Swiss Ornithological Institute
Swiss Ornithological Institute
The Sempach Bird Observatory is a bird observatory and ornithological research centre, also known as the Swiss Ornithological Institute, which is based at the town of Sempach in the district of Sursee in the canton of Lucerne in Switzerland. It overlooks Lake Sempach. Founded in 1924, it is a non-profit organization and the largest private field research institute in Switzerland. It carries out a bird ringing program as well as other ornithological research, conservation biology and public education. Wikipedia.
News Article | April 18, 2017
IMAGE: Are barnacle geese capable of predicting climate change? They need to arrive at their breeding grounds just as the snow has melted. But the climate in the Arctic is changing... view more The breeding grounds of Arctic migratory birds such as the barnacle goose are changing rapidly due to accelerated warming in the polar regions. They won't be able to keep up with this climate change unless they can somehow anticipate it. A research team from the Netherlands Institute of Ecology (NIOO-KNAW) employed computer models to assess the future of the geese and their young. Results are being published online by the scientific journal Global Change Biology. It's the time of year when barnacle geese and many other migratory birds prepare to depart for their breeding grounds above the Arctic Circle. From their wintering grounds in the Netherlands, the geese fly all the way up to the Barentsz Sea in northern Russia, where they should arrive just as the snow has melted. But in the polar regions, the climate is warming much more rapidly than in more temperate areas like the Netherlands - a phenomenon known as 'Arctic amplification'. It's hard enough for humans to get to grips with the accelerated warming, let alone for barnacle geese, as an earlier NIOO-led study showed. After all, how can they tell from their wintering grounds if the snow has begun to melt thousands of kilometres away? So is it possible for the barnacle geese to advance their spring migration nonetheless, to predict climate change? Ecologist Thomas Lameris and his fellow researchers from NIOO, and also the Swiss Ornithological Institute among other institutions, have tried to find the answer. "This is the first study that tests if migratory birds are in any way able to adjust their timing to the accelerated warming in the polar regions. We used a model to show that the availability of enough edible grass to build up reserves for their journey is not a problem for the barnacle geese. It's the unpredictability of the climatic changes in their breeding grounds that spells trouble for them." If the geese continue to mistime their arrival, their reproductive success will be reduced. Lameris: "They miss their optimal breeding window and the peak in local food abundance, so fewer goslings will survive." Some compensation for this comes from the fact that as well as starting earlier, the breeding season is becoming longer. This gives the goslings more time to grow. But that's not enough. To establish the barnacle geese's potential for anticipating climate change, the researchers built a model that tracks individual geese as they fly to their breeding grounds in northern Russia and make stopovers along the route. "In the model, the geese have to make a choice each day: stay in their present location and continue to feed, or fly to the next stopover." The researchers tested the model for various gradations of climatic warming. The barnacle goose is an ideal 'model species' for studying the effects of climate changes, because researchers have been able to study this animal for decades. But it's not just about a single species. Lameris: "Our results are probably valid for many more species of Arctic-breeding migratory birds, and certainly for other geese such as the white-fronted and the brent goose." On the whole, geese are clever birds. Goslings learn the migration route from their parents, including the best places to stop over and build up fat reserves. "So if they do change the timing of their arrival, it would be easy to pass that on to the next generation", Lameris argues hopefully. "The main question is whether geese and other migratory birds can adapt as fast as the climate changes, to keep up." With more than 300 staff members and students, NIOO is one of the largest research institutes of the Royal Netherlands Academy of Arts and Sciences (KNAW). The institute specialises in water and land ecology. As of 2011, the institute is located in an innovative and sustainable research building in Wageningen, the Netherlands. NIOO has an impressive research history that stretches back 60 years and spans the entire country, and beyond.
