The use of territorial gardening versus kleptoparasitism by a subtropical reef fish (Kyphosus cornelii) is influenced by territory defendability

Many territorial herbivorous animals increase the productivityor quality of the prey community on their territory. However,this gardening tactic may be vulnerable to kleptoparasitismunless gardeners can exclude others from the patch. We investigatedthe influence of territory defendability on the decision ofwestern buffalo bream (Kyphosus cornelii) to defend an algalgarden or to leave their territories and invade those of conspecifics.Fish monitored while away from their territories did kleptoparasitizethe gardens of conspecifics. We manipulated the structural complexityof territories through the addition of short or tall simulatedvegetation. Increasing the height of simulated vegetation onthe territory decreased the defendability of territories butincreased their safety for fish; territories with tall vegetationwere more easily invaded by conspecifics, but fish returnedmore rapidly to these territories after being disturbed. Ina paired experiment, fish spent more time away from their territories(roving) when tall vegetation was added than when short vegetationwas added. However, this effect was influenced by depth, witha greater difference between treatments on deeper territories,and by body size, with a greater difference for larger fish.These results support the prediction that territory-holdingindividuals faced with a trade-off between defending their owngarden or kleptoparasitizing from others adjust their use ofthese tactics based on the defendability of resources.     

Determinants of territory size of the dusky gregory

To test the effect of food abundance and intruder pressure as determinants of territory size, the dusky gregory Stegastes nigricans were used as subjects on a coral reef in southern Taiwan during November to December 2000. Adults were used as intruders to provoke aggressiveness in a conspecific territory owner. The owner's maximum distance of attack (MDA) was used to delineate the territory size. While the owner of a territory appeared to defend a single boundary against different conspecifics, size variations among territories were evident. The effect of an intruder's identity on territory‐size regulation was not clear because for each territory examined, the MDA was found to be neither linked to the body size of the intruder nor to the amount of algae in the intruder's territory. Moreover, no significant differences were found between the MDAs that the owner maintained against neighbours and non‐neighbours even though, when conspecifics intruded in pairs, the probability was significantly higher for the first attack to be launched on a neighbour than on a non‐neighbour. Also when a neighbour and a non‐neighbour appeared simultaneously near the territory, the bite rate against the neighbour was also significantly higher. An inverse relationship between the amount of algae in the defended territory and the MDA of the owner indicates that food abundance might account for variations among territories. By contrast, territory size was not linked to the body size of the owner.     

Competitor intrusions and mate-search tactics in a territorial marine fish

Recent theoretical studies have drawn attention to the importanceof understanding the costs females experience during mate choiceand mating and how females resolve the trade-offs presentedby such costs. In garibaldi damselfish (Hypsypops rubicundus)females defend permanent feeding and shelter territories andmust leave their territories to search for and spawn with nestingmales. Both mate searching and spawning occur in bouts, separatedby returns to the territory. I used focal female observationsto test predictions of the hypothesis that such behavior isa means of minimizing the amount of food lost to competitorsthat enter the female's territory while she is searching foror spawning with males. Consistent with this hypothesis, therewas a strong likelihood that the number of intruders enteringthe territory would increase linearly, and hence their totalimpact exponentially, with time away. In addition, the averageduration of searching bouts and the duration of a spawning boutwere significantly inversely related to a measure of territorialintruder pressure. Most intruders were heterospecific food competitors;incidence of intrusion by conspecifics was rare, and intrudingconspeciflcs did not contest the owner upon her return. In addition,the time females spent in their territories before beginninganother bout of searching was not positively related to theduration of the previous bout. Thus, there, is no support forthe alternative hypotheses that returning to the territory isa means of preventing takeover of the territory by conspedflcsor is the result of fatigue.     

