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• Lang, E. M., Thiersch, A., Thommen, H. & Wackernagel, H. 1962: Was füttern die Flamingos. (Phoenicopterus ruber) ihren Jungen. (What do flamingos (P. ruber) feed to their chicks?) Der Ornithologische Beobachter 59: 173 – 176.

In a breeding colony of Flamingos at the Zoological Garden of Basle samples of the liquid fed by the parents birds to young ones could by analysed. These investigations revealed that this liquid is not regurgitated pre-digested food, but a secretion produced by a yet unknown tissue (see Studer-Thiersch 1967). It is red, contains blood and a rich amount of carotenoids and as to its nutritional value can be compared with the milk of the mammals.

• Studer-Thiersch, A. 1963: Füttern die Flamingos ihre Jungen mit Blut? (Do flamingos feed their chicks with blood?) Zolli-Bulletin Nr. 10: 10 – 12.

In the secretion which is fed to the flamingo chick by its parents blood is a regular component, decreasing with increasing age of the chick. The proof that the blood comes from the adult bird was given by catching drops from the bill of a bird just interrupted while feeding the chick.

• Studer-Thiersch, A. 1964: Balzverhalten und Systematik der Gattung Phoenicopterus. (Courtship movements and systematic of the genus Phoenicopterus.) Der Ornithologische Beobachter 61: 99 – 102.

The motions of the main courtship movements of the three forms of the genus Phoenicopterus, Wing Salute, Inverted Wing Salute and Twist Preen, based on film sequences are presented. The differences in the performance of these movements are very slight in ruber and roseus, while clearly distinguished in chilensis. Therefore the classification of ruber and roseus as one species (ruber) and of chilensis as a separate one is proposed.

• Studer-Thiersch, A. 1966: Altes und Neues über das Fütterungssekret der Flamingos Phoenicopterus ruber. (Old and recent remarks on the feeding secretion of the flamingos P. ruber.) Der Ornithologische Beobachter
  63: 85 – 89.

Attention is drawn to a paper of Bartlett (1869), in which he states that flamingos, seeming to be in breeding condition, produce a liquid containing blood, and that they probably feed their young with this secretion. These early findings were completely escaped to the notice of later authors. In the present paper, Bartlett’s observations are quoted in full and compared with results obtained at the Zoological Garden Basle. Bartlett, A. D. 1869: remarks upon the habits of the Hornbills (Buceros). Proceedings of the Zoological Society London: 142 – 146.
Supplement:
A description of Gallet (1949) has to be mentioned at this place. He had observed that in chicks after they had been forced to flee a swelling of the crop became visible which didn’t disappear while resting afterwards. Several autopsies revealed that the swelling was due to more or less coagulated blood. After several hours of rest the blood seemed to be absorbed. These haemorrhages, as Gallet called them, often led to the chick’s death, but paradoxically many of the chicks with such a remarkable swelling survived, as Gallet reports. In the light of our nowadays knowledge he probably had found the feeding secretion in the crop already partly digested, and intensely coloured by blood and carotinoids. The death of chicks might have been due to other reasons.
Gallet, E. 1949: Les flamants roses de Camargue. Payot, Lausanne.

• Studer-Thiersch, A. 1967: Beiträge zur Brutbiologie der Flamingos (Gattung Phoenicopterus). (Contributions to the breeding biology of the flamingos (genus Phoenicopterus).) Der Zoologische Garten (NF) 34: 159 – 229.

