THE BREEDING BEHAVIOUR OF THE WHITE BOOBY SULA DACTYLATRA*

The aim of this paper is to describe the form and interpret the motivation, function and derivation of breeding behaviour in the White Booby. Attention is paid to adaptive aspects and an effort made to correlate behaviour with environment? particularly colony density and associated degree of competitive behaviour. The absence, simplicity or complexity of certain displays can be correlated with the extent to which highly developed social and /or pair interaction are needed. Throughout I have tried to place White Booby behaviour in the framework of behaviour in the Sulidae as a group and particularly to compare it with Gannet behaviour, since the latter nest more densely than other sulids and show more extreme aggression and greater ritualization of behaviour patterns used in interpair and wider social communications. The White Booby provides an interesting contrast. After a brief account of morphology and voice the points are made that White Booby colonies are generally smaller and much less dense than those of the Gannet or Peruvian Booby and also that White Boobies breed in a wide variety of habitats. Site establishment, pair formation, later pair relations, social interactions, body maintenance behaviour, incubation and care of young are described and an account of behaviour in the young is given. The male establishes the site and shows yes /no headshaking as an aggressive, site-ownership display, often performed after landing. He attracts the female with a sky-pointing display which is homologous with sky-pointing in the Gannet, where, however, it subserves a different and, it is argued, phylogenetically older function, signalling that a bird is about to leave the site rather than serving as an advertizing display. In the White Booby it is thus a good example of a motivationally and functionally emancipated display. When the pair meet, mutual jabbing, a hostile-looking and relatively undifferentiated meeting ceremony, and bill-touching occur. Symbolic nest building plays an important part in White Booby pair behaviour, though the nest is structurally negligible. Nest building is associated with copulation, in which the female is not gripped. Bill-up-face-away is a bill-averting posture used when a booby moves away from its mate. It is probably an appeasement posture and, so far as the situation “I am about to move” is concerned, seems to have taken the place of Gannet sky-pointing, the latter having become the booby's advertizing. Wing rattle is a movement probably partly functional in preparing feathers for flight, but is also used as signal behaviour prior to take-off, particularly during the frequent flights around the breeding area that White Boobies show early in the season. Wing flapping, sometimes with rotary headshaking, is mainly feather maintenance behaviour. The forms of headshaking and head flinging are described. Reciprocal allo-preening occurs; it is suggested that it can do so without disadvantage since White Boobies possess mutual jabbing—an interaction which can accommodate any aggression engendered by the pair pointing bills at each other, as required for reciprocal allo-preening. The average incubation spell in the male is 30 hours and in the female 25 hours; all sulid males show this tendency to spend longer on the site. Seasonally, too, there is a marked sex-difference in site attendance and this is depicted in graphs for different categories of White Boobies. The young are left unguarded from about four weeks of age and move off the site. They are fed about 1.4 times per day. They respond to adult investigation or attack by beak-hiding—an effective appeasement posture. Soon, they perform aggressive territorial behaviour and dispel other young and adults. They return to the site to be fed for around 50 to 60 days after they become free-flying and show all forms of territorial behaviour. The discussion is mainly concerned with the correlation between nesting density, aggression and associated appeasement behaviour. It is concluded that, overall, the White Booby's ritualized postures and displays are less well differentiated than those of the Gannet, though individual behaviour patterns may be more complex. The pair relationship in the White Booby approximates more closely to that normally found in birds, where the male is not outstandingly aggressive to his mate.     

