Phantom of the forest or successful citizen? Analysing how Northern Goshawks (Accipiter gentilis) cope with the urban environment

Abstract

By 2040, roughly two-thirds of humanity are expected to live in urban areas. As cities expand, humans irreversibly transform natural ecosystems, creating both opportunities and challenges for wildlife. Here, we investigate how the Northern Goshawk ( Accipiter gentilis ) is adjusting to urban environments. We measured a variety of behavioural and ecological parameters in three urban and four rural study sites. City life appeared related to all parameters we measured. Urban female goshawks were overall 21.7 (CI 95% 5.13–130) times more likely to defend their nestlings from humans than rural females. Urban goshawks were 3.64 (CI 95% 2.05–6.66) times more likely to feed on pigeons and had diets exhibiting lower overall species richness and diversity. Urban females laid eggs 12.5 (CI 95% 7.12–17.4) days earlier than rural individuals and were 2.22 (CI 95% 0.984–4.73) times more likely to produce a brood of more than three nestlings. Nonetheless, urban goshawks suffered more from infections with the parasite Trichomonas gallinae , which was the second most common cause of mortality (14.6%), after collisions with windows (33.1%). In conclusion, although city life is associated with significant risks, goshawks appear to thrive in some urban environments, most likely as a result of high local availability of profitable pigeon prey. We conclude that the Northern Goshawk can be classified as an urban exploiter in parts of its distribution.

To get sick or not to get sick—Trichomonas infections in two Accipiter species from Germany

“…The study was carried out between 2014 and 2016 at seven study sites in Northern Germany (Merling de Chapa et al 2020 ). The Northern goshawks were sampled in urban and rural sites, the Eurasian sparrowhawks were just sampled in rural locations while we were not able to access sparrowhawks at our urban locations.…”

“…The urban sites were three cities with human populations of more than 1 million each: Berlin, Cologne and Hamburg. The rural sites were located in the area of Barnim, the lower Rhine area near Kleve in an area close to the border between Germany and Netherlands, rural areas around Schleswig as well as areas inside the Teutoburg forest around Bielefeld (Merling de Chapa et al 2020 ). Eurasian sparrowhawks were sampled in two rural forests: in the region of Kleve and, in the year 2015, also in the region of Barnim.…”

“…The threatening role of trichomonosis seems to be particularly important for birds of prey that nest in or near urban areas (Boal 1997 ; Boal et al 1998 ; Amin et al 2014 ). In a recent study, we showed that prevalence of T. gallinae in Northern goshawks was higher in the urban environment than in the rural one (Merling de Chapa et al 2020 ). A high prevalence with T. gallinae was observed in urban breeding goshawks, with a prevalence of 100% in Poland (Wieliczko et al 2003 ) and 65% in Germany (Krone et al 2005 ) as well.…”

“…On the basis of this genetic characterisation, the single clonal strain A1 was detected as the causative agent of this emerging infectious disease and the epidemic passerine mortality (Lawson et al 2011a). The disease trichomonosis is described to have an enormous impact on numerous wild bird populations (Boal et al 1998;Robinson et al 2010;Lawson et al 2011b;Amin et al 2014;Merling de Chapa et al 2020). However, the overall prevalence of Trichomonas spp.…”

“…The disease trichomonosis is described to have an enormous impact on numerous wild bird populations (Boal et al 1998 ; Robinson et al 2010 ; Lawson et al 2011b ; Amin et al 2014 ; Merling de Chapa et al 2020 ). However, the overall prevalence of Trichomonas spp.…”