摘要:

Abstract and SummaryHow a Common Tern (Sterna hirundo) Colony Defends itself against Herring Gulls (Larus argentatus)The subject of this study is the anti‐predator behaviour of a small common tern colony near a large herring gull colony on the island of Mellum, West Germany (Fig. 1). In 1980 the number of gulls crossing this tern colony increased during the terns' chick‐stage (Fig. 4). Observed predation of tern chicks was independent of tide and time of day (3., Fig. 5). The frequency of tern reactions corresponded to the number of herring gull crossings (Fig. 5, Table 1). The terns' responses increased between morning and evening (Fig. 8).Tern up‐flights and attacks increased absolutely and as a percentage, with the advance of the breeding season (Fig. 3, 4). They were positively correlated with the observed chick predation and the number of pairs with chicks, most markedly with chicks older than 5 days (Figs. 3, 4; Table 1). This increased defence was maintained by fewer pairs as, by then, many had lost their own broods (Fig. 4). As the breeding season progressed, herring gulls increasingly became the main cause of tern up‐flights and the object of the attacks (Figs. 9–11). The up‐flights of the whole colony, which occurred frequently and spontaneously during incubation, were observed only rarely after hatching and were almost exclusively a response to herring gulls (Figs. 10, 12).The lower herring gulls flew over the colony, the more frequently common terns flew up or attacked and the more individuals were involved in these responses (Figs. 6, 13, 14). During the breeding period, communal up‐flights and attacks by terns increased as a percentage (Figs. 12, 13, 15–17). Group‐attacks effected changes in the gulls' flying‐routes more often than did individual attacks (Fig. 18).Despite the defence behaviour and its adaptation to the predation pressure, herring gulls often succeeded in robbing chicks. This is why the breeding success of the common tern was poor (<0.4 chicks/nest). Possible reasons for

ISSN:0044-3573    

DOI:10.1111/j.1439-0310.1984.tb01369.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract and SummaryAdult 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 dispersio

ISSN:0044-3573    

DOI:10.1111/j.1439-0310.1984.tb01370.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract and SummaryThe comparison of local song variations between a migratory and a sedentary population of starlings shows the species‐specificity of the basic categories and of their variation range. Local variations were studied for different themes in the repertoire, near Kaiserslautern (West Germany) during the reproductive season of 1982. Results were compared with those previously obtained in Brittany (France). In the study area in Germany, 80 % of the individuals migrate in autumn whereas the Breton starlings remain near the colony all year. To compare the whistles of individuals of different regions, by examing the important variations in their frequency modulation, it is necessary to know the general basic features of the whistles. Using sonograms, the whistles of starlings can be divided into 8 general classes according to particular criteria: rhythmicity, modulation etc. Five themes, among these 8 classes, are sung by all or most of the individuals (“specific themes”).The analyses of whistles give us the following results:1The songs of the migratory population studied in W. Germany contain basic features corresponding to those known in the sedentary French population.2Like the Breton starlings, those in Germany show a “theme‐specific” dialect distribution: the rhythmic theme shows several variants in an area of a few km2, whereas the uniform simple theme presents only one variant over several 100 km2. For the five themes, the dialectal mosaic is totally different: two birds can have the same variant of one given theme and sing different dialects of another.3The themes which, in France, show a great number of variants over a small area present the same tendency towards strong subdivision in dialects in Germany.In the two study areas, no correlation could be found between dialectal boundaries and ecological factors.4Considering that two starling populations with very different characteristics show such similarities in their basic song structures and also in their pattern of local variation (in the parameters concerned and in the sizes of the dialect areas) we may suppose that the basic structure of the specific themes could be determined by a genetic program. Some characteristics, like the precise details of the frequency modulation, may be due more to learning and may conform to the lo

ISSN:0044-3573    

DOI:10.1111/j.1439-0310.1984.tb01371.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract and SummaryThe distance calls (DC) of free‐living and recently captured zebra finches (ZF) were investigated in order to establish the extent of variation in the structure within and between individuals, colonies, sexes, geographic localities and subspecies. Most work was carried out on the Australian subspeciesP. g. castanotisin south‐eastern Australia. The calls were analysed sonographically and analysis of two frequency and two temporal parameters were undertaken. The spectral structure of the calls was also assessed subjectively. The main findings are as follows:1Each individual has its own uniquely structured DC. The calls of males are more distinct than those of females.2The differences between individuals are sufficiently large to expect that they could probably be perceived by individuals.3The DCs differ between the sexes. The female call is significantly longer. InP. g. castanotisthe male call has two elements — a tonal element followed by a noise element; it also has fewer harmonics. The differences could be detected by ear. The Timor subspecies is thought to have lost the noise element.4Adjacent colonies have DCs that are not significantly different.5DCs from different and distant geographic localities are not significantly different except for a few locations where distinct local forms of the DC exist. The changing composition of colonies is thought to erode the development of dialects.6The DCs of both subspecies have the same basic complex tone with the same harmonic configuration. The calls of males are of the same duration in both subspecies but those of females are longer inP. g. castanotis. The calls ofP. g. guttatahave a higher fundamental frequency, fewer harmonics and a higher emphasized frequency (FMA).7The DC inP. g. castanotisis probably used to keep pairs together in the large flocks. It may also be used to detect rela

ISSN:0044-3573    

DOI:10.1111/j.1439-0310.1984.tb01372.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Book reviewed in this article:Bücher/Books: Tyler, M., ed. (1983): The gastric brooding frog (Der magenbrütende Frosch).Paepke, H.‐J. (1983): Die Stichlinge (Sticklebacks). Die Neue Brehm‐Bücherei, A.Eisenberg, J. F., and D. G. Kleiman, eds. (1983): Advances in the study of mammalian behavior (Fortschritte der Säugetierforschung).Ankel‐Simons, F. (1983): A survey of living primates and their anatomy (Eine Übersicht über die heute lebenden Primaten und ihre Anatomie).Wood‐Gush, D. G. M., M. Dawkins and R. Ewbank, eds. (1981): Self‐awareness in domesticated animals (Zum Ich‐Bewußtsein dom

ISSN:0044-3573    

DOI:10.1111/j.1439-0310.1984.tb01373.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY