The alternation of mutualistic ant species affects the population growth of their trophobiont mealyhug

Many species of honeydew-producing Homopteran insects have Tniitualistic relationships with ants which defend them against their natural enemies in return for honeydew. In many cases of this type of mtitualism (trophobiosis), a particular honioplcran can associate with a range of mutualistic ant species. We studied the influence of alternation of two ant species, Lasius niger and Pristomyrmex pungens. both of which are mutualistic partners of the citrus mealybug Pseudococcus citriculus , on population growth of their trophobiont mealybug. The growth rate of the mealybug populaiion was significantly higher with attendance by either ant species than without it throughout the year. However, in the field, the mealybug population was significantly larger on trees where a L. niger colony made its territory than on trees where a P. putigens colony made its territory. When the attending ant species changed from L. niger to P. pungens , the mealybug population significantly decreased compared with the population that L. nigcr continued to attend. In contrast, the mealybug population increased following the reverse shift, from P. pungens to L. niger. These results indicate thai, for the mealybug. L. niger is a more effective mutualistic partner than P. pungctis. This deviation was due to a difference in attack behavior by ihc two ant species. Behavioral responses by attending ants to artificial models of natural enemies were more aggressive in L. niger than in P. pungens. The territories of the two ant species were completely separated, and territory takeovers of one ant species by the other were occasionally observed. These facts suggest that interspecific competition between the two ant species is an important factor in determining the spatial distribution of the two species. Thus, we conclude that interspecific competition between the two ant species indirectly affects the population growth of their common trophobiont mealybug.     

The social behaviour of the Pin-tailed Whydah Vidua macroura in northern Ghana

This paper describes the pattern of territory usage by male Pin-tailed Whydahs Vidua macroura , and the display postures used by territorial males, intruding males and visiting females are described. Each territory holder used one or two favoured display sites at which he was visited by, and displayed towards females in groups of one to eight. The frequency of display flights and song output reflected the diurnal pattern of visits by females. Each female was courted by up to six males, but the number of copulations observed was too few to indicate the type of mating system used. The operative sex ratio was estimated at 1:6 (females to territory holders), and the results of a removal experiment suggested that a proportion of males was prevented from breeding.     

A test for repertoire matching in eastern song sparrows

Repertoire matching occurs when one songbird replies to another with a song type that the two birds share. Repertoire matching has previously been demonstrated to occur at well above chance levels in a western population of song sparrows, where it is hypothesized to serve as a low level threat in a hierarchy of aggressive signals. Here we test for repertoire matching in an eastern population of song sparrows. Previous work indicates that this eastern population differs from the western one in having lower levels of song sharing between neighboring males and in showing no association between song sharing and territory tenure. Here we confirm that males in this eastern population on average share few whole songs with their neighbors. The eastern males are familiar with their neighbors’ repertoires, as evidenced by a stronger singing response to stranger song than to neighbor song. Males in the eastern population did not repertoire match: when played an unshared song type from a specific neighbor, they did not reply with a song type shared with that neighbor more often than expected by chance or more often than in response to playback of a control song (an unshared stranger song). The results thus demonstrate a qualitative difference in vocal signaling strategies between two populations of the same species.     

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.     

Habitat quality,population dynamics,and group composition in Colobus Monkeys (Colobus guereza)

Data from an Ethiopian population of Colobus guerezashow that territory size is fixed by the high density of the population. Groups undergo fission when their size results in fewer than 10 trees per individual within the group’s territory. The daughter groups produced by fission emigrate into suboptimal habitat, which acts as a demographic sink. Comparative analyses using data from other East African populations demonstrate that mean territory size is inversely related to population density and that density, in turn, is a function of the size of the forest block. Since both group size and reproductive rates can be shown to be positively correlated with type of forest, it is concluded that this relationship reflects the fact that local population densities reach their ceiling more rapidly in small forest blocks because the animals’ access to alternative territories is limited. The number of males in a colobus group is shown to be a function of the number of females in it. Multimale groups have lower reproductive rates than one-male groups, probably because the stress generated by competition among the males causes temporary infertility among the females.     

