How Birds Cooperate to Defeat Cuckoos

Why help another when you can help yourself? Cooperation is very common in nearly all life, from genes and cells to humans and other animals. However understanding why can be difficult: being selfish seems more rewarding. In a new study published in Science, we investigated whether the evolution of cooperative breeding in birds could be linked to defending their nests.

Cooperative breeding is when three or more individuals contribute to the care of young. While this happens in many animals, it is the social system of approximately 9% of birds, and is particularly prevalent in sub-Saharan Africa and Australasia.


However, understanding why evolution drove such behaviour remains controversial. Some studies have linked its occurrence with variable and unpredictable environmental conditions, while others have linked it to stable and predictable conditions.

Lees meer: Livescience

Biparental incubation patterns in a high-Arctic breeding shorebird: how do pairs divide their duties?

Bron: Behavioral Ecology (2014) 25 (1): 152-164 doi:10.1093/beheco/art098
Auteurs: Martin Bulla, Mihai Valcu, Anne L. Rutten, Bart Kempenaers
Abstract: In biparental species, parents may be in conflict over how much they invest into their offspring. To understand this conflict, parental care needs to be accurately measured, something rarely done. Here, we quantitatively describe the outcome of parental conflict in terms of quality, amount, and timing of incubation throughout the 21-day incubation period in a population of semipalmated sandpipers (Calidris pusilla) breeding under continuous daylight in the high Arctic.

Incubation quality, measured by egg temperature and incubation constancy, showed no marked difference between the sexes. The amount of incubation, measured as length of incubation bouts, was on average 51min longer per bout for females (11.5h) than for males (10.7h), at first glance suggesting that females invested more than males. However, this difference may have been offset by sex differences in the timing of incubation; females were more often off nest during the warmer period of the day, when foraging conditions were presumably better.
Overall, the daily timing of incubation shifted over the incubation period (e.g., for female incubation from evening–night to night–morning) and over the season, but varied considerably among pairs. At one extreme, pairs shared the amount of incubation equally, but one parent always incubated during the colder part of the day; at the other extreme, pairs shifted the start of incubation bouts between days so that each parent experienced similar conditions across the incubation period.

Our results highlight how the simultaneous consideration of different aspects of care across time allows sex-specific investment to be more accurately quantified.

Rainfall to Blame for Decline in Arctic Peregrines

Rain, crucial to sustaining life on Earth, is proving deadly for young peregrine falcons in Canada's Arctic.
 
A University of Alberta study recently published in Oecologia shows that an increase in the frequency of heavy rain brought on by warmer summer temperatures is posing a threat not seenin this species since before pesticides such as DDT were banned from use in Canada in 1970.

The study is among the first to directly link rainfall to survival of wild birds in Canada.

Lees meer: ScienceDaily

Barn owl nestlings recognise their siblings' calls

Instead of competing aggressively for food, young barn owls are known to negotiate by calling out.

A team of scientists in Switzerland discovered that the owlets have remarkably individual calls.

They suggest this is to communicate each bird's needs and identity in the nest.

The findings were announced in the Journal of Evolutionary Biology by Dr Amelie Dreiss and colleagues at the University of Lausanne, Switzerland.

Lees meer: BBC Nature

True variety of bird alarm calls discovered

Japanese Great Tits use specific alarm calls for different predators, research has shown, increasing our knowledge of bird communication.

A study analysed the species' calls and found they made jar sounds for snakes and different chicka sounds for crows and martens. This is the probably first evidence that birds can communicate vocally about the type of predator threatening them.

Lees meer: Birdwatch

Why bird migration is getting earlier each year

The causes of ever-earlier arrival times in our migratory birds have been revealed by researchers.

Experts have long suspected climate change is driving the well-documented advancing migration pattern, but new research reveals that individual birds migrate like clockwork, and arrive at the same time each year. However, the warming climate is producing earlier nesting and hatching each year, and this appears to be linked to the overall earlier migration times.

