Northern Harrier (Circus cyaneus) Science Article 3 abstract The use of habitats by hunting Hen Harriers Circus cyaneus just prior to the settlement period was investigated on Orkney, where numbers have declined by 70% over the last 20 years. Both males and females hunted over areas that were closer to subsequent breeding territories. Neither sex […]

Northern Harrier (Circus cyaneus) Science Article 1 abstract Hen Harrier chicks were wing-tagged in four regions in Scotland and in North Wales between 1990 and 1995, and resighted or recovered dead as fully grown birds during the non-breeding season (August to April) throughout Britain and Ireland, and on the Continent, until April 1997. Results were […]

Northern Harrier (Circus cyaneus) Science Article 2 abstract Egg and liver samples of Montagu’s and Marsh Harriers from the 1990’s were examined for their burden of DDT and PCB. The DDT burden in both species was distinctly higher in the eggs than in juveniles and adults, whereby the values for the adults were clearly higher […]

Northern Goshawk (Accipiter gentilis) Science Article 2 abstract Delayed density-dependent mortality induced by delayed numerical response of predators can drive prey populations to fluctuate in high-amplitude cycles. We studied numerical response of goshawks Accipiter gentilis to varying densities of their main prey (forest grouse) in western Finland during 1979_/1996. Occupancy rate of goshawk territories tracked […]

Northern Goshawk (Accipiter gentilis) Science Article 3 abstract Age-dependent breeding performance is arguably one of the best-documented phenomena in ornithology.The existence of age-related trends has major implications for life-history theory, but the proximatereasons for these patterns remain poorly understood. It has been proposed that poor breeding performanceof young individuals might reflect lack of foraging skills.We […]

Northern Goshawk (Accipiter gentilis) Science Article 6 abstract Northern goshawks (Accipiter gentilis; hereafter, goshawks) occurthroughout forests of North America and have received muchattention as a target species for management (Reynolds et al. 1992,Iverson et al. 1996, Andersen et al. 2003). Goshawks nest in foreststands with high timber volumes and dense overstory canopiesabove relatively open understories […]

Northern Goshawk (Accipiter gentilis) Science Article 4 abstract The Northern Goshawk Accipiter gentilis typically prefers woodland habitat for nesting and hunting. In recent decades, however, the species has started colonising urban environments across Europe. Here I present the first study on the ranging behaviour of urban-breeding Goshawks. Each year from 1997 to 1999, I tracked […]

Northern Goshawk (Accipiter gentilis) Science Article 1 abstract While many studies have shown that patterns of partial brood loss often differ with offspring sex, food availability or between years, the question of whether family-size adjustment varies between sites has achieved little attention. I investigated this in Finnish northern goshawks Accipiter gentilis, and found that partial […]

Northern Goshawk (Accipiter gentilis) Science Article 5 abstract Age at first breeding has a large influence on fitness and hence is crucial to the evolution of life-history strategies. Goshawks Accipiter gentilis start breeding aged 1-4 years. Using 30 years of data and both lifetime reproductive success (LRS) and lind as a fitness estimate for 74 […]

Northern Harrier (Circus cyaneus) Science Article 4 abstract Hen Harriers Circus cyaneus and Montagu’s Harriers Circus pygargus are medium-sized raptors that differ in size (Hen Harrier being slightly bigger than Montagu’s Harrier) and breeding system (Montagu’s Harriers are semi-colonial and Hen Harriers defend nesting-hunting territories). In contrast, the diets of the two species when in […]