News Article | April 19, 2017
Each spring, barnacle geese have to fly a long way to their breeding grounds. It's a couple of thousand kilometres to Arctic Russia, where they have to arrive just as the snow has melted. Are they able to predict the vastly changing climate there from their wintering grounds? Credit: Jasper Koster The breeding grounds of Arctic migratory birds such as the barnacle goose are changing rapidly due to accelerated warming in the polar regions. They won't be able to keep up with this climate change unless they can somehow anticipate it. A research team from the Netherlands Institute of Ecology (NIOO-KNAW) employed computer models to assess the future of the geese and their young. Results are being published online by the scientific journal Global Change Biology. It's the time of year when barnacle geese and many other migratory birds prepare to depart for their breeding grounds above the Arctic Circle. From their wintering grounds in the Netherlands, the geese fly all the way up to the Barentsz Sea in northern Russia, where they should arrive just as the snow has melted. But in the polar regions, the climate is warming much more rapidly than in more temperate areas like the Netherlands - a phenomenon known as 'Arctic amplification'. It's hard enough for humans to get to grips with the accelerated warming, let alone for barnacle geese, as an earlier NIOO-led study showed. After all, how can they tell from their wintering grounds if the snow has begun to melt thousands of kilometres away? So is it possible for the barnacle geese to advance their spring migration nonetheless, to predict climate change? Ecologist Thomas Lameris and his fellow researchers from NIOO, and also the Swiss Ornithological Institute among other institutions, have tried to find the answer. "This is the first study that tests if migratory birds are in any way able to adjust their timing to the accelerated warming in the polar regions. We used a model to show that the availability of enough edible grass to build up reserves for their journey is not a problem for the barnacle geese. It's the unpredictability of the climatic changes in their breeding grounds that spells trouble for them." If the geese continue to mistime their arrival, their reproductive success will be reduced. Lameris: "They miss their optimal breeding window and the peak in local food abundance, so fewer goslings will survive." Some compensation for this comes from the fact that as well as starting earlier, the breeding season is becoming longer. This gives the goslings more time to grow. But that's not enough. To establish the barnacle geese's potential for anticipating climate change, the researchers built a model that tracks individual geese as they fly to their breeding grounds in northern Russia and make stopovers along the route. "In the model, the geese have to make a choice each day: stay in their present location and continue to feed, or fly to the next stopover." The researchers tested the model for various gradations of climatic warming. The barnacle goose is an ideal 'model species' for studying the effects of climate changes, because researchers have been able to study this animal for decades. But it's not just about a single species. Lameris: "Our results are probably valid for many more species of Arctic-breeding migratory birds, and certainly for other geese such as the white-fronted and the brent goose." On the whole, geese are clever birds. Goslings learn the migration route from their parents, including the best places to stop over and build up fat reserves. "So if they do change the timing of their arrival, it would be easy to pass that on to the next generation", Lameris argues hopefully. "The main question is whether geese and other migratory birds can adapt as fast as the climate changes, to keep up." Explore further: Climate change has mixed effects on migratory geese More information: Thomas K. Lameris et al, Potential for an Arctic-breeding migratory bird to adjust spring migration phenology to Arctic amplification, Global Change Biology (2017). DOI: 10.1111/gcb.13684
Naef-Daenzer B.,Swiss Ornithological Institute |
Gruebler M.U.,Swiss Ornithological Institute
Animal Biotelemetry | Year: 2014
Background: Radio-tracking is increasingly used to assess key characteristics of population dynamics. Since in many species re-encounter rates are frequently below 1.0 and vary with time and/or life-history stages, known-fate approaches to analyses may not apply. Cormack-Jolly-Seber (CJS) models estimate apparent survival on the basis of individual encounter histories. These models allow for complex re-encounter models and constitute an ideal tool to estimate apparent survival where re-encounter rates vary. However, the implications of radio-tag characteristics and sample size on the precision of survival estimates and the potential to determine temporal variation in survival have rarely been investigated. Here we analyze radio-tracking data from juvenile barn swallows (Hirundo rustica) that were instrumented with four types of transmitters similar in mass but differing in radiated power (n=560, 132 broods). Results: For all transmitter types re-encounter probabilities varied between 0.2 and 0.75, depending on radiated power and bird age. Higher-power transmitters significantly improved the re-encounter rates and thus, the precision of survival estimates. Apparent survival varied with age, with a minimum around the break-up of families. Later on survival increased again and approached the rate of adults. Analyses of random sub-samples revealed that sample size strongly affected the variance in survival estimates, and thus the power in discerning temporal or between-group variation in survival. Small samples substantially underestimated the survival to independence. In small subsamples the standard errors of estimates were particularly large in later re-encounters. Consequently, model selection results of different survival models on the basis of small random sub-samples were highly inconsistent. Conclusions: Investigating population processes requires modeling of time- and cohort-dependent survival rates, often for short time periods. We show that CJS estimates of apparent survival from small samples revealed rough patterns in barn swallow survival with samples of c. 50 individuals. However, small samples underestimated the number of survivors reaching independence. Inference on underlying mechanistic models based on Akaike's Information Criterion (AIC) model selection was unreliable with sample sizes below 200 individuals. As samples are often limited for practical reasons, maximizing re-encounter rates by optimal choice of telemetry hardware and field logistics is a way to increase the precision of survival estimates. © 2014 Naef-Daenzer and Grüebler; licensee BioMed Central Ltd.
