| 1. |
- Bengtsson, Hans, et al.
(författare)
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Development of Parent‐Young Interaction in Asynchronously Hatched Broods of Altricial Birds
- 1981
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Ingår i: Zeitschrift fuer Tierpsychologie / Journal of Comparative ethology. ; 56:3, s. 255-272
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Tidskriftsartikel (refereegranskat)abstract
- In bird species which have developed a brood reduction strategy, initial inequality among siblings is established through asynchronous hatching. After hatching, the maintenance of a weight hierarchy within the brood and its spread is governed by the allocation of feeds to the chicks and by the rate of parental feeding. In the present study, the initiation of parental feeding and subsequent changes in the feeding procedure were studied in asynchronously hatched broods of the great tit Parus major and the blackbird Turdus merula. During the period of hatching the brood was roused by a parental feeding call on most visits to the nest which made feeding niore effective. Late-hatched young initially increased their chances to receive feeding offers by showing a high rate of spontaneous begging. In addition, they were more dependent than the older young on a high rate of mobility in order to be fed and they showed increasing mobility with age. Crucial changes in the feeding procedure took place at the end of the hatching period when the parents ceased to emit feeding calls and in the last few days before the abandonment of the nest when the biggest young started to jump towards the parents at feeding. These periods were identified as critical for late-hatched young. We argue that parental feeding rate is a feature of parent-young interaction that develops in order to adapt parental investment in individual nestlings to changes in food conditions when the brood is being raised.
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| 2. |
- Rydén, Olof, et al.
(författare)
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Differential begging and locomotory behaviour by early and late hatched nestlings affecting the distribution of food in asynchronously hatched broods of altricial birds
- 1980
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Ingår i: Zeitschrift fuer Tierpsychologie / Journal of Comparative ethology. ; 53, s. 209-224
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Tidskriftsartikel (refereegranskat)abstract
- Distribution of food to early and late hatchcd nestlings was studied in asynchronously hatched broods of the grr,it tit P~rcrs major, the blackbird Turdus mcrula, and the fieldfare T. pilaris. Food distribution is related to the locomotory and begging behaviour and positions in the nest of these nestlings. Late hatched (small) nestlings were found to beg more often per feed than bigger nectlings and move more towards favoured positions in the nest to counteract selective feeding of bigger young. The functional significance of these differences in the behaviour of early and late hatched nestlings are discussed. It is argued that they are adaptive by 1) ensuring that each nestling survives when food supplies are ample, and 2) by mediating an optimal brood reduction when food is insufficient to raise the entire brood. The roles of asynchronous hatching, and selective feeding which follows from differential behaviour of early and late hatchcd young are discussed in relation to food conditions during the breeding season.
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| 3. |
- Bengtsson, Hans, et al.
(författare)
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Parental feeding rate in relation to begging behavior in asynchronously hatched broods of the great tit Parus major: An experimental study.
- 1983
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Ingår i: Behavioral Ecology and Sociobiology. - 1432-0762. ; 12:3, s. 243-251
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Tidskriftsartikel (refereegranskat)abstract
- Four experiments manipulated the stimulus situation encountered by great tits on their feeding visits to the brood in order to explore its effect on feeding rate. Three broods containing 8, 8, and 10 nestlings were studied. A higher feeding rate was observed under the following conditions: (1) after a period of food deprivation, as compared with normal conditions and satiation through artifical feeding; (2) in periods when recorded begging calls were played during feeding visits, as compared with control periods; and (3) after temporary removal from the nest of heavier, as compared with lighter, siblings. The lighter nestlings benefitted more (in terms of weight gain) from the increase in parental feeding rate following the playing of begging calls than did the heavier nestlings. Differences in weight within broods did not affect the amount of food the parents brought. It is concluded that parental feeding rate is affected not simply by the begging of the hungriest nestling but rather by the behavior of all the nestlings, which makes possible an adjustment of the feeding rate to the average hunger level of the brood.
