Posts tagged birds
Articles and news from the latest research reports.
Baby owls sleep like baby humans
Researchers at the Max Planck Institute for Ornithology and the University of Lausanne have discovered that the sleeping patterns of baby birds are similar to that of baby mammals. What is more, the sleep of baby birds appears to change in the same way as it does in humans. Studying barn owls in the wild, the researchers discovered that this change in sleep is strongly correlated with the expression of a gene involved in producing dark, melanic feather spots, a trait known to covary with behavioral and physiological traits in adult owls. These findings raise the intriguing possibility that sleep-related developmental processes in the brain contribute to the link between melanism and other traits observed in adult barn owls and other animals.
Sleep in mammals and birds consists of two phases, REM sleep (“Rapid Eye Movement Sleep”) and non-REM sleep. We experience our most vivid dreams during REM sleep, a paradoxical state characterized by awake-like brain activity. Despite extensive research, REM sleep’s purpose remains a mystery. One of the most salient features of REM sleep is its preponderance early in life. A variety of mammals spend far more time in REM sleep during early life than when they are adults. For example, as newborns, half of our time asleep is spent in REM sleep, whereas last night REM sleep probably encompassed only 20-25% percent of your time snoozing.Although birds are the only non-mammalian group known to clearly engage in REM sleep, it has been unclear whether sleep develops in the same manner in baby birds. Consequently, Niels Rattenborg of the MPIO, Alexandre Roulin of Unil, and their PhD student Madeleine Scriba, reexamined this question in a population of wild barn owls. They used an electroencephalogram (EEG) and movement data logger in conjunction with minimally invasive EEG sensors designed for use in humans, to record sleep in 66 owlets of varying age. During the recordings, the owlets remained in their nest box and were fed normally by their parents. After having their sleep patterns recorded for up to five days, the logger was removed. All of the owlets subsequently fledged and returned at normal rates to breed in the following year, indicating that there were no long-term adverse effects of eves-dropping on their sleeping brains.
Despite lacking significant eye movements (a trait common to owls), the owlets spent large amounts of time in REM sleep. “During this sleep phase, the owlets’ EEG showed awake-like activity, their eyes remained closed, and their heads nodded slowly”, reports Madeleine Scriba from the University of Lausanne (see video). Importantly, the researchers discovered that just as in baby humans, the time spent in REM sleep declined as the owlets aged.
In addition, the team examined the relationship between sleep and the expression of a gene in the feather follicles involved in producing dark, melanic feather spots. “As in several other avian and mammalian species, we have found that melanic spotting in owls covaries with a variety of behavioral and physiological traits, many of which also have links to sleep, such as immune system function and energy regulation”, notes Alexander Roulin from the University of Lausanne. Indeed, the team found that owlets expressing higher levels of the gene involved in melanism had less REM sleep than expected for their age, suggesting that their brains were developing faster than in owlets expressing lower levels of this gene. In line with this interpretation, the enzyme encoded by this gene also plays a role in producing hormones (thyroid and insulin) involved in brain development.
Although additional research is needed to determine exactly how sleep, brain development, and pigmentation are interrelated, these findings nonetheless raise several intriguing questions. Does variation in sleep during brain development influence adult brain organization? If so, does this contribute to the link between behavioral and physiological traits and melanism observed in adult owls? Do sleep and pigmentation covary in adult owls, and if so how does this influence their behavior and physiology? Finally, Niels Rattenborg from the Max Planck Institute for Ornithology in Seewiesen hopes that “this naturally occurring variation in REM sleep during a period of brain development can be used to reveal exactly what REM sleep does for the developing brain in baby owls, as well as humans.”
Birds and humans have similar brain wiring
You may have more in common with a pigeon than you realise, according to new research.
It shows that humans and birds have brains that are wired in a similar way.
A researcher from Imperial College London and his colleagues have developed for the first time a map of a typical bird brain, showing how different regions are connected together to process information. By comparing it to brain diagrams for different mammals such as humans, the team discovered that areas important for high-level cognition such as long-term memory and problem solving are wired up to other regions of the brain in a similar way. This is despite the fact that both mammal and bird brains have been evolving down separate paths over hundreds of millions of years.
The team suggest that evolution has discovered a common blueprint for high-level cognition in brain development.
Birds have been shown in previous studies to possess a range of skills such as a capacity for complex social reasoning, an ability to problem solve and some have even demonstrated the capability to craft and use tools.