Researcher Dr Jenny Gill of the University of East Anglia said: “We have known that birds are migrating earlier each year, particularly those that migrate over shorter distances, but the reason why has puzzled ornithologists for years. It’s a particularly important question because the species which are not migrating earlier are declining in numbers.”

Lees meer: Birdwatch

How Pigeons May Smell Their Way Home

Homing pigeons, like other birds, are extraordinary navigators, but how they manage to find their way back to their lofts is still debated. To navigate, birds require a 'map' (to tell them home is south, for example) and a 'compass' (to tell them where south is), with the sun and the earth's magnetic field being the preferred compass systems.

A new paper provides evidence that the information pigeons use as a map is in fact available in the atmosphere: odors and winds allow them to find their way home.

Lees meer: ScienceDaily

'Early birds' find worms for dinner

Birds, such as great and blue tits, search for food in the morning but only return to eat it in late afternoon, scientists have found.

The team believe the behaviour maximises their chances of avoiding predators during the day without starving to death overnight.

Researchers from the University of Oxford tracked the birds' winter foraging movements using tiny tags.

All five of the studied species of songbirds behaved in the same way.

The results are published in the Royal Society journal Biology Letters.

Lees meer: BBC Nature

Three Swifts Probably Flew Non-Stop For 200 Days

In September of 2011, three alpine swifts took to the air in southwest Africa, and stayed there for almost 200 days. They fed on the wing. They slept on the wing. By the time they firmly settled back on solid surfaces, it was April of 2012 and they had travelled across the Sahara to the Mediterranean.

By fitting the birds with tiny trackers, Felix Liechti from the Swiss Ornithological Institute showed that they probably flew non-stop for almost seven months. It’s possible that they landed occasionally, but very rarely and never for more than a few minutes at a time.

Lees meer: Not exactly rocket science

'Shy' Male Birds Flock Together -- And Have Fewer Friends

Male birds that exhibit 'shy' social behaviour are much more likely to join flocks of birds with a similar personality than their 'bold' male counterparts, a new study has found. But shy birds also have fewer social partners than bold birds.

The research, carried out by scientists from Oxford University and the Australian National University, used a new way of analysing the social networks that link individual animals to each other -- a kind of 'Facebook for birds' -- to reveal how differences between individuals underpin the way that social interactions occur across populations.

The study of great tits (Parus major) in Wytham Woods, near Oxford (UK), also found that shy male and female birds don't interact with as many different individuals as bold males or females, and that shy males and females tend to have more stable relationships than bold ones -- being seen with the same individuals more often over time.

Lees meer: ScienceDaily

Birds Choose Sweet-Smelling Mates

For most animals, scent is the instant messenger of choice for quickly exchanging personal profiles. Scientists, however, have long dismissed birds as odor-eschewing Luddites that don't take advantage of scent-based communications.

In a first-of-its-kind study, however, a Michigan State University researcher has demonstrated that birds do indeed communicate via scents, and that odor reliably predicts their reproductive success. The study appears in the current issue of Animal Behaviour and focuses on volatile compounds in avian preen secretions.

Lees meer: ScienceDaily

Bright Birds Make Good Mothers

Female blue tits with brightly coloured crowns are better mothers than duller birds, according to a new study led by the University of York.
 
Unlike humans, birds can see ultra-violet (UV) light. While the crown of a blue tit looks just blue to us, to another bird it has the added dimension of appearing UV-reflectant.

The three-year study of blue tits, which also involved researchers from the University of California Davis, USA and the University of Glasgow, showed that mothers with more UV-reflectant crown feathers did not lay more eggs, but did fledge more offspring than duller females. These brightly coloured mothers also experienced relatively lower levels of stress hormones during arduous periods of chick rearing.

Lees meer: ScienceDaily

Hue of Barn Swallow Breast Feathers Can Influence Their Health

A new study conducted at the University of Colorado Boulder and involving Cornell University shows the outward appearance of female barn swallows, specifically the hue of their chestnut-colored breast feathers, has an influence on their physiological health.

