Do the Ticks of Birds at an Important Migratory Hotspot Reflect the Seasonal Dynamics of Ixodes ricinus at the Migration Initiation Site? A Case Study in the Danube Delta

Abstract

Migratory birds play important roles as distributors of ticks within and between continents. In the Old World, the most important migratory route of birds links Asia, Europe and Africa. During their migration, birds use various stopover sites, where they feed and rest and where ticks may attach or detach, creating new natural foci for vector-borne diseases. Danube Delta is one of the most important migration hotspots and so far no studies were focused on ticks of migratory birds herein. The aim of the present study was to assess the species diversity and seasonal dynamics of ticks parasitizing migratory birds in Danube Delta Biosphere Reserve. Migratory birds were trapped on Grindul Lupilor (44°41′N; 28°56′E) using mist nets during 4 migratory seasons (2 spring and 2 autumn) in 2011 and 2012. From each bird, all the ticks were collected and identified based on morphological features. Epidemiological parameters (prevalence, mean abundance, mean intensity) were calculated and all data were analysed statistically based on the season (spring and autumn), regional status of birds (migrants and breeding) and foraging behaviour (ground feeders, reed-bed feeders, foliage feeders). A total of 1434 birds (46 species) were captured. Ticks were found on 94 birds (10 species). Significantly more migratory birds hosted ticks, compared to resident birds. The 400 collected ticks belonged to four species: Ixodes ricinus (92.25%), I. arboricola (6.25%), I. redikorzevi (1.00%) and Haemaphysalis punctata (0.50%). A higher prevalence was found for I. ricinus in spring, with higher prevalence of nymphs in this season, while larvae occurred with the same prevalence in both seasons. Larval intensity was higher during spring and nymphs were more abundant during autumn. The seasonal differences in our study may be related not to the local seasonal dynamics of ticks, but on the seasonal dynamics at the site of migration initiation.

Ticks (Acari: Ixodida) on birds (Aves) migrating through the Polish Baltic coast

“…The total prevalence of tick infestation from 2011 to 2012 at Wicie ringing station, Poland, was 40.7% in spring and 40.0% in autumn. Similar levels of infestation have been recorded in other Western and Eastern bird migration routes in Europe (Nuorteva and Hoogstraal 1963;Hoogstraal et al 1964;Kahl 1971;Kaiser et al 1974;Walter et al 1979;Osacar-Jimenez et al 1998;Comstedt et al 2006;Mikula et al 2011;Nowak-Chmura et al 2012;Movila et al 2013;Sándor et al 2014;Ciebiera et al 2014). The tick prevalence on migratory birds on the Polish Baltic coast has increased from 31% in spring and 22% in autumn since 1981 (Nowak-Chmura et al 2012).…”

“…were found on birds during migration (Hornok et al 2014a, b). In the Danube Delta I. ricinus was dominant, however I. arboricola, I. redikorzevi and H. punctata also occurred (Sándor et al 2014), in Greece I. frontalis, I. acuminatus, H. aegyptium and H. marginatum were recorded (Diakou et al 2016). In Egypt and Cyprus detailed research by Nuorteva and Hoogstraal (1963), Hoogstraal et al (1963Hoogstraal et al ( , 1964, Kaiser et al (1974) indicated that birds are able to transport at least 13 ticks species H. rufipes, A.…”

“…Ixodes ricinus was the most abundant species of tick on migratory birds during the study. The northward, spring migration is characterized by a higher number of this tick species and a higher number of nymphs compared to the southward, autumn migration (Siuda 1993;Nowak-Chmura et al 2012;Hornok et al 2014a, b;Sándor et al 2014). Ixodes ricinus is one of the most abundant tick species in central Europe (Hasle et al 2009).…”

Piroplasms in feral and domestic equines in rural areas of the Danube Delta, Romania, with survey of dogs as a possible reservoir

“…Such a geographical delimitation may result from higher humidity (Gray et al, 2013) as well as the ecological diversity of the habitats (Mihalca et al, 2012;Sándor et al, 2014). These qualities, collectively, represent more suitable conditions for the ticks.…”

Letea Virus: Comparative Genomics and Phylogenetic Analysis of a Novel Reassortant Orbivirus Discovered in Grass Snakes (Natrix natrix)

“…As one of Europe's largest wetlands, the Danube Delta Biosphere Reserve (DDBR) located in the southeast of Romania, is a very biodiverse and heterogeneous complex of ecosystems [10]. The region is a major hub for bird migration along main African-Eurasian fly corridors, with ecoclimatic conditions suitable for abundant and diverse populations of arthropod vectors [11][12][13][14], which may allow pathogen import and maintenance [15][16][17][18].…”