Two populations of the kentrurostylid ciliate Pseudokeronopsis erythrina Chen et al., 2011 were isolated from a brackish wastewater treatment plant, Pisa, Italy and from a nutrient-rich freshwater body, the East Lake, Wuhan, China. The populations were thoroughly investigated for their morphology, focusing on cell body plasticity. The study was supplemented with 18S rDNA phylogenetic analysis and mitogenome sequencing, following the integrative taxonomy approach. The Italian population possesses a great variation in terms of the frontal area, and the numbers of left marginal rows, and dorsal kineties. Additionally, the number of left marginal anlagen and dorsal kineties anlagen varied. For instance, additional small anlagen appeared in the left marginal rows, and two dorsal kineties anlagen derived from a single dorsal kinety. The Wuhan population resembled the type population (originally isolated from Guangzhou, China), differing only by the presence of an extra dorsal kinety. The existence of giant individuals characterized both new populations of P. erythrina although with some differences in their respective frequency and features. The 18S rDNA sequences of the Italian, Wuhan, and type populations were identical. Phylogenetic analyses showed that these three populations formed a distinct cluster within the clade containing P. songi, P. parasongi, and P. flava. The structure of the P. erythrina mitochondrial genome is also provided. The content of this genome closely resembled Pseudourostyla cristata, except for the absence of genes nadh3 and nadh6. Our findings suggest that the Wuhan population represents an intermediate form between the type and Italian populations. The greater morphological plasticity observed in the Italian population underscores the importance of molecular data and integrative analyses in species identification.

Studying pigeons during homing has offered an opportunity to investigate visual-functional brain lateralization in the context of free flying and long distance navigation. In the current study we examine at a high scale of spatial resolution the flight paths of pigeons, which vary with respect to monocular and binocular treatment, as they familiarise themselves with landscape and landmark features during repeated flights home from two locations. The analysis of the flight paths of monocularly occluded pigeons revealed that pigeons using the right eye/left hemisphere visual system were more likely to display more tortuous paths over tracts of 500 m along the flight path home compared to both pigeons using the left eye/right hemisphere visual system and control birds. Accompanying this finding was the observation that pigeons using the right eye/left hemisphere system were more likely to perform flight "loops", suggesting that, without right hemispheric visual processing, pigeons are more motivated to seek out visual input, behaviourally expanding the now monocularly reduced visual field. Taken together, the data are consistent with a more important role of the left eye/right hemisphere system in processing visual features of the landscape, which may contribute to the construction of the familiar landmark-based map used for navigation. More broadly, our data are consistent with the hypothesis that the right cerebral hemisphere of the avian brain plays a more important role in memorising and using the relational properties of visual stimuli to guide performance on spatial tasks. Pigeons challenged to learn visual landscape features with only the left or right eye displayed different patterns of flight behaviour.Birds using the right eye/left hemisphere showed a greater high spatial resolution tortuosity than birds using the left eye/right hemisphere.The results are consistent with an important role of the avian right brain hemisphere in memory-based, visuo-spatial tasks.

Migratory behaviour allows individuals to inhabit areas with optimal environmental conditions throughout the year. To reduce energy expenditure and the risk of mortality while migrating, birds may schedule their departures basing on environmental cues that provide seasonal and/or local information. In this study, we aimed to identify the possible effect of environmental factors on the spring migration of 30 Eurasian teal Anas crecca tracked between 2014 and 2018 from Italian wintering areas. We used Cox proportional hazard and generalized estimating equation models to evaluate the environmental cues that affect teal's decision to start migratory movements from the wintering grounds and continue migration from stopover sites. Apart from the anticipated effect of photoperiod, the onset of spring migration was not substantially influenced by environmental variables, whereas the speed of migration seemed to be influenced by both seasonal (increased ground temperature, an indicator of spring advancement) and local (low cloud cover and northward blowing winds, which support migratory flight) environmental cues. The slow migration observed in teal may favour a strategy in which migratory timing is modulated mainly by the conditions encountered during the journey rather than at the start of the migration. This suggested low impact of local environmental variables on the onset of spring migration could have important consequences both for the management of this species for hunting purposes and for the way the species might respond to the ongoing climatic change.