List of Content
Introduction
The flamingo flock in the Zoological Garden Basel – Observations in captivity and observations in the wild – Questions – General remarks to breeding behaviour
Copulation behaviour
Posture during copulation – Behaviour of the female before copulation –
Plunging the bill into the water by the female during copulation – Copulation partners – Time and place of copulations
Behaviour at the nest
Interest in nest sites – Nest selection – Nest building
Egg laying
Incubation
Nest building activity – Protection of the nest against water – Aggressive behaviour – Interruptions of incubating –Change overs – Recognition of the egg - Replaced eggs – Lost eggs – Influence of external factors on breeding motivation – Comparison of breeding mood between males and females
Hatching
Behaviour of the chick while on the nest
Behaviour of the parents while chick on the nest
Leaving the nest
Behaviour of chick and parents after the chick has left the nest
Guiding the chick – Brooding and time spent on nests - Aggressive behaviour of the parents while guiding the chick - Aggressive behaviour of the chicks with each other – Weakening of the tie between chick and parents - “Crèche” formation - Foraging movements of the chicks - Swimming of the chicks – Sleeping postures of the chicks - Occurrence of breeding behaviour in juveniles
Feeding the chick
Feeding secretion (with a photo showing the oesophagus glands, site of the secretion of the feeding liquid) - Releasing of and position during feeding – Feeding of only the own chick – Time of feeding – Duration and frequency of feeding – Frequency of the chick’s calling during feeding – “Helping” at feeding by not familiar birds - Behaviour of not familiar birds towards chicks
German summary
List of literature

• Studer-Thiersch, A. & Wackernagel, H. 1969: Beobachtungen an den Basler Flamingos aus dem Jahr 1968. (Observations on the Basel flamingos in 1968.) Der Ornithologische Beobachter 69: 65 – 69.

During copulation the male flamingo hangs by his feet over the female’s upper arms (photos confirming the sketches of Suchantke 1959) and does not thrust feet and lower legs under them as described by Allen (1956) and Rooth (1965).
During a hail storm the breeding birds and even many non-breeding birds lay down with outstretched necks (photo). It is discussed, if this behaviour may be interpreted as inadaequate “submissive posture”. Also in situations, when flamingos are suddenly frightened by tactile, acoustic and optical stimuli (heavy rain, lightening, thunder etc) they seem to tend to behaviour patterns avoiding aggression of probably lower intensity.
Allen, R.P. 1956: The flamingos: their life history and survival. Research report No. 5 of the National Audubon Society., New York.
Rooth, J. 1965: The flamingos on Bonaire. Uuitgaven “Natuurwetenschappelijke Studiekring voor Suriname and de Nederlandse Antillen“, Utrecht 41.
Suchantke, A. 1959: Die Paarung beim Flamingo. Der Ornithologische Beobachter 56:
94 – 97.

• Studer-Thiersch, A. 1969: Beobachtungen an freilebenden Flamingos in Südspanien. (Observations on wild flamingos in South Spain.) Der Ornithologische Beobachter 69: 239 – 252.

In 1967, between March 8 and June 13, flamingos living in a salt lake in Southern Spain were observed. The number of birds present varied between 2000 and 6000 individuals.
The activity pattern of the flamingos at day time changed during the observation period. In the middle of April the display, nest building and copulation activity decreased and finally ceased, but nest building started again for a short period some weeks later during light rainfall. These observations as well as some other data on breeding of the flamingos in the Camargue, seem to indicate, that rainfalls might have the role of a proximate factor for breeding in the Greater flamingo.
The activity pattern of the flamingos during day and night, their behaviour before starting off on flights over different distances and their reaction to disturbances are described. The behaviour of the flamingos kept in captivity doesn’t very differ much from the behaviour of wild birds.

• Studer-Thiersch, A. 1974: Die Balz der Flamingogattung Phoenicopterus unter besonderer Berücksichtigung von Ph. ruber roseus. (The courtship display of the flamingos, genus Phoenicopterus with special reference to P. ruber roseus.) Zeitschrift für Tierpsychologie 36: 212 – 266.

