to increase its rank. Relinquished control of the entire domain enabled a previously subordinate male to establish a territory in the undefended portion of the aquarium. Reduction in defended area related to a reduction in territorial males' spawning success relative to dominants. These results suggested that primary males, like conditional breeders, would adopt the tactic that enabled them to spawn despite the constraints of competition.     

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.     

Size-dependent use of territorial space by a rock-dwelling cichlid fish

Territoriality fundamentally influences animal mating systems and patterns of population structure. Although territory ownership is already known to contribute importantly to male reproductive success and the ecological coexistence of African rock-dwelling cichlids, the significance of variation in territory features has received little attention in these fishes. In Lake Malawi, males of Pseudotropheus tropheops "orange chest" defend territories on either of two substrate classes at Harbour Island: flat rock slabs lacking crevices and caves, or structurally complex boulder fields containing cave shelters. Focal watches of this species demonstrated that both territory size and occupancy on either substrate type depend on the size of male residents. Males larger than a threshold size exclusively held the largest and most structurally complex territories. After removal of conspecific residents, more vacant territorial areas on cave-containing substrate were reoccupied by "orange chest" males in full breeding coloration compared to vacant areas on flat substrate. These findings suggest competition among "orange chest" males for complex rocky substrate. Defense of caves was associated with enhanced male courtship rates: the number of caves within a male's territory was a better predictor of courtship activity than was male size or territory area. In addition to territories being crucial for male reproductive success and therefore likely playing a role in sexual selection, male-male competition for caves in rock-dwelling cichlids may be promoted by the ecological advantage of enemy-free space. Smaller "orange chest" males lacking caves tended to move into adjacent boulder fields in the presence of predators, particularly at night. In contrast, males defending caves were more likely to remain on their territories when nocturnal predators were present. The territorial behaviors of P. tropheops "orange chest" that we observed in situ provide an instructive natural framework for testing the roles of substrate and ecology in the mating systems of rock-dwelling cichlid fishes.     

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.     

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.     

Caribbean damselfish with varying territory quality: correlated behaviors but not a syndrome

The behavioral syndrome hypothesis suggests that individualanimals within a population behave differently due to specificbehavioral types, and these should be consistent across behaviorsor in different contexts. In contrast, for animals that livewithin an environment in which territory quality can changeover time, natural selection should have favored behavioralflexibility and modulation of the cost of defense in relationto territory quality. This would require assessment of the territoryfollowed by displays of appropriate types and intensities ofbehavior. We examined the territorial behavior of male beaugregorydamselfish (Stegastes leucostictus) by enhancing territory qualityusing artificial breeding sites and comparing their behaviorto males on lower quality natural sites. When male fish weredefending high-quality artificial territories, they had higherlevels of aggression toward male conspecifics and courtshiptoward females than when on low-quality natural territories.We also found that aggression and courtship behaviors were correlatedon natural sites but not on artificial sites. Behaviors werenot correlated within individuals when males switched from naturalto artificial territories or from artificial to natural territories.These results indicate that males assess their current territoriesand adjust behaviors accordingly and that courtship and aggressivebehaviors are not linked within a permanent behavioral syndrome.     

Territory Availability at Different Spatial Scales does not Affect Fighting Investment in Males of the Lycaenid Butterfly Strymon mulucha

In territorial species, rivals investment in fights over territories may increase when the availability of suitable areas for defense is low. This should occur because low territory availability may increase the costs to maintain and acquire territories. Although such process occurs in small spatial scales (local scale), territory availability in larger scales (regional scale) may also affect fighting investment, as losers should incur additional dispersing costs to find new territories. In this study, we used males of the hilltopping butterfly Strymon mulucha to evaluate the hypothesis that males should invest more in territorial fights when the costs to find new territories are higher (both at local and at regional scale). We timed male–male contests for territories located in 12 hilltops and measured male density per territory in each hilltop (local scale). We also quantified the distance between hilltops containing suitable areas for territories (regional scale). Male–male contests lasted 21 s on average, and copulations did not occur during the observations. The duration of contests was unrelated to the male density per territory or to the distance among hilltops, indicating that the investment in fights was unaffected by the availability of territorial sites, independent of the spatial scale. As male–male contests in S. mulucha are longer than the mean contest duration in other butterfly species and mating is extremely rare, we suggest that the value of each territory may be high enough to favor males that always invest as much as possible in contests.     

