Tag Archives: study

Clever crows can plan for the future like humans do

Clever crows can plan for the future like humans do

(Markus Boeckle And Professor Nicky Clayton 14 July 2017)

This contrasts with all of the previous studies in future planning, which have focused on naturally occurring behaviour. For example, we know that California scrub jays cache their food according to their future needs. And that bonobos, chimpanzees and orangutans select, transport and save appropriate tools for future needs.

General intelligence

These studies have shown that animals can plan for the future – but they left an important question open for debate. Are animals only able to plan to use abilities that have evolved to give them a specific advantage, or can they flexibly and intelligently apply planning behaviour across various actions? Most critics would say the former, as the animals were tested in naturally occurring behaviours.

But the new research provides the first compelling evidence that animal species can plan for the future using behaviour that doesn’t typically occur in nature. This supports the view that at least some cognitive abilities in animals don’t evolve just in response to specific problems. Instead, it suggests that animals can apply these behaviours flexibly across problems in a similar way to humans.

It seems that, in corvids and apes, intelligence is not a system to solve a predefined set of problems (dedicated intelligence) but rather a computational system to improvise new solutions (improvisational intelligence). But it is still unclear what this cognitive system exactly is and how it evolved.

What’s needed now is neuro-biological evidence of general intelligence in animals. We also need to investigate how flexible and improvisational behaviour evolved. Then we might be able to see how crows’ ability to plan for the future fits in with their broader cognitive powers.

Humans aren’t as unique as we used to think. Not, at least when it comes to making plans for the future. Scientists originally thought humans were the only animals that made plans but, over the past decade, studies on non-human primates and the crow family have challenged this perspective.

For example, we’ve seen that these animals are able to store tools for later use, cache food in places where it will be needed the most, and hide pieces of the sort of food they know will be running low in the future.

In all these studies, the animals had to consider what to do, where to do it and when to prepare for certain specific future events. The latest research shows that ravens can indeed anticipate the “what, where and when” of a future event on the basis of previous experiences. But unlike the previous studies, this work tested the birds in behaviour they don’t normally show in the wild. This provides evidence that they have a much more general ability to plan for the future than previously thought.

Food hoarding is common in members of the crow family (corvids) because they often eat from perishable animal carcasses, which provide lots of food but are only available for a short amount of time. To create a suitable cache of food they need to work out what to store, where to put it and when to do so.

The new study, published in the journal Science, tested the birds outside this naturally occurring behaviour, which may have evolved specifically because it gives crows a survival advantage. Some crow species are known to naturally use tools to retrieve food. So the researchers tested whether the birds could store and retrieve a tool so they could get at their food after a gap of 17 hours – something we wouldn’t expect them to do naturally. The scientists didn’t give the birds a chance to learn this behaviour first but they were still able to instantly select the tool out of a number of unnecessary items.

In another experiment, the researchers taught ravens to select a token from a number of items that they could then exchange for food. Again, the birds then showed that they could plan for the future using this new behaviour. They were able to store this token and then retrieve and use it when they were offered the chance to exchange it for food 17 hours later.

This contrasts with all of the previous studies in future planning, which have focused on naturally occurring behaviour. For example, we know that California scrub jays cache their food according to their future needs. And that bonobos, chimpanzees and orangutans select, transport and save appropriate tools for future needs.

General intelligence

These studies have shown that animals can plan for the future – but they left an important question open for debate. Are animals only able to plan to use abilities that have evolved to give them a specific advantage, or can they flexibly and intelligently apply planning behaviour across various actions? Most critics would say the former, as the animals were tested in naturally occurring behaviours.

But the new research provides the first compelling evidence that animal species can plan for the future using behaviour that doesn’t typically occur in nature. This supports the view that at least some cognitive abilities in animals don’t evolve just in response to specific problems. Instead, it suggests that animals can apply these behaviours flexibly across problems in a similar way to humans.

It seems that, in corvids and apes, intelligence is not a system to solve a predefined set of problems (dedicated intelligence) but rather a computational system to improvise new solutions (improvisational intelligence). But it is still unclear what this cognitive system exactly is and how it evolved.

