Territorial behaviour by males of Philanthus multimaculatus (Hymenoptera: Sphecidae) with a review of territoriality in male sphecids

Males of Philanthus multimaculatus Cameron defended a perch site near a nesting aggregation against other conspecific males. Vigorous aerial clashes between a resident and an intruder were common, with the resident male ejecting the invader in the vast majority (84 per cent) of cases. One copulation was observed at the perch thus supporting the hypothesis that territoriality was related to securing a favourable location for mating. Male reproductive strategies in the Sphecidae are reviewed; territoriality appears to occur in this group when (1) receptive females are clumped in space, (2) there are cues that permit males to identify superior localities for reproduction, and (3) these locations are small enough to be relatively easily defended.     

Hilltopping in the Pipevine Swallowtail Butterfly (Battus philenor)

In central Arizona, receptive females of the pipevine swallowtail, Battus philenor, are widely scattered in time and space, and in this region the butterfly's mating system is one in which males patrol mountain peaks. Hilltopping males engage intruding males in ascending flights that appear to be ritualized aerial combat with individuals defending patrolling sites for relatively short periods on any given day. The day-to-day appearance of marked males is irregular, unlike the site fidelity shown by males of many other hilltopping insects. The distinctive pattern of male territoriality in B. philenor may be partly a response to very low male and female density in the observed population. Males at the hilltop chase, court, and attempt to copulate with virgin females released near them. Males assess the receptivity of females rapidly, and receptive females permit a lengthy copulation to occur after a courtship that lasts less than 30 s. During an initial copulation males pass a spermatophore that weighs about 6% of their body mass, with partners on following days receiving a smaller but still substantial donation.     

The Hilltopping Mating System of Leschenaultia adusta (Loew) (Diptera: Tachinidae)

Males of the tachinid fly Leschenaultia adusta perch on small trees and shrubs on the highest parts of Usery Peak in central Arizona. Individuals select twig perches on the downwind side of these plants and fly out spontaneously from time to time or in response to another passing insect. Conspecific males elicit chases that on occasion escalate into elaborate, high-speed pursuit flights that go back and forth near the plant for several minutes. Although several males sometimes perch together briefly in the same plant, typically only one individual remains at a site for more than an hour on any given day. These site-faithful males can be considered territorial residents; they constituted about one-quarter of the males marked during the study. More than half of these residents returned to the same perch plant for two or more days. Perch plants varied in their attractiveness to male flies; male preferences were largely consistent across two years of study. Given that females were occasionally observed mating at male-occupied plants, we place the mating system of L. adusta within the hilltopping territorial category in which males compete for landmark perching sites attractive to receptive females. As is true for other hilltopping insects, receptive females of L. adusta appear to be rare and widely distributed.     

Hilltopping Behavior of Polistes commanchus navajoe (Hymenoptera: Vespidae)

Males of the paper wasp Polistes commanchus aggregate in large numbers on hilltops in central and southeastern Arizona where individual males defend perch sites on shrubs, trees or rocks. Residents chase intruders away quickly and exhibit strong site fidelity at their perches. Takeovers are rare as are prolonged battles for possession of a site. Males have only weak preferences for peaktop perch sites as opposed to those lower on hillsides, and a similarly weak preference for perches in shrubs as opposed to those on rocks. Receptive females appear occasionally at the male aggregation sites to mate with perch holders. The relatively weak territoriality exhibited by P. commanchus may stem in part from the high density of males at peaktops and the correspondingly high rate of interactions. The evolution of hilltopping in a species whose reproductive females are clumped spatially at nest sites poses a puzzle for the ecological analysis of mating systems.     