It has been known that in North American barn swallows, both males and females, those with darker ventral feathers have higher reproductive success than those with lighter colors, said Cornell Senior Research Associate Maren Vitousek, who led the new research while a postdoctoral researcher at CU-Boulder. Although there is evidence that breast feather color is significantly influenced by genetics, melanin-based plumage color like that in barn swallows also has been tied to social status and even to circulating testosterone, she said.

Lees meer: ScienceDaily

Pigeons Fly Home With a Map in Their Heads

It is a fascinating phenomenon that homing pigeons always find their way home. A doctoral student in biology at the University of Zurich has now carried out experiments proving that pigeons have a spatial map and thus possess cognitive capabilities. In unknown territories, they recognize where they are in relation to their loft and are able to choose their targets themselves.

Lees meer: ScienceDaily

Birds Outpace Climate Change to Avoid Extinction

A new study has shed light on the potential of birds to survive in the face of climate change. In the analysis, based on more than fifty years' detailed study of a population of great tits near Oxford, UK, a team of scientists were able to make predictions about how the birds could cope with a changing climate in the future. They found that for small, short-lived birds like the great tit, evolution can work fast enough for genetic adaptation to keep pace with a changing environment. However, even for such fast-evolving species, evolution on its own is not enough.
  
Lees meer: ScienceDaily

Gannets Don't Eat Off Each Other's Plates

Colonies of gannets maintain vast exclusive fishing ranges despite doing nothing to defend their territory from rival colonies, scientists have discovered.

A team of researchers led by the University of Leeds and the University of Exeter observed that northern gannets, which can fly hundreds of kilometres on a single fishing trip, avoided visiting the fishing grounds of gannets from neighbouring colonies.

The findings, published in the journal Science, could transform our understanding of animals' foraging patterns because individual gannets do nothing to enforce this territory or communicate its boundaries when out at sea. A bird entering from a neighbouring colony would be free to fly and fish unhindered.

Lees meer: ScienceDaily

Size-biased allocation of prey from male to offspring via female: family conflicts, prey selection, and evolution of sexual size dimorphism in raptors

Auteurs:  Sonerud, GA; Steen, R; Low, LM; Roed, LT; Skar, K; Selas, V; Slagsvold, T
Bron: OECOLOGIA  Volume: 172   Issue: 1   Pages: 93-107   DOI: 10.1007/s00442-012-2491-9   Published: MAY 2013
Abstract: In birds with bi-parental care, the provisioning link between prey capture and delivery to dependent offspring is regarded as often symmetric between the mates. However, in raptors, the larger female usually broods and feeds the nestlings, while the smaller male provides food for the family, assisted by the female in the latter part of the nestling period, if at all. Prey items are relatively large and often impossible for nestlings to handle without extended maternal assistance. We video-recorded prey delivery and handling in nests of a raptor with a wide diet, the Eurasian kestrel Falco tinnunculus, and simultaneously observed prey transfer from male to female outside the nest. The male selectively allocated larger items, in particular birds and larger mammals, to the female for further processing and feeding of nestlings, and smaller items, in particular lizards and smaller mammals, directly to the nestlings for unassisted feeding. Hence, from the video, the female appeared to have captured larger prey than the male, while in reality no difference existed. The female's size-biased interception of the male's prey provisioning line would maximize the male's foraging time, and maximize the female's control of the allocation of food between her own need and that of the offspring. The male would maximize his control of food allocation by capturing smaller prey. This conflict would select for larger dominant females and smaller energy-efficient males, and induce stronger selection the longer the female depends on the male for self-feeding, as a proportion of the offspring dependence period. 

