News Article | November 2, 2015
1543 different species of moths and beetles and more than 250.000 individuals have been registered on a single urban rooftop in Copenhagen over 18 years of monitoring. That corresponds to 42 % of all the species of moths in Denmark and 12 % of the beetles. More interestingly, the insect community has changed significantly during that period. The results are published today in the Journal of Animal Ecology led by researchers from the Center for Geogenetics and the Center for Macroecology, Evolution and Climate at the Natural History Museum of Denmark at the University of Copenhagen. "As temperature increases we see a corresponding change in the insect community, specifically for the resource specialists - the insects that feed on only one species of plant. Earlier studies have confirmed that specialist species also respond rapidly to destruction of their habitats, so we are dealing with a very sensitive group of animals" says one of the lead authors postdoc Philip Francis Thomsen from the Center for Geogenetics. The nut weevil (Curculio nucum) is an example of a resource specialist, feeding only on hazel. It lives further north in Europe than its close relative the acorn weevil (Curculio glandium), which feeds only on acorns. While the nut weevil was only registered in the first half of the study, the acorn weevil only appeared in the last part of the study, suggesting that specialist species are moving northwards in Europe. Using the entire dataset, the study was able to confirm this trend and highlights the increased pressure on the most northern species, which may be 'squeezed out' of their range in the long term. "We are likely to lose some specialist species as they retreat north, but more new specialist species will arrive from the south. This trend is theoretically expected but extremely rare to confirm with observations across this many species. Insects are often over-looked and under prioritised for long term studies" says the other lead author Peter Søgaard Jørgensen, PhD from the Center for Macroecology, Evolution and Climate. It was two employees from the Natural History Museum of Denmark with extensive entomological expertise, Ole Karsholt and Jan Pedersen, who collected and identified all the insects. The monitoring took place every week from 1992 to 2009 through spring, summer and autumn using a light trap at the roof of the museum at 17.5 meters height. What started out as a hobby based on scientific curiosity, ended up in an extensive faunal and climate change study. "Long-term monitoring, even without a pre-defined purpose, can be of incredible value when trying to understand and predict biodiversity in a changing world. Species monitoring is under prioritised in Denmark and primarily driven by personal interest from committed enthusiasts. Without those individuals we would basically be in the dark about the majority of species in Denmark. The same is probably true for many other European countries. We hope this study can push nature monitoring back onto the political agenda" says Philip Francis Thomsen. Seven species of moths and two species of beetles were registered for the first time in Denmark by Karsholt and Pedersen, including the multicolored Asian lady beetle (Harmonia axyridis), which has since spread to most of the country and is now considered invasive. Also species living in habitats at least 10 km away were registered as well as some migrating moths from countries south of Denmark. "Some insects are very mobile and only eat as larvae. It is therefore not unusual to find them further from their habitats as adults. However, it is an impressive diversity of species registered. Even though the study is limited to one site, there is no reason to believe that the trend we see here would be different at other sites" says Peter Søgaard Jørgensen. For each group of species, the scientists calculated an index for the temperature related change across their entire habitat range in Europe for the study period. The specialist moth species experienced an increase of 0.14 °C between 1993 and 2008 and the specialist beetle species 0.42 °C between 1995 and 2008. "The results confirm that climate change is impacting biodiversity right now. It is not something that will happen far into the future or only if we reach a two degree temperature increase" says Peter Søgaard Jørgensen. Explore further: Arctic beetles may be ideal marker of climate change
News Article | October 31, 2016