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| 4. |
- Nilsson, J. A.
(författare)
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Causes and consequences of natal dispersal in the marsh tit, Parus palustris
- 1989
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Ingår i: Journal of Animal Ecology. - : JSTOR. - 0021-8790. ; 58:2, s. 619-636
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Tidskriftsartikel (refereegranskat)abstract
- Dispersal distance, measured as the number of territories between place of birth and place of first breeding, was analysed within and between sexes in juvenile marsh tits in relation to factors potentially caiusing variation in dispersal pattern. Dispersal distance of males was positively influenced by both population density and hatching date. In females, dispersal distance were positively related to population density, number of siblings and wing length. Early-hatched females dispersed further than those hatched in the middle of the season. Dispersal distance in females was positively related to the number of recruits among their offspring. Females surviving for more >1 breeding season had dispersed further as juveniles than females breeding only once. In males, dispersal distance did not affect survival or breeding success. Males are severely affected by the density of already established individuals, and have no time to choose flock ranges according to quality. Thus, males try to become established as soon as possible after independence. Late-hatched males disperse further and are less successful at establishing themselves than early-hatched males. Females, especially those hatched early, more easily become established and can afford to monitor several flock ranges and to be selective in their choice of flock range. This selectivity results in long dispersal distances for early-hatched females and a high lifetime reproductive success for long dispersers. -Author
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| 5. |
- Nilsson, Jan-Åke, et al.
(författare)
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Effects of Dispersal Date on Winter Flock Establishment and Social Dominance in Marsh Tits Parus palustris
- 1988
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Ingår i: Journal of Animal Ecology. - : JSTOR. - 1365-2656 .- 0021-8790. ; 57:3, s. 917-928
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Tidskriftsartikel (refereegranskat)abstract
- (1) We studied the effect of sex, size, age and prior occupancy on social dominance winter flock establishment in a population of marsh tits Parus palustris L. (2) When sex was accounted for, time of establishment in the winter flock-prior occupancy, was critical for the outcome of later aggressive interactions juveniles within flocks. Residents won all interactions with intruders irrespective controlling for sex. (3) Success in, and timing of, establishment were closely linked with hatching lower proportion of late-hatched than early-hatched juveniles became established winter flocks; they also became established later. Even small differences in hatching greatly influenced dominance and the probability of becoming established flock. (4) Since early establishment depends on early hatching, dominance and survival juveniles are determined by how early their parents start breeding. Furthermore, will be strong selection for quick establishment after
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| 6. |
- Brännäs, Eva, 1951-
(författare)
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Effects of abiotic and biotic factors on hatching, emergence and survival in Baltic salmon (Salmo salar L.)
- 1988
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with important factors that affect the temporal organization of emergence and early survival of Baltic salmon (Salmo salar L.). The study population was obtained from the Norrfors hatchery (63°50'N,20°05'E), Umeälven (Ume river) in Northern Sweden. The main objectives of the thesis has been to study; a: the effect of female and egg characteristics on embryonic survival, b: the effect of egg size, temperature and photoperiod on the emergence pattern and c: the impact of early or late emergence on survival in relation to predation and limited territorial space.The main results are summarized as follows: (1) Fecundity and egg size increased with increasing weight of females. No effect of female size were found on egg colour. Longer impoundment and later stripping increase egg colour. Egg mortality was not correlated with egg colour. Stripping date was found to have the strongest effect on mortality. (2) Egg size had no effect on the timing of emergence but fry of different egg size emerged synchronously. Fry from large eggs left the gravel as heavier fry and with a larger proportion of yolk left compared to fry from small eggs. (3) The number of days and number of degree days from hatching to 50% emergence decreased exponentially with increasing temperature. Synchronization of emergence increased with increasing temperature. Fry emerged with more yolk at 12 °C compared to 6 °C. (4) Eggs kept in a LD 16:8 light regime hatched mainly during the light period, while eggs kept in constant darkness hatched continously over a 24 hour period. Alevins kept at different light regimes (light>4h) from hatching until emergence left the gravel during the dark period. Daylength had no effect on the annual onset of emergence. (5) In a laboratory stream channel, predator presence at emergence increased mortality especially in early emerging fry. If the predator was introduced after completed emergence high mortality was noted among late emerging fry. The presence of fish predators and a limited territorial space for fry seemed to make early and late emergence hazardous and to favour a "peak" emergence. In the presence of a predator the fry changed their behaviour by reducing their swimming activity.