Birds arrange eggs in their nests to better detect imposters

Most birds build their own nests and incubate their own eggs. However, some birds like the cuckoo have managed to get around this inconvenience by simply laying their eggs in the nests of other species and letting someone else do the hard work of keeping the eggs warm and protected until the chick hatches. The ‘host’ (the poor sucker who ends up taking care of the other birds’ eggs) does everything they can to try and make sure the eggs that they’re sitting on are just their own. On the other hand, the ‘brood parasite’ (the freeloader bird that just lays in the nests of others) does everything they can to make their eggs indiscernible from the eggs of their host.

Of course, neither host nor parasite is trying to achieve anything consciously; their eggs are shaped by evolution and there is natural selection both on the brood parasite to produce eggs that are very similar to the host they are attempting to parasitize, and on the host to be extra discerning in telling which eggs are their own.

Lees meer: Scientific American

Behavior of Seabirds During Migration Revealed

The behaviour of seabirds during migration -- including patterns of foraging, rest and flight -- has been revealed in new detail using novel computational analyses and tracking technologies.

Using a new method called 'ethoinformatics', described as the application of computational methods in the investigation of animal behaviour, scientists have been able to analyse three years of migration data gathered from miniature tracking devices attached to the small seabird the Manx Shearwater (Puffinus puffinus).

Lees meer: ScienceDaily

Bird Navigation: Great Balls of Iron

Every year millions of birds make heroic journeys guided by Earth's magnetic field. How they detect magnetic fields has puzzled scientists for decades. Today, the Keays lab at the Research Institute of Molecular Pathology in Vienna has added some important pieces to this puzzle.

Their work, published in Current Biology, reports the discovery of iron balls in sensory neurons. These cells, called hair cells, are found in the ear and are responsible for detecting sound and gravity. Remarkably, each cell has just one iron ball, and it is in the same place in every cell. "It's very exciting. We find these iron balls in every bird, whether it's a pigeon or an ostrich" adds Mattias Lauwers who discovered them "but not in humans." It is an astonishing finding, despite decades of research these conspicuous balls of iron had not been discovered.

Lees meer: ScienceDaily

Ecology Buys Time for Evolution: Climate Change Disrupts Songbird's Timing Without Impacting Population Size (Yet)

Songbird populations can handle far more disrupting climate change than expected. Density-dependent processes are buying them time for their battle. But without (slow) evolutionary rescue it will not save them in the end, says an international team of scientists led by the Netherlands Institute of Ecology (NIOO-KNAW) in Science this week.
Yes, spring started late this year in North-western Europe. But the general trend of the four last decades is still a rapidly advancing spring. The seasonal timing of trees and insects advance too, but songbirds like Parus major, or the great tit, lag behind. Yet without an accompanying decline in population numbers, it seems, as the international research team shows for the great tit population in the Dutch National Park the Hoge Veluwe.

Lees meer: ScienceDaily

Baby Birds Blackmail Parents for More Food

Baby birds appear to be pretty helpless creatures, cheeping incessantly and stretching their featherless necks out of the nest to get food plopped directly in their mouths. But when hunger strikes and the nest’s cupboards are empty, what’s a baby bird to do? Certain species, like the pied babbler, have figured out a way for young birds to blackmail their caretakers in order to get more food.

All the adults in a pied babbler community share the burden of breeding and feeding their collective offspring. For the first few months of their lives, baby pied babblers rely completely on these adults to keep their tummies full.

Lees meer: Discover

The effect of group size on vigilance in Ruddy Turnstones Arenaria interpres varies with foraging habitat

Fuller, R. A., Bearhop, S., Metcalfe, N. B., Piersma, T. (2013), The effect of group size on vigilance in Ruddy Turnstones Arenaria interpres varies with foraging habitat. Ibis, 155: 246–257. doi: 10.1111/ibi.12020

