ALBERT

Description / Table of Contents: Summary In the present paper (part I: J. Orn. 121: 121–143, 1980), the sun orientation of birds, its way of functioning, ontogenetic development, and biological significance are described in the light of current experimental evidence. Theoretically, the sun can be used to determine which compass direction is the home direction (≙ true navigation), to set a compass course, and to maintain a given direction during flight. Most of the available evidence speaks against the sun's being used for determining the home direction after displacement, whereas many findings in several species of birds demonstrate use of the sun as a “sun compass” and for maintaining directions. Using the sun compass to go in a constant direction, the birds compensate for the sun's apparent movement, i. e. they fly at angles to the sun's azimuth direction which vary according to the time of day. The magnitude of these angles seems to depend on the birds' internal clock only, and the birds apparently consider the different rates of change of the sun's azimuth during the day (greater around noon than in early morning or late afternoon). Experiments with young homing pigeons show that the sun compass is not a completely innate orientation mechanism, but that the relation between sun azimuth, time and geographic direction is learned. A young pigeon must experience the sun at different hours of the day to establish a sun compass for the entire day. The age at which the sun compass is learned strongly depends on the bird's flying experience. The sun compass seems to be developed as soon as the bird encountered the necessity of orienting, which normally will be about the end of its third month. The details of the learning process are not yet known. The sun does not seem to be necessary for the development of the ability to navigate; in fact, some findings with young pigeons seem to indicate that the navigational system is already developed before the sun compass is added to it. Afterwards, however, the sun compass is used preferentially whenever the sun is visible. Under overcast skies, it is replaced by an equally effective non-visual system. In day-migrating birds — young Finnish starlings — sun compass orientation could not be demonstrated during the first autumn migration period, but the starlings were shown to use it during the following spring period. It is not clear, though, whether these data from handraised birds reflect the natural situation correctly. The available evidence does not yet allow a realistic estimate of the significance of the sun compass for orientation during migration; theoretical considerations and the few present data, however, make it appear improbable that the sun compass acts as a reference system for the innate migratory direction.

Description / Table of Contents: Summary Results of 6 years (1973–1978) of systematic ringing and regular nest controls of a great reed warbler population in Northern Bavaria are given (data of 487 nests) as well as results on a population of the reed warbler (data of 645 nests). Numbers of great reed warblers fluctuated in different parts of the study area. The whole population, however, remained fairly constant. Data on the arrival of males in the breeding area are given. Distances between neighbouring nests of great reed warblers varied from 7 to about 300 m. Differences in nest densities in the reed warbler could be found. The mean first egg laying dates in the great reed warbler and the reed warbler were May 29 and June 13 respectively. The great reed warbler showed a distinct steeper decrease in its egg laying pattern than the smaller species. Average clutch size in the great reed warble was 4.73 eggs and 3.85 eggs in the reed warbler. In both species clutch size decreased during the season. Great reed warbler nestlings hatched on the 12th to 14th day after the last egg had been laid, reed warbler nestlings on the 11th to 13th day. The incubation period was mainly 14 days in the great reed warbler and 13 days in the reed warbler. In the great reed warbler 59.7 % of the nests were successful. The fledging success of successful nests was 73.2 %, accordingly the total nest success was 43.7 %. The corresponding data in reed warbler were 66.6 %, 82.9 % and 55.2 %. On average great reed warblers produced 2.00 fledglings per clutch, reed warblers 2.15. In the great reed warbler a reproduction rate of 2.24 fledglings per female was calculated. The reproduction rate in reed warbler was estimated substantially higher. Great reed warbler nestlings were much more sensitive to rain and cold weather than reed warbler nestlings of the same age. Two great reed warbler males were proved to make a second brood. The same is supposed for the other species but could not be proved so far. Polygyny was proved several times in the great reed warbler. Age and behaviour of polygynous males in different years are reported. Two great reed warblers were found breeding with their former mates at last year's breeding place. Most of the great reed warblers ringed as breeding birds returned into the study area. Nearly one third of the great reed warbler nestlings returned for breeding. Three reed warblers ringed as nestlings could be controlled in the study area during breeding period after 1 year and 2 years respectively. Distances of returned great reed warblers in relation to their birth places and their former breeding places are specified. One third of the great reed warbler population originates from the study area. Two females breeding in the study area were ringed as nestlings 78 km and 500 km apart. One-year-old to nine-year-old great reed warblers were found breeding. Data on the age composition of breeding birds are given. Plant species supporting the nests of great reed warbler and reed warbler were investigated. Differences in the spatial and temporal habitat selection of both species are described.