News Article | October 26, 2016
Perched among the branches and needles of California's redwood forests are nestled wayfaring hoary bats (Lasiurus cinereus). A migratory species capable of traveling hundreds of miles, hoary bats may wander throughout western North America before settling into California's north coast...to sleep. While it's not unusual for some species of bat to migrate or other species to hibernate, it is unusual to find a species of bat that does both. Hoary bats are one of North America's largest bats at 5 inches in length and also one of the continent's most distinguished with its frosted fur for which it takes its name. Researchers with the U.S. Forest Service's Pacific Southwest Research Station have documented the first recorded evidence of hoary bats going into a state of torpor, or hibernation. Published earlier this month in Scientific Reports and just in time for National Bat Week, Oct. 24-31, "First Direct Evidence of Long-distance Seasonal Movements and Hibernation in a Migratory Bat" reports newly discovered behaviors in hoary bats. "It's commonly assumed that species that migrate do so to reach areas that allow them to continue feeding and remain somewhat active throughout the winter," said lead author Ted Weller, an ecologist with the Forest Service. "But our findings surprised even our own research team by showing that hoary bats spend much of the winter in hibernation." In September 2014, Weller and his colleagues tagged several bats within Humboldt Redwoods State Park with GPS tracking devices and another group of bats with a device that monitored light levels, body temperatures and activity, which allowed them to understand how bats responded to varying weather conditions. "While such tracking and monitoring technology has existed for a while, it hasn't been until somewhat recently that these units were made small enough to be affixed to animals of this size," Weller said. A month later, two of the GPS-equipped bats were recaptured and their data downloaded. One of the bats met the expected behavior of "site fidelity," with its longest single-day trek being about 4 miles from the initial capture site. The second bat was surprising in that it had produced multiple single-day treks ranging from 30 to 45 miles. However, it was the third bat recaptured several months later that produced the most intriguing behavior. For the month of October, Bat VHF5 flew more than 600 miles, making a loop into southern Oregon, then into interior California, then over to the Nevada-California border, and then back again into interior California. "It's hard to determine what led to such a journey," Weller said. "Was he seeking favorable temperatures and humidity for roosting and foraging? Was he trying to intercept females to mate with as they migrated to their wintering grounds?" The monitoring devices attached to the other group of bats also offered new insights into the species. Two bats from that group were recaptured in spring, with one of the bat's devices having captured 224 days of data. Based on lowered body temperatures and inactivity, that bat exhibited the signs of being in a torpor state from November 2014 through April 2015, including a 40-day stretch without flying. Which again leads researchers to the question: Why would a species capable of migrating hibernate? The answer could lie within the bats' roosting habitat. "Hoary bats roost outside in trees as opposed to inside caves," Weller said. "It's possible that hoary bats are evolved to hibernate, but would freeze if they did so in their northern summer territories." The Redwoods, in particular, are ideal in that they offer an environment with lots of shelter, cool temperatures and plenty of moisture to reduce the risk of dehydration. Similar to other migratory species, understanding seasonal movements and wintering habits are essential for conservation efforts. And because most bat research is confined to summer when bats are most active, these findings are especially useful. "This research has provided us with a valuable look into the lives of hoary bats rarely before seen, and until now, never before documented to this extent," Weller said. "Knowing more about their lives outside of the summer months will help us better understand what steps might best promote their conservation." Research partners included Wildlife Veterinary Consulting out of Livermore, Colorado, the Swiss Ornithological Institute out of Sempach, Switzerland, Bat Conservation International out of Austin, Texas, the U.S. Geological Survey Science Center out of Fort Collins, Colorado. USDA is an equal opportunity provider, employer and lender.