The Adriatic Sea is one of the main foraging areas for marine turtles of the Mediterranean Sea, but the specific high-use sites are poorly known, due to the scarceness of satellite tracking data available for juvenile turtles frequenting the area. In the present study, we tracked 8 juvenile and adult loggerhead turtles (Caretta caretta) that were released along the north-western Adriatic coast after a rehabilitation period having been equipped with Argos-linked satellite transmitters. Tracked turtles displayed quite variable movement patterns, but mostly remained in the north-western Adriatic, especially during the summer months. A marked preference for specific coastal sites was revealed in many turtles, that actively moved towards these specific locations when released south of it or having spent the winter away. Pooling these data with those obtained in previous studies on a further 10 turtles, we highlighted the presence of two main high-use areas, north and south of the Po River delta, where future conservation actions may then be focused.

Satellite tracking studies have identified some of the migratory corridors and foraging sites of Mediterranean loggerhead sea turtle ( Caretta caretta ) rookeries over the past few decades. However, due to a lack of information for breeding rookeries in Libya and Turkey, our understanding of the distribution and connectivity of adult loggerheads is limited. We satellite-tracked 17 female loggerhead turtles breeding in one of the main nesting areas in Turkey to identify (1) migratory pathways, and (2) their foraging areas. Females were tracked for 96-657 d (mean: 271 d), and followed 3 general migratory directions (southeast, southwest and northwest/west). While migrating, individuals alternated oceanic and neritic movements, generally travelling significantly slower when in neritic waters (average speed reduction: 20%). Five turtles stopped between 1 to 3 times in stopover sites for <6 d before resuming their migration. While 1 turtle resided in oceanic foraging areas, the remaining 16 loggerheads settled in 12 distinct neritic foraging grounds; 2 turtles shared one site and 4 turtles shared another site. The identified foraging grounds were widely distributed across the Eastern and Central basin, in locations known to be frequented by loggerhead turtles from other rookeries. The present findings reveal links between foraging areas and one of the main breeding sites in Turkey, providing useful information for species conservation.

How animals navigate across the ocean to isolated targets remains perplexing greater than 150 years since this question was considered by Charles Darwin. To help solve this long-standing enigma, we considered the likely resolution of any map sense used in migration, based on the navigational performance across different scales (tens to thousands of kilometres). We assessed navigational performance using a unique high-resolution Fastloc-GPS tracking dataset for post-breeding hawksbill turtles (Eretmochelys imbricata) migrating relatively short distances to remote, isolated targets on submerged banks in the Indian Ocean. Individuals often followed circuitous paths (mean straightness index = 0.54, range 0.14–0.93, s.d. = 0.23, n = 22), when migrating short distances (mean beeline distance to target = 106 km, range 68.7–178.2 km). For example, one turtle travelled 1306.2 km when the beeline distance to the target was only 176.4 km. When off the beeline to their target, turtles sometimes corrected their course both in the open ocean and when encountering shallow water. Our results provide compelling evidence that hawksbill turtles only have a relatively crude map sense in the open ocean. The existence of widespread foraging and breeding areas on isolated oceanic sites points to target searching in the final stages of migration being common in sea turtles.