Influences on variation in territorial tenures of male white-faced dragonflies (Leucorrhinia intacta) (Odonata: Libellulidae)

Some individuals in species with extended periods of territorial occupancy may change territory locations within a single bout of territorial activity. Length of occupancy of mating territories among males in a local population of white-faced dragonflies (Leucorrhinia intacta) varied from more than 6 h to 15 min or less. Males with short tenures often established territories in several locations on the pond during a day. Several hypotheses have been proposed to explain shifting territorial sites rather than remaining in a single site during one bout of territoriality. We attempted to test the hypothesis that males shift to leave low-quality sites. Site quality may be affected by costs of defense in relation to intruder rate and the mating benefits of holding the territory. To test whether variation in these possible effects of benefits and costs of territoriality influenced tenure, we manipulated local quality of oviposition substrate and perch density. The quality of oviposition substrate, but not perch density, influenced both potential benefits and costs of territoriality. Female density was higher in areas with good substrate, but so were rates of males intruding into the territories, rates of chasing by territorial males, and local density of territorial males. More matings occurred in areas with good substrate, but among males with tenures of 15 min or more, mating success per male and tenure lengths did not differ statistically among treatments. Defense costs were low for all treatments and perhaps were not an important influence on tenure duration. Territorial males in this population probably adjusted local density to expected mating success by initial choice of site rather than by varying tenure length. Variation in tenure length at a site resulted, in part, from stochastic external factors, such as predation attempts.     

Seasonal effects of density on territory occupation by males of the satyrine butterfly Paryphthimoides phronius (Butler 1867)

Territorial defense in butterflies may be related to both population density and climatic conditions. If these factors change throughout the year, males are expected to adaptively adjust their behavior in order to maximize reproductive success. In this study, we analyzed the annual dynamics of territory occupation by males of the satyrine butterfly Paryphthimoides phronius at a mildly seasonal subtropical site in southeastern Brazil. We investigated the relationship between the number of defended sites, number of males disputing mating areas, proportion of males adopting alternative mate-locating tactics, and the proportion of time invested in territorial disputes with annual variations in temperature and male density. We found little support for the influence of temperature on the dynamics of territory occupation. On the other hand, the number of defended sites increased with male density, whereas the number of males inside each territory, the proportion of satellite males, and the proportion of time spent in territorial disputes were unrelated to variations in population abundance. Territory defense seems to be adopted whenever possible. We conclude that, instead of increasing the number of individuals disputing the same territory during months of high population abundance, males apparently opt to colonize and defend new and, maybe, suboptimal areas.     

The mating system of a bee fly (Diptera: Bombyliidae). I. Non-resource-based hilltop territoriality and a resource-based alternative

The mating system of an undescribed Australian bee fly (Comptosiasp. near lateralisNewman) was studied in Southeast Queensland. Males perched in clearings on a wooded hilltop and darted toward nearby flying insects. On sunny days males interacted with other insects about once per minute. A minority of these interactions was with conspecific males. They had the effect of determining ownership of the perching area. Most conspecific interactions occurred withtin 90 min of the first male's arrival each day, although territories were occupied for an average of 4.6 h per day. The same territories were used by different generations of flies for at least 4 years, while other apparently similar clearings on the hilltop remained unoccupied. Following removal of resident males, replacement males occupied the sites in 12.5 min on average. Females were not observed on the hilltop except when mating at territories. No interactive courtship behavior was detectable prior to midair coupling. Copulations lasted for 118 min on average. We interpret this as a landmark-based mating system and discuss it in relation to the concept of lek polygyny. Observations of Comptosiasp. near lateralismatings at a nonhilltop, resource-based encounter site suggest that the mating system of this species varies in response to the distribution of resources.     

