Adult phenotypes are shaped by developmental processes during early life. This also applies to reproduction and dominance-related behaviours before maturation, called precocious sexual behaviours. However, beyond largely anecdotal reports, the onset of such behaviours is rarely studied. Here we document the development of precocious sexual behaviours in the ruff Calidris pugnax, a lekking shorebird with pronounced sexual dimorphism and three genetically determined morphs that correspond to alternative reproductive tactics. To document how behaviours develop and diversify, we compiled a comprehensive ethogram in ruff chicks and examined age-related changes in behaviours. Using 6-min video recordings of interactions with a stuffed dummy chick, we analysed occurrence and duration of behaviours in 24 hand-raised chicks (3-15 days post-hatching, every other day). We documented 34 distinct behaviours belonging to five categories: ‘maintenance’, ‘movement’, ‘stationary’, ‘social non-sexual’, and ‘social precocious sexual behaviour’. Behavioural expression in chicks changed markedly with age, largely through shifts in the occurrence of a behaviour. Notably, ‘precocious sexual behaviours’ such as ‘circling’, ‘mounting’, and ‘strutting’, display and mating behaviours typical to adult ruffs, were already expressed from day 5 onwards, increasing in occurrence with age. This suggests that ruff chicks start to express motor coordination of these behaviours long before sexual maturity. The ethogram will function as framework for future analyses, for example to quantify sex, morph, and individual variation, and the developmental origins of complex social behaviours.

Conventional sex roles imply that males compete more vigorously with each other for fertilizations, whereas females are more selective in choosing a mate. As a consequence, mating and reproductive success is typically more variable in males (Bateman's principles). However, Charles Darwin already mused that some species may defy these principles, resulting in stronger sexual selection in females than males, but empirical evidence has been mixed. We studied the potential for sexual selection in two sympatric coucals-a bird family with high sex-role variability. In sex-role-reversed black coucals, females compete for territories while males provide parental care. In white-browed coucals, sex roles are flexible. Females of both species had steeper Bateman gradients than males, suggesting females benefit from multiple mating. Male black coucals benefitted from sneaking copulations with their social mate while she prepared clutches for other mates-a male strategy not conceptually included in Bateman's principles that focuses on the number of mating partners, but not on increasing reproductive success by repeatedly mating with the same partner. Our findings support reversed Bateman's principles, with females having a higher potential for sexual selection than males. Sex-role flexibility allows females to secure additional mates and emancipate themselves from parental care, and it allows males to invest in parental care and emancipate themselves from pre-copulatory competition.

Nest survival is a key determinant of birds' breeding success, particularly in ground-breeding birds, where nest predation is a major cause of reproductive failure. Birds can maximise their nesting success by optimising aspects of the sociospatial environment of a nest, for example, by reducing the risk of predation or flooding. Previous research showed that ruff (Calidris pugnax) females nest closer to leks and to nests of conspecifics, and in some years, further from the shoreline and from meadow edges than expected by chance. However, whether and how social and environmental factors affect nest survival remains unclear. To fill this gap in knowledge, we analysed daily nest survival in a breeding population of ruffs, using nest locations from six breeding seasons. Following a Bayesian approach, we estimated daily nest survival rates to assess the impacts of social, spatial and temporal factors on ruff nest survival in three models focusing on distinct sources of mortality: (i) all sources of mortality (Overall model), (ii) all sources of mortality except for predation (No-predation model) and (iii) only predation (Predation model). We also studied the effects of an intervention to protect nests at increased risk of failure by replacing their eggs with plastic dummies and artificially incubating the collected clutches. Overall, younger nests and those at intermediate distances to other nests had the highest daily nest survival, whereas laying date and distance to paths had a negative effect on daily nest survival in the No-predation model. The use of dummy eggs reduced nest mortality of protected nests at strong risk of failure from flooding and cattle trampling, as well as the impact of predation. We highlight that identifying the sources of nest mortality is necessary to inform species and habitat management, ameliorate productivity and improve the recovery of endangered wader populations.