Significant changes in the distribution of plants on Earth can be a reality by 2050. The prediction is made by scientists from Center for Macroecology, Evolution and Climate at the University of Copenhagen, based on fossilized pollen. The pollen stems from plants that existed during previous periods with climate changes - similar to those expected in this century. We still cannot physically travel in time, but ancient fossils can - like a time machine - give us knowledge about the past and the future. In a study published today in Nature, scientists use fossilized pollen to examine the future of biodiversity on Earth under climate change. The scientists predict profound changes in the distribution of plants globally. Lead-author of the study, Associate Professor David Nogués-Bravo from Center for Macroecology, Evolution and Climate at the Natural History Museum of Copenhagen, says, - Surprisingly, our results forecast major shifts in abundance and composition of plants in forests, grasslands and other plants communities. These transformations will occur already by the middle of this century. It means that our own grandchildren will encounter largely different landscapes compared to those we know today. They will see new species in forests, on prairies and scrublands, while other species, that are common in those areas today, will be gone. The prediction is based on records of fossilized pollen from plants that lived between 20,000 years ago to present. During this time, ice sheets melted and global temperatures rose by 4 to 5 degrees, similar to the temperature rises expected for this century. Professor Jack Williams from the University of Wisconsin-Madison, co-author of the study, elaborates, - The fossil record gives us a natural model system for studying species responses to climate change. We can see that ecosystems were transformed by past climate changes, for ecosystems both on land and in waters - and across many regions. Thus, we can expect similarly profound changes throughout the Earth. The records of pollen used in the study comprised 100 European plant taxa from 546 sites, and 87 North American plant taxa from 527 sites. The study shows that one third of North American plants and more than half of European plants may face increased threat status in the future due to climate change. Central North America and southern Europe are the most exposed regions. - The findings of our study based on paleorecords highlight the vital importance of biological archives. Archives like those at Natural History Museums, Botanical Gardens and digital internet databases. They provide conservation assessments directly relevant and useful for conservation policies of today and for the future, concludes Professor Carsten Rahbek, senior-author on the article.
News Article | December 14, 2016
Bird's wings generally become shorter and more rounded the closer they live to the equator. Birds with smaller wings are to a greater extent restricted to stay in the same area, because their wings have not evolved for long distance travel. This new knowledge, published by scientists from the Center for Macroecology, Evolution and Climate, University of Copenhagen, helps us to better understand how life on Earth has developed. "If only I had wings like a bird I could go anywhere in the world". This wish is shared among children throughout the Earth. But is it really so? Scientists have discovered that the closer a bird lives to equator the shorter and more rounder its wings are. Short round wings have not evolved in order to aid travel over long distances, meaning these birds stay within a relatively restricted area throughout their life. First author and Post Doc Jonathan Kennedy from Center for Macroecology, Evolution and Climate, University of Copenhagen, explains; - Although it might seem obvious that all birds are capable fliers because they have wings, our results challenge this assumption. Actually, birds that are found in different parts of the world have very different wing types. In many cases, birds will not fly longs-distances, unless their wings have specifically evolved for it. Our results provide new knowledge about how species spread across the world and improve our understanding of how life on earth has evolved. Birds in the tropical rain forests of South America, Africa and New Guinea generally have smaller and more rounded wings compared to birds in temperate regions, like Europe or North America, whose wings tend to be longer and more pointed. The reason is that the wing shape reflects the bird's life style, Jonathan Kennedy elaborates; - Some birds have long projected wings specially evolved to travel long distances. For example nomadic birds like the Dusky Woodswallow are able to fly numerous miles in order to find food. Other birds, like the sedentary Dark Batis, do not need to make long journeys in search of food, because it lives in tropical areas in which food is available year round. Instead, these birds have short and round wings developed to maneuver quickly between trees and bushes in the dense rainforest in which they occur. The scientists behind the study have created the first global map to show the distribution of bird's across Earth as a result of their wing shape. The map is based on measurements of 782 different kind of birds found across the globe. With the map, the scientists have been able to show that different wings types have had a big impact upon where bird species are found in the world, Jonathan Kennedy comments; - Now we have finally shown what scientists have long suspected. A bird's wing plays a major role in determining where on Earth it is found. This knowledge gives us a solid foundation to better understand how bird species have spread across the Earth in search of food and places to live.
