RESUMEN

The present study aimed to test intestinal scrapings of the Northern Goshawk (Accipiter gentilis) and the Eurasian Sparrowhawk (Accipiter nisus) from Lithuania for S. calchasi and other Sarcocystis species characterised by bird-bird life cycles. The protozoan parasite Sarcocystis calchasi can cause respiratory and neurological diseases in a variety of birds; however, the distribution of this parasite is not well-examined. Sarcocystis species were identified with nested PCR and sequencing of the partial ITS1 region. Sporocysts and/or sporulated oocysts of Sarcocystis spp. were observed in 16 (100%) Northern Goshawks and 9 (56.3%) Eurasian Sparrowhawks. Four species, S. columbae, S. halieti, S. turdusi, and S. wobeseri, were confirmed in the Eurasian Sparrowhawk. Apart from the latter four species, S. calchasi, S. cornixi, S. kutkienae, and S. lari were established in the Northern Goshawk. A higher prevalence of Sarcocystis spp. and species richness in Northern Goshawks is associated with the differences in the diet of two examined Accipiter species. This study is the first report of S. calchasi in Lithuania. Furthermore, the genetically distinct species Sarcocystis spp. 23LTAcc, which is most closely related to S. calchasi, was found in three Northern Goshawks.

RESUMEN

Urbanization causes the simplification of natural habitats, resulting in animal communities dominated by exotic species with few top predators. In recent years, however, many predators such as hawks, and in the US coyotes and cougars, have become increasingly common in urban environments. Hawks in the Accipiter genus, especially, are recovering from widespread population declines and are increasingly common in urbanizing landscapes. Our goal was to identify factors that determine the occupancy, colonization and persistence of Accipiter hawks in a major metropolitan area. Through a novel combination of citizen science and advanced remote sensing, we quantified how urban features facilitate the dynamics and long-term establishment of Accipiter hawks. Based on data from Project FeederWatch, we quantified 21 years (1996-2016) of changes in the spatio-temporal dynamics of Accipiter hawks in Chicago, IL, USA. Using a multi-season occupancy model, we estimated Cooper's (Accipiter cooperii) and sharp-shinned (A. striatus) hawk occupancy dynamics as a function of tree canopy cover, impervious surface cover and prey availability. In the late 1990s, hawks occupied 26% of sites around Chicago, but after two decades, their occupancy fluctuated close to 67% of sites and they colonized increasingly urbanized areas. Once established, hawks persisted in areas with high levels of impervious surfaces as long as those areas supported high abundances of prey birds. Urban areas represent increasingly habitable environments for recovering predators, and understanding the precise urban features that drive colonization and persistence is important for wildlife conservation in an urbanizing world.

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RESUMEN

Prey have evolved anti-predator defences that reduce or eliminate the risk of predation. Predators often reproduce at specific sites over many years causing permanent threats to local prey species. Such prey may respond by moving elsewhere thereby reducing local population abundance, or they may stay put and adjust their behavior to the presence of predators. We tested these predictions by analyzing population abundance and anti-predator behavior within 100 m of and 500 m away from nests of sparrowhawks Accipiter nisus and goshawks A. gentilis for 80 species of birds. Population abundance of prey was reduced by 11% near goshawk nests and by 15% near sparrowhawk nests when compared with nearby control sites in similar habitats. Flight initiation distance (FID) of prey, estimated as the distance at which birds took flight when approached by a human, increased by 50% in the presence of hawk nests, providing evidence of adjustment of anti-predator behavior to prevailing risks of predation. Susceptibility to predation was estimated as log transformed abundance of the observed number of prey items obtained from prey remains collected around nests minus log transformed expected number of prey according to point counts of breeding birds. FID increased from 10 to 46 m with increasing susceptibility of prey species to predation by the goshawk and from 12 to 15 m with increasing susceptibility of prey species to predation by the sparrowhawk. These findings suggest that prey adjust their distribution and anti-predator behavior to the risk of predation.

RESUMEN

Sarcocystis is a large genus of protozoan parasites with complex heteroxenous life cycles. For many species, either the intermediate or the definitive host is still unknown. In this study, 116 Accipiter hawks (Eurasian sparrowhawks and northern goshawks) were investigated for the presence of Sarcocystis spp. in their intestinal tract or their faeces. To gain a wide distribution, samples were collected throughout Germany within 2 years. It was possible to detect Sarcocystis-like oocysts in 65 samples. Sequencing of the ITS region or species-specific PCR identified 33 samples as Sarcocystis turdusi/Sarcocystis sp. ex A. nisus (18), Sarcocystis calchasi (6), Sarcocystis columbae (3), Sarcocystis cornixi (3) and Sarcocystis sp. ex Phalacrocorax carbo (3). Besides the known infestation with S. columbae, S. sp. ex A. nisus and S. calchasi the Accipiter hawks were thereby confirmed as definitive host of S. turdusi, S. cornixi and S. sp. ex Phalacrocorax carbo for the first time.

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