Migratory behaviour in birds shows a remarkable variability at species, population and individual levels. Short-distance migrants often adopt a partial migratory strategy and tend to have a flexible migration schedule that allows a more effective response to extreme environmental variations. Weather seasonality and environmental heterogeneity have been reported as significant factors in the diversification of migratory behaviour for Mediterranean migrants, but relatively few studies investigated the migration patterns of non-passerine birds migrating within the Mediterranean basin. In this study, we investigated the migratory strategy of 40 Eurasian Stone-curlews Burhinus oedicnemus tagged with geolocators and GPS-GSM tags and belonging to continental and Mediterranean populations of the Italian peninsula. The proportion of migrants was higher in continental populations, but we observed a significant variability also within Mediterranean populations. All birds spent the winter within the Mediterranean basin. Continental Stone-curlews departed earlier in spring and later in autumn and covered longer distances than those from Mediterranean areas. The speed of migration did not change between seasons for continental birds, while Mediterranean individuals migrated faster in spring. The likelihood of departure for autumn migration of GPS-tagged birds increased when temperatures were near or below 0 °C suggesting that Stone-curlews tend to delay departure until weather conditions worsen abruptly. As a consequence of global warming in the Mediterranean, the frequency of migratory birds in the considered populations might decrease in the near future. This could affect the distribution of species throughout the year and should be taken into account when targeting conservation measures.

Migratory behaviour in birds shows a remarkable variability at species, population and individual levels. Short-distance migrants, in particular, often adopt a partial migratory strategy and tend to have a rather flexible migration schedule which allows them to respond more effectively to extreme environmental variations, like those due to climate change. Weather seasonality and environmental heterogeneity at regional and local scales have been reported as significant factors in the diversification of migratory behaviour for some species of Mediterranean migrants. Relatively few studies, however, investigated the migration patterns of non-passerine birds migrating within this area. In this study we investigated the migratory strategy of the Eurasian Stone-curlew Burhinus oedicnemus using data collected on 40 individuals tagged with geolocators and GPS-GSM tags, belonging to two continental and two Mediterranean populations of the Italian peninsula. The proportion of migrants was significantly higher in continental populations, but we observed a significant variability also within Mediterranean populations. GPS-tagged migrants traveled less than 1000 km, spending the winter within the Mediterranean basin. Continental Stone-curlews i) departed earlier in spring and later in autumn and ii) covered longer distances than those from Mediterranean areas. The speed of migration did not change between seasons for continental birds, while Mediterranean individuals tended to migrate faster in spring. The likelihood of departure for autumn migration of GPS-tagged birds significantly increased when temperatures were near or below 0 °C suggesting that Stone-curlews tend to delay departure weather conditions worsen abruptly. Thus it can be speculated that the frequency of migratory birds in the considered populations may decrease in the near future due to the effect of global warming in the Mediterranean. This could have a significant effect on the distribution of species throughout the year and should be taken into account when targeting conservation measures.

Pelagic seabirds are tied to their breeding colonies throughout their long-lasting breeding season, but at the same time, they have to feed in a highly dynamic marine environment where prey abundance and availability rapidly change across space and seasons. Here, we describe the foraging movements of yelkouan shearwater Puffinus yelkouan, a seabird endemic to the Mediterranean Sea that spends its entire life cycle within this enclosed basin and whose future conservation is intimately linked to human-driven and climatic changes affecting the sea. The aim was to understand the main factors underlying the choice of foraging locations during the reproductive phases. A total of 34 foraging trips were obtained from 21 breeding adults tagged and tracked on Tavolara Archipelago (N Sardinia, Italy). This is the largest and most important breeding area for the species, accounting for more than 50% of the world population. The relationships between foraging movements during two different breeding stages and the seasonal changes of primary productivity at sea were modeled. Movements appeared to be addressed toward inshore (<20 km), highly productive, and relatively shallow (<200 m) foraging areas, often in front of river mouths and at great distances from the colony. During incubation, the Bonifacio Strait and other coastal areas close to North and West Sardinia were the most preferred locations (up to 247 km from the colony). During the chick-rearing phase, some individuals reached areas placed at greater distances from the colony (up to 579 km), aiming at food-rich hotspots placed as far north as the Gulf of Lion (France). The need for such long distance and long-lasting foraging trips is hypothesized to be related to unfavorable conditions on the less productive (and already depleted) Sardinian waters.