What’s needed now is neuro-biological evidence of general intelligence in animals. We also need to investigate how flexible and improvisational behaviour evolved. Then we might be able to see how crows’ ability to plan for the future fits in with their broader cognitive powers.

Waterbirds threatened by invasive carp

Netta_rufina.jpg

(Physorg 10 July 2017)

The presence of the carp, a freshwater invasive species spread worldwide, is alarmingly reducing the populations of diving ducks and waterbirds, according to a study published in the journal Biological Conservation by Alberto Maceda Veiga from the University of Barcelona and Raquel López and Andy J. Green from the Doñana Biological Station (EBD-CSIC).

This is the first study which clearly shows the ecological impact of the carp on water birds in Mediterranean shallow lakes, and it warns about the dramatic effect of this invasive species on other species such as the white-headed duck (Oxyura leucocephala) and the red-crested pochard (Aythya farina), classified as endangered species by the International Union for Conservation of Nature (UICN).

The carp (Cyprinius carpio) is considered one of the most threatening alien exotic species worldwide, according to the UICN. This species, from the European and Asian continents, is included in the Spanish Catalog of Exotic Invasive Species and can live in a wide range of habitats, even the most degraded ones. Quite valued in sport fishing and aquaculture, the carp causes well-known ecological impacts in several countries, but there is a lack of studies on the effects on some organisms such as water birds.

The authors have studied the natural reserves in the lakes of Medina (Cadiz) and Zoñar (Cordoba) in Andalusia. These shallow depths are quite emblematic in the south of the Iberian Peninsula and are areas where many water birds hibernate—one of the reasons why the Board of Andalusia tried to eradicate the carp.

According to first author Alberto Maceda Veiga, member of IRBio and expert in the Doñana Biological Station (EBD-CSIC), “Fishermen value the carp, and since it has been found around the peninsula for a while, some people think it is an indigenous species. Therefore, studies like this one are important, because they clearly show the ecological impact in our ecosystems to raise awareness among people regarding the ecological problems caused by the invasion of the carp.”

“The shallow lakes such as the ones in Medina and Zoñar are important lacustrine systems for the preservation of aquatic biodiversity in semi-arid regions such as the Mediterranean. Our scientific study concludes that there would be a severe impact on many water bird populations if all lakes were invaded by this exotic species,” says Maceda.

An exotic species that alters aquatic habitats

This exotic invasive species is likely to live in calm waters rich in natural nutrients or which are derived from polluted waters (for example, fertilisers from agriculture). However, the nutrition of the carp alters the natural dynamics of these lakes to such an extent that it can eradicate the carpet plants, traits of these lacustrine environments.

For the first time, the new study describes in detail the biological impacts on birds that use the water, including omnivorous species (such as diving ducks) and vegetarians (coots). Since the carp eradicates aquatic plants, it also ends with many invertebrates that use those as shelter and which are food for the birds. Also, the carp is a predator of marine invertebrates. The ecological impact is lower for species such as the mallard. On the other hand, piscivorous species are organisms that can benefit from the invasion of the carp.

“The carp excavates and breaks aquatic plants while eating. Also, the sand it has moved during this process ends up on the plants and kills them. Directly or indirectly, as a final result, the plant carpet disappears,” says Alberto Maceda.

“In this context, it is expected that short and soft winters such as the ones in the south of the peninsula and the effects that come from the climate change strengthen the ecological impact of the carp, which will be active during a longer time over the year.”

How to avoid the ecological impact of the carp?

The new article, published in the journal Biological Conservation, reviews a wide period of time that includes two invasion cycles of the carp in the lake of Medina—the widest in the province of Cadis and second in Andalusia, counting with all the present birds. Including a long temporary margin that includes two invasion cycles prevents the bias caused by yearly demographical changes or late responses from the community of unnoticed organisms.

“The carp is an ecological problem for our territory and its populations should be controlled. Manipulating environmental conditions which make it easier for the carp to spread is a possibility to reduce the grouping and dispersal of this invasive species. However, when the invasion is not localized, the most efficient protocol is to use fishnets or electrofishing. The population of carps should certainly be controlled using ethical protocols of animal welfare and of management of the corresponding biological waste,” conclude the authors.