The Behavioral Ecology of Libellula luctuosa (Burmeister) (Anisoptera: Libellulidae): I. Temporal Changes in the Population Density and the Effects on Male Territorial Behavior

A single population of a common pond dragonfly, Libellula luctuosa, was studied at a site where the density of males increased dramatically during the breeding season. Early in the summer one active male was found on each territory on the pond. Satellite males were only occasionally found on the territories. Later in the season the number of males per territory increased so that two or more males simultaneously defended on many of the territories, and several satellite males occupied each of the territories. The number and rate of female visitations per day did not change over the summer. These factors resulted in a change in the operational sex ratio with variations in male density. Male behavior was also altered with increasing population density. As male density increased, males were less likely to be seen perching on their territories and more likely to be seen performing aggressive acts such as chasing nearby territorial males and chasing intruders. At high male density, the duration of territorial behaviors was shorter than at low male density. Thus, the percent of a time budget spent in any one activity did not change despite the change in number of males present. Male activity in L. luctuosa is not strictly determined by the opportunity for aggression. Costs of aggression associated with territoriality are minimized by maintaining flexible territorial behaviors.     

Territoriality and male-biased sexual size dimorphism in Argia reclusa (Odonata: Zygoptera)

In Odonata, many species present sexual size dimorphism (SSD), which can be associated with male territoriality in Zygoptera. We hypothesized that in the territorial damselfly Argia reclusa, male–male competition can favor large males, and consequently, drive selection pressures to generate male-biased SSD. The study was performed at a small stream in southeastern Brazil. Males were marked, and we measured body size and assessed the quality of territories. We tested if larger territorial males (a) defended the best territories (those with more male intrusions and visiting females), (b) won more fights, and (c) mated more. Couples were collected and measured to show the occurrence of sexual size dimorphism. Results indicated that males are larger than females, and that territorial males were larger than non-territorial males. Larger territorial males won more fights and defended the best territories. There was no difference between the mating success of large territorial and small non-territorial males. Although our findings suggest that male territoriality may play a significant role on the evolution of sexual size dimorphism in A. reclusa, we suggest that other factors should also be considered to explain the evolution of SSD in damselflies, since non-territorial males are also capable of acquiring mates.     

Territory re‐establishment in Cyprinodon variegatus lacepede

Cyprinodon variegatus males were allowed to establish territories in small aquaria. The ability of a male to maintain a territory was examined under conditions that varied group composition and sequentially varied space availability. Three cohorts of males were identified: non‐territorial individuals, rarely territorial individuals, and frequently territorial individuals. The results indicate that group social structure is not affected by changes in available space. Although no single male was always territorial in trials that varied group composition, a small number of males were frequently territorial. Often these successful males were temporarily displaced, but they typically regained a territory in subsequent trials.     

Mate acquisition tactics in polyandrous spotted sandpipers (Actitis macularia): the role of age and experience

We consider resource-defense polyandry and mate-access polyandryas female mating tactics in spotted sandpipers (Actitis macularia).These tactics can be distinguished by the resource females defend,female interclutch movement, expected reproductive success aftermoving, and male and female dispersion. We examine these characteristicsrelative to patterns observed in a 17-year study of spottedsandpipers, a species traditionally considered resource-defensepolyandrous. On average, 26% of spotted sandpiper females eachyear were monogamous. Older females were more likely to be polyandrous,and polyandrous females of each age employed different matingtactics. Yearlings were typically sequentially resourcedefensepolyandrous. Two-year-olds were primarily simultaneously polyandrous,exhibiting equivalent proportions of resource-defense and mate-accesspolyandry. Older females were primarily simultaneously resource-defensepolyandrous. Females tended to stay on territories where theyand/or their mates had greater breeding experience (i.e., manyclutches laid for females, many clutches diat hatched for males);females that moved went to territories where their mates hada history of breeding success. Location changes between clutchesby polyandrous females were better described by breeding experienceon a territory than by age.     

Alternative Mating Behaviors of Young Male Bullfrogs

Yearling male bullfrogs often attempt to intercept and matewith females attracted to older, larger males (male parasitism)instead of defending a territory and attracting their own mates.Mating behaviors like male parasitism are thought to occur onlywhen individuals suffer some strong disadvantage in using thebehaviors that are more typical of their species. In this paper,I consider the relative benefits and costs of territorialityvs male parasitism for yearling males. Yearlings employing maleparasitism are only occasionally successful at mating, and inyears of reduced male-male competition, they produce significantlyfewer young than territorial males of their age. Yearling malesthat vary in the degree to which they employ territorial behaviorsinstead of male parasitism do not differ measurably in growthrate or chances of mortality; however, indirect informationsuggests that territoriality should entail a greater chanceof mortality. A computer simulation based solely on observeddemographic parameters predicts that yearling males should beterritorial whenever they can compete as effectively as two-year-oldmales. This condition appears to provide little restrictionon the breeding tactics of yearling males; however, data onmale-male aggressive encounters show that the size differencesbetween one-year-old and two-year-old males are usually sufficientto preclude yearling males from competing successfully. Thus,the observed behavioral plasticity of yearling males may bebest interpreted as a means of adjusting their behavioral tacticsto levels of male-male competition that can vary within andbetween breeding seasons.     