Professor Murray Shanahan, author of the study from the Department of Computing at Imperial College London, says:
“Birds have been evolving separately from mammals for around 300 million years, so it is hardly surprising that under a microscope the brain of a bird looks quite different from a mammal. Yet, birds have been shown to be remarkably intelligent in a similar way to mammals such as humans and monkeys. Our study demonstrates that by looking at brains that are least like our own, yet still capable of generating intelligent behaviour, we can determine the basic principles governing the way brains work.”
The team developed their map by analysing 34 studies of the anatomy of the pigeon brain, which is typical for a bird. They focussed on areas called ‘hub nodes’, which are regions of the brain that are major centres for processing information and are important for high level cognition.
In particular, they looked at the hippocampus, which is important for navigation and long-term memory in both birds and mammals. They found that these hub nodes had very dense connections to other parts of the brain in both kinds of animal, suggesting they function in a similar way.
They also compared the prefrontal cortex in mammals, which is important for complex thought such as decision making, with the nidopallium caudolaterale, which has a similar role in birds. They discovered that despite both hub nodes having evolved differently, the way they are wired up within the brain looks similar.
The long-term goal of the team is to use the information generated from the wiring diagram to build computer models that mimic the way that animal brains function, which would be used to control a robot.
The study was published this month in the Frontiers in Computational Neuroscience journal.
Sleep consolidates memories for competing tasks
Sleep plays an important role in the brain’s ability to consolidate learning when two new potentially competing tasks are learned in the same day, research at the University of Chicago demonstrates.
Other studies have shown that sleep consolidates learning for a new task. The new study, which measured starlings’ ability to recognize new songs, shows that learning a second task can undermine the performance of a previously learned task. But this study is the first to show that a good night’s sleep helps the brain retain both new memories.
Starlings provide an excellent model for studying memory because of fundamental biological similarities between avian and mammalian brains, scholars wrote in the paper, “Sleep Consolidation of Interfering Auditory Memories in Starlings,” published in the current online edition of Psychological Science.
“These observations demonstrate that sleep consolidation enhances retention of interfering experiences, facilitating daytime learning and the subsequent formation of stable memories,” the authors wrote.
The paper was written by Timothy Brawn, a graduate researcher in psychology at UChicago; Howard Nusbaum, professor of psychology; and Daniel Margoliash, professor of psychology, organismal biology and anatomy. Nusbaum is a leading expert on learning, and Margoliash is a pioneer in the research of brain function and its development in birds.
Birds evolved ultraviolet vision several times
Ultraviolet vision evolved at least eight times in birds from a common violet sensitive ancestor finds a study published in BioMed Central’s open access journal BMC Evolutionary Biology. All of these are due to single nucleotide changes in the DNA.
Modern daytime birds either have violet sensitive or ultraviolet sensitive vision. Being ultraviolet sensitive alters visual cues used to select a mate, avoiding predators, and in finding food. Researchers from Uppsala University and the Swedish University of Agricultural Sciences sequenced the genes responsible for producing the light sensitive pigment (SWS1 opsin) from 40 species of birds, in 29 families.
Generating a phylogenetic tree from these sequences shows that there have been at least 14 shifts between violet and ultraviolet sensitive colour vision and back. An ancestor of Passeriformes (perching birds including larks, swallows, blackbirds, finches, birds of paradise, and crows) and Psittaciformes (parrots and allies) changed from the ancestral violet sensitive colour vision to ultraviolet and, in some cases passerines have reverted back to violet vision.
Anders Ödeen and Olle Håstad, who performed this research commented, “There are two different amino acid alterations that can each change bird colour vision from violet to ultraviolet. One particular single nucleotide change has occurred at least 11 separate times. In general during evolution once a colour shift has occurred all species from this ancestor keep it meaning that the rest of the eye and physiology, must also evolved to ‘cement’ in the new colour sensitivity.”
(Image: webexhibits.org)
Sensitive Males Provide Clues to Mind Reading in Birds
The male Eurasian jay is an accommodating fellow. When his mate has been feasting steadily on mealworm larvae, he realizes that she’d now prefer to dine on wax moth larvae, which he feeds her himself. The finding adds to a small but growing number of studies that show that some animals have something like the human ability to understand what others are thinking.
Wrens Teach Eggs to Sing
Mothers usually set about teaching their offspring the moment they’re born. But the females of one Australian bird can’t wait that long.