The Breeding System of the Acorn Woodpecker in Central Coastal California

Adult spatial relationships and social organization in a marked population of alpine mammals, the pika (Ochotona princeps), were studied over a 3-year period in the Rocky Mountains of Colorado. Home range size, distances between centers of activity of dyads, and weighted overlaps of home ranges of dyads were used to define space use patterns. Disappearance and establishment of individuals reflected the temporal component of space use. Relative frequencies of foraging (haying and feeding), surveillance, and communication (short calling, long calling, cheek rubbing) behaviors were recorded. Social relationships among adults were defined by agonistic interactions (aggression) and affiliative behaviors (social tolerance, vocal duets, copulations). Males and females occupied individual home ranges of equal size on talus, their obligate habitat type. Adjacent home ranges were normally occupied by pikas of the opposite sex. Replacement of home ranges was always by a member of the same sex as the previous occupant. A high degree of affiliative behavior was expressed between spatially contiguous heterosexual dyads. Aggression was greater among intrasexual than heterosexual dyads, and spatial overlaps among intrasexual conspecifics were less than among heterosexual conspecifics. Ecological constraints, such as the distribution of food (primarily located in meadows adjacent to the talus) and the short summer reproductive season (placing a premium on early appropriately timed litter;;) have apparently led to a facultatively monogamous mating system. Males can neither monopolize essential resources sufficiently to attract several females, nor defend groups of females as social repulsion among females further increases their dispersion.     

Nectar and flower production of Lobelia telekii inflorescences, and their influence on territorial behaviour of the scarlet-tufted malachite sunbird (Nectarinia johnstoni)

The alpine zone of Mount Kenya is a typical equatorial, high-altitude habitat with a harsh environment, large fluctuations in physical conditions and an impoverished flora and fauna. A common flowering plant is Lobelia telekii , which has large inflorescences with up to 2000 flowers. The long hanging bracts of this plant ameliorate the physical environment around the flowers, damping the fluctuations in temperature and relative humidity. The scarlet-tufted malachite sunbird ( Nectarinia johnstoni ) is a highly active nectarivore that obtains most of its food from the nectar of L. telekii. Sunbirds are more likely to visit the younger, male flowers at the apex of the inflorescence, which are larger and contain twice as much sugar as the older, female flowers lower down the spike. Male flowers will gain from multiple visits by exporting more pollen, while female flowers probably need to be visited only a few times for successful fertilization. Male sunbirds were resident on their territories all year and vigorously defended them from conspecifics. All territories contained about four times the number of flowers visited by the territory occupants in a day. Males on territories with a large number of flowers suffered more intrusions than males on low quality territories and spent more time in flight. After an intrusion the resident male frequently fed near where the intrusion took place. Males that subsequently attracted mates defended about twice as many flowers as males that did not breed, although undefended inflorescences were present. Some males apparently defended territories suitable for a pair, others only for a single bird.     

Conflicting Territory Use in Males and Females of a Monogamous Ungulate,the Kirk's Dikdik

In monogamous mammals it is often unclear why males do not defend larger territories to attract more than one female. I investigated the territoriality of the monogamous Kirk's dikdik, Madoqua kirki, a dwarf antelope, in which food resources increase with territory size and some males defend enough resources for more than one female. Yet, all males are paired monogamously. When males were removed from small territories, their female partners spent more time outside of their territories than females in large ones. When females were removed, their male partners almost never left. Pairs in small territories spent more time together than pairs in large ones. Paired males left mostly together with their females, apparently not on their own initiative. Presumably because females in small territories left more often, their males spent more time outside in the female's company than males in large territories. I argue that males in smaller territories can keep better track of their females and that they can effectively reduce their females' time outside. Male intrusion pressure was unrelated to territory size, but it increased in the presence of unguarded females. If large territories decrease the ability to mate guard, and if unguarded females attract competing males, then defending large territories may be uneconomical, even it they could attract more than one female. On the other hand, territories must be large enough to satisfy the requirements of a single female.     