Choice of Lookout Posts by Territorial Amberwing Dragonflies, Perithemis tenera (Anisoptera: Libellulidae)

Many territorial insects use specific perches, or lookout posts, from which they perceive and react to conspecific males and females. We investigated the lookout post choice of territorial male amberwing dragonflies (Perithemis tenera). An observational study indicated that males rarely perched directly at their oviposition site; rather, they perched farther out from shore than, and within 2 m from, their oviposition site. In an experimental study, we provided an array of perches at different distances from the shore and oviposition site to eliminate perch limitation as a factor in perch choice. The results of the experimental study confirmed the patterns evident in the observational study; males perched farther from shore than their oviposition site was located. Interestingly, in both the observational and the experimental study, when neighbors were close, a male perched away from his closest neighbor, which usually resulted in his oviposition site being closer to his neighbor than he was. Thus, male amberwings apparently alter their perch choice within their territories in response to the location of other males. These lookout post locations may provide the best opportunity for the territorial male to perceive passing females and intruding males, while minimizing conflict with their neighbors.     

Male mate-locating behavior inEuphydryas chalcedona (Lepidoptera: Nymphalidae) related to pupation site preferences

Males of the checkerspot butterfly (Euphydryas chalcedona)patrol and perch near but not on the larval foodplant in search of females. Experiments with tethered butterflies show that searching males chase virgin females for longer times than they do mated females or males. The larvae leave the larval food-plant to pupate. The correspondence between the distance from the larval foodplant to pupation sites and where males search for females suggests that male mate-locating behavior has evolved to maximize the rate of encounters with newly emerged, virgin females. These conclusions are compared to a recent analysis of butterfly mating systems by Odendaal et al. (Am. Nat. 125: 673–678, 1985).     

Impact of predation by spiders on a territorial damselfly (Odonata: Calopterygidae)

Summary Predation by orb-weaving spiders and crab spiders on the damselfly Calopteryx haemorrhoidalis was studied at a small stream in Southern France. One species of orb-weaving spider, Larinioides folium, caught 76% of the damselflies which fell prey to spiders. Displacement experiments on spiders on sections of bank and the positioning of webs in male territories show that the density and distribution of damselflies is not influenced by orbweb density or by the position of webs. Predation rates corresponded to orb-web density, but neither for sex nor for stage was there a relationship with damselfly density. Mean daily predation rates ranged between 0.9% for females and 4.1% for adult males. Predation risk to adult damselflies by orb-weaving spiders was male biased, whereas among tenerals there was no bias. Males were captured more frequently at territories near the water. Captures show a maximum at noon when territorial disputes of adult males were most frequent. After orbwebs were placed within territories predation rate of males was strongly increased. Predation risk to adult females in the direct vicinity of the stream was less than in the bank vegetation where they perch close to orbwebs. The risk of predation by crab spiders, which catch damselflies at their perching sites, was not sex-biased.     

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.     

Male mating success,sexual size dimorphism,and site fidelity in two species of Malacoctenus (Labrisomidae)

Synopsis In both Malacoctenus hubbsi and Malacoctenus macropus, males defended preferred oviposition sites from both other males and potential egg predators. In M. hubbsi, adult females were larger than adult males. Larger M. hubbsi males were not associated with territory parameters that were correlated with higher mating success, and male size was not correlated with mating success. Male size did affect mating success when territory parameters were statistically controlled for, but the failure of large males to associate with better territories eliminated any mating advantage for larger males. In M. macropus, males are larger than females. Larger males defended preferred oviposition sites, and had higher mating success than did smaller males. Male M. macropus also had much higher site fidelity than male M. hubbsi. These results suggest that the evolution of the differences in site fidelity and sexual size dimorphism between these two species may be due to sexual selection acting differentially in these two species.     

Male foraging avoidance in female feeding territories in a harem polygynous cichlid in Lake Tanganyika

We studied foraging site partitioning between the sexes in Neolamprologus tetracanthus, a shrimp-eating Tanganyikan cichlid with harem-polygyny. Females maintained small territories against heterospecific food competitors within large territories of males, foraging exclusively at the inner side of their own territories (foraging areas). Males fed as frequently as females in their own territories, but mostly outside female foraging areas, although they frequently entered female territories and repelled food competitors from the territories. Soon after removal of the resident females, however, harem males, as well as many food competitors, invaded the vacant territories and intensively devoured prey of female foraging areas. This indicates that although female foraging areas appear to contain more food than outside the areas, harem males refrained from foraging there when the resident females were present. We suggest that harem males will attempt to keep female foraging areas in good condition, whereby they may get females to reside in male territories and/or promote female gonadal maturation.     