In the Zoological Garden of Basel the mass or group display of the flamingos, genus Phoenicopterus, was studied with special attention to the following points: origin of the display movements, differences in the display between the three forms of the genus Phoenicopterus ruber, roseus and chilensis; function of the group display. During a stay in Spain, observing wild flamingos (roseus) the results obtained from birds in captivity were checked.
The following elements occur during group display: 2-s Call and Head-Flagging, in their original situation serving to call and to look for the mate; Wing Salute, Inverted Wing Salute and Wing Leg Stretch, derived from the stretching movements wing flap, both wing stretch and stretching of one wing and one leg; Twist Preen, a formalized preening behind the wing, the aggressively motivated Hooking, False Feeding and, rarely, circling flights.
Nearly all real display elements, Hooking and False Feeding not belonging to them, occur originally during the changing of mood which often leads to a change of the place too. Formalization not only concerns the single movements but also the sequence of movements performed by the single bird, which is rather fixed: Wing Salute –Twist Preen – Inverted Wing Salute – Twist Preen. Most often several birds take part in the group display, and it reaches highest intensity in groups of 10 – 30 birds. Male and female perform the same movements which are not orientated to another bird except in chilensis. Group display therefore seems to be originally a formalized changing of motivation and of place of the whole group of birds, which acts to build up a loose coherence of the birds.
Differences in the display of the three Phoenicopterus-forms concern the performance of the homologous movements, the frequencies of the movements and of their sequences, their correlation and their orientation. The display of ruber seems to be the most primitive of the three, its movements being less formalized and the display itself less emancipated from the original behaviour in the females. The evolution of the display of roseus and chilensis from a display similar to that of ruber took different directions as is indicated by the different ways of formalization of the Wing Salute and the different performance of the Inverted Wing Salute, The differences in the group display of ruber and roseus are only slight. Chilensis differs from these two not only by the differences in the movements but also by the evolution of a display directed towards a mate which can be derived from the group-referring display of ruber and roseus. According to the different degree of differences in the group display of the three forms of the genus Phoenicopterus it does not seem justified to give them all the same status of classification. The formation of two species, the monotypic species chilensis, and the polytypic species ruber with the subspecies ruber and roseus would correspond best to these findings.
Group display of roseus occurs throughout the year, but most often before breeding (continouos display). At this time it has a stimulatory effect on the synchronization of the mates and on pair formation, but it does not act as pre-copulation behaviour. During the continuous display which is not bound to the later nesting place birds of similar breeding readiness form small groups. It is supposed that they form loose groups during display in which they remain also after having stopped displaying. Later, in the breeding colony, they will breed together in groups in which the nests lie extremely close together. In the different parts of the colony egg-laying is highly synchronized.
The breeding of roseus is very irregular and erratic in regard to the time, duration and place, as are the rainfalls in most parts of their breeding range. These seem to act as ultimate factor for breeding to which the flamingos may react very quickly: If the breeding conditions become favourable the birds of a group, already individually known to each other since display, may stimulate each other in a very effective way to a quick and especially synchronous egg laying by nest building and bickering for nests at low intensity. Synchronous egg laying in groups seems to favour the breeding success as it reduces the losses by predators and the losses of eggs when breeding birds desert nest and egg at the end of the season.
Dependent on the situations at the breeding sites, quite different types of colonial breeding may result from the group display. If there are constant favourable conditions the group may just begin to breed after displaying and thus form a colony characterized by the steady or wave-like addition of new groups. If the breeding conditions are only favourable at irregular times and for short periods the birds have to wait after displaying (how long they can delay breeding is not known) until the breeding conditions change. Then a varying number of groups may begin to breed at once.
The formation of groups during display can be regarded as adaptation to the special ecological conditions at the breeding grounds.

• Studer-Thiersch, A. 1992 in Johnson, A.: What is the potential life-span of a Greater flamingo? IWRB Flamingo Research Group, Newsletter Nr. 6: 54; Studer-Thiersch, A. 1995 - 2008: Notes on “Basel’s veteran flamingos” in Johnson, A. (ed.): IWRB Flamingo Specialist Group, Newsletter Nr 7: 49; 1998 in Johnson, A.(ed.): IUCN Flamingo Specialist Group, Newsletter Nr. 8: 33; 2001 in Johnson, A. & Arengo, F. (eds.):IUCN Flamingo Specialist Group, Newsletter Nr. 10: 44 & 2004 Nr. 12: 30; 2008 in Childress, B., Arengo, F. & Bechet, A. (eds.): 2008; Flamingo. Bulletin of the IUCN-SSC/Wetlands International Flamingo Specialist Group, No. 16: 67.