Context Dependent Territory Defense: The Importance of Habitat Structure in Anolis sagrei

Territoriality is a potentially costly endeavor, and several mechanisms for mitigating the costs of territoriality have been investigated in the wild. For example, territory owners can reduce the costs of defending territory boundaries by prioritizing defense of the most valuable areas within territories, investing less energy in low quality areas. We staged pairwise encounters between adult male lizards on natural territories in the wild, to test whether male brown anoles, Anolis sagrei, would differentially defend certain regions of their territories over others. Based on our observations that male A. sagrei spend most of their time on elevated perches on tree trunks or branches compared with sites on the ground, we predicted that territory residents would respond more aggressively to territory invasions that took place on elevated perches than to invasions on the ground. We measured significant differences in the behavior of residents following invasion on the ground vs. on the elevated perches, and results partially supported our hypothesis. Males performed more displays and approached intruders more often when territory invasion took place on the ground, but were quicker to attack intruders that entered territories on elevated perches. Our hypothesis was only partially supported, potentially indicating that elevated perches are preferred as outposts to monitor valuable sites on the ground. Our study provides evidence that territory defense varies not just among individuals, but also within individuals at different locations in a territory.     

Prey availability affects territory size,but not territorial display behavior,in green anole lizards

The availability of food resources can affect the size and shape of territories, as well as the behaviors used to defend territories, in a variety of animal taxa. However, individuals within a population may respond differently to variation in food availability if the benefits of territoriality vary among those individuals. For example, benefits to territoriality may differ for animals of differing sizes, because larger individuals may require greater territory size to acquire required resources, or territorial behavior may differ between the sexes if males and females defend different resources in their territories. In this study, we tested whether arthropod abundance and biomass were associated with natural variation in territory size and defense in insectivorous green anole lizards, Anolis carolinensis. Our results showed that both male and female lizards had smaller territories in a habitat with greater prey biomass than lizards in habitats with less available prey, but the rates of aggressive behaviors used to defend territories did not differ among these habitats. Further, we did not find a relationship between body size and territory size, and the sexes did not differ in their relationships between food availability and territory size or behavioral defense. Together, these results suggest that differences in food availability influenced male and female territorial strategies similarly, and that territory size may be more strongly associated with variation in food resources than social display behavior. Thus, anole investment in the behavioral defense of a territory may not vary with territory quality.     

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.     

Spawning dynamics of orange roughy,Hoplostethus atlanticus,in mid-slope waters of New Zealand

Synopsis The social and reproductive biology of the sand tilefish,Malacanthus plumieri (Malacanthidae), was studied at Glover's Reef, Belize, where this species occurs in colonies over sand-rubble flats. Individuals each occupy a home burrow refuge and a surrounding home range. Home range overlap among adjacent fish of the same sex is low, and individuals defend exclusive use of much of their home range against all conspecifics except mates (i.e., territoriality). Areas defended by males overlap the territories of up to 6 females; and male territory area is positively related to the number of female residents. Males maintain dominance over females within their territories by aggression, including intervention into some female disputes. Females spawn pelagically-dispersed eggs as frequently as every day. Each female spawns near her burrow, almost exclusively with the male whose defended area encompasses her territory (harem polygyny). Tilefish colonies therefore consist of a mosaic of female territories over which adjacent male territories are superimposed. Histological evidence and observation of behavioral sex change in one female revealed thatM. plumieri is capable of protogynous sex reversal. Females did not change sex in response to removal of one male. Occurrence of small transitional fish indicates that the onset of sex change is controlled by factors other than size-related social hierarchies within harems or colonies.     

Spawning behavior and haremic mating system in the corallivorous butterflyfish,Chaetodon trifascialis, at Kuroshima Island, Okinawa

Territorial and spawning behavior ofChaetodon trifascialis were investigated on a small patch of reef at Kuroshima Island, Okinawa, Japan. Three males and 8 females inhabited the reef, each individual defending a territory against conspecifics of the same sex. Each male territory included 2 or 3 female territories. In the daytime, each male frequently visited the females living in its territory. At dusk in the full or new moon periods, courtship began within the female territories, pair spawning subsequently occurring within or near those territories. When a male actively courted a female in the territory of a second male, the latter male immediately chased off the intruder. Thus, mating occurred only between a male and females living in former's territory. This is the first report of a haremic mating system among butterflyfishes (Chaetodontidae).     