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| 7. |
- Smith, Henrik G., et al.
(författare)
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Intraspecific variation in migratory pattern of a partial migrant, the Blue Tit (Parus caeruleus) : An evaluation of different hypotheses
- 1987
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Ingår i: The Auk. - : Oxford University Press (OUP). - 0004-8038 .- 1938-4254. ; 104:1, s. 109-115
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate hypotheses explaining intraspecific variation in migratory behavior in partial migrants, a local population of Blue Tits (Parus caeruleus) was studied in southern Sweden. Birds born in the study area and recaptured there in winter were compared with birds recaptured at a nearby bird station where a large number of migrant Blue Tits were passing. By comparing sex ratios among migrants and residents, we concluded that, among juveniles, more than 40% of the females and a significant proportion of the males migrated, while considerably fewer adult females and virtually no adult males did so. Migrant and resident Blue Tits did not differ in size as nestlings, but more late- than early-hatched males migrated. No differences in hatching date were determined for females, presumably because most of them migrated. Our findings are consistent with the "dominance hypothesis" as an explanation of partial migration, i.e. that the individuals lowest in rank migrate. The fitness gain that leads dominants to stay as residents may be lower winter mortality or a higher probability of establishing a territory in spring. In either case, keener competition for breeding territories among males than among females as a cause tor higher residency cannot be excluded.
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| 8. |
- Ekström, Peter, et al.
(författare)
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Ontogenetic development of serotoninergic neurons in the brain of a teleost, the three-spined stickleback. An immunohistochemical analysis
- 1985
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Ingår i: Developmental Brain Research. - : Elsevier BV. - 0165-3806. ; 17:1-2, s. 209-224
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Tidskriftsartikel (refereegranskat)abstract
- The ontogenetic development of serotoninergic neurons in the brain of the stickleback was investigated with the indirect immunocytochemical peroxidase-antiperoxidase technique, using a specific antibody to serotonin (5-hydroxytryptamine, 5-HT). Formation of neuronal populations takes place during embryonic development. By 80 h after fertilization, the first 5-HT perikarya have appeared in the ventricular zone of the hypothalamus (nucleus recessus lateralis) and the raphe region. At 108 h the first 5-HT perikarya can be observed in area praetectalis. At 118 h a transient group of 5-HT neurons appears rostral to the nucleus recessus lateralis, and at this same age the first 5-HT perikarya may be visualized in nucleus recessus posterioris. A group of 5-HT neurons appears in the dorsolateral tegmentum at 166 h (one day after hatching, which occurs at 120-144 h after fertilization). Differentiation of the neuronal populations, in terms of migration and formation of subdivisions, starts between 80 h and 94 h, and seems to be completed between 1 and 5 days after hatching. Raphe nuclei form an anterior group comprising nuclei raphe dorsalis, raphe medialis and a ventrolateral group, and a posterior group comprising a nucleus raphe pallidus/obscurus complex, a lateral nucleus reticularis paragigantocellularis and a ventromedial nucleus raphe magnus. The posterior and ventral raphe nuclei, which are well developed at the time of hatching, have not been visualized in the adult stickleback. While formation of 5-HT neuronal systems, as well as their primary efferent pathways, takes place during early ontogenetic development, the establishment of terminal areas and their subsequent differentiation apparently takes place during later ontogenetic stages. Most presumptive target areas are penetrated by 5-HT axons at hatching, although terminal formation does not seem to start until later. A considerable number of 5-HT neuronal groups present in the embryonic and newly hatched stickleback have not been visualized in the adult stickleback. This may be due to selective cell death, changes in transmitter phenotype or maturation of axonal transport processes during development.