Description / Table of Contents: Summary Several aspects of the social organization have been studied in a breeding colony (16 pairs) in North-eastern Greece from April until August 1979: Colony synchronization was measured at the beginning and at the end of nest-hole excavation, egg-laying and incubation. The degree of synchrony increased between the end of excavation and the onset of laying. The rates of courtship-feeding and copulation increased a few days before the first egg was layed and decreased again at the end of the laying period. Every pair defended a part of the river bank although it only used the burrow and one or some perches there. Territorial conflicts especially appeared between a settled and an intruding pair. Although the attacks were performed several times more frequently by the territory owners, that pair withdrew from a part of its territory and the other moved up. These territorial conflicts only lasted a few days.

Description / Table of Contents: Summary Mortensen's (1899, 1912) initiation of scientific bird marking is preceded by numerous attempts starting already in the antiquity. Marks were used not only for domestic animals, but also for wild birds as herons, storks, swans, geese, birds of prey, doves, swallows. Systematic bird marking is a logical consequence of the 18th and 19th century's ornithology with its growing interest in faunistics espially in distribution of birds. Research will be necessary to trace additional practice of bird marking outside the traditional European and North American way of handling animals.

Description / Table of Contents: Summary The Rock Partridge is the only bird species of the Turkestanian-Eastmediterranean fauna found in the inner Alpine area. It lives preferentially on south facing slopes with a minimal winter snow cover. Nevertheless, winter conditions are critical for the species (food, heat loss) so that it often selects favourable man-made habitats (e.g. isolated barns and cowsheds, abandoned or even inhabited mountain-villages and their environment). This fact and the type of the breeding habitat selected suggest that the species colonised the Alps only after glaciation, possibly following man into this area.

Description / Table of Contents: Summary 1. 24 first year ♂ and 3 first year ♀, ringed as nestlings, returned in next years. 12 of 17 colour-ringed birds came from first broods. 2. 6 ♂ and the 2 ♀ were “Heimatansiedler”, 1 ♂ “Fremdansiedler”, 6 ♂ “geburtsortstreu” and 2 ♂ “Geburtsorts-Rücksiedler”. 3. The mean distances between the first territory and the birth nest of the “geburtsortstreue” ♂ and of the other ♂ were 818±368 m and 184±118 m respectively. 4. Adult ♀ showed greater settling distances than adult ♂. 5. The percentage of first year ♂ was very high. 6. 79 % ♂ and 50 % ♀ returned to their breeding population in next years. 7. The mean density of the population was 42 pairs or 3,6 pro 10 ha. Unpaired adults amounted 7 %. 8. Data on pair formation, mate-faithfulness and bigyny are treated. 9. Calculation of mortality from the data of returned birds yielded a mortality of young ♂ of 65 %, a life expectancy of one year and a mean life time of 1,5 years. 10. Sexual mature individuals derived from 2,5 % of all eggs laid and from 4,6 % of all youngs fledged. 11. The computed mortality of adult ♂ is 47,5 % and of adult ♀ 66,7 %. The life expectancy is 1,6 and 1,0 years for adult ♂ and ♀ respectively. 12. Allowing for the annual losses of adults a survival rate of first year birds of about 46 % is necessary. 13. The mean annual composition of the population should be: 4,6 % “geburtsortstreue” juveniles, 41,3 % non-autochthonous juveniles, 37,4 % “ortstreue” adults and 16,7 % unknown adults.