Patterns of territory size and defence level in rural and urban tawny owl (Strix aluco) populations

The effect of different variables on the territory size and defence level of tawny owl ( Strix aluco L.) populations was studied in two habitats: mixed farmland (1976–1978) and town (1986–1988). Territory size was determined by plotting the position of territorial challenges (hoots) of males which were individually recognizable in most cases. No differences were found in size, defence, number of competitors and biomass between territories in farmland and in town, but territories in town were more fragmented and showed a larger nearest neighbour distance. Size of rural territories was adequately predicted both by some structural habitat features and food supplies, while size of urban territories was affected only by habitat structure and by years of territory occupancy. No effect on territory size by competing neighbours was found in either habitat, thus confirming that behavioural interactions between the owners of territories and potential settlers prevent a decrease of territory size.
Defence level of urban territories was affected by 'social'variables (nearest neighbour distance and years of occupancy), structural variables (percentage of poplar grove and diversity), and food supply, while in rural territories only structural variables (fragmentation or natural vegetation) and food supplies affected defence level.
This was due to different settlement tactics in the two areas, depending on the extent and quality of suitable habitat.     

Male Territoriality in the Bumblebee Wolf,Philanthus bicinctus (Mickel) (Hymenoptera,Sphecidae): Observations on the Behaviour of Individual ♂♂

Observations were made on the behaviour of male Philanthus bicinctus (Mickel) which defend territories around the nesting burrows of ♀♀. ♂♂ were individually identified with small number tags and focal-animal samples were taken of the behaviour of these ♂♂. Intense interactions were observed between territorial ♂♂ and 1) conspecifics and 2) intruding insects which resembled conspecifics. Evidence is presented which suggests that ♂♂ scent mark their territories.     

Androgen control of social status in males of a wild population of stoplight parrotfish, Sparisoma viride (Scaridae)

In the protogynous stoplight parrotfish (Sparisoma viride), large males defend territories that encompass the home-ranges of several mature females. However, high-quality habitat is in short supply, such that smaller, competitively inferior males do not defend territories. We investigated the role of 11-ketotestosterone (11KT) and testosterone (T) in the regulation of territorial behavior in a wild population of a protogynous reef fish, the stoplight parrotfish, at Glover's Reef, Belize. Radioimmunoassay of plasma samples from individuals of known social status revealed that nonterritorial males have lower levels of T and 11KT than territorial males. Nonterritorial males allowed access to vacant territories underwent pronounced increases in T and 11KT. When sampled 1 week after territory acquisition, levels of T and 11KT in new territorial males were significantly higher than the levels in established territorial males, but by 3 weeks after territory acquisition, there was no significant difference. We further investigated the hypothesis that such short-term increases in androgen levels are a response to intense male-male interactions during territory establishment. Simulated territorial intrusion promoted increased plasma levels of both T and 11KT while access to vacant territories without neighboring territorial males did not. These findings suggest that the endocrine system plays a role in fine-tuning the levels of territorial aggression exhibited by male stoplight parrotfish. We discuss these results in light of recent theory in behavioral endocrinology.     

Possible relationships between morphology,territory quality,and skin color of American Kestrels1

ABSTRACT Carotenoid‐based coloration of skin and plumage has been found to be correlated with individual quality in many species of birds during the breeding season. However, less is known about the possible role of these signals during the nonbreeding season, particularly among nonpasserines that defend winter territories. American Kestrels (Falco sparverius) are sexually dimorphic raptors that defend winter territories and possess carotenoid‐based morphological features known to be correlated with individual quality. Much is known about winter territory use and habitat segregation by male and female kestrels, but possible relationships among morphological features, individual quality, and habitat quality have not been examined. Our objective was to examine possible relationships between morphology, territory quality, and skin color of American Kestrels. Male kestrels had brighter skin than females, and the skin color of male kestrels was positively correlated with size (wing chord and tail length) and territorial quality (hunting territories with less canopy and more grass cover). No such relationships were found for female kestrels. Skin color appears to be an honest indicator of quality for male American Kestrels and may serve both intersexual (territory acquisition) and intersexual (mate choice) functions during the breeding and nonbreeding seasons.     

