Nearby Territories Research Articles

Natal and Breeding Dispersal in a Co-Operative, Extra-Group-Mating Bird

Natal and breeding dispersal of yearling and adult Superb Fairy-wrens Malurus cyaneus were studied for five years in Canberra, Australia. Superb Fairy-wrens are co-operative breeders and exhibit male philopatry and female-biased dispersal. Dispersal by yearling males was prompted mainly by breeding vacancies in nearby territories, and most males acquired a social mate without leaving their natal territory. All females dispersed in their first year, in two discrete phases. Early dispersal by females appears to be volitional, whereas late dispersal is forced by aggression by mothers. Early-dispersing females fledged earlier and dispersed further than latedispersing females. Females travelled further than males, and either gained a breeding position at age one year, or disappeared. Obligate dispersal by young females appears to be costly, contradicting predictions of philopatry by co-operative breeding theory. Dispersal by established breeders was uncommon, and was female-biased. The role of the unusual mating system of the species is discussed, and dispersal patterns in this species are compared and contrasted with those of its congener M. splendens.

Dispersal of wolves (Canis lupus) in northeastern Minnesota, 1969–1989

We examined the dispersal patterns of radio-collared wolves (Canis lupus) from 21 packs in the Superior National Forest, Minnesota, from 1969 to 1989. A total of 316 wolves (542 wolf-years) were captured, radio-collared, and followed during 21 years of radio-tracking; 75 were identified as dispersers. Both sexes dispersed equally. Of the adults, yearlings, and pups, 8, 75, and 16%, respectively, dispersed. Most dispersers left when they were 11–12 months old, only a few wolves dispersing as adults. Dispersal occurred mainly in February–April and October–November. Adults dispersed short distances into nearby territories, but yearlings and pups dispersed both short and long distances. Yearling and pup dispersal rates were highest when the wolf population was increasing or decreasing and low when the population was stable. Adults had the highest pairing and denning success. Yearlings had moderate pairing and low denning success, and pups had low pairing and denning success. Yearlings and pups that dispersed a short distance had a higher success of settling in a new territory, likely reflecting available vacancies in nearby territories. Thirty-five percent of the known-age wolves remained in their natal territory for >2 years; two wolves were known to have remained for >7 years. The relative weight of pups at capture apparently did not affect their age or success of dispersal or the tendency to disperse.

Coupling Delayed Breeding with Short‐distance Dispersal in Cooperatively Breeding Birds

AbstractShort‐distance dispersal in cooperatively breeding birds is demonstrated and a new model describes how it could be causally related to delayed breeding. Nonbreeders are hypothesized to wait for specific, adjacent territories of high quality. Strong, predictable differences in territory quality select for extended natal philopatry in comparison with species whose young disperse upon maturity. A nonbreeder's ability to discriminate territory quality, and competitive advantages of age and proximity in obtaining nearby breeding positions, are necessary conditions of this model. Direct benefits to both males (potential for inheritance of a breeding position on the natal territory) and females (priority to nearby territories of high quality) result from philopatry. This model differs from most others by emphasizing potential direct benefits of delayed dispersal, rather than assuming constraints, such as habitat saturation. Short‐distance dispersal is widespread in other bird and mammal social systems characterized by natal philopatry and delayed breeding, suggesting a general application of this model.

Male Parental Care and Extrapair Copulations in the Indigo Bunting

Abstract Levels of parental care by male Indigo Buntings (Passerina cyanea) were predicted to be lower and the tendency to pursue extrapair matings greater when (1) the opportunity of additional matings (extrapair copulations) was high, (2) the male was cuckolded, and (3) the clutch or brood size was small. Observations of male care revealed that approximately 10% of all males fed nestlings at least once, whereas more than 30% fed fledglings. Males in their first breeding season were never seen feeding young. Males made more trips off their territories when females were fertilizable on nearby territories, but other measures of parental care (feeding young and time spent within 10 m of nest) were not affected. Cuckolded males (known through genetic analyses of parents and offspring) tended to feed young less often, but forayed off their territories significantly less than apparently uncuckolded males. Finally, males with small clutches or broods gave slightly, but not significantly, less care than males with large clutches or broods. These results suggest that the relationship between mating effort and parental effort is complicated by the presence of extrapair copulations as a type of mating effort, and that factors not included in current theory on parental care might influence a male's parental care.

