Director Bart Kempenaers, head of the Department Behavioural Ecology and Evolutionary Genetics was appointed as honorary member of the world's largest ornithological society. The society thus honors and celebrates his valuable contributions to ornithology and his commitment to science.
More and more artificial lighting at night has consequences, especially for nocturnal wildlife that is not adapted to such high light levels. This influences many aspects of behavior such as foraging, commuting or mating. Scientists of the Research Group Acoustic and Functional Ecology now show in a new study that artificial light at night can also have fatal effects on moths. Many moth species can hear in the ultrasonic range and make various, often successful, evasive maneuvers in flight when they sense an approaching, hunting bat. Although this predator-prey interaction is triggered by sound, the study shows that a light-polluted night sky can suppress the evasive flight behavior of moths. Even if occasionally last desperate maneuvers are carried out, the artificial light could severely reduce the moths’ capability to avoid bats, and ultimately their survival.
Image © Christophe - stock.adobe.com
Sleep in mammals is composed of two major states, non-rapid eye movement (NREM) sleep and REM sleep, a paradoxical state with wake-like brain activity. In many mammals, after cooling during NREM sleep, the brain warms up during REM sleep, potentially preparing it to perform adaptively upon awaking. Researchers from the “Avian sleep” group in collaboration with researchers from the Neuroscience Research Center of Lyon studied brain temperature in pigeons and bearded dragon lizards, which have two sleep states similar in some respects to mammals. While they found brain cooling during NREM sleep and small, but consistent brain warming related to REM sleep in pigeons, brain temperature did not change when bearded dragons switched to the sleep state with wake-like brain activity. Therefore, the researchers challenge the hypothesis that the universal function of sleep states characterized by wake-like brain activity is to warm the brain in preparation for wakefulness.
Copyright Image: Damond Kyllo
In birds and other species alike, pairs can face considerable difficulties with reproduction. Scientists of the Department of Behavioural Ecology and Evolutionary Genetics have now shown in an extensive analysis of 23,000 zebra finch eggs that infertility is mainly due to males, while high embryo mortality is more a problem of the females. Inbreeding, age of the parents and conditions experienced when growing up had surprisingly little influence on reproductive failures.
Copyright drawing: Yifan Pei
Researchers led by Manfred Gahr in Seewiesen have investigated the relationship of bird families. For the first time, they have been able to clarify the relationship of all families of non-passerine birds and almost all families of passerine birds. The new family tree is based on gene sections that do not code for proteins, but contain sequences that are specific to the families and their genera.
Copyright image: André Labetaa
Across virtually all human cultures, couples prefer to conceal sexual intercourse from the sensory perception of conspecifics. Yitzchak Ben Mocha from the former Humboldt Research Group in Seewiesen has analysed ethnographies from 249 cultures and found this striking uniformity of human preference despite the considerable cultural differences. Relying on his previous finding of a parallel phenomenon in the Arabian babbler, Ben Mocha developed the "cooperation maintenance hypothesis" to explain why individuals conceal matings from the sensory perception of conspecifics. Using this hypothesis, Ben Mocha predicts in which social species habitual concealment of mating by dominant group members may be found.
Scientists of the department Behavioural Neurobiology have investigated the neural basis of the vocal interaction of zebra finch pairs that form lifelong partnerships. The researchers found that in males, the neurons of a specific brain area (the so-called HVC) were activated as soon as they heard the calls of their female partner, even if the later was not present. What is particularly exciting, however, is the finding that in the presence of females, i.e. in a normal social context, the HVC neurons are only activated by the calls of the females, if the males were able to anticipate them in advance. In this case, in a way that has not yet been clarified, a neuronal excitation and then a reaction of the mentioned male HVC neurons occurs before the call of the female. The male was thus able to respond more quickly to the female calls, which probably plays an important role for pair bonding and thus breeding success.
Hummingbirds are the smallest birds with the fastest heart rate and the largest flight muscles, just to name a few record-breaking characteristics. Some species communicate through complex sounds that are learned early in life, comparable to the process of language acquisition of humans. How exactly these complex sounds are produced has now been discovered by scientists from Seewiesen in collaboration with the Zoologische Staatsammlung München using three-dimensional computer tomography scans, with which they were able to create a high-resolution digital map of the morphology of the vocal organ (syrinx) of the black hummingbird. Due to its location on the outside of the thoracic cavity and the course of the muscles, the syrinx is not affected during the extensive flight movements. The small organ also contains ossicles that are potentially related to the production of high-pitched sounds. Altogether, the hummingbird syrinx enables precise control and production of the sounds.
Migratory starlings are avian athletes that fly long distances in conditions that can push them very close to their physiological limits. Glucocorticoids are hormones that increase during endurance exercise to provide ready-to-use fuel to satisfy the high energy demands; however, prolonged exposure to high glucocorticoids is detrimental. A new study of researchers from Seewiesen, the US and Poland with European starlings in the wind tunnel show that dietary anthocyanins – antioxidants present in colored berries selected by birds especially during migration –control excessive secretion of glucocorticoids when birds are flying for long durations. This supports the novel idea that dietary anthocyanins have important metabolic functions that also attenuate the endocrine stress response triggered by endurance flight.
Male pectoral sandpipers typically visit several potential breeding sites during the short arctic summer. The decision about where to go next seems to be made opportunistically: they often leave in the direction the wind takes them. Researchers of the Max Planck Institute for Ornithology in Seewiesen tracked the flight path of 80 males with the help of small satellite transmitters and found that breeding areas in the Russian Arctic are more likely to be visited under tailwind conditions. In an environment where the summer is short and mating opportunities are unpredictable, individuals may save time and energy by using wind support.
Parrots are considered extraordinarily clever animals. Alex, the famous Harvard-based African grey parrot, communicated with a vocabulary of more than 500 human words, could answer questions and classify objects spontaneously. Scientists from the Max-Planck-Institute for Ornithology based at the research station outpost for parrot comparative cognition in the Loro Parque in Tenerife, Spain, have shown that parrots exhibit a high level of social intelligence and cooperativeness. They readily help others, even when there is no immediate opportunity for reciprocation. Moreover, they reciprocate received favours and do not appear jealous, if conspecifics obtain a better reward than themselves. This further supports that they have evolved a level of intelligence comparable to that of great apes, crows and dolphins.
Noise pollution is one of the leading environmental health risks in humans. In zebra finches, noise affects their health and the growth of their offspring: Researchers at the Max Planck Institute for Ornithology in Seewiesen found that traffic noise suppresses normal glucocorticoid profiles in the blood, probably to prevent negative effects of chronically elevated levels on the organism. In addition, the young chicks of noise-exposed parents were smaller than chicks from quiet nests.
The focus of the new Max Planck Institute of Animal Behaviour in Radolfzell and Konstanz will be the investigation of Collective Behaviour. Besides of the existing departments of Martin Wikelski and Iain Couzin, another research department will be established. Margaret Crofoot from the University of California in Davis will investigate the formation of complex societies using the group behaviour of monkeys as an example. She is particularly interested in how the collective behaviour of a group emerges from the contacts and relationships between individuals.
(Image: Axel Griesch)