Janne Ouwehand

University of Groningen | RUG · Centre for Ecological and Evolutionary Studies (CEES)

Conditions experienced by an individual during migration have the potential to shape migratory tactic and in turn fitness. For large birds, environmental conditions encountered during migration have been linked with survival and subsequent reproductive output, but this is less known for smaller birds, hindering our understanding of mechanisms drivi...

Climate change alters ecological interactions, and, because observed phenotypic responses are often insufficient 1,2 , evolutionary responses are required ³ . However, these have rarely been reported, and species seem to either adapt through plasticity ⁴ or suffer population declines ⁵ . Earlier work suggested that especially long-distance migrants...

Seasonality affects the availability of resources within the African non-breeding environment of migratory songbirds. We are generally unaware of how songbirds respond to such seasonal dynamics, especially at small spatial scales that are relevant for individual birds. In this study we focus on the question of how migratory songbirds use small scal...

By travelling vast distances, migratory birds take advantage of earth's seasonality. Afro-Palearctic migrants can profit from lush spring conditions in temperate regions for chick rearing, but must also gain sufficient energy reserves to cross the Sahara. Rainfall during the dry season in Africa may influence the food available to birds to accumula...

Climate change has been driving long-distance migratory birds to alter their schedules under the threat of being mismatched with their food peak at the breeding grounds. It is important to study the relative contribution of environmental, genetic and ontogenetic components in various spring timing traits in the wild in order to predict the true pot...

Currently, the deployment of tracking devices is one of the most frequently used approaches to study movement ecology of birds. Recent miniaturization of light‐level geolocators enabled studying small bird species whose migratory patterns were widely unknown. However, geolocators may reduce vital rates in tagged birds and may bias obtained movement...

Light‐level geolocator tags use ambient light recordings to estimate the whereabouts of an individual over the time it carried the device. Over the past decade, these tags have emerged as an important tool and have been used extensively for tracking animal migrations, most commonly small birds. Analysing geolocator data can be daunting to new and e...

Environments change rapidly, and it is unclear whether organisms with complex life‐styles, such as avian migrants, are able to adjust sufficiently. For understanding human impacts on ecosystem functioning, it is crucial to understand how well, and by which mechanisms species are able to adapt. To improve the understanding of migrants’ ability to ad...

Avian breeding populations have been shown to be regulated by territorial behaviour, often creating a surplus of non-breeding individuals. However, most evidence is of a male non-breeder surplus, whereas for a surplus to actually buffer a population both non-breeding males and females should be present. Here, we provide descriptive and experimental...

1.Properly timed spring migration enhances reproduction and survival. Climate change requires organisms to respond to changes such as advanced spring phenology. Pied flycatchers Ficedula hypoleuca have become a model species to study such phenological adaptations of long-distance migratory songbirds to climate change, but data on individuals’ time...

Each year more than two billion songbirds cross the Sahara, but how they perform this formidable task is largely unknown. Using geolocation tracks from 27 pied flycatchers, a nocturnally migrating passerine, we show that most birds made diurnal flights in both autumn and spring. These diurnal flights were estimated to be part of non-stop flights of...

Timing of arrival in long-distance migration could have fitness consequences: too early arrival impairs survival chances, whereas too late arrival reduces current reproductive success. Evolution thus may have favoured a phenotype that arrived at the optimal time. However, individuals within populations of long-distance migrant species arrive over a...

Understanding what drives or prevents long-distance migrants to respond to environmental change requires basic knowledge about the wintering and breeding grounds, and the timing of movements between them. Both strong and weak migratory connectivity have been reported for Palearctic passerines wintering in Africa, but this remains unknown for most s...

On August 26, 2006, we (Sander Bot and Janne Ouwehand) observed a Sooty Tern in Tanji bird reserve, Western Division, The Gambia. This sighting represents the first confirmed record of Sooty Tern for The Gambia.

Eén van de kenmerkende soorten van het Nederlandse laagveengebied is de Meervleermuis (Myotis dasycneme). In Nederland zijn verschillende gebieden aangewezen als Natura 2000-gebied voor de Meervleermuis, waarvan er vijf in Fryslân liggen. Maar zijn de aangewezen gebieden wel de juiste? Waar verblijven de Meervleermuizen overdag? Via welke routes ko...

A population of pond bats (Myotis dasycneme) inhabits a network of foraging areas and separate male, female-breeding and temporary colonies. These are interconnected by commuting routes which are also used for foraging. The functioning of these networks is crucially important for the conservation of the species. Observations and anecdotal evidence...

Bizarre prey: unusual food picked up by Herring Gulls and Lesser Black-backed Gulls In this note, the unusual or even bizarre prey is described as found in the course of an ecological study of Herring Gulls and Lesser Black-backed Gulls nesting at Texel. The diet of these omnivorous species is at least potentially spectacularly varied, but most in...

Report on breeding biology and chick developments in Lesser Black-backed Gulls and Herring Gulls breeding on Texel, results of field work in 2006-2008 including tracking data using GPS and radio telemtry and colour-ringing results

Environmental protection organisations involved in farmland-bird conservation promote the use of organic fertilisers, especially farmyard manure, to enhance the availability of earthworms, which are an important prey for farmland-birds. We studied changes in earthworm numbers in a field experiment on a semi-natural grassland with three different ty...

A comparative study of the diet of Guillemots Uria aalge and Razorbills Alca torda killed during the Tricolor oil incident in the south-eastern North Sea in January 2003. Atlantic Seabirds 6(3): 147-164. In Jan-Feb 2003, some 4000 oiled seabirds washed ashore in The Netherlands following the Tricolor oil spill in the English Channel. Hundreds of co...