THE BIOLOGY OF ABBOTT'S BOOBY SULA ABBOTTI

766 pairs of Abbott's Boobies Sula abbotti were located on Christmas Island (Indian Ocean), the species' sole breeding ground, and a further 1,058 pairs conservatively estimated to have been missed. To these may be added an arbitrarily chosen figure of two-thirds the number of juveniles which were on the island at the time of the estimate, to represent sub-adults which were probably away at sea, giving a total of 4,200-5,100 individuals. An independent assessment, based on the number of birds flying in to the island, gave a conservative figure of 3,500-4,500 individuals. This represents a very large increase over previous figures which were merely guesses. The distribution of abbotti is mapped in detail. Its correlation with topographical features is described. Nests are usually placed over 70 feet high in dense jungle, above the 500 foot contour. Abbotti is the only sulid that nests relatively solitarily, but even so there may occasionally be three nests in a tree. The most densely populated area held 90 pairs in 876,000 m². The morphology of all ages is described and weights and measurements given. Adult males averaged 1,503 g, females 1,600 g. The species can be sexed on bill colour (pink in female, blue-grey in male) but the juvenile is virtually indistinguishable from the male. Adults apparently suspend moult during breeding and resume it as their offspring approaches independence. The breeding cycle occupies more than 15 months and egg-laying seems restricted to April-July. Breeding must therefore be biennial (or less frequent). The large egg constitutes more than 7% of the female's weight, more than twice as much as in S. bassana (also uniparous) and considerably more than any other sulid. Incubation takes 56 days and incubation stints average about 52 hours. The growth of abbotti is remarkably slow. A comparison is made with that of S. leucogaster on the same island at the same time. The chick is at first fed by complete regurgitation, a habit not shown by any other sulid. Feeds average one per day until the chick is about two months old, and are iess frequent thereafter. Males and females take approximately equal shares in feeding the young. The fledging period is probably 24 weeks or more and is followed by three to four months of post-fledging dependence. Several features of abbotti's breeding biology suggest that it is a distant, oceanic forager. Abbotti is markedly unaggressive, both in rival and pair situations, and the effects of this are traced in the composition of its behaviour repertoire. It is suggested that marked inhibition of close-range aggression has evolved to reduce the likelihood of falling from the tree tops, a particularly potent danger since a grounded abbotti is doomed. Some other aspects of behaviour (e.g. longdistance pair interactions, restrained chick begging) support this interpretation. Abbotti's chief ritualised behaviour pattern is the “ecstatic” meeting ceremony Mutual Wing Waving, which is probably important in maintaining the pair bond, in a species needing such prolonged co-operation in breeding. Wing Waving is also used as a territorial (agonistic) display. Head Jerking, the only other conspicuous ritualised display, is chiefly aggressive but frequently occurs in the pair context. The main elements of abbotti's behaviour are summarised (Table 8) within the sulid framework. The Discussion considers the probable adaptiveness of abbotti's plumage and morphology, the evidence for classing abbotti as a distant forager, its behavioural peculiarities compared with the family norm, and the phylogenetic implications. The future prospects for Sula abbotti are a matter for concern, since Christmas Island is destined for further phosphate mining, involving substantial destruction of cover. It has been suggested that “tree islands” in the key areas would help conserve a significant proportion of the world's abbotti population. It is hoped that a survey of abbotti's numbers and distribution around 1972 will help evaluate the effect which destruction of habitat has already had and provide a basis for estimating future prospects.     

THE BREEDING BIOLOGY OF THE GANNET SULA BASSANA ON THE BASS ROCK, SCOTLAND

The Bass colony is increasing—in 1962 there were 5,350–5,700 breeding pairs; 1,340–1,430 pairs of non-breeders with nests or sites (mainly pairs in their season before first breeding) and 2,000–2,500 “club” birds without nest or site. 15% of nests were occupied by both birds of a pair at the time of the count. Oldest males return to the colony in January, followed by experienced females, considerably later by young adult-plumaged birds, immature birds later still, and the few one year-olds that return usually not until May and June. Mid-cliff sites are the first to be re-colonized each year. Gannets usually breed in their fifth year and there is some evidence that females breed earlier than males. The characteristics of Gannet nests and sites are described. Nests function in raising the egg and young above the morass of the breeding colony, and reach a density of about 2.3 per square metre. Nests are demolished and their positions changed more often than might be suspected. The extremely strong social tendency which causes Gannets to establish their sites amongst or very close to existing breeders probably is the factor ensuring high density and this contributes to synchronization of laying. Egg laying is analysed. Experienced pairs forming an isolated group of 20 nests began laying later and showed less synchronization than two other groups of the same size but from the middle of a dense mass, probably due to the greater social stimulation experienced by the non-isolated groups. The date for first and median eggs was also earlier in larger than smaller groups in the same year. The effect of density as distinct from group size is also discussed. Early eggs are mainly laid on cliff or cliff-edge sites and in large nests. Different groups within the colony produced the median egg within 2–3 days of the end of April each year. In the fullest documented group the mean date was also constant from year to year and closely approached the median, implying a considerable degree of synchronization within the gannetry as a whole. Laying in the observation colony became progressively earlier in successive years, probably due to recovery from previous disturbance. Nevertheless, individual females tended to lay in a fixed position each year with relation to the mean for the group. Increasing age of the female causes earlier egg laying and heavier eggs for up to at least five years. It is suggested that the survival value of seasonally synchronized laying in the Gannet is maximum utilization of a seasonally dependable and abundant food supply for the production of young with the optimal chance of post-fledging survival. The spread of laying acts as an insurance against possible adverse conditions. There is a considerable reserve of unutilized breeding capability within the colony (adult non-breeders, a pre-maturity period longer than physiologically necessary for egg production, and a one-egg clutch when in fact two young can easily be reared). The mean of 393 Gannet eggs was 104.5 gm. (range 81–130). Eggs constitute about 3.4% of adult female weight and lose 9–13% in weight during incubation. Replacement laying of the invariable one-egg clutch takes 6–32 days. The mean incubation period was 43.6 days. Male incubation spells averaged 35.6 hours; female's 32.0 hours. Copulation ceases immediately after egg laying. During three seasons, 82% of eggs laid in the observation colony hatched. Inexperienced pairs hatched 62.6% of eggs laid; experienced pairs hatched 86%. Some of the processes of incubation and chick rearing depend on the maturation of innate abilities and not on experience Inexperienced breeders do not seem inferior to experienced ones in finding enough food for their young. Parental care of the new chick is described; the pterylosis of the chick is figured. A summarized account of plumage development is given. Food fish and chick feeding are described. The average frequency of feeds throughout a continuous two-day watch was 2.7 feeding bouts per chick per day. Adult fishing trips usually took 7–13 hours and the estimated fishing range is over 100 miles, and possibly up to 400 miles, from the breeding colony. Despite this, 15% of daylight hours are spent by the pair together at the nest in addition to the constant guarding of the chick by one or other. Gannet young have a very compressed growth period compared with boobies and fledge at 3,100–4,100 gm., after a steady growth uninterrupted by periods of starvation or arrested development after an average 90 days. 92.3% of all eggs which hatched in 500 nests in the observation colony during three years of the study gave fledged young. Excluding inexperienced birds, there was no difference in the fledging success of eggs laid at different dates in the breeding season, in accordance with the proved abund- ance of food. However, post-fledging survival is probably higher among young fledging at the peak period (first half of September) than later and the few relevant ringing returns tend to support this. Breeding success at the small colony at Bempton was less compared with groups from the Bass for the years 1961–3. Causes of chick loss before and during fledging are discussed. They are unimportant compared with the great mortality in the first year of life after fledging. The adaptive significance of black plumage in the juvenile Gannet probably lies in reduced attack-releasing qualities of such plumage on the male parent. The Gannet alone in the Sulidae produces young which leave the nest with large fat deposits, and which are not fed at all by the parents after fledging. This is possibly another result of adaptation to using a seasonally abundant food supply to the maximum. The present Gannet population increase is discussed in relation to cessation of human predation, the possible impetus given by a temporary but large increase in pelagic fish during the war, but also the overall steady downward trend in fishing returns since the early part of this century. One cannot explain the steady and considerable rise in Gannet numbers only in terms of increased food supply. The fact that, at a time of population expansion and obviously favourable conditions, Gannets are still far from utilizing their full recruiting powers, needs investigating further. It may be partly due to the relative slowness of evolutionary change in a long-lived species with slow population turn-over, if the Gannet has evolved its characteristics in response to an environment different from the present one.     