Owls’ wings could hold the key to beating wind turbine noise

(Science Daily, IOP publishing 4 July 2017)

Inspiration from owls’ wings could allow aircraft and wind turbines to become quieter, suggests a new study. Researchers studied the serrations in the leading edge of owls’ wings, gaining new insight into how they work to make the birds’ flight silent. Their results point towards potential mechanisms for noise suppression in wind turbines, aircraft, multi-rotor drones and other machines.

A new study has revealed how inspiration from owls’ wings could allow aircraft and wind turbines to become quieter.

Researchers from Japan and China studied the serrations in the leading edge of owls’ wings, gaining new insight into how they work to make the birds’ flight silent.

Their results, published in the journal Bioinspiration and Biomimetics, point towards potential mechanisms for noise suppression in wind turbines, aircraft, multi-rotor drones and other machines.

Lead author Professor Hao Liu, from Chiba University, Japan, said: “Owls are known for silent flight, owing to their unique wing features, which are normally characterised by leading-edge serrations, trailing-edge fringes and velvet-like surfaces.

“We wanted to understand how these features affect aerodynamic force production and noise reduction, and whether they could be applied elsewhere.”

The researchers analysed owl-inspired feather wing models with and without leading edge serrations, by combining large-eddy simulations — a mathematical model for turbulence used in computational fluid dynamics to simulate air flows — and Particle-Image Velocimetry (PIV) and force measurements in a low-speed wind tunnel.

They discovered leading-edge serrations can passively control the transition between laminar, or streamline air flow, and turbulent air flow over the upper wing surface, at angles of attack (AoA) between zero and 20 degrees. This means they play a crucial role in aerodynamic force and sound production.

Professor Liu said: “We found, however, that a trade-off exists between force production and sound suppression. Serrated leading-edges reduce aerodynamic performance at lower AoAs than 15° compared to clean leading-edges, but can achieve noise reduction and aerodynamic performance at AoAs above 15°, which owl wings often reach in flight.

“These owl-inspired leading edge serrations, if applied to wind turbine blades, aircraft wings or drone rotors, could provide a useful biomimetic design for flow control and noise reduction.

“At a time when issues of noise are one of the main barriers to the building of wind turbines, for example, a method for reducing the noise they generate is most welcome.”

Palm cockatoos beat drum like Ringo Starr

(Physorg 28 June 2017; Photo C. Zdenek)

This was slowly acquired over the seven year study by patiently stalking the birds through the rainforest with a video camera.

“Each of 18 male palm cockatoos, known for their shyness and elusiveness, was shown to have its own style or drumming signature,” said Professor Heinsohn.

“Some males were consistently fast, some were slow, while others loved a little flourish at the beginning.

The palm cockatoo drumming is part of the species courtship ritual that involves a lot of calls and movements to attract a mate.
The research is part of a broader study of the palm cockatoo’s conservation needs on Cape York Peninsula where they suffer low breeding success and loss of habitat due to mining activity.

Professor Rob Heinsohn said while songbirds and whales can belt out a musical tune, few species recognise a beat.

But the shy and elusive palm cockatoo, iconic to Cape York Peninsula in far North Queensland, plays the drums and crafts the sticks.

“The large smoky-grey parrots fashion thick sticks from branches, grip them with their feet and bang them on trunks and tree hollows, all the while displaying to females,” said Professor Heinsohn, from the ANU Fenner School of Environment and Society.

“The icing on the cake is that the taps are almost perfectly spaced over very long sequences, just like a human drummer would do when holding a regular beat.”

Professor Heinsohn said the palm cockatoo’s ability to drum has been known for a long time but this is the first research to secure the footage to analyse it.

The trouble with being a handsome bird

(SD, Monash University 28 June 2017; Photo Kaspar Delhey)

Male birds often use brightly colored plumage to be attractive to females. However, such eye-catching trimmings may also attract unwanted attention from predators. Now, a new study led by Monash University has found that showy males indeed perceive themselves to be at a greater risk of predation.

The study’s lead author, PhD student Alex McQueen, from the School of Biological Sciences, studied risk-taking behaviour in Australia’s favourite bird, the superb fairy wren, also known as the blue wren. Every year, male wrens change their color from dull brown to a stunning combination of brilliant azure blue, with contrasting dark-blue and black plumage.

