ALBERT

Description / Table of Contents: Summary This paper is based on field studies of the singing and wing flapping of the skylark. After being converted from an optical signal into an electrical one employing a light sensitive resistor fixed to binoculars, the wing beat frequency was superimposed onto a carrier frequency from a UJT-oscillator The bird song and the acoustic FM-signal representing the flapping of the wings were registered on tape and subsequently visualized by aKay Vibralizer 7030 A. From the sonagrams the following results were obtained: -the skylark song is fragmented into bits of vocalisation at rates hardly resolvable by the human ear -notes are uttered at a rate of 43 Hz -calls are uttered at a rate of 10 Hz -the mean duration of the calls is 63 ms -the intervals between calls last about 35 ms -none of the uttering speeds is related to the wing beat frequency which was found to be 16.3±1.5 Hz in calm air and 16.7±1.4 Hz under slight counter current Special attention was given to the duration of the intervals between notes and calls. The median of these intervals was found to be only 11.7 ms and thus too short for a complete inspiration or expiration. Furthermore a strong positive correlation exists between the duration of a note or call and the subsequent interval, whereas the correlation is weaker for a note or call and the preceeding interval. It is concluded that the short intervals are used to refill the air sacs in compensation for the volume of air dispensed for vocalization. With regard to the results from song fragmentation and their comparison with the presumed ventilation frequency, the following vocalization mode is proposed: -all sound production is superimposed onto outward air streams; -for the skylark, in which the probable ventilation frequency of 6 Hz is within the range of the call rate, it is assumed that a substantial number of the silent intervals are long enough for complete inspiration, and that synchronization of the breathing cycle and the calling cycle is possible; For some other birds, like the wren or the song sparrow, in which fragmentation frequencies are higher and the ventilation frequencies lower (as they do not fly and sing simultaneously), the „one interval — one inspiration“ — model is not tenable. Therefore, a different respiration model must be taken into consideration: -the basically silent inspirations are serially interrupted by short expirations linked with sound production („mini-breaths“ according toCalder) -the expiratory air stream is stopped and accelerated at the rate of the song fragmentation frequencies („pulsations“ according toBerger &Hart) -the second model should also be valid for the skylark when calls are uttered at frequencies higher than the ventilation frequency -it is suggested that in the skylark long intervals following prolonged calls are filled with several complete respiratory cycles

Description / Table of Contents: Summary Marsh Tit nestlings were isolated in sound proof rooms and reared in 4 experimental groups. While the groups II and III remained in isolation, group I heard natural songs from a tape and group IV artificial songs (fig. 1, 2). In all groups the species-specific song “Klapperstrophe” develops (fig. 3, 4), composed of series of “Klapperelements”. Its variability in the groups is similar to its variability in the songs of wild Marsh Tit populations (fig. 14). The complex song types of the natural song, however, which combine different notes in repeated groups (fig. 3), cannot be found in anyone of the groups. Instead the isolated birds develop improvised songs originating in part from calls (fig. 11), which are often similar in the experimental groups. As in natural song mixed songs can also be found (fig. 7). Group IV learned one artificial song (fig. 12), but group I none of the natural songs from tape. Group members share most of their songs (fig. 5, 6). There are only a few individual notes and some individual mixed songs (tab. 1, fig. 13). ♀ can sing too, but they sing their irregular songs only rarely (fig. 8). Like ♂ they sing notes of their respective group, but not so many notes and songs as ♂. After leaving the nest young Marsh Tits begin to improvise and to imitate the songs played by the tape. In June songs can already be heard (fig. 8–13). The majority of notes and songs are crystallized from august to october, so young Marsh Tits have learned their songs by autumn. Many wild Marsh Tit-♂ in southern Germany react to “Klapperstrophe” songs of the experimental groups as if to a population specific “Klapperstrophe” (test-criteria: singing and agonistic approach to the speaker; fig. 15). Only a few wild ♂ respond to improvised songs. Song development of Marsh Tits is discussed in comparison to other species. The influence of learning on the species specific development of simple and complex songs is different. While structure and pattern of the “Klapperstrophe” are probably innate, the songs consisting of note-groups and the details of the “Klapperelement” are transmitted by learning (tradition). Marsh Tits settle in their hatching area, can establish a territory soon after leaving the nest and stay in this territory throughout their life. The early establishment of a territory explains the simultaneous crystallization of song, which is significant for the occupation of territory in autumn too.