COMPARATIVE ETHOLOGY OF THE CICONIIDAE. THE WOOD-STORKS (GENERA MYCTERIA AND IBIS)*

This paper reports on an 11-year study of the comparative behaviour of the four species of wood-storks. All species were studied under natural conditions at breeding colonies in the U.S.A., East Africa, India, and Indonesia. In addition, observations were made on hand-reared young of two species (Mycteria americana and Ibis ibis). Various aspects of signal (display) and non-signal behaviour are described. The most common ritualised display away from the nest is the Forward Threat. At the neBt, the following displays are seen, mainly during courtship and pair-formation: Aerial Clattering Threat, Forward Clattering Threat, Snap Display, Anxiety Stretch, Flying Around, Gaping, Balancing Posture, Swaying Twig-Grasping, Display Preening, Up-Down, and Copulation Clattering. Each of these patterns is described in the text and many of them are illustrated. The four species treated here are similar to each other in most behaviour patterns. They do show some quantitative differences in courtship displays, particularly in the Up-Down, a common “greeting” display shown to the mate at the nest. The behavioural and morphological evidence now available does not justify the separation of M. americana into a monotypic genus, and I suggest that all four wood-storks be combined in the genus Mycteria. Thus, the wood-storks include: M. americana, M. cinerea, M. ibis, and M. leucocephala.     

Displays of the Honeyeater Manorina melanocephala

Investigated displays of Noisy Miners, Manorina melanocephala, in Australia. This unusual bird lives in colonies and many ♂♂ care for the offspring of each ♀ flight displays, 11 non-flight displays, and several components of facial displays (including a variable eye patch) are described. The eye patch provides a large yellow and black augmented eye, important in intimidation. No stereotyped sequence of courtship behaviour precedes copulation. Displays are used to advertise nest locations. A greeting display, the corrohoree, is extremely common. The possibility of the evolution of submissive display from threat is discussed. Special vocalisations of ♂♂ and ♀♀ are use in a duet. The maintenance of bonds among many individuals in a colony may be more important than strong pair bonds. Group cohesion is probably maintained by flight display, nest display, mobbing, and other communal activities. High interspecific aggression results in few resident species in colonies. This level of interspecific aggression might be maintained by incorporating much intraspecific mimetic display and ritualised submissive behaviour.     

4. THE SOUTH AFRICAN CLIFF SWALLOW

Short, L.L. &; Horne, J. F. M. 1980, Vocal and other behaviour of the Green Barbet in Kenya. Ostrich 51:219–229.

Brief field studies of the Green Barbet Stactolaema olivacea in coastal Kenya, with emphasis on vocalizations, document its social behaviour, including communal roosting of four birds in a cavity. Green Barbets are aggressive, interacting strongly with a number of species. Erecting of the crown feathers, cocking of the tail, and woodpeckerlike swinging movements characterize displays. Wing Flutters and audible Bill Wiping are visual-auditory displays. Vocalizations include the Grating Call, Kek Call, Chuk Call and Chowp Call. These are agonistic and agonistic-reproductive in function. The Chowp Call comprises the song, used in simultaneous singing and duetting.     

STUDIES OF THE PURPLE HERON,PART 2: BEHAVIOUR PATTERNS

Tomlinson, D. N. S. 1974. Studies of the Purple Heron, Part 2: Behaviour patterns. Ostrich 45: 209–223.

Some aspects of Purple Heron Ardea purpurea behaviour have been covered although the study is not complete. Further observations are needed, especially on pair formation, nest building and copulation. Many of the displays described for the Ardeidae are clearly homologous and only slight differences exist. The throat puffing component in the Aggressive Upright Display appears unique to A. purpurea as does the clappering and sudden retraction of the neck in the Stretch Display. Birds raised in captivity provided valuable information on agonistic behaviour patterns and the behaviour of young.     