Description / Table of Contents: Summary As a social bird the Bald Ibis shows behaviour patterns for group contact as well as for pair contact: greeting, display, aggressive behaviour of adults and sibling competition, appeasement behaviour, social preening, nesting behaviour, and “Paarsitzen” (spatial bond). Some of them may be reinforced by changing body-shape and colour of unfeathered skin. Greeting, some forms of display and ritualized aggressions are important for normal intraspecific interactions. Social preening, copulations (false copulae also) and nesting behaviour do not only stimulate the partner, they also synchronize activity within a colony. Paarsitzen might indicate longer lasting monogamy. The vocal inventory is rather uniform, but some calls may vary individually. — The Bald Ibis shows a strong sibling competition. Siblings force to prevent each other to gape by violent pecking and thus releasing appeasement behaviour. Sibling competition stops with about 800 g at the end of the period of rapid body growth. As the Bald Ibis is breeding with the first egg, this behaviour may allow survival of the runt because of its longer lasting aggressivity when there is sufficient food supply.

Description / Table of Contents: Summary The Bolle's PigeonColumba bollii which lives in laurel forests is, despite many fears, not yet extinct on Tenerife. It still inhabits wooded crevices in the North-East of the island which are virtually inaccessible. Only increased protection can it save from extinction. The Laurel PigeonColumba junoniae, until now only known from La Palma and Gomera, is also present in small number on Tenerife.

Description / Table of Contents: Zusammenfassung 1975–1979 wurden Wasseramseln in drei verschiedenen Flüssen im Küstenbereich der Provinz Västerbotten untersucht unter besonderer Berücksichtigung der Wanderungen, Ortstreue und Populationsstruktur im Winter. Die Anzahl der Wasseramseln zeigte klare jahreszeitliche Unterschiede mit einem Maximum in den Monaten Dezember und Januar. Die Geschlechter- und Altersverteilungen variierten deutlich während des Winters; ♂ und Altvögel überwogen vor allem am Ende des Winters gegenüber ♀ und Jungvögeln. Die überwinterten Wasseramseln zeigten eine ausgeprägte Ortstreue; ca. 17 % der Vögel kehrten im folgenden Jahre zu den gleichen Flüssen zurück. Zwei Wiederfunde von Wasseramseln, die im Untersuchungsgebiet beringt worden waren, aus Norwegen und eine Kontrolle aus Finnland deuten auf Herkunft und Zugwege der in Nordschweden überwinternden Wasseramseln hin. Diese Wiederfunde stimmen mit den Untersuchungen vonAndersson &Wester (1976) überein. Die Körpergewichte und Flügellängen zeigten gute Übereinstimmung mit Untersuchungen in Südschweden (Andersson &Wester 1971, 1972). Es wird vorgeschlagen, die Populationsstruktur überwinternder Wasseramseln anhand eines Modells der „dominance-influenced migration“ (Gauthreaux 1978) zu erklären.

Description / Table of Contents: Summary In July/August 1979 and 1980, hunting ospreys were filmed in Mid-Finland by means of a slow-motion-camera. Search flight and vertical dive are shown as differenciated processes. When striking through the water surface, the ospreys reached a velocity of 30–70 km/h. They stayed under water up to one second. Special measures are taken to get into the air again: 1. Alteration of direction and length of the stroke, 2. upstroke with primaries upside down as slot wings, 3. increase of the stroke length (by about its double), 4. reduction of the stroke period by about one fifth resulting in a stroke velocity 2–2 1/2 times as high. The ospreys lower their prey in rhythmical intervals, which is interpreted as a measure to facilitate the upstroke. The tail stabilizes the flight thus avoiding the bird's rotation of its transverse axis. In most cases the osprey renews its clasps with both feet after a short flight and transports its prey with the fish's head in front. Then the water is tossed out of the feathers. The osprey compensates for the loss of height by accellerating its wing strokes at extremely short upstrokes. In some flights the eagle opens its bill simultaneously to its upstrokes. The birds stretch out their toes and let the fish go off when it seems impossible for them to lift a strong prey full of fight out of the water despite all measures taken. The ospreys are able to interrupt their dive in the very last moment even if they are already close to the water surface. Their stretched toes clap together in a short time of only 2/100 seconds.