Factors affecting the territory distribution of Skylarks Alauda arvensis breeding on lowland farmland

The distribution of breeding Skylarks on lowland farmland was examined on a monthly basis on 13 farms in southern England in 1996. General linear models identified crop type and field area, shape and boundary characteristics as significant independent predictors of Skylark territory numbers in most or all months. Models predicted territory numbers best during the height of the breeding season and less well during territory establishment in March and abandonment in July. From March to May, crop height had no significant effect on Skylark territory distribution, but in June and July it had a highly significant quadratic effect, models suggesting an optimal vegetation height of around 0.55 m in these months. Set-aside held high territory densities, permanent pasture low densities. Spring cereals held higher territory densities than winter cereals. This could best be explained by differences between the two cereal types in crop structure. There was evidence of a positive correlation between crop height diversity and territory density at the farm scale. The results are discussed with reference to the species' recent severe population decline.     

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.     

PLS-PM analysis of forest fires using remote sensing tools. The case of Xurés in the Transboundary Biosphere Reserve

Forest fires have environmental, social and economic impacts in many areas. Various factors related to territory directly influence both the number and the surface area of each fire. The link between different variables (climate, social and environmental) in the risk of fire and in the characteristics of fires is studied here through Partial Least Squares - Path Models. In addition, images from the Sentinel-2 sensor and geographic information systems are used to create a cartographic base of fires in the Transboundary Biosphere Reserve of Galicia and the Site of Community Importance of Xurés (Galicia) between 2015 and 2020. In all, seven variables are analyzed in this study area using the partial least squares-path modeling method: climate, topography, land use, type of environmental protection, the anthropogenic factor, fire defense, and fire data (severity and area). The parameters for each variable are used to obtain weights and thus determine the importance of each one. The areas where the problem of forest fires is greatest are those with the greatest environmental protection. Up to 31% of the surface area of the Natura 2000 Network was burned in the 6-year study period. Topography and land use are also shown to be relevant factors in the effects of forest fires in this territory. By contrast, higher population density and the development of infrastructures such as roads and water tanks mitigate the impact of fires. The problem of forest fires encompasses many variables that need to be studied. By contextualizing each study area as far as possible, specific measures to prevent and reduce damage can be drawn up.     

The genetic asymmetry of the hybrid green frogs Rana esculenta (Amphibia: Ranidae) complex of Ukraine

Research of the alleles of the species-specific genes in the gametal cells of Rana kl. esculenta hybrids proved the existence of three local populations within the territory of Ukraine. Their hybrids reject either the genome of lake frog (Danube lowland), either the previous one or another one genome (basin of Severskiy Donets river), either the genome of pond frog (the residuary territory of the areal). The research of skin transplants rejection of hybrids' parental species has shown that despite the orientation of genome elimination of this population the graft of lake frog always starts identifying and rejecting earlier. That is why the genetic skewness of hybrids becomes apparent at the skin level and corresponds to its manifestations at the organism level.     

The functional significance of multiple nest-building in the Australian Reed Warbler Acrocephalus australis

The vast majority of bird species build a nest in which to breed. Some species build more than one nest, but the function of most multiple nest-building remains unclear. Here we describe the unusual nest-building behaviour of the Australian Reed Warbler Acrocephalus australis , and test experimentally the hypotheses that multiple nest-building is related to individual condition or territory quality, and plays a role in mate assessment. Australian Reed Warblers built two types of nest structures: 'type I' nests, which were used for eggs and nestlings, and 'type II' nests, which were structurally distinct from type I nests, did not support eggs, nestlings or adults and were not essential for successful breeding. The number of type II nests built in each territory varied. Type II nests were only built before breeding had commenced in a territory and females were not observed participating in their construction, supporting a role in female mate choice. Birds provided with supplementary food built significantly more type II nests than control birds. However, supplementary-fed birds did not have greater pairing success, and the addition of further type II nests to territories did not increase the pairing rate or type II nest construction in those territories. There was no relationship between the presence of type II nests and either reproductive success or likelihood of nest predation. We discuss the implications of these results in light of previous suggestions regarding the function of multiple nest-building in birds.     

