The Presence of Microplastics in the Gastrointestinal Tracts of Song Thrushes (Turdus philomelos) Wintering in Apulia (Southern Italy)-Preliminary Results.

The term microplastics (MPs) describes a heterogeneous mixture of particles that can vary in size, color, and shape. Once released into the environment, MPs have various toxicological and physical effects on wildlife. The Song Thrush (Turdus philomelos) is a migratory species, staying in Italy in late autumn and winter. The aim of this study is to assess, quantify, and characterize the presence of microplastics in Song Thrushes hunted in the Apulia region of Italy. The birds (n = 360) were hunted in the Bari countryside and donated for research purposes by hunters. MPs were classified in relation to their shape in fibers, films, fragments, and pellets; then, they were divided according to their color and the length of the particles was measured. Nikon image analysis software was applied to the litter size measurements. Of the total of 360 birds, MPs were detected in the stomachs of 129 birds shot in December and 128 birds shot in January. The majority of ingested MPs were fibers that were observed in all contaminated birds. Film fragments were observed in every contaminated specimen. Among all the MPs found, 31.75% were red, 30.13% were black, and 25.91% were blue, while the other colors were less represented. This study provides the first analysis of MPs bioaccumulation in Song Thrushes wintering in the Apulia region, and the high contamination of thrushes confirmed the ubiquity of MPs in terrestrial ecosystems.

Toxoplasma gondii infection in ticks infesting migratory birds: the blackbird (Turdus merula) and the song thrush (Turdus philomelos).

Toxoplasmosis, caused by the protozoan Toxoplasma gondii, is the zoonosis widespread all over the world. Birds constitute an important group of T. gondii intermediate hosts often attacked by definitive hosts, e.g. domestic cats. Due to confirmation of an additional way of T. gondii transmission via tick bite, the aim of our study was to state and evaluate the infection prevalence of ticks feeding on blackbirds (Turdus merula) and song thrushes (Turdus philomelos). The real-time PCR amplification of the B1 gene fragment was used for detection of T. gondii infection in 157 Ixodes ricinus ticks removed from captured birds. The results showed the thrushes as hosts intensively attacked by ticks (prevalence 88.5% and 70% for blackbirds and song thrushes, respectively), and T. gondii infected individuals were detected. Among all ticks infected, 7 (5.8%; n = 120) were collected from blackbirds, and 2 (5.4%; n = 37) from song thrushes. The thrushes small body sizes and their tendency to urban ecosystems colonization, suggest that they relatively often become a pray of domestic cats, and combined with our findings, are potentially involved in maintenance the T. gondii population, especially in anthropogenic habitats, where the presence of toxoplasmosis is likely to constitute a serious danger to public health.

Migratory songbirds exhibit seasonal modulation of the oxygen cascade.

Migratory flight requires birds to maintain intensive aerobic exercise for many hours or days. Maintaining O2 supply to flight muscles is therefore important during migration, especially since migratory songbirds have been documented flying at altitudes greater than 5000 m above sea level, where O2 is limited. Whether songbirds exhibit seasonal plasticity of the O2 cascade to maintain O2 uptake and transport during migratory flight is not well understood. We investigated changes in the hypoxic ventilatory response, haematology and pectoralis (flight) muscle phenotype of 6 songbird species from 3 families during migratory and non-migratory conditions. Songbirds were captured during southbound migration in southern Ontario, Canada. Half of the birds were assessed during migration, and the rest were transitioned onto a winter photoperiod to induce a non-migratory phenotype and measured. All species exhibited seasonal plasticity at various stages along the O2 cascade, but not all species exhibited the same responses. Songbirds tended to be more hypoxia tolerant during migration, withstanding 5 kPa O2 and breathed more effectively through slower, deeper breaths. Warblers had a stronger haemoglobin-O2 affinity during autumn migration (decrease of ∼4.7 Torr), while the opposite was observed in thrushes (increase of ∼2.6 Torr). In the flight muscle there was an ∼1.2-fold increase in the abundance of muscle fibres with smaller fibre transverse areas during autumn migration, but no changes in capillary:fibre ratio. These adjustments would enhance O2 uptake and transport to the flight muscle. Our findings demonstrate that in the O2 cascade there is no ideal migratory phenotype for all songbirds.

Compensation for wind drift in the nocturnally migrating Song Thrushes in relation to altitude and wind.