AQUATIC MATING STRATEGIES OF THE MALE PACIFIC HARBOR SEAL (PHOCA VITULINA RICHARDII): ARE MALES DEFENDING THE HOTSPOT?

Compared to the harem and resource defense systems of terrestrial mating pinnipeds, males of aquatic mating species appear unable to monopolize females or resources. We investigated movements, acoustics, and aquatic territorial behavior of male harbor seals, Phoca vitulina richardii , in Elkhorn Slough, California, using VHF telemetry, hydrophones, and acoustic playback experiments. During the mating season 22 males increased time spent in the water and away from haul-out locations, exhibiting activity patterns similar to Atlantic subspecies. Two acoustic display patterns were observed. At one location multiple males aggregated to display with acoustic activity peaking one month before peak estrus. At two other locations, lone males displayed primarily during peak estrus. Acoustic display areas were non-adjacent with a mean ± SE size of 4,228 ± 576 m², similar to harbor seal display patterns in the Moray Firth, Scotland. Underwater playbacks of male vocalizations were used to define territorial boundaries by inducing responses from territory-holding males. Four solitary males defended adjacent territories (mean area 39,571 ± 18,818 m²) along a travel corridor, similar to observations of harbor seals at Miquelon, Newfoundland. Acoustic display stations appeared to be subcomponents of larger territories. Males exhibited site fidelity to territories for at least 2–4 yr. Females moved through territories freely. The establishment of male-display territories along female-traffic corridors resembles terrestrial systems described as hotspot leks.     

Mating behavior and thermoregulation of the reindeer warble fly,Hypoderma tarandi L. (Diptera: Oestridae)

Hypoderma (=Oedemagena) tarandi L. (Diptera: Oestridae) is characterized by a mating strategy in which both sexes meet and mate at two types of distinct topographical landmarks. In the expansive, treeless vidda (= tundra-like) biome, mating places are unique, rocky areas located along rivers and streams or in rocky areas of drying river and stream beds. In wooded valleys below the vidda, flies mated at certain topographical areas along dirt road tracks/paths. Thermoregulatory activities of males occupying perches at mating places included selection of substratum at perch site, orientation of body to sun's rays, crouching, stilting, and flights into upper cooler air. On warm sunny days males perched for just 1–2 min before flying up into cooler air to promote cooling. Laboratory and field studies revealed that flies could not metabolically cool down when held at 25–38°C. Time spent at mating places depended on temperature, duration of sunshine, and wind velocity. Males were very aggressive in pursuing allHypoderma-sized objects that passed by them or that landed near them, but they did not defend specific perch sites. Males either pursued and caught females in flight, or they hopped onto females that landed near them. During 5 years, 74 males and 14 females were seen at mating places. Dissection of six females caught at mating places revealed them to be recently eclosed flies full of fat body and with all eggs intact; two not paired with males were non-inseminated. Three experimentally paired females remainedin copulo for 10, 13, and 19.5 min.     

The Resource-Based Mating System of the Mediterranean Pollen Wasp Ceramius fonscolombei Latreille 1810 (Hymenoptera, Vespidae, Masarinae)

Males of C. fonscolombei patrol and perch at water collection sites or at plants of Reseda, both of which are important resources for female brood care. The mating system can be classified as resource defense polygyny modified by the existence of alternative male mating tactics. Occupying temporary territories at watercollection sites constitutes the primary tactic which is more profitable for larger males. The secondary tactic of patrolling at flowers provides a nonaggressive alternative through which smaller males gain at least some mating success. Males at water collection sites occupy considerably smaller ranges but spend a higher proportion of time patrolling than males at flowers. They frequently grapple with other males, an activity that is absent at flowers. Males at water collection sites copulate about 2.5 times more frequently than males at flowers. The copulation frequency of the males at water collection sites is positively correlated with their body size, while copulation frequency is negatively correlated with body size at flowers. Males patrolling at water collection sites and males patrolling at flowers do not differ in body size, indicating that the decision between alternative mating tactics is not made relative to body size but is influenced by other factors.     