Description / Table of Contents: Summary In 1978 the number of breeding pairs has been taken in North Germany (District of Lüchow-Dannenberg, Lower Saxony). In 1979 and 1980 a color-marked population has been studied (1979: 14 territories, 1980: 13 territories in an area of 45 ha). The density in 4 sample areas (total area 148 km2) was 0.126 singing males per 10 ha. The first birds, exclusively males, arrived in the breeding area about May 10. In each case the arrival of the population covered a period of 20 days. The type of the occupation of territories by males depended on the time of their arrival. Early arriving males start with occupying large areas in which other males often settle in the future period. Late arriving males take possession of smaller territories from the beginning. Of 8 color-marked 4 have been checked in the following year. 2 of these males occupied the territory of the previous year whereas the others settled within a distance of 400 m und 2 km respectively. 7 color-marked females did not return at all. Only one of 47 color-marked first year birds (2.1 %) returned to its birth place and occupied a territory 130 m away. With the beginning of the breeding period some males try to occupy new territories and often mate with a second female (7.7 % in 1979 and 30 % in 1980). The departure of the population began in early July. The last adult birds could be observed at the end of July, the last first year birds were seen in the first decade of August. The later the males arrived in the breeding area the faster they began constructing the nests. After mating females were more actively engaged in nest-building than males. The sizes of 43 nests are given, their appearance described and differences from those of the redbacked shrike (Lanius collurio) and the garden warbler (Sylvia borin) stated. The nest sites were located in thorny shrubs. Varieties of the genusRubus, dog rose (Rosa canina), blackthorn (Prunus spinosa), and hawthorn (Crataegus laevigata) were preferred. The mean height of the nests was 64.6 cm, the mean height of the vegetation above the nests was 203.2 cm. The location of nests and the density of nest site vegetation are described. The nests were preferably exposed to SE. The mean distance between nests occupied by pairs breeding close together was 145 m. The time span between the arrival of the first male and the laying of the first egg was 9 and 10 days respectively. The mean laying-season was 45 days and May 5 was the median start of egg laying for all broods of the years 1978–1980. The mean size of full clutches was 5.02 eggs, the mean incubation period was 12.7 days and the mean nestling period 10.9 days. Females were more engaged in incubation and brooding than the males. The percentage of second clutches was 15.4 and 27.3 respectively. The mean distance between the first and second nest was 38.8 m. First nests were left because of unfavorable nest sites and disturbances. There were no pairs breeding twice. On the average 53.3% of all clutches were successful. The mean rate of hatching in these nests was 93.8% and fledglings derived from 88.8% of all eggs laid. 57.3% nestlings fledged from the total of all eggs laid (1979: 47, 1980: 24). The reproduction rate theoretically necessary to keep a population of small birds at a constant level was reached only in 1979. The largest portion of all unsuccessful nests was lost even before the clutches were full. Singing-activity of males is highest in mid May. During their song flights highly excited males can clap their wings on their backs rhythmically. The song period of paired males averaged 30 days. Data were treated with regards to the behavior of adult birds during the time of pair formation and breeding.

Description / Table of Contents: Summary Since 1975 the occurrence of the tick speciesI. arboricola on the peregrine falcon was studied in Baden-Württemberg, West Germany. 7 out of 40 eyries, all of them located in caves, were infested with this tick species. In contrary eyries on ledges were never infested. The mortality rate of the tick infested nestlings was high (74 %). This high mortality rate may be due to the loss of blood, to toxins, to tick transmitted blood parasites, bacteria, rickettsiae and viruses. The proportion of infested nestlings was 11.8 %. The intensity of infestation (number of ticks per nestling) was high with a maximum of 320 larvae, nymphs and females on one bird. The ticks were concentrated at the base of the bill, around the eyes, on the vertex but also on the back, wings and thighs and around the cloaca. The control of the ticks on the nestlings was carried out with a 1 % watery suspension of Antorgan®, the eyries were treated with a 3 % suspension of Antorgan. We suggest to treat the eyries at least three times a year againstI. arboricola: Shortly after the young birds have left their nests, shortly before the adult falcons are laying in spring and at the time when the nestlings are banded.