News Article | October 27, 2016
We long suspected that they sleep and mate on the wing. Now, for the first time, there’s evidence that common swifts probably have to do both, because they spend an astonishing 10 months per year without landing – a world record for sustained flight in nature. Their nearest rival is the alpine swift, which flies non-stop for up to six months a year. In Europe, common swifts land for two months to breed, spending the nights roosting in their nests. Then they’re off to Africa – where no one has ever found roosting sites belonging to them – before returning again in Europe 10 months later to breed. “It had been hypothesised in the 1950s and 1960s that they spend such prolonged periods in flight,” says Anders Hedenström of the University of Lund in Sweden. Now, he and his colleagues have shown that they do, by fitting seven swifts with lightweight data loggers and monitoring their movements and location for two years. “Three of them never reached the ground for 10 months,” says Hedenström. “The others did land briefly, for a few nights, but never for more than half a per cent of the total time of their migratory periods.” “It’s a great confirmation of what has been long expected for common swifts,” says Felix Liechti of the Swiss Ornithological Institute in Sempach, Switzerland, who found that alpine swifts can stay aloft for six months at a time. “They fly for even longer than alpine swifts, but this is mainly due to the shorter breeding period of common swifts.” Swifts can live for up to 20 years, and Hedenström calculates that the distance they fly over their lifetime amounts to travelling to the moon and back up to seven times. Hedenström retrieved the data loggers when the birds returned to Europe. Accelerometers revealed flight trajectories and times when they were grounded. Light sensors enabled the researchers to work out the birds’ geographical location using day lengths and times of sunrise and sunset. Hedenström says it’s almost inevitable the birds must sleep on the wing, as long suspected. “Assuming that like other animals, swifts need sleep, logically they must do it in the air,” he says. One possibility is that like dolphins and frigate birds swifts can “sleep” by switching off one half of their brain, or sometimes both, for short periods, perhaps as they cruise up and down thermals. “It may be they can find a thermal and go round and round,” he says. Hedenström’s team also found that the swifts do two massive ascents each day, one at dawn and the other at dusk, spiralling up to altitudes of 2 or 3 kilometres. “My guess is that this is when they sleep,” says Hedenström. “They may take power naps by gliding on the way back down. I’d love to test it, but you’d have to somehow measure brain activity with implants.” But not everyone is convinced about the sleep theory. “Gliding downwards, even smoothly at a metre a second, will result in 300 metres of height loss per 5 minutes, so there wouldn’t be time for a lot of sleep,” says Felix. Jerry Siegel of the University of California, Los Angeles, is not sure all animals do have to sleep regularly. “We recently found that dolphins and killer whales go about four months without sleep after birth, with their mothers not having any sleep behaviour,” he says. There was no evidence of sleepiness afterwards, he says. “All this work indicates that sleep differs greatly across species, without it being obligatory under all circumstances.” So is the common swift’s airborne record ever going to be broken? Hedenström doubts whether any other species could challenge it. Although some birds like albatrosses and Arctic terns migrate over huge distances, they often touch down on land or water to feed and rest. But among common swifts, it could be that the juveniles are the true record holders, Hedenström says. “Juveniles don’t breed for the first year, so it could be that they stay up for two years.” But finding out could be tricky, he says, because once they have flown the nest they never return, so recovering the data from a tagged bird would be practically impossible.
Bauer S.,Swiss Ornithological Institute |
Bauer S.,Netherlands Institute of Ecology |
Hoye B.J.,University of Colorado at Boulder |
Hoye B.J.,Deakin University
Science | Year: 2014
Animal migrations span the globe, involving immense numbers of individuals from a wide range of taxa. Migrants transport nutrients, energy, and other organisms as they forage and are preyed upon throughout their journeys. These highly predictable, pulsed movements across large spatial scales render migration a potentially powerful yet underappreciated dimension of biodiversity that is intimately embedded within resident communities. We review examples from across the animal kingdom to distill fundamental processes by which migratory animals influence communities and ecosystems, demonstrating that they can uniquely alter energy flow, food-web topology and stability, trophic cascades, and the structure of metacommunities. Given the potential for migration to alter ecological networks worldwide, we suggest an integrative framework through which community dynamics and ecosystem functioning may explicitly consider animal migrations.