In 1974 still 11 Greater flamingos which had been acquired in 1932 and 1938 were alive. As these birds have been leg banded only in 1944 the exact time spent in the zoo is unknown as are their age, their origin and the original flock size. In 1989 their number had decreased to 6, in 2001 to 2 birds. The last of them, a female, died in 2007. All birds were pinioned according to the usual practice at these early days.
From the last 6 birds, 4 males and 2 females still alive in 1989, one male never had bred before, the other 5 had participated in breeding more or less every year, 4 of them however without success within the last 10 years.
From the 2 remaining birds in 2001 the male had a very lively life. He had raised a chick in 1973 and went on breeding, though unsuccessfully, with same female for the next 9 years. This changed completely when the pair got divorced. With the new mate the male became the most successful breeder for the next 12 years raising a chick every year when breeding took place in the flock. But once more the male chose a new mate and the breeding success decreased drastically. In the following years he bred regularly but only twice with success. If he was the genetic father of both young is doubtful as one of the chicks hatched from a second egg in the same nest laid by his mate. However, she was seen copulating with another male in the days before the renewed egg-laying, while her mate was incubating the first egg. In the breeding season 2003 the male was found drowned at the edge of the colony just nearby to his nest.
The surviving veteran female lost interest in breeding during the last ten years of her life. In 1997 she was seen incubating for the last time. In 1999 she laid an egg but left it on the same day and in 2000 she only sometimes visited her mate for short time at the chosen nesting site. When she died in 2007 she was brightly coloured, but had become an old bird with difficulties in moving around and decreased eyesight. Nevertheless, she had no problems in her familiar surroundings to find food and join the group. But finally she was killed by a fox like 3 other birds of the last 6 veteran flamingos of 1989.

• Studer-Thiersch, A. 2000: What 19 years of observation on captive Greater Flamingos suggest about adaptation to breeding under irregular conditions. Waterbirds 23, spec. publ. (1): 150 - 159

In the Basel Zoo, Switzerland, I studied the behavior of the Greater Flamingo (Phoenicopterus ruber roseus) in a group of color-ringed birds with breeding success for the past 42 years. The “courtship-display”, a group display occurring occasionally throughout the year, may last for hours in the pre breeding months. The ritualized movements, identically performed by both sexes indicate changing mood, or place, or both. Highest synchronization occurs in groups of 15-25 birds. This behavior brings birds of similar breeding readiness together weeks before breeding, often at places far away from a possible breeding site, and is interpreted as preparation for a prospective collective change of activity (to breeding), and of place (to the breeding site). If breeding conditions improve, these groups may begin egg-laying within a few days. The duration of the pair bond varies from changing the mate every season to several years, probably depending on the number of birds present. Molting of the remiges is highly variable, ranging from replacing only a few feathers to loosing all within a few days, from molting every year to skipping 1 year or 2. Chicks are capable to flight before they are full-grown. The highly developed behavior of social stimulation, the formation of breeding groups independent from breeding time and breeding site allowing a quick initiation of breeding after arrival at the nesting area, the early attainment of flight capability in the chicks and the pattern of molting the remiges, enable the Greater Flamingo to reproduce successfully in a habitat characterized by irregular climatic conditions, that often lead to irregularly available feeding and breeding sites.

• Studer-Thiersch, A. 2000: Behavioural demands on a new exhibit for Greater Flamingos at the Basel Zoo, Switzerland.
  Waterbirds 23, spec. publ. (1): 185 – 192

When the group of Greater Flamingos in the Basel Zoo, Switzerland, had to be moved to another area the opportunity was taken to develop a new exhibit respecting the behavioral demands to a greater extent than it had been possible at the old enclosure. The main aims which should be achieved at the new location were an improvement of the feeding situation to a more natural one and a reduction of the formerly observed high egg losses in the breeding colony, which were interpreted as a husbandry problem. By different structures in the new exhibit these goals could largely be reached: a more natural behavior over the year, an increase of activity in general, particularly of foraging behavior and of behaviors of social stimulation. The start of breeding has become calmer and egg losses in the settling colony reduced.