The effects of male body size on territorial and mating success in the landmark-defending fly Hermetia comstocki (Stratiomyidae)

Abstract.

• 1 Males of Hermetia comstocki Williston compete for territorial control of certain agaves and yuccas. Winners copulate with females that visit these plants solely to acquire a mate.
• 2 Males vary in body weight by more than an order of magnitude and larger flies almost always defeat smaller ones in aerial contests for control of landmark territories.
• 3 The mean body size (as measured by wing-length) was significantly greater for males retaining residency at a site for at least one hour compared to males unable to do so. Likewise, males able to return to a perch site in the study area on more than one day were larger on average than males unable to do so.
• 4 Male preferences for landmark territories remained similar across years. Large males dominated the perch landmarks most likely to be occupied by males and most likely to be visited by females.
• 5 Despite the fighting and territorial advantages enjoyed by large males, the mean size of males found mating with females was not significantly larger than that of the general population.
• 6 The apparent failure of large males to secure a statistically significant mating advantage may be a statistical consequence of the small sample size of males observed mating. On the other hand, any mating advantage of large males may be reduced because (a) receptive females visit many different landmarks, (b) females mate with the first male they encounter at a landmark, regardless of his size, (c) there are usually many vacant landmarks available for smaller males, and (d) even popular territories are often open to small males, thanks to the low site-tenacity of territory owners.

     

The social ecology of the Pyrenean desman (Galemys pyrenaicus) (Insectivora: Talpidae), as revealed by radiotelemetry

The social organization, spatial utilization and movement patterns of free-ranging desmans ( Galemys pyrenaicus G.) were studied by radiotracking individuals in the French Pyrenees. During the period of study, May to July, single adult male and female desmans formed a pair and defended their shared territory from neighbouring conspecifics by vigilance and scent-marking behaviour. Other adults did not form pair bonds and remained solitary. In such pairs, the territory of the adult male was always larger than, and completely enclosed, that of the paired female. Neighbouring pairs occupied contiguous territories of similar length. The territories of neighbouring males overlapped to a small extent, but the territory of one male and that of a neighbouring female were never seen to overlap. Juveniles were observed to utilize the territory of resident pairs, prior to their dispersal. Paired adults and juveniles exploited their ranges on a regular daily basis, whilst those of solitary adults, being larger than those of the former, were utilized on a 48–hour basis. Paired males appeared to invest more time in defending the borders of their shared territory than did females which, in contrast, spent most of their time within the centre of the territory. Despite some degree of territorial overlap between neighbouring conspecifics, their mutual avoidance, achieved through a system of temporal range utilization, resulted in few agonistic encounters.     

Uncertainty in territory quality affects the benefits of usurpation in a Mediterranean wrasse

Individuals should defend sites when the expected benefits ofthe territory exceed the cost of defense. However, if territoryqulaity is unpredictable or difficult to assess, the expectedpattern of territorial behavior is less clear. In a Mediterraneanwrasse, Symphodus ocellatus, mating success is skewed with 2%of nesting males getting more than 20% of the spawning success.Yet, variation in mating success is not explained by any knownphysical characteristic of males or their territories. Instead,females prefer nests with a recent history of mating successbecause males are less likely to desert the offspring she leavesbehind. Thus, territory quality is transient and determinedby interactions between the sexes. I measured the frequencyof territorial takeovers and the uncertainty in mating successamong days at a nest. Observations indicated that S. ocellatusmales usurped their neighbor's successful nests when males wereunsuccessful and larger than their successful neighbor. Sitesthat achieved mating success had a significantly higher probability(0.84) of remaining sucessful between consecutive days thanunsuccessful territories had of becoming successful (0.30).Unsuccessful males obtained higher and more certain fitnessreturns if they usurped a successful neighbor's territory. Interactionswithin and between the sexes drive uncertainty in success, whichinfluences territorial behavior in this species.