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| 9. |
- Broberg, Birgitta, 1949-, et al.
(författare)
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Keramik, kammar och skor från 7 medeltida städer : fyndstudie
- 1981
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The 1970s are characterized by a very marked expansion of urban archaeology. A large number of archaeological finds were collected and are now stored in museums all over the country.When the project The Medieval town started in 1976 the intention was to devote comparatively large space in the reports of the respective towns to the treatment of this material. This has, however, not been realized. The main reason why the archaeolocigal finds have not been dealt with to the extent which was originally planned, is their inaccessability. The finds from large urban excavations which are important for future research have often not been worked through and published. This makes it very difficult to make full use of the material. We should, however, like to draw attention to the fact that there exists today an archaeological material of finds which as regards quantity, quality, and geographical distribution could materially increase our knowledge of the medieval towns in Sweden.In 1980 an attempt was made by the proiect The Medieval Town to see to which extent limited work on single categories of objects could contribute towards an answer to specific questions. The selection of object categories and methods was made on the basis of questions concerning the early urbanization of Central Sweden. The wide distribution of the archaeological finds made possible comparisons to elicit similarities and differences between towns and excavated sites. The present study of finds should also be seen as an attempt to discover methods for dealing summarily with finds in such a way that on the basis of the questions posed, tendencies would emerge that could motivate further studies.The finds included in this study have come from most of the large archaeological excavations which took place in Central Sweden in the 1970s, altogether 15 in number. The following seven towns are represented: Enköping, Lödöse, Nyköping, Söderköping, Uppsala, Visby, and Örebro. The three categories of finds which have been chosen as best suited for this study are medieval pottery, combs, and shoes.The find study comprises a total number of 12 200 potsherds, 113 classified combs, and 965 classified shoes. In order to make it possible to deal with the material, the respective objects were classified according to rather rough criteria. Then followed a listing of the objects related to class and strata, 1, 2, 3 etc where the lowest figure represents the bottom layer. In additions to the tables the material is also accounted for in histograms where the reciprocal relations between the three different find categories are more clearly shown. A preliminary dating has also been included.The prerequisite condition for this mode of work is that all the finds are related to specific strata. To present a tabular account of the finds is a method which corresponds completely with the aim of the find study which is largely based on comparative studies between different materials and towns. Detailed studies have also in certain cases been made of the different find categories.Emphasis is laid on a comparison between finds from sites with a well documented 12th century archaeological material, that is places like Lödöse, Söderköping, Visby, and to some extent Nyköping. What finds have been collected from the different places during thes pre-urban stage? Is it possible to obtain information from the finds as regards the function of the place and the stage of development it had reached in the 12th century?A large part of the find report deals with archaeological material from the transition period between the 12th and the 13th centuries. In Lödöse, Söderköping, and Visby it has been possible to establish for this period the occurrence of a change, that is an expansion of the settlement. What are the reasons for this expansion? How is this change reflected in the finds from the respective towns?The work carried out within the project on the Central Swedish towns has confirmed the importance of the 13th century with regard to the foundation of towns. For this reason the study has been concentrated on the ways in which the finds can throw more light on different aspects of the urbanizing process, its prerequisite conditions, completion, and possible regional differences. Apart from elucidating these questions the material can be used to outline the development of the settlement in the respektive towns. In the course of the work it became evident that it is of vital importance to make the archaeological finds from Central Sweden accessible. It is of importance for continued archaeological work and for research concerning the rise and development of the towns.The introductory chapter (Chapter 1) which deals with background (1.1), aim (1.2), extent (1.3), and method (1.4) is followed by a short presentation of the towns represented. This is done