News Article | February 3, 2016
A complex network analysis of hummingbirds and the nectar plants they feed on was used to determine the level of resource specialization in 46 hummingbird communities distributed widely from the Northern USA to Southern Brazil. The study is published today in the journal Proceedings of the Royal Society B by a team of more than 30 scientists. "Using hummingbirds as an example, we have demonstrated a distinct pattern for ecological specialization across a large geographical space. No matter where we look across the Americas it holds true that high food specialization in a community is linked to a high proportion of smaller-ranged species. The explanation for this is thought to be that a stable climate over a long period of time is able to foster both. Patterns like these help us explain and understand biodiversity on a large scale" says lead author and MSc student Jesper Sonne from the Center for Macroecology, Evolution and Climate at the University of Copenhagen. "With this study, we demonstrate that environmental factors such as the climate not only associate with species ranges, but also with local specializations, such as those between hummingbirds and nectar plants. It gives us an insight into how evolutionary and ecological processes jointly structure biological communities in a broad sense." For the hummingbird communities that were investigated, the smallest species ranges were around 40,000 km2 which compares to an area smaller than the size of Denmark, while the largest ranges were about 1,000 times greater. Hummingbirds with even smaller ranges exist but were not included in the study because no information is available on their interactions with plant communities. The study included 130 hummingbird species, representing ca. 40 % of all hummingbird species. The Volcano Hummingbird (Selasphorus flammula), White-bellied Mountain-gem (Lampornis hemileucus) and Fiery-throated Hummingbird (Panterpe insignis) are all examples of species that were classified as smaller-ranged in the study. All three live only in Costa Rica and western Panama and they were found to be locally specialized to feed on particular nectar plants. The results also indicate that aggregations of smaller-ranged species are more vulnerable to environmental change than previously thought. "Species with smaller geographical ranges are naturally more sensitive to environmental change, and if the same community of species is also highly specialized to forage on few food resources, it will be less capable of adapting to a changing environment" says co-author and Assistant Professor Bo Dalsgaard from the Center for Macroecology, Evolution and Climate. Hummingbirds and their nectar plants have long served as model system for examining ecological and evolutionary processes because of their strong mutual dependencies. They are also known to thrive in an array of environments throughout the Americas from Alaska to Tierra del Fuego. Hummingbirds can weigh as little as 2 grams and have extremely diverse bills, adapted to fit their nectar plants. Explore further: High-speed video and artificial flowers shed light on mysteries of hummingbird-pollinated flowers More information: High proportion of smaller-ranged hummingbird species coincides with ecological specialization across the Americas , Proceedings of the Royal Society B: Biological Sciences, rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2015.2512
News Article | December 14, 2016
Tropical bird wings look different than those from other regions, say scientists. Birds with longer and pointier wings dominate temperate areas, like Europe and North America (red). Birds with smaller and rounder wings dominate in tropical areas, like southern Africa and South America (Blue). The left bird, Dark batis (Batis crypta), has smaller round wings. The bird on the right, Dusky Woodswallow (Artamus cyanopterus), has long pointy wings evolved for long-distance flying. Painting by Jon Fjeldså. Some birds have short wings, and some have long wings. Some birds have pointed wings, and some have rounded wings. And those distinctions may have to do with where they live. A new study finds that birds that live closer to the equator have shorter, rounder wings than those that live farther away. This is a pattern that scientists have always suspected to be the case, but there had not been a comprehensive assessment of the evidence – until now. A team of researchers studied thousands of specimens in natural history museum collections, representing 782 species of corvoid birds, in an effort to suss out patterns of diversity across the globe. Their results were published Wednesday in the journal Proceedings of the Royal Society B. "The pattern has generally been thought to be quite likely by scientists for some time. But this was really the first actual empirical evaluation of it across a large group of birds," study lead author Jonathan Kennedy, a researcher at the Center for Macroecology, Evolution and Climate at the Natural History Museum of Denmark, University of Copenhagen, tells The Christian Science Monitor in a phone interview. "This research corroborates previous studies that documented a link between a bird's morphology, including wing shape, and where the bird occurs in the landscape," Robb Brumfield, the director of Louisiana State University's Museum of Natural Science, who was not part of the new research, agrees in an email to the Monitor. These findings are unsurprising, Dr. Kennedy