Compensation for wind drift in relation to the side-wind velocity and altitude was investigated in Song Thrushes during autumn migration. The birds were recorded at night flying above the prominent leading line of a marine spit which coincided with the general direction of their migration. Among the large size passerine species, Song Thrushes were identified by a combination of five flight characteristics typical only of this species during particular periods of autumn. The thrushes showed different reactions to the crosswinds: complete and partial compensation for the displacement and drift. Under normal visibility, the completeness of compensation depended both on the velocity of the side-wind and altitude. The degree of compensation achieved was reduced with an increase of altitude, regardless of the wind. Under the same wind conditions, the angle of drift (the angle between the track direction and the leading line) increased with altitude, but the number of birds that compensated for drift decreased. On average, at heights below 300 m agl, the thrushes were capable of compensating completely for moderate winds; between 300 and 600 m agl compensation was partial; but above 600 m the birds drifted completely. Birds of the same species flying above the same terrain may demonstrate different reactions to the same crosswind depending on altitude. Meanwhile, flight tracks gradually deviated from the leading line with an increase in altitude, the headings of the birds got closer to the general migratory direction. It is more likely that the birds control displacement using the visual flow regulation principle by the angular velocity of the landmarks below them running aside in relation to their flight direction, which is inversely proportional to the altitude. Low flying thrushes promptly reacted to the shifting of the leading line of the spit with an average angular velocity of more than 0.8°/s perpendicular to the direction of flight and compensated completely for drift. Shifting of the leading line with an angular velocity of less than 0.4°/s, the high flying birds did not seem to notice or did not try to compensate for displacement deliberately.

Morphological and molecular identification of Isospora massardi Lopes, Berto, Luz, Galvão, Ferreira & Lopes, 2014 (Chromista: Miozoa: Eimeriidae) from thrushes Turdus spp. (Passeriformes: Turdidae) in South America.

In the current work, Isospora massardi Lopes, Berto, Luz, Galvão, Ferreira & Lopes, [10] is identified from white-necked thrushes Turdus albicollis Vieillot, 1818, rufous-bellied thrushes Turdus rufiventris Vieillot, 1818 and from a new host, the yellow-legged thrush Turdus flavipes (Vieillot, 1818) in a new locality, the Itatiaia National Park, in Southeastern Brazil, providing a preliminary genotypic characterization via sequencing of the mitochondrial cytochrome c oxidase subunit 1 (COI) and 18S small subunit ribosomal RNA genes. The oocysts and sporocysts of I. massardi of the current study are morphologically similar to the original description and are uniform in the proportionality of width on length, but exhibited different patterns of size associated with each host species. Furthermore, a genotypic difference of 3% was found in the COI sequences from T. flavipes and T. albicollis. Therefore, an ecological discussion is introduced aimed at associating these morphometric and genotypic differences with an ongoing speciation process.

To cross or not to cross - thrushes at the German North Sea coast adapt flight and routing to wind conditions in autumn.

BACKGROUND: Although many aspects of passerine migration are genetically determined, routing appears to be flexibly adjusted to the conditions experienced on each individual journey. This holds especially true for routing decisions taken when confronted with large bodies of water. Once taken, these decisions can be hardly altered or revised. In this paper, we analysed stopover and routing decisions taken by three species of thrushes, blackbirds, redwings and song thrushes, at the German North Sea coast. METHODS: Birds were equipped with radio-telemetry tags at stopover sites along the coast during autumn migration and subsequently tracked by an automated receiver network covering the coastline and islands of the German Bight. RESULTS: The thrushes resumed migration in nights with a favourable northward wind component and clear skies. About 40% of the tagged individuals have taken an offshore instead of an alongshore oriented flight route. Routing decisions were influenced by the strength of the eastward wind component with offshore oriented flights taking place primarily under weak winds or winds blowing towards the west. Thrushes that took an offshore oriented route stopped over at the coast longer than those flying alongshore. Interestingly, offshore as well as alongshore oriented flights co-occurred within single nights and under comparable weather conditions. CONCLUSIONS: Migratory flight and routing decisions of thrushes at the German North Sea coast are highly dependent on weather, in particular wind. Still, we found evidence that weather may not be the sole reason for individual routes taken. Physical condition, morphology or animal personality lend themselves as possible additional factors of influence. Enabling a more detailed understanding of thrush migration over and along the German North Sea, our data help to better judge risks that migratory birds are facing when en route conditions are altered, for example by artificial obstacles such as offshore wind turbines.

Different Competence as a Lyme Borreliosis Causative Agent Reservoir Found in Two Thrush Species: The Blackbird (Turdus merula) and the Song Thrush (Turdus philomelos).