in order to make it possible to see the different investigations in their context. The brief descriptions of the towns include first of all the earliest written reference, the importance and function of the town etc and are based on the ref>orts on the respective town. Each description is accompanied by a modern town plan where all archaeological observations and extant medieval buildings have been marked. The investigation dealt with in the report on the finds have been marked in green.Chapters 3, 4, and 5 contain an account ot the three find categories: pottery (Chapter 3), combs (Chapter 4), and shoes (Chapter 5). Each town and investigation is presented in succession. The different materials are accounted for in tabular form as well as in illustrations accompanied by comments. The chapter on pottery begins with a presentation of the classification system used. By and large it follows Dagmar Selling's ABC-system, first published in Wikingerzeitliche und frühmittelalterliche Keramik in Sweden, 1955. Al coresponds to so called early western European black pottery. All to Vendish pottery, Bl to so called late black pottery, Bll to white-and red-fired earthenware, C to stoneware. From these main groups have been chosen sub-groups important for this study and the pottery has been divided into 15 classes in all. To the tables belong histograms from which the relationship between the different classes of pottery emerges more easily. A sparse hatching has been used where the sherds are 1 - 9 in number and a closer one for 10 - 19 sherds. The black colour stands for twenty of more potsherds. As well as a classification of the material, certain detailed studies have been made. With regard to A-and Bl-pottery all the different shapes of rims and decorations are recorded and in the case of large finds stratigraphically. Detailed studies have also been made of the decoration of Bll: 1-pottery, This means that all variations of ornaments are illustrated. Combs and shoes are accounted for in the same way, that is both in numerical tables and histograms, There are only differences in the hatching of the staples. As regards combs sparse hatching means 1 comb, 2 - 4 combs have been more closely hatched, and numbers exceeding four are marked in black. In the case of shoes sparse hatching stands for 1 - 4 shoes, closer hatching for 5 - 9, and black any exceeding number of shoes. For both these find categories all existing variations in shape are illustrated. At the end of each chapter the material from Lödöse is dealt with. Combs and shoes from here have been classified according to the principles used elsewhere in this study. The classification used in the present study has, however, not been followed when dealing with pottery, as the Lödöse material has been previously catalogued according to another but similar system. The system used for classifying the Lödöse pottery is presented in figure 39. To the system belongs a "key" which facilitates a comparison between the two systems.Chapter 6 contains an analysis. By way of introduction chapters 3, 4, and 5, dealing respectively with pottery, combs, and shoes, are summarized. Apart from the descriptive introduction, the analysis is largely devoted to comparative datting. Chapters 6.3 and 6.4 compare the periods when different types of pottery, combs, and shoes occur in the different towns. This is done on the one hand for the Central Swedish region represented by Enköping, Nyköping, Söderköping, Uppsala, and Urebro, and on the other for material from Eastern and Western Sweden. Western Sweden is represented by Lödöse and Oslo, Eastern Sweden by Söderköping and Visby. The discussion concerning the dating is carried out on the basis of diagrams which show within which periods the different classes of obiects occur in the respective towns (figures 85 - 90).The aim in the study of the finds has been to try and see to which extent archaeological finds can be used to elucidate an historical process, in this case the early urbanization of Central Sweden. In chapter 6.5 an attempt is made to summarize the prerequisite conditions for the growth of the regional centres and in chapter 6.6 we discuss how the completion of urbanization can be studied in more detail by means of the archaeological finds.In the work on the finds other aspects on the material have come to light. Differences mainly as regards pottery have led to a discussion about coastal versus inland towns and whether the towns had different contacts. The internal structure of the towns is dealt with in two chapters. In chapter 6.8 general topographicahl conditions are discussed with an emphasis on the development of the settlement in two towns, Söderköping and Uppsala. Chapters 6.9 deals with the crafts which had important functions in the medieval towns. The medieval crafts are best represented in the material from Lödöse but an attempt is made to compare it with corresponding conditions in Söderköping.The concluding chapter 6.10 presents views on future work where the necessity for work on the archaeological fin
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