Cecilia Nilsson

• PhD
• Researcher at Lund University

Light cues elicit strong responses from nearly all forms of life, perhaps most notably as circadian rhythms entrained by periods of daylight and darkness. Atypical periods of darkness, like solar eclipses, provide rare opportunities to study biological responses to light cues. By using a continental scale radar network, we investigated responses of...

Nocturnal avian migration flyways remain an elusive concept, as we have largely lacked methods to map their full extent. We used the network of European weather radars to investigate nocturnal bird movements at the scale of the European flyway. We mapped the main migration directions and showed the intensity of movement across part of Europe by ext...

Weather surveillance radars are increasingly used for monitoring the movements and abundances of animals in the airspace. But analysis of weather radar data remains a specialised task that can be technically challenging. Major hurdles are the difficulty of accessing and visualising radar data on a software platform familiar to ecologists and biolog...

Advances in information technology are increasing the use of radar as a tool to investigate and monitor bird migration movements. We set up a field campaign to compare and validate outputs from different radar systems. Here we compare the pattern of nocturnal bird migration movements recorded by four different radar systems at a site in southern Sw...

Abstract It has been suggested that birds migrate faster in spring than in autumn because of competition for arrival order at breeding grounds and environmental factors such as increased daylight. Investigating spring and autumn migration performances is important for understanding ecological and evolutionary constraints in the timing and speed of...

Weather radars detect more than weather, they also continuously register the movements of billions of animals aloft in the lower atmosphere. This makes archived, unfiltered weather radar data a goldmine for biological monitoring purposes, providing coverage of the aerial habitat in a way no other method can. Here we present two datasets of biologic...

With the continued development of tracking technology and increasing interest in animal movement, our understanding of migration behavior has become more comprehensive. However, there are still many species that have not been well studied, particularly sea birds. Here, we present the first year-round Global Positioning System (GPS) tracking data of...

Weather radar networks have great potential for continuous and long-term monitoring of aerial biodiversity of birds, bats, and insects. Biological data from weather radars can support ecological research, inform conservation policy development and implementation, and increase the public’s interest in natural phenomena such as migration. Weather rad...

Aircraft collisions with birds span the entire history of human aviation, including fatal collisions during some of the first powered human flights. Much effort has been expended to reduce such collisions, but increased knowledge about bird movements and species occurrence could dramatically improve decision support and proactive measures to reduce...

Applications of remote sensing data to monitor bird migration usher a new understanding of magnitude and extent of movements across entire flyways. Millions of birds move through the western USA, yet this region is understudied as a migratory corridor. Characterizing movements in the Pacific Flyway offers a unique opportunity to study complementary...

Large networks of weather radars are comprehensive instruments for studying bird migration. For example, the US WSR‐88D network covers the entire continental US and has archived data since the 1990s. The data can quantify both broad and fine‐scale bird movements to address a range of migration ecology questions. However, the problem of automaticall...

Many species of migratory birds have evolved the ability to migrate at night, and the recent and rapid expansion of artificial light at night has markedly altered the nighttime sky through which they travel. Migrating birds regularly pass through heavily illuminated landscapes, and bright lights affect avian orientation. But risks to migrating bird...

Among the many unique flight behaviours of Common Swifts Apus apus, the most puzzling may be their ascents to high altitudes during both dusk and dawn. Twilight ascents have been hypothesized to be functionally related to information acquisition, including integration of celestial orientation cues, high‐altitude visual landmarks and sampling of wea...

Current climate models and observations indicate that atmospheric circulation is being affected by global climate change. To assess how these changes may affect nocturnally migrating bird populations, we need to determine how current patterns of wind assistance at migration altitudes will be enhanced or reduced under future atmospheric conditions....

Many migratory species have experienced substantial declines that resulted from rapid and massive expansions of human structures and activities, habitat alterations and climate change. Migrants are also recognized as an integral component of biodiversity and provide a multitude of services and disservices that are relevant to human agriculture, eco...

Chapman, J., Shamoun-Baranes, J., Dokter, A., Leijnse, H., Liechti, F., Koistinen, J., Nilsson, C., van Gasteren, H., Alves, J., Sapir, N., Hüppop, O., Reynolds, D. & Bauer, S. (2018) The European Network for the Radar surveillance of Animal Movement (ENRAM). Presentation EGU2018-12875 at European Geosciences Union General Assembly 2018, Vienna, A...

That birds migrate in the reverse direction of the expected is a phenomenon of regular occurrence which has been observed at many sites. Here we use three different methods; tracking radar, radiotelemetry and ringing, to characterize the flights of these reverse migrants and investigate possible causes of reverse migration of nocturnally migrating...

Goal-oriented migrants travelling through the sea or air must cope with the effect of cross-flows during their journeys if they are to reach their destination [1-3]. In order to counteract flow-induced drift from their preferred course, migrants must detect the mean flow direction, and integrate this information with output from their internal comp...

1. Animals that use flight as their mode of transportation must cope with the fact that their migration and orientation performance is strongly affected by the flow of the medium they are moving in, i.e. by the winds. Different strategies can be used to mitigate the negative effects and benefit from the positive effects of a moving flow. The strate...

In order to fully understand the orientation behaviour of migrating birds, it is important to understand when birds set their travel direction. Departure directions of migratory passerines leaving stopover sites are often assumed to reflect the birds' intended travel directions, but this assumption has not been critically tested. We used data from...

The nocturnal migration of many passerines starts after sunset and reaches peak intensity during the dark hours of the night. Birds destined for high arctic breeding grounds encounter a special situation, as they will experience continuous daylight when reaching the high latitudes during the final part of spring migration. How does this affect the...

By recording nocturnally migrating passerines with tracking radar we have investigated how coastlines affect the migrants’ flight paths. Birds could use coastlines as an orientation aid or as a reference cue to compensate for wind drift while migrating. However, on the small scale of Falsterbo Peninsula in southern Sweden, we found very little effe...

In order to compare the two species’ flight performance over the exposed and windy Falsterbo Peninsula, where thermal conditions seldom are very favorable, we used tracking radar to study flight parameters of sparrowhawks Accipiter ni-sus and common buzzards Buteo buteo during autumn migration. The results showed a clear difference between sparrowh...

Migrating birds are expected to fly at higher airspeeds when minimizing time rather than energy costs of their migratory journeys. Spring migration has often been suggested to be more time selected than autumn migration, because of the advantage of early arrival at breeding sites. We have earlier demonstrated that nocturnal passerine migrants fly a...

It has been suggested that time selection and precedence in arrival order are more important during spring than autumn migration. Migrating birds are expected to fly at faster airspeeds if they minimize duration rather than energy costs of migration, and they are furthermore expected to complete their journeys by final sprint flights if it is parti...

Nocturnal passerine migrants could substantially reduce the amount of energy spent per distance covered if they fly with tailwind assistance and thus achieve ground speeds that exceed their airspeeds (the birds’ speed in relation to the surrounding air). We analysed tracking radar data from two study sites in southern and northern Scandinavia and s...

Vast numbers of insects and passerines achieve long-distance migrations between summer and winter locations by undertaking high-altitude nocturnal flights. Insects such as noctuid moths fly relatively slowly in relation to the surrounding air, with airspeeds approximately one-third of that of passerines. Thus, it has been widely assumed that windbo...

Using tracking radars, we investigated the variability of flight directions of long-distance nocturnal passerine migrants across seasons (spring versus autumn migration) and sites at the southern (56° N) and northern (68° N) ends of the Scandinavian Peninsula (Lund versus Abisko). Whilst most migrants at Lund are on passage to and from breeding sit...