Territorialité et agressivité intra- et interspécifique dans les mosaïques de fourmis arboricoles

Tropical arboreal ants are distributed in a mosaic pattern in the canopy of forests and tree crop plantations each of them characterised by their status of dominance. One can distinguish ‘dominant’ species, characterised by extremely populous societies and highly developed interspecific as well as intraspecific territorial behaviour. They tolerate on their territory nonterritorial and less populous species classified as ‘non-dominants’. Nonetheless, many species do exist whose status is intermediary. Usually, they behave like non-dominant species but are able, under certain conditions, to defend a territory. They are cited as ‘sub-dominant’. According to the chemical trapping method employed by researchers, the structure of mosaics have most often been studied using an index of dominance, characterised by the number of negative or positive associations between one species and the others. This index only covers the relative presence or absence of the different species on the same trees. It only gives a punctual statement on the structure of the mosaic without any notion of evolution of the mosaic in time. It does not take into account the behavioural intra- and interspecific interactions. Aggressive interactions between species depend on genetic and environmental factors. Many studies have shown that aggressiveness is closely related to a mechanism of interindividual discrimination, permitting an individual to discriminate between nestmates and non-nestmates. This colonial recognition is based on the existence of a ‘colonial odour’ as a result of a blending of ‘individual odours’. Each individual odour is due to cuticular hydrocarbons which play the role of a contact pheromone. The colonial odour also depends on the environmental odour of the nest. Aggressiveness which results from this mechanism of recognition can be expressed through different mechanisms such as territorial behaviour, dominance hierarchy, and ritualised aggressive behaviour. Territorial behaviour is the expression of a strong intraspecific aggressiveness, by which workers of a colony defend an area of their vital domain against neighbouring conspecifics. In arboreal ant mosaics, dominance hierarchy can exist between dominant ants, and should explain the overturning of dominant ants in time. Ritualised behaviours were observed under intra- and interspecific low-aggressiveness conditions and allow to economise the loss of one or several workers during fights whose issue are uncertain. Their systematic study would greatly facilitate understanding of the evolution of arboreal mosaics.     

Seasonal dynamics of agonistic displays in territorial and non-territorial males of goitered gazelle

Aggression serves a great variety of social functions, one of which is protection of individual territories from intruders. Territorial males of many antelope species show aggressive noncontact displays, and only rarely fight. It has been suggested that ungulate males tend to have more frequent and longer aggressive interactions with rivals of similar age or social status than with males of dissimilar status. In the present paper, we test whether territorial and non-territorial males behave in a similar manner and avoid fights, and whether or not they preferentially direct aggressive and longer agonistic interactions towards males of similar age or social status, rather than towards other classes of males. We found that territorial males usually avoided straight fights with peers, and instead mainly used noncontact displays in aggressive interactions. In contrast, non-territorial males used fights considerably more often, especially during the onset of territoriality in April to May, when these males had their most frequent aggressive interactions. Territorial bucks aggressively interacted most frequently with non-territorial males and significantly less often with other territorial males, but agonistic noncontact displays between territorial males lasted the longest. In contrast, non-territorial males addressed their aggressive noncontact displays and fights most often to peers and less frequently to sub-adults. Asymmetry in the social status of territorial vs. non-territorial males was likely responsible for the distinctively different agonistic behaviors shown by the two types of males, which in turn are likely due to the different costs and benefits each male can accrue from these aggressive interactions.     

The Effect of Habitat Structure and Density of Nests on Territory Size and Territorial Behaviour in the Black-headed Gull (Larus ridibundus L.)

We studied the effects of vegetation structure and nest density on territory size and aggression in the black-headed gull (Larus ridibundus). Vegetation structure influenced the types of aggressive behaviour, but not territory size. The proportion of overt aggression (attacks, fights) was highest in barren areas or those with short, sparse vegetation, and lowest in plots covered with dense, tall grass. We explain this by decreased visibility of conspecifics in habitats isolated by vegetation. In such areas, total aggression did not decrease, because the low proportion of attacks and fights was offset by an increase of more moderate (“upright”) displays. Only when nest density was high did the vegetation reduce the frequency of agonistic behaviour — but then it comprised almost exclusively attacks and fights. As expected, greater nest density was related to reduced territory size and an increased proportion of overt aggression. A high proportion of attacks and fights occurred in the plot with the lowest nest density, where at the same time there were also numerous first-year breeders. We conclude that, when analyzing the effects of habitat conditions on aggressive behaviour, it is important to consider the structure of behaviour, and not only the total frequency of all types of agonistic interactions.     