Description / Table of Contents: Summary So-called “diving after” is the description given to a mode of behaviour employed by many insect-eating birds: prey which has fallen is followed immediately in a reflex-type action with the bird diving vertically down behind it. The prerequisite for this is that the prey is desired by the bird. The prey item must have been taken by the bird, or this at least must be imminent. The function of the behaviour consists in the fact that the retrieving of lost prey requires less energy than the seeking and taking of new prey items. It is postulated that the behaviour of gulls, crows or raptors in dropping animal prey, which they cannot otherwise deal with, in order to smash it open, is evolved from the “diving-after-behaviour”, as the pattern of movement after the dropping of the prey is the same.

Description / Table of Contents: Summary Radar observations by means of a 23 cm-equipment in the area of the German Bight between April 2nd and May 16th, 1971 are compared with the independently registered migration on Heligoland (Fig. 1). During the first half of April the radar migration pattern indicated a strong migration; after that the intensity noticeably decreased for about ten days. This was also observed on Heligoland, especially in the daily arrivals of resting birds (Fig. 6), the numbers of ringed birds (Fig. 7) as well as in the daily numbers of species (Fig. 10). Against that the increase of radar recorded activity, which began around the end of April and grew up to the heaviest migraton period during the first 10 days of May, disagreed in quantity with the Heligoland findings. Only the number of species, which got in touch with the isle, however, indicated moreover invisible strong migration on Heligoland. According to the flight directions the radar investigations allowed the identification of several movements, which varied in strength of activity (Fig. 2) and in hourly recording of migration intensity during the daytime (Fig. 5). Most of the birds flew over Heligoland in broad front movements, directed from SW to NE. In April these birds were weather migrants, primarily starlings and thrushes (Fig. 8 and 9). In May, however, they were mainly insectivorous passerines, i. e. typical migrants. The radar data allowed to separate both groups of migrants by different daytime periods of activity. Broad front movements, directed from W to E and concentrated in the coastal areas of the Netherlands and Niedersachsen (Lower Saxony), were only limited to April. This part of migration was clearly dominating at night during the first half of April. The pattern of these movements coincided with the arrivals of waders and ducks (Tab. 1) on Heligoland. Also a tremendous number of starlings, crows and thrushes that winter in Great Britain passed the observation area in the same direction, as was seen by recoveries of birds ringed on Heligoland. During the last 10 days of April “Bandzug” began as a straight north directed migration movement. The mainly involved species — insectivorous passerines — passed the area at night on two narrow flyways. The appearance of these typical migrants on Heligoland not only coincided with the beginning of “Bandzug” but also with the pattern of these movements in May, when the heaviest activities occurred (Fig. 2 d and Tab. 2). Nevertheless the results were not identical in quantity. The broad front movements from SE-England to Scandinavia were only recorded on Heligoland when this migration was extensively diverted because of bad weather conditions. On such days in the NW part of the area numerous echos appeared on the radar screen flocking with southeasterly flight directions into the German Bight (Fig. 4). At the same time a remarkable number of different English winter guests was observed on Heligoland.

Description / Table of Contents: Summary The abundance of light and dark phases within a larger colony of the Eleonora's falcon was studied during five breeding seasons. These colour phases are described for adult and fledged falcons. Dark falcons amount to 33.5% at present and seem to have been constant during the last 13 years (1965–1977). About 30.7% of all fledglings showed the dark plumage. The phases of the breeding pairs are distributed randomly. The heredity of phases is according to the Mendelian laws; “dark” (= AA, Aa) is dominant and “light” recessive. In the population studied the abundance of homozygote dark forms (AA) is about 3.4%, the heterozygote (Aa) about 30.1%, and the recessive (aa) about 66.5%.

Description / Table of Contents: Summary Around Göppingen—Geislingen—Laichingen 126 broods of the Tawny Owl and 80 of the Long-eared Owl have been examined. Correlations between start of egg-laying, number of eggs and young, losses and breeding success to altitude, kind of nestsite, weather conditions and food are discussed and compared with results of other regions. The Tawny Owl always stays at the same place. There are relatively low changes in density and breeding success according to a high adaptibility concerning choice of nestsite and food (changing to birds in years with few voles). Long-eared Owls perform, at least in the high regions of the Schwäbische Alb (600–850 m), “invasions” causing highly variable densities. In good weather conditions and high density of field-voles the breeding success may be extraordinarily high. So parallels to the results from Scandinavia can be found.

