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 | 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.
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.
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.
Schaub M.,Swiss Ornithological Institute |
Jakober H.,Friedrichstrasse 8 1 |
Stauber W.,Bismarckstrasse 6
Ecology | Year: 2013
A mechanistic understanding of the dynamics of populations requires knowledge about the variation of the underlying demographic rates and about the reasons for their variability. In geographically open populations, immigration is often necessary to prevent declines, but little is known about whether immigration can contribute to its regulation. We studied the dynamics of a Red-backed Shrike population (Lanius collurio) over 36 years in Germany with a Bayesian integrated population model. We estimated mean and temporal variability of population sizes, productivity, apparent survival, and immigration. We assessed how strongly the demographic rates were correlated with population growth to understand the demographic reasons of population change and how strongly the demographic rates were correlated with population size to identify possible density-dependent mechanisms. The shrike population varied between 35 and 74 breeding pairs but did not show a significant trend in population size over time (growth rate 1.002 6 0.001 [mean 6 SD]). Apparent survival of females ( juveniles 0.06 6 0.01; adults 0.37 6 0.03) was lower than that of males ( juveniles 0.10 6 0.01; adults 0.44 6 0.02). Immigration rates were substantial and higher in females (0.56 6 0.02) than in males (0.43 6 0.02), and average productivity was 2.76 6 0.14. Without immigration, the Red-backed Shrike population would have declined strongly. Immigration was the strongest driver for the number of females while local recruitment was the most important driver for the number of males. Immigration of both sexes and productivity, but not local recruitment and survival, were subject to density dependence. Density-dependent productivity was not effectively regulating the local population but may have contributed to regulate shrike populations at larger spatial scales. These findings suggest that immigration is not only an important component to prevent a geographically open population from decline, but that it can also contribute to its regulation. © 2013 by the Ecological Society of America.
Kery M.,Swiss Ornithological Institute |
Gardner B.,U.S. Geological Survey |
Monnerat C.,Center Suisse Of Cartographie Of La Faune Cscf
Journal of Biogeography | Year: 2010
Aim: (1) To increase awareness of the challenges induced by imperfect detection, which is a fundamental issue in species distribution modelling; (2) to emphasize the value of replicate observations for species distribution modelling; and (3) to show how 'cheap' checklist data in faunal/floral databases may be used for the rigorous modelling of distributions by site-occupancy models. Location: Switzerland. Methods: We used checklist data collected by volunteers during 1999 and 2000 to analyse the distribution of the blue hawker, Aeshna cyanea (Odonata, Aeshnidae), a common dragonfly in Switzerland. We used data from repeated visits to 1-ha pixels to derive 'detection histories' and apply site-occupancy models to estimate the 'true' species distribution, i.e. corrected for imperfect detection. We modelled blue hawker distribution as a function of elevation and year and its detection probability of elevation, year and season. Results: The best model contained cubic polynomial elevation effects for distribution and quadratic effects of elevation and season for detectability. We compared the site-occupancy model with a conventional distribution model based on a generalized linear model, which assumes perfect detectability (p = 1). The conventional distribution map looked very different from the distribution map obtained using site-occupancy models that accounted for the imperfect detection. The conventional model underestimated the species distribution by 60%, and the slope parameters of the occurrence-elevation relationship were also underestimated when assuming p = 1. Elevation was not only an important predictor of blue hawker occurrence, but also of the detection probability, with a bell-shaped relationship. Furthermore, detectability increased over the season. The average detection probability was estimated at only 0.19 per survey. Main conclusions: Conventional species distribution models do not model species distributions per se but rather the apparent distribution, i.e. an unknown proportion of species distributions. That unknown proportion is equivalent to detectability. Imperfect detection in conventional species distribution models yields underestimates of the extent of distributions and covariate effects that are biased towards zero. In addition, patterns in detectability will erroneously be ascribed to species distributions. In contrast, site-occupancy models applied to replicated detection/non-detection data offer a powerful framework for making inferences about species distributions corrected for imperfect detection. The use of 'cheap' checklist data greatly enhances the scope of applications of this useful class of models. © 2010 Blackwell Publishing Ltd.
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.
Almasi B.,Swiss Ornithological Institute |
Roulin A.,University of Lausanne |
Jenni L.,Swiss Ornithological Institute
Hormones and Behavior | Year: 2013
Trade-offs between the benefits of current reproduction and the costs to future reproduction and survival are widely recognized. However, such trade-offs might only be detected when resources become limited to the point where investment in one activity jeopardizes investment in others. The resolution of the trade-off between reproduction and self-maintenance is mediated by hormones such as glucocorticoids which direct behaviour and physiology towards self-maintenance under stressful situations. We investigated this trade-off in male and female barn owls in relation to the degree of heritable melanin-based coloration, a trait that reflects the ability to cope with various sources of stress in nestlings. We increased circulating corticosterone in breeding adults by implanting a corticosterone-releasing-pellet, using birds implanted with a placebo-pellet as controls. In males, elevated corticosterone reduced the activity (i.e. reduced home-range size and distance covered within the home-range) independently of coloration, while we could not detect any effect on hunting efficiency. The effect of experimentally elevated corticosterone on female behaviour was correlated with their melanin-based coloration. Corticosterone (cort-) induced an increase in brooding behaviour in small-spotted females, while this hormone had no detectable effect in large-spotted females. Cort-females with small eumelanic spots showed the normal body-mass loss during the early nestling period, while large spotted cort-females did not lose body mass. This indicates that corticosterone induced a shift towards self-maintenance in males independently on their plumage, whereas in females this shift was observed only in large-spotted females. © 2013 Elsevier Inc.
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.