Sex ratio variation is of fundamental importance for population ecology, and the evolution of sex roles and life-histories. Yet, the ecological mechanisms underlying such variation remain often unknown. Using a multiyear dataset from captive and wild precocial Ruffs Calidris pugnax , we show that poorer survival and later fledging of males relative to females result in a female biased sex ratio of the fledgling population. Both sex-specific survival and maturation time contributed equally to an increasing sex ratio bias from hatching to fledging in this sexually dimorphic bird. On average, juvenile females fledged three days earlier than males due to expedited wing development, despite the higher absolute rate of wing growth in males. We argue that sex differences in growth, maturation, and offspring survival are likely the result of strong pre-sexual selection on males to achieve dominance and may help to enforce the Darwinian sex roles observed in this species. ### Competing Interest Statement The authors have declared no competing interest. Max Planck Society Academy of Finland, 128384, 278759 Ministry of the Environment, https://ror.org/03rtq6c48 Finnish Environment Institute, https://ror.org/013nat269 Kone Foundation, https://ror.org/05jwty529 Deutsche Bundesstiftung Umwelt, https://ror.org/05pmq5w14

Studies on bird behavior have benefited from the miniaturization of tracking devices and the opportunities for massive data collection facilitated by extensive satellite and cellular infrastructures. However, assessments of the effects of tracking devices on the behavior and survival of birds are rarely conducted and disseminated – raising animal welfare concerns, risking project failure, and hindering optimization of tracking methods within the ornithological community. We quantified the effects of tracking devices on banded dotterels Anarhynchus bicinctus – a threatened, small‐bodied (median 59 g), partially migratory shorebird native to New Zealand and a priority for conservation planning on Austral flyways. We deployed ten 1.2‐g archival GPS loggers and ten 1.8‐ to 2‐g Argos satellite transmitters on breeding dotterels in Kaikōura, New Zealand. Including leg rings and silicone‐tubing leg‐loop harness, deployments constituted 2.7–4.3% of an average individual's mass (or 1.9–3.4% for the device alone). Both tracking devices documented the curiously mixed winter strategies characteristic of banded dotterels: migrants flew north to the upper North Island or south to the Canterbury Plains, while other individuals stayed resident in Kaikōura. Compared to a control group of 74 dotterels without tracking devices, neither technology had adverse effects on subsequent breeding outcomes, annual apparent survival, behavior, or body condition, but Argos satellite trackers provided data over a longer period than archival GPS loggers. One possible reason for the absence of adverse effects could be that banded dotterels (and other Charadriinae species) primarily rely on ground‐based locomotion, characterized mainly by walking and running – movements that are less hindered by the added mass of auxiliary attachments. Our findings support the ‘3% rule' (i.e. using device weight alone as a guideline), but we suggest that deployment limits of tracking devices could be refined by considering both the species' ability to carry additional weight and its primary mode of locomotion.

Climate change is expected to raise sea-levels and increase sea-level variation, which can have negative effects on the biodiversity of low-lying coastal areas. Using long-term mareograph (1970-2023) and breeding data (2002-22), we studied the occurrence of wind floods and their influence on breeding success in two endangered wading birds, the southern dunlin (Calidris alpina schinzii) and the ruff (Calidris pugnax) in managed coastal meadows in the northern Baltic Sea. In both species, flooding was an important cause of nest losses (dunlins 23.9 %, ruffs 21.4 %). Nest losses due to flooding increased from 10 % to 46 % during the 20-year dunlin study period, and from 9 % to 49 % during the seven-year ruff study period. Dunlins, but not ruffs, breed now closer to the shoreline than in the beginning of the study period. This can likely be explained by long-term overgrowth and increase in sward height in upper meadows due to lacking or inappropriate management. After a water level rise of 40 cm or more, flood losses in dunlins increased sharply, while in ruffs only moderately. Importantly, the frequency of floods reaching such critical levels has increased during the last 50 years. These flooding events require strong winds, but not actual storm winds. The increased flooding risk should be considered when planning the management of meadow habitats. Narrow elongated areas along shorelines should be avoided. Instead, management should secure attractive short growth habitats in the upper parts of meadows that are safe from flooding.

