Abundance of migratory and wintering geese in relation to vegetation succession in man-made wetlands: The effects of grazing regimes

The man-made wetlands in young polders in The Netherlands are important stopover and wintering sites for geese. We studied trends in vegetation composition and goose density in two study areas. One was located in a nature reserve situated in a polder reclaimed from an estuary, the other in a reserve in a polder reclaimed from a freshwater lake. In the former we compared an area of spontaneous vegetation succession with a summer-grazed area. In the latter the effect of reed Phragmites australis cover and height on field selection of geese was studied in an area grazed year-round by cattle and horses. In both study areas the area of short grassland (reed cover about 1%, reed heigh

The annual cycle of Montagu's Harrier Circus pygargus: Driven by voles and grasshoppers

Year-round research on European Montagu's Harriers should help to clarify what governs their numbers and distribution in breeding and wintering areas, in order to provide a firm basis for the conservation of this vulnerable species. During the breeding season, the Dutch Montagu's Harrier Foundation investigates distribution, numbers and breeding success, diet, prey abundance and habitat use. Set-aside land and field margins (agrienvironmental schemes) contain high numbers of voles, one of the most important prey species, and are used intensively by hunting harriers. The number of breeding pairs seems to be enhanced by increasing the area and quality of set-aside land through agri-environment schemes. Migratory movements of Montagu's Harriers are tracked using satellite telemetry. Harriers from NW Europe follow a western route via Gibraltar or a more central route via Italy towards wintering areas in the Sahel of West Africa. In spring, the harriers returned via the same routes and thus did not engage in loop migration. Research in the wintering quarters focuses on the spatial distribution of wintering harriers, food choice, prey abundance and habitat use. Non-migratory grasshoppers are an important prey in winter, at least in years when migratory grasshopper species do not swarm. Montagu's Harriers move southward during the winter which is hypothesized to be related to a seasonal south-ward shift in productivity and food availability. Satellite telemetry and colour-marking are also used to determine the connectivity between different breeding populations. Before and during their autumn migration, harriers seem to visit other breeding populations, which might be related to prospecting behaviour

The annual cycle of Montagu's Harrier <i>Circus pygargus</i>:Driven by voles and grasshoppers

Year-round research on European Montagu's Harriers should help to clarify what governs their numbers and distribution in breeding and wintering areas, in order to provide a firm basis for the conservation of this vulnerable species. During the breeding season, the Dutch Montagu's Harrier Foundation investigates distribution, numbers and breeding success, diet, prey abundance and habitat use. Set-aside land and field margins (agrienvironmental schemes) contain high numbers of voles, one of the most important prey species, and are used intensively by hunting harriers. The number of breeding pairs seems to be enhanced by increasing the area and quality of set-aside land through agri-environment schemes. Migratory movements of Montagu's Harriers are tracked using satellite telemetry. Harriers from NW Europe follow a western route via Gibraltar or a more central route via Italy towards wintering areas in the Sahel of West Africa. In spring, the harriers returned via the same routes and thus did not engage in loop migration. Research in the wintering quarters focuses on the spatial distribution of wintering harriers, food choice, prey abundance and habitat use. Non-migratory grasshoppers are an important prey in winter, at least in years when migratory grasshopper species do not swarm. Montagu's Harriers move southward during the winter which is hypothesized to be related to a seasonal south-ward shift in productivity and food availability. Satellite telemetry and colour-marking are also used to determine the connectivity between different breeding populations. Before and during their autumn migration, harriers seem to visit other breeding populations, which might be related to prospecting behaviour.</p

Satellite tracking of two Montagu’s Harriers (Circus pygargus): dual pathways during autumn migration

Autumn migration routes of two Dutch female Montagu’s Harriers (Circus pygargus) were documented for the first time using satellite telemetry. Both migrated to their African wintering area—one via the Straits of Gibraltar through the Mediterranean and the other via Italy/Tunisia. The rate of travel was comparable to values reported for larger raptor species.

Migratory connectivity and population-specific migration routes in a long-distance migratory bird

Knowledge about migratory connectivity, the degree to which individuals from the same breeding site migrate to the same wintering site, is essential to understand processes affecting populations of migrants throughout the annual cycle. Here, we study the migration system of a long-distance migratory bird, the Montagu’s harrier Circus pygargus, by tracking individuals from different breeding populations throughout northern Europe. We identified three main migration routes towards wintering areas in sub-Saharan Africa. Wintering areas and migration routes of different breeding populations overlapped, a pattern best described by ‘weak (diffuse) connectivity’. Migratory performance, i.e. timing, duration, distance and speed of migration, was surprisingly similar for the three routes despite differences in habitat characteristics. This study provides, to our knowledge, a first comprehensive overview of the migration system of a Palaearctic-African long-distance migrant. We emphasize the importance of spatial scale (e.g. distances between breeding populations) in defining patterns of connectivity and suggest that knowledge about fundamental aspects determining distribution patterns, such as the among-individual variation in mean migration directions, is required to ultimately understand migratory connectivity. Furthermore, we stress that for conservation purposes it is pivotal to consider wintering areas as well as migration routes and in particular stopover sites

Data from Trierweiler et al. (2014) Proc R Soc Lond B-reference-data

Knowledge about migratory connectivity, the degree to which individuals from the same breeding site migrate to the same wintering site, is essential to understand processes affecting populations of migrants throughout the annual cycle. Here, we study the migration system of a long-distance migratory bird, the Montagu's harrier Circus pygargus, by tracking individuals from different breeding populations throughout northern Europe. We identified three main migration routes towards wintering areas in sub-Saharan Africa. Wintering areas and migration routes of different breeding populations overlapped, a pattern best described by ‘weak (diffuse) connectivity’. Migratory performance, i.e. timing, duration, distance and speed of migration, was surprisingly similar for the three routes despite differences in habitat characteristics. This study provides, to our knowledge, a first comprehensive overview of the migration system of a Palaearctic-African long-distance migrant. We emphasize the importance of spatial scale (e.g. distances between breeding populations) in defining patterns of connectivity and suggest that knowledge about fundamental aspects determining distribution patterns, such as the among-individual variation in mean migration directions, is required to ultimately understand migratory connectivity. Furthermore, we stress that for conservation purposes it is pivotal to consider wintering areas as well as migration routes and in particular stopover sites