Factors affecting stopover duration in birds are still much discussed. Field studies report contradictory evidence regarding the effect of fuel reserves on bird decision to depart from a stopover site, while the majority of laboratory tests performed on passerines reported a positive relationship between body conditions and migratory restlessness. In recent years, a few studies integrating laboratory and field investigations suggested that the amount of migratory restlessness could be a proxy of the individual willingness to depart from a stopover site in night-migrating passerines, but similar studies are lacking for other groups of birds. In this paper the factors affecting stopover length in the Wood sandpiper Tringa glareola (Charadriiformes Scolopacidae) were studied by integrating field observations and laboratory tests during spring migration. Our aims were to investigate (1) the influence of body conditions on migratory restlessness and (2) the influence of body conditions and of the amount of migratory restlessness on stopover duration, after controlling for meteorological conditions. Contrary to our expectations, we did not find any relationship between body condition and migratory restlessness nor stopover duration, while for the 1st time in a non-passerine species, evidence was produced that the amount of migratory restlessness is significantly related to the likelihood of leaving the stopover area. Our results emphasize the relevance of the studies integrating field and laboratory tests to understand the physiological and ecological factors affecting migratory behaviour in different bird species.Highlights Body conditions seem to be unrelated both to migratory restlessness and stopover duration.Migratory restlessness predicts the likelihood of leaving the stopover site.The quantification of migratory restlessness seems to be a useful tool for studying the effect of intrinsic and extrinsic factors on stopover behaviour in shorebirds.

We designed a novel aggregated methodology to infer the impact of ocean motions on the movements of satellite-tracked marine turtles adopting available oceanographic observations and validated products of a numerical oceanographic forecasting system. The method was tested on an 11-months trajectory of a juvenile loggerhead turtle (LT) wandering in the Tyrrhenian Sea (Mediterranean Sea) that was reconstructed with a high-resolution GPS tracking system. The application of ad-hoc designed metrics revealed that the turtle's route shape, ground speed and periodicities of its explained variance mimic the inertial motions of the sea, showing that this methodology is able to reveal important details on the relation between turtle movements and oceanographic features. Inertial motions were also identified in the observed trajectory of a surface drifting buoy sampling the Tyrrhenian Sea in a common period. At each sampling point of the turtle trajectory, the sea current eddy kinetic energy (EKE) and a Sea Current Impact index were computed from a validated set of high-resolution ocean modeling products and their analysis showed the relevant effects of the highly variable local sea currents mechanical action. Specifically, the metric we adopted revealed that the turtle trajectory was favorably impacted by the encountered sea current advection for about 70% of its length. The presented oceanographic techniques in conjunction with high-resolution tracking system provide a practicable approach to study marine turtle movements, leading the way to discover further insights on turtle behavior in the ocean.

It has been proposed that animals migrating towards a specific destination may rely on vector navigation by maintaining a direction for a certain amount of time. In sea turtles, reliance on this strategy has been proposed especially for migrations directed towards wide targets and carried out in weak sea current flows. In the present study we tested if vector navigation could also be a feasible strategy for turtles facing dynamic oceanographic conditions by considering the case of green turtles nesting in the Comoros archipelago and migrating to their foraging grounds along the African coast. To test this hypothesis, we firstly analysed the turtles’ actual headings estimated considering the currents encountered by migrating turtles along the open sea segment of their routes. We then run individual-based models to simulate the journeys of turtles migrating in the area while relying on a vector or a true navigation strategy, and reconstructed the turtle’s water-related, i.e. motor paths, by removing the drifting effect of sea currents. Tracked turtles did not show any major change in their headings and mostly oriented towards the foraging area. While simulations did not provide homogeneous results, the turtle orientation efficiency estimated from motor paths showed that they possibly relied on a vector rather than a true navigation strategy. The present results suggest that vector navigation is a viable strategy to account for the migratory performances recorded in turtles migrating in dynamic oceanographic conditions, even if the involvement of the more sophisticated true navigation mechanism cannot be completely excluded.