Passerine birds are significantly involved in the dissemination of Borreliella spp. bacteria (formerly Borrelia burgdorferi sensu lato complex), the causative agent of most common and important tick-spread disease Lyme borreliosis. Among several dozen investigated passerine bird species, thrushes (Turdidae) have been reported as a relatively good pathogen reservoirs and disseminators. The principal aim of the study was to identify the differences in Borreliella spp. reservoir competence between two widespread and showing similar behavior thrush species. A total of 157 Ixodes ricinus ticks (19 larvae, 138 nymphs) were collected from 26 blackbirds (Turdus merula) and 20 song thrushes (Turdus philomelos) living in the same forest habitat (northeastern Poland). All, at least partially engorged ectoparasites, were tested for the presence of Borreliella spp. DNA using the nested-PCR technique. No significant difference of tick prevalence was found, with 88.5% blackbirds and 70% of song thrushes infested. Screening for Borreliella spp. in ticks revealed that both tick infection prevalence (49.2% vs. 18.9%) and mean number of infected individuals engorging on birds (2.27 vs. 0.35) were higher in blackbirds. Both the investigated thrush species presumably could participate in the pathogen circulation, although with different efficiencies. The greater reservoir competence of blackbirds suggests the differentiated dynamics of host-pathogen interactions among selected species, and consequently their potentially disparate role in the ecology of Lyme borreliosis.

Division within the North American boreal forest: Ecological niche divergence between the Bicknell's Thrush (Catharus bicknelli) and Gray-cheeked Thrush (C. minimus).

Sister species that diverged in allopatry in similar environments are expected to exhibit niche conservatism. Using ecological niche modeling and a multivariate analysis of climate and habitat data, I test the hypothesis that the Bicknell's Thrush (Catharus bicknelli) and Gray-cheeked Thrush (C. mimimus), sister species that breed in the North American boreal forest, show niche conservatism. Three tree species that are important components of breeding territories of both thrush species were combined with climatic variables to create niche models consisting of abiotic and biotic components. Abiotic-only, abiotic+biotic, and biotic-only models were evaluated using the area under the curve (AUC) criterion. Abiotic+biotic models had higher AUC scores and did not over-project thrush distributions compared to abiotic-only or biotic-only models. From the abiotic+biotic models, I tested for niche conservatism or divergence by accounting for the differences in the availability of niche components by calculating (1) niche overlap from ecological niche models and (2) mean niche differences of environmental values at occurrence points. Niche background similarity tests revealed significant niche divergence in 10 of 12 comparisons, and multivariate tests revealed niche divergence along 2 of 3 niche axes. The Bicknell's Thrush breeds in warmer and wetter regions with a high abundance of balsam fir (Abies balsamea), whereas Gray-cheeked Thrush often co-occurs with black spruce (Picea mariana). Niche divergence, rather than conservatism, was the predominant pattern for these species, suggesting that ecological divergence has played a role in the speciation of the Bicknell's Thrush and Gray-cheeked Thrush. Furthermore, because niche models were improved by the incorporation of biotic variables, this study validates the inclusion of relevant biotic factors in ecological niche modeling to increase model accuracy.

Effects of birds ingesting Heterodera rostochiensis cysts on viability of eggs and larvae.

Rate of passage through the digestive systems and effects of ingestion on viability of contents of cysts of Heterodera rostochiensis were determined in feeding trials with pigeons, thrushes, starlings, cowbirds, sparrows, and quails. Depending upon species of birds, 12-82% of the cysts ingested passed through the digestive system within 0.5 h. Pigeons required 6 h for complete evacuation. All other birds completely evacuated ingested cysts from their digestive systems within 3 h. Contents of cysts were nonviable if they were retained in the digestive system of starlings for more than 1.5 h, pigeons more than 1 h, or other birds more than 0.5 h. Cyst contents were nonviable if they remained in contact with excreta from cowbirds or quails for 4 h, thrushes for 96 h, or other species for 72 h after passage. Viability of contents of cysts was inversely related to exposure to excreta-filtrate concentration. Larvae failed to emerge from cysts that were exposed to a 25% concentration of excreta filtrate from starlings, 50% concentration from pigeons or thrushes, or 100% concentration of excreta filtrates from each of the other species. Cysts that were subjected to 44 C (avg. body temperature of cowbirds) for more than 3.5 h were nonviable. Cysts that passed through birds and collected with excrement on polyethylene or soil produced no infective larvae on potato.