Territorial Behaviour by a Clan of Spotted Hyaenas Crocuta crocuta

Territorial behaviour of a clan of spotted hyaenas, Crocuta crocuta, was investigated in the Kruger National Park over a period of 27 months. These hyaenas were highly territorial, spending ? of their total activities on territory patrol by scent-marking intensively and monitoring 64 marking posts, particularly in border regions. Females, the more philopatric sex, were most active in territory defence. Local intensity of territorial activities by residents within their 130-km² territory was directly proportional to intrusion pressure by neighbours. When clan size was reduced, the ability to defend disputed land declined and larger neighbouring clans appropriated parts of the territory. We propose a relationship between resource distribution, intrusion pressure and territory defence.     

Post-breeding dispersal by female red squirrels (Tamiasciurus hudsonicus): the effect of local vacancies

Red squirrels (Tamiasciurus hudsonicus) defend food-based territoriesyear round, and juveniles must acquire a territory before winterto survive. We experimentally removed territory owners duringthe time that juveniles were becoming independent to examinethe effect of local vacancies on dispersal patterns. Juvenilesattempted to take over removal territories most frequently.However, females with offspring still on the natal territoryactually took over twice as many territories as juveniles. Thesefemales did not appear to move because of low reproductive potentialor to increase territory quality. Instead, moving to a removalterritory allowed more of their offspring to remain on the natalterritory, which appeared to increase juvenile survival.     

Fitness consequences of divorce in the oystercatcher, Haematopus ostralegus

We investigated the fitness consequences of divorce in oystercatchers. We made a distinction between two types of divorce: in desertions the disruption of the pair bond is initiated by one of the pair members, and in usurpations by a conspecific individual. Survival and reproduction prospects for oystercatchers are largely determined by their social status (nonbreeder or breeding bird at a site of a specific quality). Changes in social status in relation to divorce showed that birds taking the initiative to leave their mate increased in fitness, relative to birds that were forced to leave their partner. Status of individuals that remained in their territory after divorce was unaffected if their mate was expelled, but declined if their mate deserted. Survival after divorce was significantly lower for birds that were expelled than for those deserting. Divorce rate, and especially desertion rate, was higher among occupants of low- than high-quality territories. In general, divorce rate increased following elevated mortality. In high-quality territories usurpations increased with increasing breeder mortality, but at low-quality territories this relation was absent. Desertion rates were similarly related to mortality in both territory types. Divorce participants thus differed strongly in their fitness prospects, depending on the type of divorce, the role played in the divorce and the quality of the territory where divorce took place. Studies that do not observe the birds during divorce cannot determine the type of divorce and the role played by the individuals, and this may lead to misleading conclusions on the costs and benefits of divorce. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.      

Male spawning success and female choice in the mottled triplefin,Forsterygion varium (Pisces: Tripterygiidae)

A detailed analysis was made of the variation in spawning success among male Forsterygion (э Tripterygion) varium. The aim was to assess whether females were mating selectively and, if so, to examine the basis of that choice. Eggs were laid on small rocks within the males' territories. Females did not distribute eggs randomly among males. Some males guarded as many as 23000 eggs in one breeding season, while others experienced little or no breeding success. Male spawning success was positively correlated with both their size and some characteristics of their territories, namely the amount of spawning substratum and the presence of a large boulder adjacent to the territory. Experimental manipulations indicated that female choice of males was based on these features. Addition of small rocks into the territories of previously unsuccessful males resulted in a significant increase in spawning success. Conversely, spawning success of the most successful males decreased when small rocks were removed from their territories. When successful males were removed, each territory was occupied by small males; however, there was no significant change in the spawning success of these males. This experiment suggested that, although territory quality was important, female mating decisions could also be influenced by male characteristics such as body size.     

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.