Androgens are pleiotropic and play pivotal roles in the formation and variation of sexual phenotypes. We show that differences in circulating androgens between the three male mating morphs in ruff sandpipers are linked to 17-beta hydroxysteroid dehydrogenase 2 (HSD17B2), encoded by a gene within the supergene that determines the morphs. Low-testosterone males had higher HSD17B2 expression in blood than high-testosterone males, as well as in brain areas related to social behaviors and testosterone production. Derived HSD17B2 isozymes, which are absent in high-testosterone males but preferentially expressed in low-testosterone males, converted testosterone to androstenedione faster than the ancestral isozyme. Thus, a combination of evolutionary changes in regulation, sequence, and structure of a single gene introduces endocrine variation underlying reproductive phenotypes.

Habitat selection determines an animal's spatial distribution at various scales. In ground-breeding birds, selecting the right nesting location can be decisive for the survival of parents and offspring. However, it remains often unclear what cues birds use to settle in their breeding habitat. Ruffs (Calidris pugnax) are waders with highly divergent sex roles: males aggregate for competitive display to attract females (reeves), who then care for the nest and offspring alone. Ruffs frequently breed in coastal wetlands of higher latitudes where they often face the threat of nest loss because of flooding or predation. We investigated which environmental and social cues determine Ruff nest distributions in a coastal meadow habitat. Using nest locations from five breeding seasons and their relative distance to other nests, leks, the shoreline, and meadow edge, we tested whether Ruff nests are randomly distributed across the suitable breeding habitat or show some level of spatial association. We first compared average nearest neighbor (ANN) distances between Ruff nests (observed and simulated) and spatial features in univariate models. Then, we examined the effect of all spatial features on nest location in a multivariate generalized linear mixed model (GLMM) using a Bayesian framework. Our results show that nest distribution is nonrandom; nests of reeves are found closer to leks of male Ruffs and other nests than expected by chance. In some years, we found nests further away from the meadow edges and shore than expected by chance. Overall, our results suggest that nesting females may use social cues and the distance to habitat boundaries when choosing a nest site. We suggest that understanding the social and environmental factors affecting female nest choice can help to improve the management and conservation routines at the breeding sites of these threatened waders. Our results indicate that lekking sites may be used to identify nesting areas of conservation management value.

Animal-borne trackers are commonly used to study bird movements, including in long-distance migrants such as shorebirds. Selecting a tracker and attachment method can be daunting, and methodological advancements often have been made by trial and error and conveyed by word of mouth. We synthesized tracking outcomes across 2745 dorsally mounted trackers on 37 shorebird species around the world. We evaluated how attachment method, power source, data retrieval method, relative tracker mass, and biological traits affected success, where success was defined as whether or not each tag deployment reached its expected tracking duration (i.e. all aspects succeeded for the intended duration of the study: attachment, tracking, data acquisition, and bird survival). We conducted separate analyses for tag deployments with remote data retrieval ('remote-upload tag deployments') and those that archived data and had to be recovered ('archival tag deployments'). Among remote-upload tag deployments, those that were a lighter mass relative to the bird, were beyond their first year of production, transmitted data via satellite, or were attached with a leg-loop harness were most often successful at reaching their expected tracking duration. Archival tag deployments were most successful when applied at breeding areas, or when applied to males in any season. Remote-upload tag deployments with solar power, satellite data retrieval, or leg-loop harnesses continued tracking for longer than those with battery power, other types of data retrieval, or glue attachments. However, the majority of tag deployments failed to reach their expected tracking duration (71% of remote-upload, 83% of archival), which could have been due to tracker failure, attachment failure, or bird mortality. Our findings highlight that many tag deployments may fail to meet the goals of a study if tracking duration is crucial. Using our results, we provide guidelines for selecting a tracker and attachment to improve success at meeting study goals.