says, because of the different advantages that different wing shapes and sizes give a bird. For example, the scientists expected to find that birds from northern, temperate regions have pointier, longer wingtips because they make it easier for the birds to soar long distances. Birds living in those chillier regions usually go on long annual migrations to winter in warmer regions closer to the equator. On the flip side, birds with shorter, rounder wings would be able to dart through dense tropical vegetation more easily. And, because they find all the food and other resources they need in the regions near the equator, they wouldn't need wings well-adapted for long journeys. This makes sense evolutionarily, too, Dr. Brumfield says. "For example, bird species found on oceanic islands will often have wing morphologies that are better for long-distance flight, reflecting their ability to have colonized the island in the first place. In contrast, bird species that spend their entire lives in the dark understory of a continental tropical forest will typically have wing morphologies that are better for short-distance flight." One of the reasons the researchers studied corvoid birds is that they are a superfamily within the Passeriform order. Passerine birds, also known as songbirds, make up about two-thirds of all bird species globally, Kennedy explains, and Corvoidea make up about a sixth of that order. But most importantly, he says, "they're present on almost all of the world's continental landmasses. That's everywhere except Antarctica." As such, Kennedy says, "I would expect that this pattern is very consistent across passerine birds." So by studying Corvoidea – crows, ravens, jays, and their relatives – the researchers were able to tap into broader patterns. Although this pattern fits with ecologists' and ornithologists' expectations, articulating the pattern could help scientists better understand broader evolutionary patterns. When Kennedy and his colleagues started to measure bird wings, they were looking to see if there was a correlation between diversification and dispersal ability. The idea was that perhaps an animal's ability to disperse across more landscapes and establish populations in new habitats would drive a diversity of species, as the animals would be adapting to new niches. So the team used wing shape as a proxy for dispersal ability. But they found, at best, a weak correlation between present-day wing morphology and diversification rates. "They suggest that there was an influence of past wing morphology," Melissa Bowlin, an ecologist and evolutionary biologist studying migratory birds at the University of Michigan-Dearborn who was not part of the research, says in a phone interview with the Monitor. "But unfortunately we don't know what the wing morphology was like in the past." So, Dr. Bowlin says, it remains an open question whether dispersal ability affects diversification. She adds that by not finding a significant relationship between the two, the research "confirms some things that we suspected about wing shape and how quickly that can evolve." She explains that because wing shape has likely evolved since the organisms diversified, that's why the researchers don't find a correlation between present-day wing shape and the diversity of corvoid species alive today. "The reason why scientists care about questions like this is that we currently have major problems with invasive species all over the world. These species are coming in and destroying native species or replacing native species, and it's a serious conservation issue," Bowlin says. "One of the things that we don't understand is what characteristics of a species make it a good invasive species. We think that dispersal ability probably affects that, but we don't know. So that's one of the things that these authors were trying to figure out. Does dispersal ability essentially make for a good invasive species?" And although that question remains open, Kennedy says his research does show that "wing morphology and its evolution is an extremely complex process. It's only by studying across a group of birds, like this, that we can expect to understand the general principles." And, he adds, "Because all birds have wings, there is this assumption that they are all particularly capable fliers." But it's just not the case that flight capability is that uniform.
News Article | March 4, 2016
A pair of elongated, whiplike legs that are actually sophisticated environment sensors distinguish an unusual arachnid known as the whip spider, also called the tailless whip scorpion. Scientists recently described eight new species of this long-legged spider that are native to Brazil, nearly doubling the number of known species in the genus Charinus. Whip spiders use only six of their eight legs for walking, reserving their "whips" — which can reach several times the spiders' body length — for exploring the world around them and locating prey, through a combination of touch and chemical signals. Thanks to the new species discoveries, Brazil now boasts the greatest diversity of whip spiders in the world. But the forest ecosystems where these new species live are threatened by human development, and the researchers suggested that stronger conservation measures are urgently required in order to protect the whip spiders' habitats, and to discover more species before their habitats are destroyed. [Ghoulish Photos: Creepy, Freaky Creatures That Are (Mostly) Harmless] There are 170 known species of whip spiders found all over the world, mostly in tropical areas in the Americas. According to the researchers, the Amazon region — known for its diverse habitats, plants and animals — was long suspected of hiding many more whip spider species than were previously known. Though some whip spiders measure up to 10 inches (25 centimeters) at the fullest extension of their "whips," most are less than 2 inches (5 cm) and are hard to spot, hiding in leaf litter, under stones and tree bark, and in caves. To identify the new species, the researchers turned their attention to specimens from the collections in four Brazilian natural history museum collections: the Butantan Institute, the National Museum of Brazil, the Museu Paraense Emi?lio Goeldi, and the Museum of Zoology of the University of São Paulo. What does it take to describe a new whip spider species? Days, weeks and ultimately months of scrutinizing the spiders' body parts under a microscope and comparing them with other known species in order to find unique and differentiating characteristics, said study co-author Gustavo Silva de Miranda. De Miranda, a graduate student at the Center for Macroecology, Evolution and Climate at the University of Copenhagen, told Live Science that he and his colleagues performed exhaustive inventory of the spiders' features, including the number of segments in the whiplike limbs, the prey-catching spines at the tips of their legs, the groupings of their eyes, and the shape of the females' genitalia, called gonopods. "If we compare all these things and see that it's very unique, then we consider it a new species," de Miranda said. Genital structures turned out to be quite an important point of comparison, de Miranda explained. In each whip spider species, the female's gonopod shape corresponded very specifically to the shape of the male's sperm sac, for perfect alignment. But even as new whip spider species are described, their behavior and habits in the wild remain elusive, de Miranda said. One study, he said, detailed confrontations between males competing for females or territory — the spiders extend and display their head appendages, squaring off without actually fighting, and the loser (the one with the smaller display) retreats after a 20-minute stare-down. "But there is still a lot to be discovered," de Miranda said. "We're trying to understand the evolution of the group, their relationships, how they are so widespread, their morphological evolution." He said this makes it imperative not only to find new species, but to preserve the fragile ecosystems where these spiders live. "If they are not protected, they will vanish from nature," de Miranda said. The findings were published online today (Feb. 17) in the journal PLOS ONE. Follow Mindy Weisberger on Twitterand Google+. Follow us @livescience, Facebook & Google+. Original article on Live Science. Copyright 2016 LiveScience, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
News Article | December 14, 2016
The left bird, Dark batis (Batis crypta) has smaller round wings. The bird on the right, Dusky Woodswallow (Artamus cyanopterus), has long pointy wings evolved for long-distance flying. Credit: Jon Fjeldså Bird's wings generally become shorter and more rounded the closer they live to the equator. Birds with smaller wings are to a greater extent restricted to stay in the same area, because their wings have not evolved for long distance travel. This new knowledge, published by scientists from the Center for Macroecology, Evolution and Climate, University of Copenhagen, helps us to better understand how life on Earth has developed. "If only I had wings like a bird I could go anywhere in the world". This wish is shared among children throughout the Earth. But is it really so? Scientists have discovered that the closer a bird lives to equator the shorter and more rounder its wings are. Short round wings have not evolved in order to aid travel over long distances, meaning these birds stay within a relatively restricted area throughout their life. First author and Post Doc Jonathan Kennedy from Center for Macroecology, Evolution and Climate, University of Copenhagen, explains: "Although it might seem obvious that all birds are capable fliers because they have wings, our results challenge this assumption. Actually, birds that are found in different parts of the world have very different wing types. In many cases, birds will not fly longs-distances, unless their wings have specifically evolved for it. Our results provide new knowledge about how species spread across the world and improve our understanding of how life on earth has evolved." Birds in the tropical rain forests of South America, Africa and New Guinea generally have smaller and more rounded wings compared to birds in temperate regions, like Europe or North America, whose wings tend to be longer and more pointed. The reason is that the wing shape reflects the bird's life style, Jonathan Kennedy elaborates" "Some birds have long projected wings specially evolved to travel long distances. For example nomadic birds like the Dusky Woodswallow are able to fly numerous miles in order to find food. Other birds, like the sedentary Dark Batis, do not need to make long journeys in search of food, because it lives in tropical areas in which food is available year round. Instead, these birds have short and round wings developed to maneuver quickly between trees and bushes in the dense