Abstract

Foraging birds can manage time spent vigilant for predators by forming groups of various sizes. However, group size alone will not always reliably determine the optimal level of vigilance. For example, variation in predation risk or food quality between patches may also be influential. In a field setting, we assessed how simultaneous variation in predation risk and intake rate affects the relationship between vigilance and group size in foraging Ruddy Turnstones Arenaria interpres. We compared vigilance, measured as the number of ‘head-ups’ per unit time, in habitat types that differed greatly in prey energy content and proximity to cover from which predators could launch surprise attacks. Habitats closer to predator cover provided foragers with much higher potential net energy intake rates than habitats further from cover. Foragers formed larger and denser flocks on habitats closer to cover. Individual vigilance of foragers in all habitats declined with increasing flock size and increased with flock density. However, vigilance by foragers on habitats closer to cover was always higher for a given flock size than vigilance by foragers on habitats further from cover, and habitat remained an important predictor of vigilance in models including a range of potential confounding variables. Our results suggest that foraging Ruddy Turnstones can simultaneously assess information on group size and the general likelihood of predator attack when determining their vigilance contribution.

Blue Tits Provide Insight Into Climate Change, Bird Study Shows

Researchers believe that the size of birds' nests created in response to changing weather patterns may be partly to blame for reproductive failures over the last two years.

An article in the April edition of The Biologist, the Society of Biology's magazine, explains that birds produce different sized nests depending on the weather. Written by Dr Charles Deeming, senior lecturer at the University of Lincoln and a Fellow of the Society of Biology, the article explains that nests are far more than just a way to hold eggs and chicks.

Lees meer: ScienceDaily

High-Speed Evolution: Cars Driving Change In Cliff Swallows

I imagine that adjusting to life around humans, with all our buildings and fast-moving transport mechanisms, is tough for a bird. It’s estimated that some 80 million birds are killed in motor vehicle collisions every year, and with an ever-growing population of people driving around and paving roads in more remote areas, things must be getting harder and harder for the animals we share our world with. But, the American Cliff Swallow (Petrochelidon pyrrhonota) isn’t one to let people ruin the neighborhood. More and more, their huge nesting populations can be found in man-made structures like bridges and overpasses, and have even become cultural fixtures in areas like California. Their new nesting sites allow them to survive even as their former habitat disappears, but it comes at a cost: by living near roadways, the birds are more at risk than ever of being on the wrong end of an oncoming vehicle.
Charles and Mary Brown have been studying the cliff swallows in Keith County, Nebraska for the past 30 years. The ultimate goal of their research is to understand why colony sizes vary, and together, the two have studied everything from parasites and diseases to social interactions between birds, with over a hundred publications between them. The American Ornithologists Union describes their three-decade long research on cliff swallows as “one of the most outstanding and most complete studies of any avian species .” Every year, the team monitors the birds and collects any dead ones they can find for further analysis. Slowly, they noticed something strange: even though nests under overpasses and on bridges should have put more swallows in harms’ way, over time, fewer and fewer swallows are winding up as roadkill.

Lees meer: Discover blogs: Science Sushi

Why bird fathers are left holding the baby

Scientists have cracked a 140 year-old mystery as to why it’s the father rather than the mother that takes care of the young in some bird species.

Darwin noted in 1871 that in most animals it is the females that spend the most time looking after the young, while males focus on competing with each other for females. Evolutionary biologists argued that this was due to female birds investing significant amounts of energy in producing eggs, making it in their interest to ensure their offspring’s survival by fully caring for them. However, in some species sex roles are reversed, and females produce the eggs but then leave it to their male mates to care for the offspring.

Lees meer: Birdwatch Magazine

Homing pigeons navigate by sound

Pigeons are known to use several methods to navigate, but perhaps the least known is sound – new research has found it to be more important than was thought.

Homing pigeons are well-known to be great navigators, returning to their home lofts using landmarks, orientation by the sun, the earth's magnetic field and also the spatial distribution of atmospheric odours . However, it seems that sound waves may play a hitherto unsuspected role in this mysterious ability.