Intraspecific variation provides the substrate for the evolution of organisms. Ruffs show exceptional phenotypic variation in physiology, appearance and behaviour linked to variation between sexes and male alternative reproductive tactics (ARTs). The male ARTs are associated with the evolution of separate morphs, which are encoded by an autosomal supergene. However, the effects of the supergene on females and chicks are much less well understood. In particular, it is still unknown, whether females also show morph-specific behavioural variation, when behavioural differences emerge during ontogeny and whether behavioural differences can be detected outside of the breeding context. To address these knowledge gaps, we repeatedly measured the activity in an unfamiliar environment, also known as exploration behaviour, of 109 hand-raised young ruffs throughout their first two years of life. We used automated tracking in an open field arena and quantified the distance moved within 10 min to examine behavioural differences between sexes, morphs and individuals. After their crouching reflex, which is a response to potential threats, subsided during the first month of life, the activity of young ruffs rapidly increased. Repeatability of individual activity was initially low but increased throughout juvenile ontogeny and was high (R = 0.5) from day 21 onwards. Variation in activity was clearly sex-linked with females moving more than males, indicating potential energetic trade-offs accompanying the strong sexual size dimorphism. In contrast, morph differences in activity remained inconsistent and elusive, both in females and in males. Our results indicate that in species in which much of the known behavioural variation is linked to mating tactics, a non-reproductive behaviour can show between-individual variation and clear-sex differences, whereas morph differences appear less pronounced.

The ruff sandpiper (Calidris pugnax) is a lekking shorebird with three male morphs that differ remarkably in behavior, ornaments, size, and endocrinology. The morphs are determined by an autosomal inversion. Aggressive Independents evolved first, female-mimicking Faeders ~4 mil year ago when a short segment of a chromosome reversed in orientation, and semi-cooperative Satellites ~70,000 years ago through a recombination of the Independent and Faeder inversion-segment genotypes. Although the genetic differences between the morphs affect numerous phenotypic traits, it is unknown whether they also affect sperm traits. Here, we use a captive-bred population of ruffs to compare ruff sperm to that of other birds and compare sperm swimming speed and morphology among the morphs. Ruff sperm resembled those of passerines, but moved differently. Faeder sperm moved the slowest and had the longest midpiece. Independents’ sperm were neither the fastest nor the least variable, but had the shortest tail and midpiece. Although the midpiece contains the energy-producing mitochondria, its length was not associated with sperm swimming speed. Instead, two of three velocity metrics weakly positively correlated with head length (absolute and relative). We conclude that there is an indication of quantitative differences in sperm between morphs, but no clear sperm polymorphism.

Camouflage represents an important component of self-protection when animals cannot easily evade predators and is often altered by behavioural responses to a predation threat. The cryptic plumage of many precocial chicks inspired early theoretical work on camouflage mechanisms, but so far, limited efforts have gone towards empirically testing the crypsis of chick plumage properties in their natural environment. We studied background matching and hiding behaviour in precocial snowy plovers Charadrius nivosus in Bahia de Ceuta, Northwest Mexico. This ground-nesting wader breeds in sparsely vegetated open habitats such as salt flats and sandy beaches. The open habitats provide a challenge for young chicks to evade predator detection. Examining background matching of wild chicks for luminance, pattern and colouration at their hiding spots, we found that chicks matched the luminance of their chosen spot better than at unchosen nearby spots. Pattern and colouration matching were age-related, with the plumage of older chicks matching their hiding spots better than those of recently hatched chicks. This suggests that with increasing mobility, chicks may be better able to find hiding places that optimise camouflage. Finally, we found that chicks were more likely to hide in soil cracks than expected by chance, suggesting that chicks chose these soil features in a barren landscape as preferred hideouts. We conclude that the cryptic plumage is an understudied but essential part of the anti-predator repertoire of precocial chicks. The plumage most likely works hand-in-hand with the anti-predator behaviours of chicks and their parents to increase survival chances of precocial young. Many chicks rely on effective camouflage to evade predators and survive until fledging. We studied how plumage characteristics and behavioural choices enable snowy plover chicks to hide effectively from approaching predators in an open landscape. These chicks leave their nest scrapes shortly after hatching, relying on their cryptic plumage for several weeks to evade predator detection. We found that chicks chose hiding spots where their plumage had a higher match in luminance and, for older chicks, a higher match in pattern and colouration than at adjacent spots. When available, chicks chose to hide in small cracks that appeared in the soil from the evaporation of moisture. This study represents the first quantitative characterisation of cryptic chick plumage features in a natural population. Our results demonstrate that plumage and behavioural responses jointly contribute to the effective camouflage of small chicks.