rainforest in which they occur." The scientists behind the study have created the first global map to show the distribution of bird's across Earth as a result of their wing shape. The map is based on measurements of 782 different kind of birds found across the globe. With the map, the scientists have been able to show that different wings types have had a big impact upon where bird species are found in the world, Jonathan Kennedy comments: "Now we have finally shown what scientists have long suspected. A bird's wing plays a major role in determining where on Earth it is found. This knowledge gives us a solid foundation to better understand how bird species have spread across the Earth in search of food and places to live." Explore further: Shape of bird wings depends on ancestors more than flight style More information: The influence of wing morphology upon the dispersal, geographic distributions and diversification of the Corvides (Aves; Passeriformes), Proceedings of the Royal Society B, rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2016.1922
News Article | October 26, 2016
Adding warmth predicted in climate-change models destabilized forest ant communities east of the Appalachian Mountains, a possible harbinger of disruption to the broader ecosystem, researchers, led by a Case Western Reserve University biologist, have found. The five-year study in the Harvard Forest of Northeast Massachusetts and Duke Forest in the Piedmont Region of North Carolina suggests the loss of stability makes communities less resilient and slower to rebound when disturbed. The research is published today (Wed. Oct. 26) in the journal Science Advances. "We've had a unique opportunity to look under the hood of how these ant communities function,and how experimental warming affects their overall stability under climate change," said Sarah Diamond, an assistant professor of biology at Case Western Reserve and leader of the study. "We've looked at not only at the direct effects of warming but at indirect effects mediated by altered species interactions," Diamond said. "There's good evidence the altered species interactions are affecting the stability of communities, making them more fragile and susceptible to environmental change." By their numbers, ants comprise more than half the macroinvertibrates in North American forests. Harvard and Duke forests are home to 60 species. The study focused on floor dwellers, which are important to the forest ecosystem as scavengers and seed dispersers. The insects aerate the soil and are regular prey to other animals. The species studied compete for food and nest sites and typically forage within a yard of their nest. The scientists erected in each forest 15 chambers--pens 5.5 yards across, encircled with plastic sheets and left open wide at the top and open enough at the bottom to allow crawling insects to migrate in and out. The researchers installed four nest boxes with Plexiglas tops at the beginning of the experiment and four more halfway through. At nine chambers at each site, heaters incrementally raised the temperature from 1.5 degrees Celsius to 5.5 degrees Celsius above ambient temperature during the study. The researchers took censuses and collected other data monthly--except when snow covered the ground--and built a statistical model called a Markov model. In the unheated chambers, colonies of different ant species were frequently coming and going. Stability for the community as a whole was characterized by near-constant overturning of nesting sites with no vacancy between occupants. "In the heated chambers, thermophilic queens and colonies were moving in and parking," Diamond said. "Other species couldn't take advantage of the nesting spaces, which had the overall effect of making the community less stable and slower to return to equilibrium--in the long run, this may make them susceptible to climate change." Although the forests are separated by about 6.5 degrees in latitude and a mean average temperature difference of 5.8 degrees Celsius, warming destabilized the ant communities in both, the statistical model showed. While loss of community stability translates to longer return times to equilibrium after disturbances, the long-term biological consequences remain an area for future exploration. Within the timescale of the experiment, relative abundance of thermophilic species grew while heat-intolerant species declined in the warmed chambers. At the warmest, southernmost site in Duke Forest, the composition of ant communities already appears to be changing. The researchers are investigating fine-scale interactions among species and correlating them with thermal tolerance. They are also extending the Markov model forward to try to answer whether communities return to equilibrium over a long period of time or never under climate change. Diamond worked with Lauren Nichols, Clint Penick and Robert Dunn of North Carolina State University's Department of Applied Ecology; Shannon Pelini of Bowling Green State University's Department of Biological Sciences; Grace Barber of University of Massachusetts' Department of Environmental Conservation; Aaron Ellison of Harvard University's Harvard Forest; Sara Helms Cahan and Nicholas Gotelli of University of Vermont's Department of Biology; and Nathan Sanders, University of Copenhagen's Center for Macroecology, Evolution and Climate. More information, including a copy of the paper, can be found online at the Science Advances press package at http://www.