Territoriality among male red-winged blackbirds

We examined male site fidelity and territorial movements in a population of individuallyidentifiable red-winged blackbirds (Agelaius phoeniceus) over an 8-year period. Based on general theory and knowledge of the ecology of this population, we predicted that males would be site conservative, and that they would voluntarily change territories only when they could expect to improve significantly their reproductive success. Because males are absent from their territories for only short periods, and probably have accurate comparative information only about nearby territories on which to base their decisions, we predicted that most moves would be over short distances. About 70% of males that bred for more than 1 year retained their original territories between breeding years. Most of the 30% of males that changed territories moved less than 200 m, often to adjacent territories. As predicted, males moving less than 200 m tended to have better reproductive success after moving than before, whereas long distance movers did not improve their success after moving. Territorial male redwings appear to monitor breeding activity on nearby territories and move when significant potential benefits are perceived and opportunities exist. Long-distance moves may be involuntary ones. The amount of information possessed about present and alternative sites, and the time and opportunity required to collect the information, are probably major constraints influencing site conservatism in this and other territorial species.

Group Territoriality in the Rattling Cisticola, Cisticola chiniana

Group territoriality was studied in an individually colourbanded population of the rattling cisticola (Cisticola chiniana) in Kenya. These birds were found to live in social groups consisting of 1-3 males and 1-5 females; the male(s) defending an all-purpose territory of variable size and quality. In one year approximately 50% of the variation in group size could be ascribed to the density of bushes in the territories. Territories with a high density of bushes were smaller in size than more open ones. The proportion of territories defended by multi-male coalitions varied between 0 and 0.71 in the four different years. Coalitions were between father and son in 57% of the cases and between two unrelated males in 43%. Members of coalitions differed in terms of body size, age and dominance. Subordinate males contributed substantially to territorial defence. Territories defended by a single or by two males, respectively, did not differ in size, but, when one male was experimentally removed from a coalition the size of the territory shrunk. Male coalitions seem able to control better territories than neighbouring solitary males. Territory vacancies were rapidly filled by subordinate males from nearby territories.

ON THE DEFINITIONS AND FUNCTIONS OF DOMINANCE AND TERRITORIALITY

Summary1. Dominance/subordinance is a relationship between two individuals in which one defers to the other in contest situations. Each such relationship represents an adaptive compromise for each individual in which the benefits and costs of giving in or not giving in are compared. Familiar associates in groups or neighbours on nearby territories may develop relatively stable dominant‐subordinate relationships based on individual recognition. Although the aggressive aspects of dominance are usually emphasized, the less conspicuous actions of the subordinate individual are actually more important in maintaining a stable relationship.2. In evolutionary terms, dominance essentially equals priority of access to resources in short supply. Usually the subordinate, who would probably lose in combat anyway, is better off to bide its time until better able to compete at another time or another place. Both individuals save time, energy, and the risk of injury by recognizing and abiding by an established dominant‐subordinate relationship.3. Dominance can be either absolute or predictably reversible in different locations or at different times. Of the various forms of dominance behaviour, rank hierarchies and territoriality represent the two extremes of absolute and relative dominance, respectively. A dominance hierarchy is the sum total of the adaptive compromises made between individuals in an aggregation or organized group. Many animals seem to be capable of both absolute and relative dominance, and within species‐specific limits the balance may shift toward one or the other. High density, or a decrease in available resources, favours a shift from relative to absolute dominance. Some species may exhibit both simultaneously. Social mammals may have intra‐group hierarchies and reciprocal territoriality between groups, while the males of lek species may exhibit ‘polarized territoriality’ by defending small individual territories, with the most dominant males holding the central territories where most of the mating takes place.4. Territoriality is a form of space‐related dominance. Most biologists agree that its most important function is to provide the territory holder with an assured supply of critical resources. Territoriality is selected for only when the individual's genetic fitness is increased because its increased access to resources outweighs the time, energy, and injury costs of territorial behaviour.5. Territoriality was first defined narrowly as an area from which conspecifics are excluded by overt defence or advertisement. The definition has been variously expanded to include all more or less exclusive areas without regard to possible defence, and finally to include all areas in which the owner is dominant. I define territory as a fixed portion of an individual's or group's range in which it has priority of access to one or more critical resources over others who have priority elsewhere or at another time. This priority of access must be achieved through social interaction.6. My definition excludes dominance over individual space and moving resources, and includes areas of exclusive use maintained by mutual avoidance. It differs from most other definitions in its explicit recognition of time as a territorial parameter and its rejection of exclusivity and overt defence as necessary components of territorial behaviour. There is an indivisible continuum of degrees of trespass onto territories, and functionally it is priority of access to resources that is important rather than exclusive occupancy.7. There is a similarly indivisible continuum in the intensity of behaviour needed to achieve priority of access to resources. Deciding whether or not an exclusive area is defended leads to the pointless exercise of trying to decide which cues indicating the owner's presence are conspicuous enough to merit being called defence. Concentrating on overt defence emphasizes the aggressive aspects of territorial behaviour rather than the equally or more important submissive aspects such as passive avoidance.