Species with alternative reproductive tactics typically show pronounced phenotypic variation between and within sexes. In some species, this variation culminates in discrete reproductive morphs that are genetically determined, facilitating studies on how genetic variation translates into phenotypic variation. In ruffs (Calidris pugnax), an autosomal inversion polymorphism underlies three reproductive morphs (Independents, Satellites and Faeders), which differ in circulating steroid concentrations in adults. Yet, it remains unknown whether morph differences in steroid concentrations already arise before adulthood. We examined variation in circulating testosterone, androstenedione and progesterone concentrations between morphs and sexes in ruff chicks and juveniles and compared the differences to those in adults. Since measured hormone concentrations only provide momentary states and show high within- and between-individual variation, we took repeated measurements to compare means, variances and skewness between groups. We found clear differences between morphs but not the sexes in early life. Between morphs, androgen concentrations in young ruffs differed in variance and skewness, but not in their means. For testosterone, Independents had a higher variance than Satellites/Faeders, whereas for androstenedione, we observed the opposite pattern. For progesterone, we did not detect clear differences between groups. Skewness values mirrored differences in morph variances. Compared to adults, premature ruffs had lower androgen concentrations. In both life stages, we detected morph-specific associations between androgen concentrations: androstenedione concentrations increased with testosterone concentrations more in Satellites/Faeders than in Independents. These observed morph differences during early life are consistent with a supergene-mediated regulation of androgen variation that underlies the diversification of adult behavioural phenotypes.

Male–male competition over matings is a key driving force in the evolution of courtship. Typically, male–male competition is an individual affair selecting for dominance and aggression. Yet, some males forgo direct confrontation improving their reproductive success through cooperation. Occasionally, this leads to specialized alternative reproductive tactics that operate at the intersection of cooperation and conflict. We informed a community game model with empirical data derived from previous studies, to examine cooperation dynamics between lekking male ruffs, Calidris pugnax, using two tactics: resident and satellite. Residents defend display courts against one another on leks of up to seven residents. Nonaggressive satellites forgo court defence and engage in cooperative co-displays with residents. Previous studies suggest such co-displays alter female mate choice, yet the exact magnitude and consequences remain unclear. We modelled the propensity for resident/satellite co-display by examining its influence on male mating success. Male mating success was a function of lek size, resident rank, satellite competitiveness within a co-display and female preference for co-display. We assumed that co-display alters female preference such that copulations are drawn from single display courts to co-display courts proportional to the existing resident mating skew. Under this assumption, all residents benefit from co-display over single display, except for α-residents co-displaying with the most competitive satellites on large leks. Thus, satellites could predominantly choose their preferred co-display partner, but achieved the highest copulation rates with lower-ranking residents on intermediate-sized leks. Co-display between the satellite and lower-ranking residents reduced the resident mating skew. However, satellite copulation rates were similar over a range of co-display partners, meaning that a variety of co-display dyads is possible, which is consistent with observations in nature. We conclude that, given our model assumptions, co-displaying reduces the impact of male dominance on mating success and ultimately alters the course of sexual selection.