Using an 'acoustic ray tracing program', scientists from Cornell University, New York (NY), USA, were able to trace sound waves generated by movements deep in the oceans and affected by different densities in the earth's crust, and found that they are key to pigeons' abilities to find their home loft.

Lees meer: Birdwatch Magazine

Environmental Change Impacts On Migratory Shorebirds Differ for Males and Females

Extensive shell fishing and sewerage discharge in river estuaries could have serious consequences for the rare Icelandic black-tailed godwits that feed there. But it is the males that are more likely to suffer, according to new research from the University of East Anglia.

Research published today in the journal Ecology and Evolution reveals very different winter feeding habits between the sexes.

Both males and females mainly consume bivalve molluscs, sea snails and marine worms, probing vigorously into soft estuary mud with their long beaks. But the study shows that females, which are larger and have longer bills, are able to peck further into the silt to secure larger, deeper buried prey in areas that the shorter-billed males cannot reach. This means that human impacts on estuaries may have different impacts on males and females, depending on which prey sizes are most affected.

Lees meer: ScienceDaily

Blue Tits rely on alien invaders

Familiar British birds are learning to use an invasive wasp species as an important food source.

A team of researchers has found that Blue and Great Tits and other native birds have learnt to peck away the tips of the galls formed by the invasive Oak Marble Gall Wasp Andricus kollari and eat the protein-rich larvae inside. These, in addition to the larvae of other native gall wasps, scale insects and various other invertebrate eggs larvae and pupae, help birds survive the crucial early spring period when other food is scarce. The researchers believe that the new food source could help counteract the effects of climate change, which is causing some birds to lay their eggs too early in the year. The chicks often hatch before their main food of oak leaf-eating moth caterpillars becomes available.

Lees meer: Birdwatch Magazine

Blackbirds in the Spotlight: City Birds That Experience Light at Night Are Ready to Breed Earlier Than Their Rural Cousins

Street lamps, traffic lights and lighting from homes are causing a rise in our night-time light levels. For some time now, scientists have suspected that artificial light in our towns and cities at night could affect plants, animals and us, humans, too. Studies, however, that have tested this influence directly are few. Scientists from the Max Planck Institute for Ornithology in Radolfzell, Germany, recently investigated how light conditions in urban areas at night affect European blackbirds (Turdus merula). They found that animals exposed to low night-time light intensities, comparable to those found in cities, develop their reproductive system earlier: their testosterone levels rise and their testes mature earlier in the year. They also begin to sing and to moult earlier. The ever-present light pollution in cities may therefore exert a major influence on the seasonal rhythm of urban animals.

Lees meer: ScienceDaily

Monogamous Birds Read Partner's Food Desires

New research shows that male Eurasian Jays in committed relationships are able to share food with their female partner according to her current desire.

The behaviour suggests the potential for 'state-attribution' in these birds -- the ability to recognise and understand the internal life and psychological states of others.

The research was carried out in Professor Nicola Clayton's Comparative Cognition lab at Cambridge University's Department of Psychology, and is published February 4 in the journal PNAS.

Researchers tested mated jays and separated males from females. The females were fed one particular larvae, either wax moth or mealworm -- a treat for the birds, like chocolates -- allowing the males to observe from an adjacent compartment through a transparent window.

Once the pairs were reintroduced and the option of both larvae was presented, the males would choose to feed their partner the other type of larvae, to which she hadn't previously had access -- a change in diet welcomed by the female.

Lees meer: ScienceDaily

Birds May Get Emotional Over Birdsong

Birds listening to birdsong may be experiencing an emotional response similar to humans listening to music, according to a study tracking neural activity in sparrows.
The research by neuroscientists at Emory University compared the effects of music on human brain activity with that of birdsong on bird brains and found indications that the birds were experiencing pleasure and distaste as a reaction to the sound.

“We found that the same neural reward system is activated in female birds in the breeding state that are listening to male birdsong, and in people listening to music that they like,” said Sarah Earp, who led the study at Emory University.

Lees meer: Wired Science