OBSERVATIONS ON THE BREEDING OF THE WOOLLYNECKED STORK

Scott, J. A. 1975. Observations on the breeding of the Woollynecked Stork. Ostrich 46: 201–207.

Little is known about the breeding of the Woollynecked Stork Ciconia episcopus in Africa. This paper discusses breeding, adult and nestling behaviour, nests and sites. Seasonal movements are discussed briefly. Eight nests were studied during 1970 to 1974. At one nest incubation was established at 30 to 31 days and the fledging period 55 to 65 days. No feeding of the young was observed at any time, though one eight hour observation period was undertaken. Few mating displays were seen and none away from the nest.     

ADAPTATIONS TO NESTING HABITAT IN THE REPRODUCTIVE BEHAVIOUR OF THE BLACK-BILLED GULL LARUS BULLERI

SUMMARY The nesting habitats adopted by most colonies of Black-billed Gulls Larus bulleri are river-beds that are subject to flooding. A number of respects in which the reproductive behaviour of Black-billed Gulls differs from that of at least most other gulls, such as Black-headed Gulls, can be viewed as adaptations, or byproducts of adaptations, to such nesting habitats:—

• (a) A different breeding site from the year before is often selected
• (b) The bulk of pair formation is accomplished before the gulls occupy their breeding sites; nesting territories are set up by mated pairs
• (c) In hostile encounters during the pair formation phase, site attachments are weak or transitory
• (d) In agonistic situations generally, attack thresholds appear to be relatively high, and fleeing thresholds relatively low
• (e) High intensity forms of“Choking” appear to be missing from the agonistic display repertoire
• (f) The growth of nest groups is rapid and orderly; nesting territories are small and the concentration of nests in the groups high
• (g) The time between occupation of the gullery site and the start of laying is short, and the synchrony of laying is high; this is probably related to the close proximity of the nests
• (h) The parents and young abandon the nest very soon after the egg hatch, and no “brood” nests are made
• (i) The young may develop locomotory powers more quickly than is the case in most other species; they can swim at an early age, and take to the water in tightly packed groups during alarms

The question of why these gulls should choose such vulnerable breeding sites is discussed.     

OBSERVATIONS ON THE BEHAVIOUR OF THE HAMERKOP SCOPUS UMBRETTA IN UGANDA

Hamerkops were studied in Uganda, mainly in the vicinity of Kampala, during January-August 1964. Behavioural observations were made of nest-building pairs, as well as of non-breeding birds.
Locomotion and feeding behaviour are described. Diving take-offs and landings, essential for entering or leaving a completed nest, are sometimes seen in other situations as well. Birds sometimes forage while on the wing, in addition to the more usual method while wading.
The most frequently seen comfort movements and maintenance activities are described. Hamerkops do not excrete onto their legs when over-heated as do the storks. The resting posture of sitting completely down on horizontal branches, which is common among Hamerkops, apparently is not known in any of the herons or storks.
Primarily hostile (Upright and Forward Threat) and primarily sexual ("Yip-purr", Nodding and False Mounting) social displays are described. During False Mounting, birds mount their partners repeatedly without making any attempt at copulation; reverse mountings, in which the other partner assumes the top position, are frequent.
The large, hollow nest and its construction are briefly described. During the 6–7 week building period at one nest, at least 8000 loads of material were added to the structure. Both members have an equal role in nest-building, and generally work independently of each other. They showed no stick-exchange displays as do herons and storks.
When all known aspects of the Hamerkop's behaviour are considered, there appears to be little similarity with either the herons or the storks. In fact, present behavioural evidence does not seem to indicate a particularly close relationship with any other birds so far studied.     