Background The ruff sandpiper Calidris pugnax is a Palearctic lekking shorebird with three genetic morphs determined by an autosomal inversion. Male morphs differ strikingly in body size, ornaments, endocrinology and mating behavior. Aggressive Independents represent the ancestral haplotype, while female-mimicking Faeders and semi-cooperative Satellites are the inverted haplotypes. Because one inversion breakpoint is homozygous lethal, the inverted haplotypes cannot recombine and are expected to accumulate deleterious mutations. The inversion regions also harbor genes involved in spermatogenesis. However, it remains unknown whether the genetic differences between the morphs also translate into differences in sperm traits. Here, we use a captive-bred population of ruffs to compare sperm swimming speed and morphology among the morphs.Results Ruff sperm morphologically resembled those of passerines, but moved differently, vibrating from side to side while slowly moving forward, rather than rotating while moving forward. Faeder sperm moved the slowest, which is consistent with the prediction of genetic deterioration over time. However, against expectation, sperm of Independents did not seem to be of the highest quality, i.e., their sperm were not the fastest nor the least variable, and they had sperm with the shortest tail and midpiece. Although the midpiece contains the energy-producing mitochondria, sperm midpiece length was not associated with sperm swimming speed. Instead, two of three velocity metrics weakly positively correlated with head length (absolute and relative).Conclusions The three genetically determined ruff morphs showed subtle differences in swimming speed and in the length of some sperm components. However, the between-morph differences in sperm swimming speed were not linked to the differences in morphology. We conclude that there is at best limited evidence for lower-quality sperm in the morphs that carry the inversion, and suggest that the potential for the evolution of morph-specific sperm adaptations may be limited in this system.Lay Summary The ruff sandpiper is a shorebird that exhibits three genetically distinct types of males, which differ markedly in body size, ornaments, hormones, and mating behavior. Aggressive Independents represent the type that evolved first. Semi-cooperative Satellites and female-mimicking Faeders evolved later through a specific type of genetic rearrangement called an ‘inversion’, in which a segment of a chromosome reversed in orientation. Due to the nature of this inversion, Satellite and Faeder chromosomes are expected to deteriorate over time. However, it remains unclear whether the genetic differences between these morphs, which affect physiological and behavioral traits, also translate into differences in sperm traits. We used a captive population of ruffs to compare sperm swimming speed and length measurements between the three types of males. Faeder sperm was the slowest, which is consistent with expectations based on genetic deterioration over time. However, against our expectations, the sperm of Independents does not appear to have better performance characteristics. Although the midpiece of a sperm is responsible for energy production, the length of the midpiece did not relate to sperm swimming speed.### Competing Interest StatementThe authors have declared no competing interest.

BACKGROUND AND PURPOSE:Acute ischemic stroke due to basilar artery occlusion (BAO) causes the most severe strokes and has a poor prognosis. Data regarding efficacy of endovascular thrombectomy in BAO are sparse. Therefore, in this study, we performed an analysis of the therapy of patients with BAO in routine clinical practice.METHODS:Patients enrolled between June 2015 and December 2019 in the German Stroke Registry-Endovascular Treatment (GSR-ET) were analyzed. Primary outcomes were successful reperfusion (modified Thrombolysis in Cerebral Infarction [mTICI] score of 2b-3), substantial neurological improvement (≥8-point National Institute of Health Stroke Scale [NIHSS] score reduction from admission to discharge or NIHSS score at discharge ≤1), and good functional outcome at 3 months (modified Rankin Scale [mRS] score of 0-2).RESULTS:Out of 6635 GSR-ET patients, 640 (9.6%) patients (age 72.2 ± 13.3, 43.3% female) experienced BAO (median [interquartile range] NIHSS score 17 [8, 27]). Successful reperfusion was achieved in 88.4%. Substantial neurological improvement at discharge was reached by 45.5%. At 3-month follow-up, good clinical outcome was observed in 31.1% of patients and the mortality rate was 39.2%. Analysis of mTICI3 versus mTICI2b groups showed considerable better outcome in those with mTICI3 (38.9% vs. 24.4%; p = 0.005). The strongest predictors of good functional outcome were intravenous thrombolysis (IVT) treatment (odds ratio [OR] 3.04, 95% confidence interval [CI] 1.76-5.23) and successful reperfusion (OR 4.92, 95% CI 1.15-21.11), while the effect of time between symptom onset and reperfusion seemed to be small.CONCLUSIONS:Acute reperfusion strategies in BAO are common in daily practice and can achieve good rates of successful reperfusion, neurological improvement and good functional outcome. Our data suggest that, in addition to IVT treatment, successful and, in particular, complete reperfusion (mTICI3) strongly predicts good outcome, while time from symptom onset seemed to have a lower impact.