News Article | December 21, 2016
Birds and human vacationers aren't the only creatures that take to the skies each year to migrate north or south. An analysis of a decade's worth of data from radars specifically designed to track airborne insects has revealed unseen hordes crossing parts of the southern United Kingdom—2 trillion to 5 trillion insects each year, amounting to several thousand tons of biomass, that may travel up to hundreds of kilometers a day. The numbers, reported in this week's issue of , are "stunning," says Silke Bauer, an ecologist at the Swiss Ornithological Institute in Sempach. "Wow," adds Larry Stevens, an evolutionary ecologist at the Museum of Northern Arizona in Flagstaff. "Can you image what these numbers look like in tropical settings, say, over the basins of the Amazon or the Congo?" Although some insect migrations are well known (think monarchs), the new work takes a systematic approach to flying insects and hints that such mass movements are surprisingly common. These airborne invertebrates, their bodies packed full of nitrogen and phosphorus, could move significant amounts of key nutrients across the globe. "Insects are little creatures, but collectively they can have a big impact; comparable in magnitude to large ocean migrations [of plankton]," says Lael Parrott, an environmental geographer at the University of British Columbia in Kelowna, Canada. In the 1970s, U.K. entomologists began to use mobile radars to assess movements of locusts and other pests in developing countries. By the late 1990s, they had designed a permanent upward-facing radar system, based at Rothamsted Research in Harpenden, U.K., that automatically logs insects of different sizes. In one early discovery, Jason Chapman, now at the University of Exeter in the United Kingdom, and colleagues found that certain large butterflies and moths that dwell in northern Europe in the summer and in the Mediterranean in the winter take advantage of favorable winds to migrate Now, Gao Hu, from Nanjing Agricultural University in China, Chapman, and colleagues have surveyed data from 2000 to 2009 collected in Harpenden and two other U.K. radar sites. The radars recorded medium-sized insects (hoverflies, ladybird beetles, and water boatmen) and large ones (hawk moths, painted lady butterflies, and aquatic beetles) flying between 150 meters and 1200 meters high; balloon sampling flights helped provide estimated counts for smaller insects. Among the medium and large insects, the radar documented 1320 mass migrations in the daytime and 898 at night over the course of the decade. These streams of insects, heading south in the fall and north in the spring, usually coincided with favorable winds, which swept them along at up to 58 kilometers an hour. That insects "have an idea of where they want to go to, when they want to go, and what winds are good [is] surprising for these tiny creatures," Bauer says. It will take more data, from other sites, to convince some entomologists that many insects migrate seasonally like birds and mammals. A European initiative is tracking birds using weather radars, and its scientists hope to get the funding to monitor insects as well. Such studies could be critical, notes zoologist Eric Warrant of Lund University in Sweden. "If, due to human influence, a large fraction of the [insect] migrant population is wiped out, it might have catastrophic consequences for those particular ecosystems."
Schmaljohann H.,Institute of Avian Research |
Naef-Daenzer B.,Swiss Ornithological Institute
Journal of Animal Ecology | Year: 2011
1.An innate migration strategy guides birds through space and time. Environmental variation further modulates individual behaviour within a genetically determined frame. In particular, ecological barriers could influence departure direction and its timing. A shift in the migratory direction in response to an ecological barrier could reveal how birds adjust their individual trajectories to environmental cues and body condition. 2.Northern wheatears of the Greenland/Iceland subspecies Oenanthe oenanthe leucorhoa arrive in Western Europe en route from their West African winter range. They then undergo an endogenously controlled shift in migratory direction from north to north-west to cross a large ecological barrier, the North Atlantic. We radiotracked these songbirds departing from Helgoland, a small island in the North Sea, over an unprecedented range of their journey. 3.Here, we show that both birds' body condition and the wind conditions that they encountered influenced the departure direction significantly. Jointly high fuel loads and favourable wind conditions enabled migrants to cross large stretches of sea. Birds in good condition departed early in the night heading to the sea towards their breeding areas, while birds with low fuel loads and/or flying in poor weather conditions departed in directions leading towards nearby mainland areas during the entire night. These areas could be reached even after setting off late at night. 4.Behavioural adjustment of migratory patterns is a critical adaptation for crossing ecological barriers. The observed variation in departure direction and time in relation to fuel load and wind revealed that these birds have an innate ability to respond by jointly incorporating internal information (body condition) and external information (wind support). © 2011 The Authors. Journal of Animal Ecology © 2011 British Ecological Society.