A comparative study of territory in the Reed warbler (Acrocephalus scirpaceus) and Sedge warbler (A. schoenobaenus)

Various aspects of territoriality were studied comparatively in a marked population of Reed and Sedge warblers at the Attenborough Nature Reserve, Nottinghamshire. Differences in arrival patterns, establishment of territory and particularly territory size were detected. In view of the dynamic nature of territory boundaries, a method is described for obtaining measures of mean territory size for comparative purposes. The sympatric species were largely separated by different breeding and feeding habitats, but there was also a degree of interspecific competition in some areas and interspecific territorialism was found to occur. Adults of both these migratory species were found to exhibit strong site fidelity, and there was some evidence to suggest that early post-fledging experience may influence initial selection of a particular area and territory for first breeding.
The adaptive significance of territory is discussed in relation to the findings presented and current hypotheses. There was some evidence which suggests that reduction of predation pressure and intraspecific interference through spacing out, as well as provision of a nest-site may be important functions of territory in these species, but no evidence that food supply or population regulation are involved. The significance of interspecific territorialism is considered in relation to interspecific competition. The various factors effecting territory size and the patterns of nesting dispersion are also considered in an attempt to account for the striking interspecific differences found between these closely related species. It is concluded that although a multiplicity of factors may well be interacting in complex fashion, the more important of these stem from contrasts in the physical properties of the two habitats.     

The effects and limits of territoriality on population regulation in grey red-backed voles,Clethrionomys rufocanus bedfordiae

The effects of breeding territoriality on the stability of grey red-backed vole (Clethrionomys rufocanus bedfordiae) populations were investigated on a control grid and a grid on which the voles were fed, in an outdoor enclosure in Hokkaido, Japan. Vole populations were monitored by live trapping from 1984 to 1986: (1) Population density was 2–7 times greater on the experimental grid to which food was added than on the control grid. Reproductive output was more closely associated with the difference in density between grids than survival or dispersal (immigration and emigration) rates. (2) The number of adult females and pregnancy rate of the experimental population were significantly greater than those of the control one. The difference in the number of adult females between the populations was greater than that in pregnancy rate. (3) The proportion of successful litters and the number of weanlings per litter were not significantly different between the control and experimental population. (4) Adult females held territories on both the control and experimental grid; they were spaced out more than would be expected from random occupation. The territories overlapped more on the experimental grid than on the control grid. (5) Mean territory size of adult females on the experimental grid was about half of that on the control grid. The territory size was correlated negatively with population density. (6) The proportion of trap sites that were used by adult females was significantly greater on the experimental grid than on the control grid. This suggests that adult females on the experimental grid used the area more extensively. This factor, in association with territory size and overlapping of territory, was also important in causing the difference in the number of adult females between the grids. (7) These results call into question the hypothesis that territoriality stabilizes the density in populations of Clethrionomys.     

An energy-based model of optimal feeding-territory size

An energy-based model of feeding territoriality is described. The model predicts an optimal territory size where the territory holder's net energy intake is maximized, on a daily or seasonal time scale. Simulated effects on optimal territory size of animal size, food availability, and competitor density are in general agreement with observed relationships in a wide variety of animals. When salmonid data are used to estimate the model parameter values, predicted territory sizes are similar to those actually observed. When emigration is allowed, the model predicts that territoriality, through individual selection alone, can regulate population size, but that this regulation breaks down when initial densities exceed some threshold value. Sensitivity analysis shows optimal territory size to be most affected by those parameters influencing food intake and energy expenditure. Some alternative criteria for optimization are also discussed. An animal maximizing net foraging efficiency has a smaller territory than one maximizing net energy, but the effects of animal size, food availability, and competitor density on territory size are the same in either case.     

Impact of spatial variation of a crucial prey,the molecricket,on hoopoe territory occupancy and reproduction

Direct benefits accrued from securing a territory of sufficient quality are important determinants of individual fitness and population persistence. Food supply is one of the main factors of animal territory quality, with spatial and temporal variation in prey availability largely dictating reproductive output and thus population dynamics. In a Swiss hoopoe population, molecrickets Gryllotalpa gryllotalpa, the most profitable prey locally, can constitute most of the food biomass delivered to chicks by parents. We first investigated the impact of molecricket prey on hoopoes' fitness‐related traits by quantifying the spatial variation in the food allocation pattern of both male and female parents to chicks across the whole population range; and second, analysed the impact of this prey on current reproduction and, using a 11 yr dataset, on the temporal occupancy rate of each territory. We found considerable but spatially repeatable variation, over the years, of molecricket biomass in the diet provisioned to chicks. This spatial heterogeneity in chicks' diet composition was mirrored both in the history of territory occupancy (2002–2012) and in current reproductive success (2012). Territories with a greater biomass of molecrickets in chicks' diet produced more fledglings in better body condition. Yet, these effects on current reproduction were exclusively demonstrated for male parents, corroborating that paternal provisioning patterns play a predominant role in hoopoe reproductive success. This study demonstrates how a single, very profitable prey species might affect spatial variation in territory settlement and individual reproductive success in a regionally endangered bird species, with potential consequences for its population dynamics and persistence.     