Gamete size variation between the sexes is central to the concept of sex roles, however, to what extent gamete size variation within the sexes relates to sex role variation remains unclear. Comparative and theoretical studies suggest that, when clutch size is invariable, polyandry is linked to a reduction of egg size, while increased female-female competition for mates favors early breeding when females cannot monopolize multiple males. To understand whether and how breeding phenology, egg size, and mating behavior are related at the individual level, we studied the reproductive histories of 424 snowy plover females observed in the wild over a 15-year period. Egg size, but not polyandry, were highly repeatable for individual females. Consistent with theoretical predictions, we found that polyandrous females were the earliest breeders and that early clutches contained smaller eggs than clutches initiated later. Neither egg size nor mating behavior showed clear signs of an age-related deterioration, on the contrary, prior experience acquired either through age or local recruitment enabled females to nest early. Taken together, these results suggest that gamete size variation is not linked to mating behavior at the individual level, and, consequently, the adaptive potential of such variation appears to be limited.

OBJECTIVES:Data regarding MR vessel-wall imaging (VWI) in patients with Moyamoya disease (MMD) is sparse, particularly in non-asian cohorts. We contribute data regarding the frequency of vessel wall contrast-enhancement (VW-CE) and its potential clinical significance in a European patient group.MATERIALS AND METHODS:Patients with a diagnosis of MMD who were examined by VWI were included in the study. VW-CE of stenoocclusive lesions of the terminal internal carotid artery and/or its proximal branches was rated qualitatively. Changes of VW-CE on available follow-up were recorded. VW-CE was correlated with diffusion-restricted lesions and magnetic resonance angiography (MRA) findings.RESULTS:Eleven patients (eight female, three male) were included. Twenty-eight stenoocclusive lesions were analyzed, of which 16 showed VW-CE (57.1%). VW-CE was mostly concentric (n=15), rather than eccentric (n=1). In all three patients in whom follow-up VWI was available, changes of VW-CE were documented. Diffusion-restricted lesions were more frequently related to stenoocclusive lesions with VW-CE (n=9) than without VW-CE (n=2), bordering statistical significance. The affected arteries were assessed as stenotic and as occluded in 14 cases each and VW-CE was seen significantly more often in stenotic (n=12) than in occluded arteries (n=4). No correlation was found between the presence of VW-CE and moyamoya stages determined by MRA.CONCLUSIONS:Our data suggest that concentric VW-CE is a relatively frequent finding in European MMD patients. VW-CE may change over time and occur in certain stages, possibly representing "active stenosing". Larger studies are needed to validate these findings and determine the clinical relevance of VW-CE in MMD.

Dispersal is an important behavioral process that plays a significant role in, among others, speciation, population viability, and individual fitness. Despite progress in avian dispersal research, there are still many knowledge gaps. For example, it is of interest to study how dispersal propensity relates to age- and/or sex-specific patterns. Here, we investigated the role of sex and life stage on natal (i.e., movement from birth site to first breeding site) and breeding dispersal (i.e., movement between sequential breeding sites) in the Kentish Plover ( Charadrius alexandrinus ) for dispersal events of more than 10 km. This small and inconspicuous wader is characterized by flexible mating behavior that includes monogamy, and serial polygynandry. Using a continent-wide dataset of ringing and re-encounter data throughout the species’ range in Europe, we found that adult females generally dispersed further than adult males between seasons, but we detected no sex difference in natal dispersal distances and no general difference between natal and breeding dispersal distances. Furthermore, females were the main group exhibiting ‘long-distance’ breeding dispersal, which we defined as dispersal greater than ≥ 108 km, i.e., the upper 10% percentile of our dataset. The data set included dispersal of two females that first bred in the Mediterranean before being detected breeding at the North Sea in the subsequent year, having dispersed 1290 and 1704 km, respectively. These observations represent the longest breeding dispersal observed within the genus Charadrius. Our long-distance dispersal records are consistent with low genetic differentiation between mainland populations shown in previous work. The dispersal of the Kentish Plover is likely linked to its breeding behavior: polyandrous females exhibit extensive mate searching and habitat prospecting. We recommend that the dispersal traits of Kentish Plover be incorporated into the species’ conservation and management planning to more accurately inform models of population connectivity and metapopulation dynamics.