Description / Table of Contents: Summary 1. In the paper the choice of nest sites of the blackcap Sylvia atricapilla in spruce forests in SW-Germany is presented. This investigation is based on 834 nest record cards which have been collected by the amateur and professional coworkers of the Vogelwarte Radolfzell in the warbler program over the period 1968–1976. 2. In SW-Germany, the blackcap often nests in spruce forests: 22% of the nests were found in spruce forests or in groups of spruces. The blackcap nests in all types of spruce forests from very small trees to tall forests. 3. In the various types of spruce forests the mean nest heights show only relatively little variation compared with that of the different nest bearing substrata: in small trees the nests are placed in green branches, in higher trees to a great extent also in the thickets of dried up branches, in tall forests either in the underwood or in spruce branches hanging down near to the ground. 4. Obviously, in the blackcap the spruce is a preferred nest site for relatively early broods. Whether, for instance, covering or special microclimatic conditions might be reasons for this is open. 5. In tall mixed forests without underwood it is often the nesting in spruce trees which enables the blackcap to settle in woods such as these. 6. The blackcap is a good example for adaptive choices of nest sites in varying conditions of one type of vegetation as the spruce forest. 7. Finally, regional differences of blackcaps' nesting in spruces are shown.

Description / Table of Contents: Summary Common crossbills working on attached or detached cones on a Hybrid Larch (Larix×eurolepis: “larch 1”), richly laden with cones, were observed. The following activities were measured: duration of the work on one cone; number of glancing movements (i.e. looking up) per unit of time (rate of glancing); number of glancing movements per cone; the moment, at which a cone was detached. For attached cones the following statements hold true: The rate of glancing remains nearly constant during any visit to the larch (Fig. 1); the same holds true for a period of several days (Fig. 3, inserted figure on the left). There is only a small difference between the duration of the work on wet cones and that on dry ones (Fig. 2). correspondingly, the same is true for the rate of glancing (Fig. 2, inserted figure). In the course of several days the number of glancing movements per cone changes (Fig. 3). This number does not depend on the number of glancing movements performed on the previous cone (Fig. 4). For detached cones the following statements hold true: Cones are detached at irregular intervals of time (Fig. 5). The number of cones detached as a percentage of the number of worked cones does not change in the course of several days (Fig. 3, inserted figure on the right). Detached cones are worked on longer than attached ones (Fig. 6). The rate of glancing for detached cones is greater than for attached ones (Fig. 6, inserted figure). The number of glancing movements in the interval between two acts of detaching does not depend on the number performed in the foregoing interval. The same holds true for the number of attached cones that are worked on between two acts of detaching and the time interval itself (Fig. 7). Most frequently, having detached a cone, the crossbill detaches the next within the following 2–4 minutes (Fig 7, inserted figure; Fig. 10). A detaching tendency is held to be responsible for the act of detaching. The strength of this tendency crosses a threshold at irregular intervals of time. The results are summarized in a flow chart (Fig. 11, graphical symbols after ISO/R 1028–1969). On an European Larch (Larix decidua: “larch 2”), not so richly laden with cones but bearing larger ones, the crossbills detached more cones and worked longer on them than on larch 1 (Fig. 9).

Description / Table of Contents: Summary TwoAepyornis eggs, from theAlexander Koenig Collection at Bonn, were arbitrarily chosen as standards for measurements of the sizes, axial and circumferential dimensions and indices, as well as radii of longitudinal and latitudinal curvatures of aepyornithiform eggshells and, notably, fragments thereof. The measurements of the curvatures of the eggshells, from which the corresponding radii are calculated, are made with a Geneva Lens Measure. The method yields precise results and permits at best reconstructions of the sizes and shapes of eggs from shell fragments. It is also applicable to the comparative study of ratite eggshell remains other than those from Madagasy Aepyornithiformes but with comparable shell characters. Such cases have been found among ratite eggshells with aepyornithoid pore patterns, from species that were widely distributed in the Old World during the Miocene and Pliocene. Localities are Lanzarote (Canary Islands), Morocco, Anatolia, Punjab, and Mongolia.