The importance of ant-rich habitats for the persistence of the Wryneck Jynx torquilla on farmland

The frequency of territory occupancy is a good indicator of territory quality. We studied territory occupancy in a Swiss population of the Wryneck Jynx torquilla , a declining farmland woodpecker, with the aim of identifying key habitat features for conservation management. Both static and dynamic approaches were applied using data on nest-site occupancy of 100 territories from six successive years. The static approach models the probability of territory occupancy; the dynamic approach estimates territory colonization and extinction. Frequently occupied territories were settled earlier in the season, suggesting that they may be of better quality, and birds settling in these territories had higher breeding success. Probability of territory occupancy increased with the area of old pear orchards and decreased with the area of vegetable cultivation. Both the area of old pear orchards and the presence of conspecifics within a territory were positively related to territory colonization, whereas territory extinction was negatively related to habitat heterogeneity. Old pear orchards were characterized by having both the highest density of ant nests and the greatest amount of bare ground. The latter is likely to facilitate access to ant prey. To ensure persistence of Wryneck populations in farmland, heterogeneous habitat matrices with high ant nest density and bare ground should be promoted. Finally, provision of artificial nesting cavities is likely to enhance territory occupancy. Providing that these key resources are present, Wrynecks are likely to persist even in intensively farmed areas.     

The mortality of two groups of infants in Spanish rural region

In this study the structure of the mortality of two groups of infants settled in the same environmental context is analysed: the comarca (a typical Spanish sub-division of territory) of La Cabrera (province of León, Spain) between the years 1880 and 1932. In this geographical region of the northwest of Spain two communities of infants from different origins are found in this time period. On the one hand, an autochthonous infant population from the births of the legitimately constituted families settled in this territory. On the other, an infant population represented by a group of children who were abandoned in a foundling hospital situated in a nearby city (Ponferrada) and who were sent to this rural "comarca" to be breast-fed by wet-nurses being paid certain quantities of money. The mortality rates and the seasonality of the deaths have been analysed for both the autochthonous and non-autochthonous children. Thus we have been able to test whether differences in the structure of mortality exist. Throughout the study, the possibility that these differences in mortality could be attributed to discriminative cultural factors, expressed through preferential care and/or attention and which show in the different models of infant mortality, is considered.     

The Dynamics of Territory Acquisition: A Model of Two Coexisting Strategies

Two potential strategies for acquiring territories are (1) fighting and taking over a territory from its owner, or (2) waiting until a territory owner dies and then taking its place. In this paper we explore territory acquisition using these two strategies, using a population dynamical model. Factors expected to affect the predominance of each strategy are injury rate, rate of successful territory takeover, birth and death rates on the territory, and birth and death rates while non-territorial. We explore the effects of these parameters on numbers of territorial and nonterritorial fighters and waiters. Waiters predominate when injury rate, birth rate of nonterritorial individuals, and death rate of territory owners are high. Fighters predominate when rate of successful territory takeover, death rate of nonterritorial individuals, and birth rate of territory owners are high. We present supportive evidence for these preditions from the literature.     

黑卷尾繁殖期领域性的初步研究

鸟类的领域性是鸟类行为生态学研究的一个重要内容。在这方面国外进展很快,但国内工作较少,专文报道除三宝鸟之外,其它颇为罕见。1987年夏季,我们在太原市南郊对该地区的夏候鸟黑卷尾(Dicrurus macrocercus)的领域行为进行了观测。现将资料整理分析如下。一、工作区与工作方法太原盆地的自然环境和鸟类群落状况已有报道,在此不再赘述。工作区选在小马—加节两村之间约190ha的区域内(图1)。其