In 1873, Charles Darwin marveled at the ability of sea turtles to find isolated island breeding sites [1], but the details of how sea turtles and other taxa navigate during these migrations remains an open question [2]. Exploring this question using free-living individuals is difficult because, despite thousands of sea turtles being satellite tracked across hundreds of studies [3], most are tracked to mainland coasts where the navigational challenges are easiest. We overcame this problem by recording unique tracks of green turtles (Chelonia mydas) migrating long distances in the Indian Ocean to small oceanic islands. Our work provides some of the best evidence to date, from naturally migrating sea turtles, for an ability to reorient in the open ocean, but only at a crude level. Using individual-based models that incorporated ocean currents, we compared actual migration tracks against candidate navigational models to show that turtles do not reorient at fine scales (e.g., daily), but rather can travel several 100 km off the direct routes to their goal before reorienting, often in the open ocean. Frequently, turtles did not home to small islands with pinpoint accuracy, but rather overshot and/or searched for the target in the final stages of migration. These results from naturally migrating individuals support the suggestion from previous laboratory work [4-6] that turtles use a true navigation system in the open ocean, but their map sense is coarse scale.

The homing journeys of nine loggerhead turtles translocated from their nesting beach to offshore release sites, were reconstructed through Argos and GPS telemetry while their water-related orientation was simultaneously recorded at high temporal resolution by multi-sensor data loggers featuring a three-axis magnetic sensor. All turtles managed to return to the nesting beach area, although with indirect routes encompassing an initial straight leg not precisely oriented towards home, and a successive homebound segment carried out along the coast. Logger data revealed that, after an initial period of disorientation, turtles were able to precisely maintain a consistent direction for several hours while moving in the open sea, even during night-time. Their water-related headings were in accordance with the orientation of the resulting route, showing little or no effect of current drift. This study reveals a biphasic homing strategy of displaced turtles involving an initial orientation weakly related to home and a successive shift to coastal navigation, which is in line with the modern conceptual framework of animal migratory navigation as deriving from sequential mechanisms acting at different spatial scales.

We modeled the oceanic migration of turtles nesting in the remote Ascension Island to gain insights into the unknown mechanisms of open sea navigation. We show that a simple strategy of maintaining a single heading for a given amount of time can account for the turtles' postnesting migrations directed to targets along the Brazilian coast, while for prebreeding migrations aimed at reaching the isolated Ascension Island, reliance on more complex, map-like systems seems crucial. Abstract Vector navigation, i.e., maintaining a constant heading for a given amount of time, is hypothesized to provide a viable basis for the navigational feats of a number of long-distance animal migrants. Since animals following this strategy are subject to drift by wind or by ocean current, performing long migrations relying on vector navigation is particularly challenging. We tested whether vector navigation could be involved in the migrations of green turtles (Chelonia mydas) that migrate between the remote Ascension Island and Brazil. To this aim, a novel approach was followed using individual-based numerical models to simulate migratory trajectories of virtual turtles that were compared to actual routes reconstructed by satellite. Simulated postnesting migrations from Ascension revealed that weak currents enabled modeled turtles to reach the Brazilian coast, but only for a limited range of headings around due West. This conclusion was corroborated by comparing modeled trajectories with the actual routes of previously tracked turtles, with a beeline vector navigation strategy providing the best fit, although a true-navigation strategy directed to the landfall site produced similar results. Finally, we tested if a vector navigational strategy was feasible for the prebreeding migration from Brazil towards Ascension, but modeled routes mostly failed to reach the island or a larger area around it, with individuals drifting away under the influence of currents. We conclude that Ascension turtles can take advantage of vector navigation when migrating towards a wide target like the Brazilian coast, while the demanding prebreeding migration likely requires more complex navigational systems.