This annual color change makes them a useful study species for measuring the risk of being brightly colored, as the behaviour of the same individual bird can be compared while he is in different colors.

As part of this study, published in the Royal Society Journal Proceedings B, researchers snuck up on unsuspecting fairy-wrens. They then broadcast fairy-wren alarm calls from portable speakers, and observed the behaviour of the birds.

“When birds hear such alarm calls, it tells them there might be a predator nearby,” says Alex. “Whether they ignore the alarm or flee to cover, and the amount of time taken to re-appear from cover, tells us how high they perceive their predation risk to be.

“We found that fairy-wrens were more cautious while they were bright blue: they fled more often in response to alarm calls, and took longer to re-emerge from hiding. They also spent more time in cover, and more time scanning their surroundings.”

Alex’s supervisor, Associate Professor Anne Peters said an interesting observation was that brown fairy-wrens appeared to take advantage of the risks faced by blue males.

Fairy-wrens go about in social groups, often made up of individuals in different plumage colors.

“When a blue male was nearby, fairy-wrens spent less time hiding in cover after fleeing in response to alarm calls, and devoted less time to keeping a look-out,” Associate Professor Peters said.

“This could be because the dull brown wrens view blue males as a colorful decoy that reduces their own risk, or because blue males are more vigilant, allowing the brown wrens to drop their guard.”

The study, which was done in collaboration with Professor Rob Magrath from the Australian National University (ANU), shows that fairy-wrens perceive themselves to be at higher risk when they display their bright blue plumage, and adjust their behaviour accordingly.

Birds’ feathers reveal their winter diet

(AOS 21 June 2017; Photo RM Jensen)
Influences outside the breeding season can matter a lot for the population health of migratory birds, but it’s tough to track what happens once species scatter across South America for the winter months. A study from The Condor: Ornithological Applications tries a new approach for determining what declining migratory grassland birds called Bobolinks eat after they head south for the winter—analyzing the carbon compounds in their plumage, which are determined by the types of plants the birds consume while growing their feathers during their winter molt.

Thanks to a quirk of photosynthesis, rice contains a different ratio of carbon isotopes than most of the native grasses in South America where Bobolinks winter. Rosalind Renfrew of the Vermont Center for Ecostudies and her colleagues took advantage of this, collecting feather samples from wintering Bobolinks in a rice-producing region and a grassland region and from breeding Bobolinks in North America. When they analyzed the feathers’ isotopes ratios, the results from South America confirmed that isotopes in Bobolinks’ feathers reflected the differences in their diets between regions with and without rice production. The samples taken in North America showed that the winter diet of most individuals was weighted more toward non-rice material, but that rice consumption was highest late in the winter, when rice is nearing harvest and the birds are preparing for their northbound migration.

Rice could be beneficial by providing the birds with needed calories as they prepare for their journey north, but it could also increase Bobolinks’ exposure to pesticides and threats from farmers who see them as pests. According to Renfrew and her colleagues, maintaining native grasslands, encouraging integrated pest management programs to reduce toxic pesticide applications, and compensating farmers for crops lost to feeding birds all would be helpful.

“The time spent coordinating the field work for this study may well have been greater than the time spent collecting the data,” says Renfrew. “It was truly a team effort, and the assistance we received from our partners was absolutely essential, especially in South America. Aves Argentinas and the Museo de Historia Natural de Noel Kempff Mercado provided priceless logistical support, and this study could not have happened without them. Some of the same partners have provided input on a Bobolink Conservation Plan that lays out actions to address threats to grassland birds in North and South America, based on results from this and other studies.”

“As Bobolink populations continue to decline, Renfrew and her colleagues use state-of-the-art isotope analysis techniques to assess the Bobolink’s diet on its South American wintering grounds,” according to John McCracken of Bird Studies Canada, an expert on grassland bird conservation who was not involved with the study. “The authors conclude that rice may have negative effects on Bobolinks, owing to its relatively low nutritional quality and from exposure to insecticides.

Högsta hönset – en personlighetsfråga?

gammalsvensk_dvärghöna.jpg

(Marie Mattsson 11 juni 2017; Foto Anna Favati)

Länge har det funnits evolutionära modeller som bygger på att djur är optimalt anpassade som konsekvens av det naturliga urvalet. Men djurindivider kan ha olika personligheter och därmed kan deras beteende ibland te sig icke-optimalt. I flera svenska studier har forskare försökt reda ut hur och varför djur har personlighet med hjälp av gammalsvenska dvärghöns.