Reversed sexual size dimorphism and parental care in the Red-footed Booby Sula sula

The 'division-of-labour' hypothesis predicts that males and females perform different roles in parental care and that natural selection acts differently on each sex so as to produce different body size optima suited to their particular roles. Reversed sexual size dimorphism in avian species (females larger than males) may therefore be an adaptive consequence of different roles of males and females in parental care. We investigated patterns of nest attendance, brooding, foraging and provisioning rate in a tropical seabird, the Red-footed Booby Sula sula , a species showing a reversed sexual size dimorphism. During incubation, females attended the nest more often than males, and spent more time brooding the small chick than did males during daytime. Males and females did not differ in the average duration of their foraging trips. During incubation, there was a positive relationship between nest attendance and the duration of foraging trips in males, but not in females. During the small-chick stage, for the same time spent at the nest, males spent significantly more time than females at sea. On average, females fed the chick more often than did males. In males, there was a significant and positive relationship between the probability of feeding the chick and the duration of the foraging trip, whereas in females, this probability was much less dependent on the duration of the foraging trip. Overall, female Red-footed Boobies achieved slightly, but significantly, more parental commitment than did males. However, these sexual differences in parental participation were small, suggesting a minimal division of labour in the Red-footed Booby. Our results suggest that the division of labour hypothesis is unlikely to explain fully the adult size dimorphism in Red-footed Boobies.     

NOTES ON THE BREEDING OF THE RED-BREASTED CHAT OENANTHE HEUGLINI

Details are given of the (underground) nest, eggs and breeding behaviour. Noteworthy points are the change in the parents' attitude to the harrier Circus macrourus when their young appeared above ground and the use of the nest as refuge for the young at that stage.     

Ousting of the Common Redstart (Aves: Turdidae: Phoenicurus phoenicurus) from its nests by the bumblebee Bombus niveatus vorticosus (Hymenoptera: Apidae)

During a study of bird nesting in SW. Anatolia, 125 man-made nest boxes have been installed, 3 m high, in the trees. These nest boxes have been occupied by several bird species (Phoenicurus phoenicurus, Parus major, Parus ater, Sitta krueperi, Certhia brachydactyla). Of the 48 Redstart nests, 19 (40 %) had been successfully invaded by the bumblebee Bombus niveatus vorticosus. This invasion occurred at different times in the nest building cycle: - during the building of the nest, - during the incubation or - after the hatching of the young. Once installed in the nest of the Redstart, the bumblebee does not directly attack the bird, but disturbs it by continuously rearranging the nesting material and by covering the bird’s brood. Eventually, the bird deserts its nest and brood. The Redstart does not display any agonistic behaviour towards the bumblebee. Nests of other bird species are never invaded.     

Territoriality in the green frog (Rana clamitans): Vocalizations and agonistic behaviour

Territorial behaviour of Rana clamitans was studied in an experimental pond containing natural vegetation and artificial shelters. Males defended territories from June through August. Five vocalizations were used in territorial advertisement and agonistic encounters. Agonistic behaviour included patrolling, splashing displays, chases, attacks and wrestling. About 23% of all encounters ended in wrestling bouts. Most bouts were less than 30 s long, but some lasted up to 45 min. Most fights were won by residents. Intruders were most successful in fights when they were larger than residents or previously had been residents of other territories. Weight loss by large males enabled some smaller males to oust residents from territories. Possible costs of fighting include energetic costs and exposure to predation. Large male body size in R. clamitans and other territorial frogs may be an adaptation for fighting.     

Aggressive behaviour of juvenile brown trout Salmo trutta, L: an analysis of the wigwag display

The wigwag display of the juvenile brown trout ( Salmo trutta , L) was analysed and found to be a ritualised display used specifically as a defensive manoeuvre in the aggressive interactions of groups of fish. Wigwag displays performed against fish of lower or equal social rank were highly effective as a defence but wigwags performed against higher ranking fish were less than 50% effective.