Malaysia-A New Federation in Southeast Asia

IN MAY i96i, the Prime Minister of Malaya, Tunku Abdul Rahman set into motion political forces that will transform the map of Southern Asia and greatly affect the political environment in this area of the world. In a speech before the Foreign Correspondents Association of Southeast Asia he said that Malaya have an understanding with Britain and the peoples of the territories of Singapore, North Borneo, Brunei and Sarawak. It is premature for me to say now how this closer understanding can be brought about but it is inevitable that we should look ahead to this objective....I What made this statement so sensational was not that the idea of a Greater Malaysia was so new. Indeed, the idea (in different form) has captured the imagination of many Malay and Indonesian nationalists for years, and during the war this sentiment was encouraged by the Japanese who hoped to channel the force of nationalism in Southeast Asia against Japan's enemies. But, in the period after the war very few persons in authority mentioned the idea of a larger political union because such proposals were either politically dangerous or impractical in that period of political change and ferment. Even the proposals for union between Singapore and the Federation of Malaya were spurned by the Malayan Government because of the unstable political situation in Singapore and the fear that Singapore's Chinese population would upset the racial balance in the Federation.2 Under these circumstances, the possibility of a wider union seemed remote. In Malaya such thoughts were expressed in public by only a few of the more radical Malay politicians who occasionally referred to the idea of Melayu Raya-generally defined as a Malaysian Empire embracing all the peoples of Malay ethnic stock and modeled after the Indonesian Republic, which would presumably become its center. What, then, were some of the circumstances in i96i which prompted the Malayan Government to reverse its apparent long-standing opposition to political union with other nearby territories? A major factor in the decision

THE FUR RESOURCES OF CHAPLEAU DISTRICT, ONTARIO

Records of the area trapped and of legally caught furs in the Chapleau district, Ontario, have been made for the seasons 1941–42 to 1946–47. From these records the area required to produce one harvested animal has been computed for most species, which should be of considerable value to persons concerned with fur production in Canada. These figures should also be useful to students of animal populations since they take into account, at least in part (specific areas actually trapped), the variation in trapping pressure that cannot be reflected in figures based on total numbers taken from large areas. This six year period seems sufficient to indicate significant trends in populations, which in certain cases might be predicted by study of past trends of province-wide returns.During the six year period the average return value for each square mile trapped was $16.90, which netted each trapper using one township an average of $607.00 each year. The average total annual fur resources amounted to $74,000.00.The distribution of the catch of marten and fisher in the district suggests that the Chapleau Crown Game Preserve may be influencing the catch of these two species in nearby territories.