Superb fairy-wren (Malurus cyaneus) mothers sing to their unhatched eggs to teach the embryo inside a ‘password’ — a single unique note — which the nestlings must later incorporate into their begging calls if they want to get fed.
The trick allows fairy-wren parents to distinguish between their own offspring and those of the two cuckoo species that frequently invade their nests. The female birds also teach their mates the password.
Fairy-wrens were known to discriminate against cuckoo nestlings on the basis of their foreign begging calls, says Sonia Kleindorfer, an animal behaviorist at Flinders University in Adelaide, who led the work. But it wasn’t known that wren nestlings learned the passwords before hatching.
“It has never been shown before that there is actually learning in the embryo stages,” says Kleindorfer. The finding, published today in Current Biology, has the potential to open up new lines of enquiry into prenatal learning in systems other than parasite-host relationships and in other animals — it could occur anywhere where it’s a benefit, she adds.
Birds of a feather don’t share a sick bed
House finches avoid sick members of their own species, say scientists, in a finding that could be useful for tracking the spread of diseases like bird flu that also affects humans.
Laboratory tests showed that the house finch, a particularly social North American species (Carpodacus mexicanus), was able to tell the difference between sick and healthy fellow birds and tended to avoid those that were unwell.
This was the first time that avoidance of sick individuals, already observed in lobsters and bullfrog tadpoles, has been shown in birds, according to a paper published in the journal Biology Letters.
"In addition, we found variation in the immune response of house finches, which means that they vary in their ability to fight off infections," says co-author Maxine Zylberberg of the California Academy of Sciences.
"As it turns out, individuals who have weaker immune responses and therefore are less able to fight off infections, are the ones who most avoid interacting with sick individuals."
This all meant that there were differences between individual birds’ susceptibility to disease, the time it would take them to recuperate and their likeliness to pass on the disease.
"These are key factors that help to determine if and when an infectious disease will spread through a group of birds," says Zylberg - and how quickly.
Testosterone regulates solo song of tropical birds
Experiment in females uncovers male hormonal mechanism
In male songbirds of the temperate zone, the concentration of sex hormones is rising in spring, which leads to an increase in song activity during the breeding season. In the tropics, there has been little evidence so far about such a clear relationship between hormonal action and behaviour, which is partly due to a lower degree of seasonal changes of the environment. Researchers of the Max Planck Institute for Ornithology in Seewiesen have now discovered that in duetting African white-browed sparrow weavers, the solo song of dominant males is linked to elevated levels of testosterone. What is more, the male-typical solo song could be activated via testosterone treatment in female birds. The study thus shows a complex relationship between song behaviour and hormone concentration also in a tropical bird species.
'Tree of life' constructed for all living bird species
Scientists have mapped the evolutionary relationships among all 9,993 of the world’s known living bird species. The study, published today in Nature, is an ambitious project that uses DNA-sequence data to create a phylogenetic tree — a branching map of evolutionary relationships among species — that also links global bird speciation rates across space and time.
“This is the first dated tree of life for a class of species this size to be put on a global map,” says study co-author Walter Jetz, an evolutionary biologist at Yale University in New Haven, Connecticut.
Bird-brains solve problems spontaneously
In certain situations animals can spontaneously solve problems without planning their actions, according to research from The University of Auckland’s School of Psychology.
Animals rarely solve problems spontaneously, yet certain bird species are able to rapidly gain access to food hung on the end of a long string, by repeatedly pulling and then stepping on the string. For over 400 years it has been a mystery as to how the birds spontaneously solve the “string pulling” problem.
The University of Auckland research shows that such problem solving is not created by birds first solving the problem in their heads. Rather, problem solving occurs online as the bird makes the food on the end of the string move.
“Crows and parrots have long been known to solve the string pulling problem immediately. What our new research shows is that these performances are due to the birds being able to react in the moment to the effects of their actions, rather than being able to mentally plan out their actions,” says Dr Alex Taylor, lead author on the study.
“Thus string pulling appears to be based on a different type of intelligence than we had thought. Instead of the crows using sophisticated cognitive software to model the world, it appears their neural hardware is sufficiently well connected and/or specialised for them to react to the effect of their actions immediately. This allows them to solve problems that other bird species cannot.”
The work, by Dr Taylor, Brenna Knaebe and Professor Russell Gray, titled “An end to insight? New Caledonian crows can spontaneously solve problems without planning their actions”, has been published in the Proceedings of the Royal Society B: Biological Sciences online.