Kery M.,Swiss Ornithological Institute |
Royle J.A.,U.S. Geological Survey
Journal of Animal Ecology | Year: 2010
1. Population assessment in changing environments is challenging because factors governing abundance may also affect detectability and thus bias observed counts. We describe a hierarchical modelling framework for estimating abundance corrected for detectability in metapopulation designs, where observations of 'individuals' (e.g. territories) are replicated in space and time. We consider two classes of models; first, we regard the data as independent binomial counts and model abundance and detectability based on a product-binomial likelihood. Secondly, we use the more complex detection-non-detection data for each territory to form encounter history frequencies, and analyse the resulting multinomial/Poisson hierarchical model. Importantly, we extend both models to directly estimate population trends over multiple years. Our models correct for any time trends in detectability when assessing population trends in abundance. 2. We illustrate both models for a farmland and a woodland bird species, skylark Alauda arvensis and willow tit Parus montanus, by applying them to Swiss BBS data, where 268 1 km 2 quadrats were surveyed two to three times during 1999-2003. We fit binomial and multinomial mixture models where log (abundance) depended on year, elevation, forest cover and transect route length, and logit(detection) on year, season and search effort. 3. Parameter estimates were very similar between models with confidence intervals overlapping for most parameters. Trend estimates were similar for skylark (-0.074 ± 0.041 vs. -0.047 ± 0.019) and willow tit (0.044 ± 0.046 vs. 0.047 ± 0.018). As expected, the multinomial model gave more precise estimates, but also yielded lower abundance estimates for the skylark. This may be due to effects of territory misclassification (lumping error), which do not affect the binomial model. 4. Both models appear useful for estimating abundance and population trends free from distortions by detectability in metapopulation designs with temporally replicated observations. The ability to obtain estimates of abundance and population trends that are unbiased with respect to any time trends in detectability ought to be a strong motivation for the collection of replicate observation data. ©2009 The Authors. Journal compilation ©2009 British Ecological Society.
Schaub M.,Swiss Ornithological Institute
Biological Conservation | Year: 2012
Energy production with wind turbines is increasing, because this form of energy production is CO 2 neutral and renewable, and because wind power is subsidised in many countries. However, wind turbines are not without impact on biodiversity, rather, they can affect bird and bat populations through collision-induced mortality. It is relatively well studied how wind turbine architecture or the surrounding habitat affect the collision risk of birds and bats. It is much less well understood how losses due to collisions affect bird and bat populations. Moreover, it is currently unknown how the spatial configuration of wind turbines in the landscape affects populations. I addressed these two questions using an individual-based simulation model inspired by the Swiss red kite Milvus milvus population. This species is a frequent collision victim at turbines and one of Europe's sole endemic species. I predicted the fate of populations in relation to the number and spatial configuration of wind turbines. I found that population growth rates declined progressively with an increasing number of wind turbines. These negative effects can be weakened if wind turbines are aggregated in power plants. Quantitatively the results strongly depended on the parametric form of the relationship between collision risk and the distance between wind turbines and kite nest location. Unfortunately, empirical knowledge about this relationship is scarce. As the effect of wind turbines depends on their total number and their spatial configuration within the area inhabited by a raptor population, I emphasise the importance of making environmental impact assessments not on a case-by-case basis but rather for an entire region with all its wind power plants, which collectively exert an impact on a raptor population. This must include the impact of extant as well as planned wind turbines in the same region in order to be biologically meaningful. © 2012 Elsevier Ltd.