Tag: all of Accipiter

POSSIBLE SPECIALIZATION FOR HUMMINGBIRD-HUNTING IN THE TINY HAWK

Tiny Hawk (Accipiter superciliosus) Science Article 1 abstract This paper describes the hunting tactics of the Tiny Hawk, Accipiter superciliosusfontanieri, in a Costa Rican rain forest, where it appears to be a hummingbird specialist. Three tactics were used by the hawks to hunt hummingbirds: typical Accipiter still-hunting (probably not specifically for hummingbirds), waiting in ambush […]

A test of the condition-bias hypothesis yields different results for two species of sparrowhawks (Accipiter)A Test Of The Condition-Bias Hypothesis Yields Different Results For Two Species Of Sparrowhawks (Accipizter)

Sparrowhawk (Accipiter nisus) Science Article 2 abstract Determination of body condition of birds is important for many field studies. However, when using trapping methods based on food as a lure, the sample of trapped birds could be biased toward individuals in poor physical condition. We provide information on body mass, body condition, and sex and […]

WEIGHTS, BREEDING, AND SURVIVAL IN EUROPEAN SPARROWHAWKS

Sparrowhawk (Accipiter nisus) Science Article 5 abstract No significant diurnal variation in mean weight was detected in trapped European Sparrowhawks (Accipiter nisus). Weights of males fluctuated rather little through the year, but were highest in March and lowest in August. During the breeding cycle, males lost weight slightly in the prelay/early laying periods, when they […]

Age-related trends in the breeding success of individual female Sparrowhawks Accipiter nisus

Sparrowhawk (Accipiter nisus) Science Article 4 abstract Overall, female Sparrowhawks improved in the mean number of young they raised per year up to the 5th year of life, and then declined. An attempt is made to find to what extent this mean trend is caused by similar trends in the breeding of individual females, and […]

The abundance of essential vitamins in food chains and its impacton avian reproduction

Sparrowhawk (Accipiter nisus) Science Article 3 abstract Birds produce fewer or less viable eggs if the micro-nutrient requirements for reproduction cannot be met. Forexample, embryos from failed eggs of European sparrowhawks Accipiter nisus often show anomalies that indicate vitamin B2deficiency. B2 is only produced by plants and is propagated through the food chain. Here, egg […]

Causes and consequences of breeding dispersal in the Sparrowhawk Accipiter nisus

Sparrowhawk (Accipiter nisus) Science Article 1 abstract Sparrowhawks Accipiter nisus were present on particular territories for only one breeding season, but others were present on the same territory for up to eight seasons. Short periods of occupancy were due partly to mortality and partly to about one third of surviving birds of both sexes changing […]

Ecology of the Northern Goshawk in Fennoscandia

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 […]

Age-dependent diet choice in an aviantop predator

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 Diet During the Nesting Season inSoutheast Alaska

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 […]

Home range size, habitat use, activity patterns and hunting behaviour of urban-breeding Northern Goshawks Accipiter gentilis

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 […]