Risk of Sperm Competition Mediates Copulation Duration, but not Paternity, of Male Burying Beetles

Males should increase their investment in ejaculates whenever they are faced with an increased risk of sperm competition. Burying beetles (Nicrophorus vespilloides), insects that breed on small vertebrate carcasses, offer an ideal model with which to examine sperm allocation tactics because females typically mate with many males prior to laying eggs. Males compete directly for control of carcasses, and males losing such contests often become satellites, lurking in the vicinity of the carcass and attempting surreptitious copulations with the resident female. We predicted that both the dominant resident male and the satellite male would increase their sperm allocation in the presence of the other, but that relative to dominant males, satellite males would allocate a greater number of sperm per ejaculate. We employed a repeated-measures design in which two full-sib rival males, differing only in their dominance status, were each mated a single time to a previously-inseminated female under two conditions, once in the absence of their rival and once in the presence of their rival. Satellite males exhibited longer copulation durations than dominant resident males when both males were present on a carcass. Copulation durations of dominant males did not differ in the presence or absence of satellite males. Contrary to expectation, the increased copulation durations of satellite males did not result in a greater share of paternity relative to dominant males. The absence of any discernible effect of increased copulation durations on paternity in satellite males could be due to post-copulatory preferences of females or, alternatively, satellite males may require longer durations of copulation to transfer the same amount of sperm as dominant males.     

Settlement Patterns of Mediterranean Fruit Flies in the Tree Canopy: An Experimental Analysis

Males of the Mediterranean fruit fly, Ceratitis capitata (medfly), defend individual leaves of host and non-host trees as mating territories and attract females via production of a sex pheromone (a behavior termed ‘calling’). Males tend to aggregate within the tree canopy, and the present study examined the influence of (1) location and (2) resources on female visitation to male aggregations. Males were placed in screen-covered containers, which were suspended on field-caged trees at two locations selected to differ in only one of the following parameters: height above ground (low versus high), leaf density (sparse versus dense), distance to main trunk (canopy edge versus center), proximity to a food source (bird feces absent or present), and proximity to a host fruit (oranges absent or present). Females were released, and we periodically recorded the number of calling males in each of the test aggregations as well as the number of females sighted within 15 cm of each male aggregation. Male calling did not differ between treatments in any of the experiments. However, females were more frequently sighted near males calling (1) in dense foliage, (2) near the central trunk, (3) near bird feces, and (4) near oranges. In an additional experiment, we compared male settlement (in the absence of females) on leaves in the same sites used previously to determine the degree of congruence between the sexes in microhabitat use. Aside from the lack of center-edge effect, males displayed the same settlement patterns as females. In a final experiment, we found no effect of male calling on the distribution of other males: released males were sighted with equal frequency near cups containing mature, calling males and cups containing immature, non-calling males. Medfly lek behavior is discussed in light of these findings.     

Nest‐site fidelity in parental male bluegill Lepomis macrochirus: spatial patterns and the influence of prior mating success

A 4 year mark–recapture study examined the pattern of nesting site fidelity of parental‐type male bluegill Lepomis macrochirus. The study results indicated that iteroparous male L. macrochirus choose new nest sites near their own previously used sites. The scale of site fidelity varied, but generally males choose to renest within shoreline areas rather than specific or exact nest locations (94% within‐year, 86% among‐years). Iteroparous males also displayed no preference to nest in proximity to neighbouring males from previous colonies to suggest social fidelity. Contrary to expectation, manipulating males' reproductive success had no significant effect on the pattern or scale of male reproductive site fidelity.