Identifying an organism's migratory strategies and routes has important implications for conservation. For most species of European ducks, information on the general course of migration, revealed by ringing recoveries, is available, whereas tracking data on migratory movements are limited to the largest species. In the present paper, we report the results of a tracking study on 29 Eurasian Teals, the smallest European duck, captured during the wintering period at three Italian sites. The departure date of spring migration was determined for 21 individuals, and for 15 the entire spring migratory route was reconstructed. Most ducks departed from wintering grounds between mid‐February and March following straight and direct routes along the Black Sea‐Mediterranean flyway. The breeding sites, usually reached by May, were spread from central to north‐Eastern Europe to east of the Urals. The migratory speed was slow (approximately 36 km/day on average) because most birds stopped for several weeks at stopover sites, mainly in south‐eastern Europe, especially at the very beginning of migration. The active flight migration segments were covered at much higher speeds, up to 872 km/day. Stopover duration tended to be shorter when birds were closer to their breeding site. These results, based on the largest satellite tracking effort for this species, revealed for the first time the main features of the migratory strategies of individual Teals wintering in Europe, such as the migration timing and speed and stopover localization and duration.

Loggerhead sea turtles (Caretta caretta) are known to display a wide range of movement patterns during the different stages of their life cycle, but empirical information to document this extensive behavioural plasticity is still limited. This is especially true for large, adult-sized individuals, that are thought to mainly forage in neritic areas. In the present paper, eight adult-sized loggerhead turtles were tracked using satellite telemetry to identify the location of their foraging grounds in the seas along the western coast of the Italian peninsula. Tracked turtles mostly stayed in the region between the Italian peninsula and the islands of Sicily and Sardinia, that was reached following quick, directed movements by the turtles from a release site to the north. In this area, two turtles took up residence in spatially limited neritic sites along the coast, while the remaining six alternated circumscribed coastal stays with long-distance, circuitous movements in the oceanic environment. An utilization distribution analysis clearly identified an area, mostly comprising oceanic waters, that was continuously used by turtles in different seasons and years. The present results contribute to the still-limited knowledge of the spatial ecology of loggerheads frequenting the Western Mediterranean Sea and highlight the presence of a potentially important oceanic region in the Southern Tyrrhenian Sea where adult-sized turtles forage for extended periods. These findings increase our knowledge of complex life history traits of loggerhead turtles and provide important information to be considered for evidence-based conservation measures.

Over the last decades, satellite tracking techniques have substantially advanced our understanding of sea turtle spatial behaviour, especially for the post-nesting migrations of females. Substantial gaps remains in our knowledge of the turtle behaviour during the remaining inter-reproductive period, that spans over 2–3years. We report the results of a prolonged tracking experiment on loggerhead turtles nesting along the Ionian Calabria, the main breeding ground in Italy. Argos satellite transmitters were deployed on eight females, a sample representing a substantial fraction of the overall population (20–25 nesting females). All turtles but one were tracked for >300days (range: 313–1523days), revealing their spatial behaviour during a complete reproductive cycle and providing novel information on a number of poorly-known aspects of loggerhead spatial ecology: i) the post-nesting migratory strategy resulted in accordance with that of most adult loggerheads tracked so far, as the nine routes of six turtles were directed towards specific sites all located in the Tunisian continental shelf, a main foraging area for Mediterranean turtles; ii) the pre-breeding migratory routes were rather variable, likely deriving from different navigational strategies adopted by migrating turtles, and their temporal pattern indicates that mating occurred away from the nesting area; iii) the 10 inter-nesting movements of four turtles revealed unusual long-distance loops mostly in oceanic waters (median of maximum distance from nesting location: 145.5km); iv) while at the foraging grounds, four turtles occupied distinct areas during summer and winter, making directed movements between the two sites, seasonal core areas were separated and their size was larger in winter than in summer (median: 498km2 vs. 258km2); v) individual females displayed an high fidelity to both sites in successive years. These findings further highlight the plasticity in loggerhead spatial behaviour and the importance of the Central Mediterranean and of the Tunisian shelf for loggerhead conservation.