Forskning kring att djur har personlighet är något relativt nytt. Med personlighet hos djur menar man att individer beter sig olika varandra, men relativt lika sig själva över tid och i olika situationer. Trots tidiga observationer av att individer kan skilja sig åt i beteenden, började personlighetsforskning hos djur först i början på 2000-talet.

Hur ser då personlighet hos ett djur ut? Hanne Løvlie är etolog vid Linköpings universitet och har forskat mycket på höns och dess vilda anfader djungelhönset.

– Att djur har olika personlighet är något som ifrågasätter idén att djurs beteenden är optimala då det kan leda till att till exempel en tuff individ är tuff också när det kan vara farligt, och en feg individ kan vara feg när det istället kanske kan löna sig att vara tuffare, berättar Hanne Løvlie.

Olika personlighetstyper kan ha olika överlevnadsstrategier

Precis som hos människan utvecklas djurens personlighet genom både arv och miljö. De flesta djur lär sig hur de ska reagera på olika saker, men de har inte obegränsat med energi, tid och kapacitet, och måste därför göra avvägningar. För ett djur kan responsen inför en situation vara en fråga om liv eller död.

–  Personligheter kan även hittas hos ryggradslösa djur. En av de allra första studierna av djurs personlighet gjordes faktiskt på spindlar. Där kunde man se att beteenderesponserna skilde sig mellan olika individer, vissa var onödigt aggressiva när aggression inte behövdes. Responser behöver inte vara antingen eller, det kan finnas flera steg på skalan mellantvå extrema sätt att reagera, säger Hanne Løvlie.

Variation i personligheter kan vara olika strategier som påverkar till exempel överlevnad. Det har gjorts studier med bland annat talgoxe där man sett att vissa personligheter överlever bra under vissa förhållanden, medan andra personligheter fungerar bättre i andra situationer. Ett utforskande och risktagande karaktärsdrag hos en hane kommer exempelvis till nytta efter en vinter med gott om mat då det sedan blir hård konkurrens om häckningsrevir, medan en mer passiv hane sparar energi och kan ha en större chans att överleva under vintrar då det istället är ont om mat.

Höns är bra forskningsobjekt

Tillsammans har Anna Favati, doktorand i etologi vid Stockholms universitet, och Hanne Løvlie har gjort flera studier på hönsrasen gammalsvensk dvärghöna, en nära släkting till röd djungelhöna som är ursprunget till de flesta tamhönsarter. Dvärghöns lämpar sig bra för den här sortens forskning eftersom de inte är så hårt avlade utan beter sig som den ursprungliga hönset.

–  Hönsen i studierna är tama vilket gör dem lätta att observera, samtidigt som de ger relevant information eftersom de är nära ursprunget i sitt beteende, berättar Anna Favati.

Höns är en grupplevande art, som under naturliga omständigheter lever i grupper med ett par tuppar och något fler hönor. De bildar inte par, utan båda könen har många sexuella partners, och för tupparnas del leder det till hög konkurrens om hönorna. Både tuppar och hönor bildar tydliga dominanshierarkier. Det är som en trappstege där de högst upp har främst tillgång till resurser som exempelvis mat eller, i hanarnas fall parningar. När den sociala ordningen väl är upprättad behöver tupparna oftast inte slåss mer, utan hackordningen blir stabil och leder till att det är få onödiga slagsmål och konflikter.

Vad kom först; hönan eller ägget?

Man vet att det finns ett samband mellan dvärghönsens personlighet och rang, men hur kommer det sig? I en av studierna så tittade man på om det finns ett samband mellan hierarki och personlighet hos höns. Individer beter sig olika beroende på var de befinner sig i rangordningen, men har en viss individ större chans att stå högt i rang på grund av sin personlighet eller har den fått personligheten tack vare sin position i hierarkin? För att undersöka kopplingen mellan personlighet och rang började forskarna med att kategorisera tupparnas personlighet genom att titta på hur de reagerar i olika situationer.

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