News Article | November 20, 2015
Satellite technology has made it possible for the first time to track the complete migration of a relocated species and reveal individual responses. Credit: Mikkel Willemoes The cuckoo is not only capable of finding its way from unknown locations; it does this through a highly complex individual decision making process. Such skills have never before been documented in migratory birds. A new study shows that navigation in migratory birds is even more complex than previously assumed. The Center for Macroecology, Evolution and Climate at the University of Copenhagen led the study with the use of miniature satellite tracking technology. In an experiment, 11 adult cuckoos were relocated from Denmark to Spain just before their winter migration to Africa was about to begin. When the birds were released more than 1,000 km away from their well-known migration route, they navigated towards the different stopover areas used along their normal route. "The release site was completely unknown to the cuckoos, yet they had no trouble finding their way back to their normal migratory route. Interestingly though, they aimed for different targets on the route, which we do not consider random. This individual and flexible choice in navigation indicates an ability to assess advantages and disadvantages of different routes, probably based on their health, age, experience or even personality traits. They evaluate their own condition and adjust their reaction to it, displaying a complicated behavior which we were able to document for the first time in migratory birds", says postdoc Mikkel Willemoes from the Center for Macroecology, Evolution and Climate at the University of Copenhagen. Previously, in 2014, the Center also led a study mapping the complete cuckoo migration route from Denmark to Africa. Here they discovered that during autumn the birds make stopovers in different areas across Europe and Africa. It was these areas the displaced cuckoos aimed for: Of the 11 birds, one flew to Poland, one to the Balkans, one to Chad and three of them flew to the Democratic Republic of Congo. From there, they followed their familiar migration route. The last five birds lost their transmitting signal. "In order to select an individual strategy, the birds should be capable of balancing perceived gains and risks of several different scenarios. Such a task would require knowledge of the current location in relation to all of the possible goals as well as distances to each of the goals. This tells us that bird migration in general is far more complex than previously assumed", says Mikkel Willemoes. The study was carried out in collaboration with Doñana Biological Station in Spain and the Max Planck Institute for Ornithology in Germany. Bird relocation studies have been carried out in the past, but recent satellite technology has made it possible for the first time to track the complete migration of a relocated species and reveal individual responses. "We have received remarkable details on the movement of adult birds. The next step is to develop smaller transmitters that will enable us to follow young cuckoos on a relocation flight. Without prior migration experience, their choices will reveal new insight on how they navigate from unknown locations" says Associate Professor Kasper Thorup from the Center for Macroecology, Evolution and Climate. Cuckoos are particularly suitable for navigation studies, as they lay their eggs inside the nests of other bird species. Growing up without contact to siblings or biological parents, the young cuckoo has no one to follow during migration. Flying alone and at night, it relies entirely on instincts, inherent abilities and the experiences gained later in life. Now, scientists can conclude that these traits are combined into a complex individual decision making strategy. The study is published in Scientific Reports. More information: Mikkel Willemoes et al. Flexible navigation response in common cuckoos Cuculus canorus displaced experimentally during migration, Scientific Reports (2015). DOI: 10.1038/srep16402
Roura-Pascual N.,University Of Gironagirona |
Sanders N.J.,Center for Macroecology |
Hui C.,Stellenbosch UniversityMatieland 7602 South Africa
Global Ecology and Biogeography | Year: 2016
Aim: To examine the relationship between island characteristics (area, distance to the nearest continent, climate and human population size) and ant species richness, as well as the factors underlying global geographical clustering of native and exotic ant composition on islands. Location: One hundred and two islands from 20 island groups around the world. Methods: We used spatial linear models that consider the spatial structure of islands to examine patterns of ant species richness. We also performed modularity analyses to identify clusters of islands hosting a similar suite of species and constructed conditional inference trees to assess the characteristics of islands that explain the formation of these island-ant groups. Results: Island area was the best predictor of ant species richness. However, distance to the nearest continent was an important predictor of native ant species richness, as was human population size for exotic species richness. Native species appear slightly more modulated (i.e. well grouped in species assemblages that are present over a distinct cluster of islands) than are exotic species. Exotic species, while still exhibiting some modularity, tended to be widely distributed among island groups. Interestingly, ocean currents accounted for most of the variation in modularity and thus species composition for both native and exotic ant species. Main conclusions: Contrary to previous work, both native and exotic species appeared to be confined to particular island regions, and patterns in the distribution of both native and exotic species were limited by a similar suite of factors. However, the distribution of exotic ant species appeared to be more influenced by human-related variables and less structured relative to those of native ant species, perhaps due to the long-term (and increasing) influence of human-mediated dispersal that favours exotic species. © 2016 John Wiley & Sons Ltd.