Description / Table of Contents: Summary 1972–80, breeding data of the Dipper in the Harz Mountains were collected. A mean of 18 days is required for nest building (n=18). Egg-laying starts on average of April 21 and shows an altitudinal retardation of 5.92 days per 100 m. This runs parallel to the melting of snow and the beginning of vegetation development respectively. The mean breeding period is 16.5 days (n=16). The mean clutchsize is 4.86 eggs (n=88) and decreases by 0.17 eggs per ten-day period and by 0.20 eggs per 100 m. The mean breeding success amounts to 3.91 young (n=66), which is 80% of the eggs laid. This decreases by 0.13 young per ten-day period. It shows a maximum at 4–500 m and decreases at lower and higher altitudes. The amount of second broods is to 11.8%, second clutches consisted of 4.38 eggs (n=8) and 3.0 fledged young (n=5) leave the nest. With reference to the altitude, the main distribution lies at 3–400 m; above this the population density decreases for every height increase of 120–130 m to half and below the occurrence is reduced by dams and towns. A calculation for the West Harz Mountains can be assessed from the breeding success and survival rates, and that is, that the population of the Dipper is stable between 265 and 685 m and the upper and lower occurrences are based on the „surplus“.

Description / Table of Contents: Summary The territorial songs of two geographically isolated chiffchaff populations are analyzed. Songs ofPh. c. abietinus (Elburz Mts., Iran) are nearly identical with those of Scandinavianc. abietinus and Central Europeanc. collybita. One third of the notes ofPh. c. sindianus (NW Himalayas) ascend in frequency at the beginning. Such notes are lacking inPh. c. collybita andc. abietinus, but exist in the Siberianc. tristis. Playback experiments confirm the differences. Original songs ofc. sindianus elicit a distinctly weaker reaction by Germanc. collybita than local songs. Artificial songs (made from natural notes) of ascendingsindianus notes elicit ro reaction (J4, fig. 11). Earlier findings on parameters important for releasing territorial behaviour in the Central Europeanc. collybita are largely confirmed and new results suggest minor differences only. 1) Notes in which the frequency of the second part is as high as the first part (P6, J11, J12; fig. 10, 12) may release strong or weak reactions. This depends on additional characteristics of the note, mainly of its 2. part. 2) Notes with very steep ascending angle (max. 91,5° : P7, also P6, J12, fig. 10, 12) release a strong reaction.Ph. c. canariensis with notes as steep as inc. abietinus andc. sindianus differ in the second part of the note. It inhibits the reaction ofc. collybita of Central Europe. Regarding acoustical and morphological characteristics,Ph. c. sindianus is close toPh. c. tristis. It cannot be treated a separate species. The nearest relative ofc. abietinus is the Central Europeanc. collybita.

Description / Table of Contents: Summary Under conditions of captivity, with food freely available, Red-backed Mousebirds(Colius castanotus) had a daily food intake of about 75 % of their own body mass (37–56 g food). Food intake was distributed uniformly over the whole light period. Body temperature and metabolism of mousebirds fed ad lib. are in the same range as reported for other birds of similar size (mean body mass 69 g). The thermal conductance varies from 2, 1 to 2,5 J/g · h · K (predicted value 2,44). Sub-maintenance feeding leads to a gradual decrease of body temperatgure and metabolism following the loss of body mass; tghe diurnal rhythm of both doesn't change. The thermal conductance decreases to more favourable values (better insulation) between 1,9 and 2,1 J/g · h · K due to a smaller diffeence of body temperature and ambient temperature caused by falling body temperatures versus deeper ambient temperatgures. The relation between body temperature and metabolism (Q10) at the beginning of fasting was determined as about 2 indicating that as this time the decline in metabolism and body temperature closely follows physico-chemical conditions. After a long period of food deprivation and a loss of body mass of about 35 %, the birds enter a state of torport. Metabolism of torpid birds may fall to less than 1/3 (on average; lowest reduction observed: 95 %) of basal levels depending on the actual body temperature reached after cooling. The critical level of body temprature is about 18 °C, below which no spontaneous arousal seems to be possible. The birds fall in uincontrolled hypothermia. While entering in torport Q10 increases to about 20 indicating an active process of depressing metabolism. Spontaneous arousal (with a Q10〉20) from torpidity lasts between 20–90 min, depending on body temprature and ambient temperature. On a minimal maintenance diet the Colies were able to undergo torpot on 16 consecutive fasting days without difficulties. It is expected that torpor is an adaptation to a vegetable nourishment which is of low energy content, only poorly convertible and often not reachable in sufficient portions. Presumable torpor occurs regularly to minimize nocturnal energy loss.