Moult Patterns Research Articles

Molt Patterns, Biometrics, and Age and Gender Classification of Landbirds on Saipan, Northern Mariana Islands

Abstract Molt strategies and plumage development by age and gender are poorly understood for resident tropical landbirds. We used data from six banding stations on Saipan, Northern Mariana Islands, and examination of 267 museum specimens to describe patterns of molt and to establish criteria for assessing age and gender of nine native resident landbird species on the island. Feather replacement sequences in the majority of Saipan's resident landbirds were typical of related species. Preformative molts occurred in at least eight of the nine species; these and definitive prebasic molts were incomplete to complete, and prealternate molt appeared to be absent for all species. We developed criteria for classifying gender of sexually dimorphic species using plumage cues, presence of brood patch or cloacal protuberance, and biometrics. We confirmed whether or not both brood patch and cloacal protuberance were reliable indicators of gender during breeding in monomorphic species. Distinct periods or seasons of mol...

Seasonality of breeding, moult and fat deposition of birds in subtropical lowlands of southern Brazil

The circannual timing of migration, breeding and moult is fundamental for understanding avian life histories. However, much of our knowledge of such processes is derived from studies of bird of temperate regions, with few studies on subtropical or tropical birds. We studied the annual patterns of moult, development of brood patches and fat deposition in a subtropical lowland bird community in southern Brazil and examined the relationship between these patterns and temperature, precipitation and day length. We made 1702 captures of 97 species of birds. Moult and breeding overlap partially in the overall community. Moult of contour feathers occurred year-round, whereas moult of flight feathers occurred from the end of October to the end of May. Migratory species had a shorter moult period than resident species. Breeding peaked in spring (September-December). Fat was deposited seasonally, and the fattest individuals were observed between the end of the moult period and the beginning of breeding. Our data showed that ultimate factors (photoperiod and temperature) influenced vital processes of the life cycles of birds studied. The patterns detected in the seasonality and duration of breeding, moult and fat deposition in this community are generally similar to those of birds in temperate zones.

Combining stable isotope analyses and geolocation to reveal kittiwake migration

Determining migratory strategies of seabirds is still a major challenge due to their relative inaccessibility. Small geolocators are improving this knowledge, but not all birds can be tracked. Stable isotope ratios in feathers can help us to understand migration, but we still have insufficient baseline knowledge for linking feather signatures to movements amongst distinct water masses. To understand the migration strategies of kittiwakes Rissa tridactyla and the link between stable isotopes in feathers and the areas in which these were grown, we tracked 6 kittiwakes from Hornoya, Norway, with light level geolocators over 1 yr. Then we analysed the stable isotopes of carbon and nitrogen in their 1st and 7th primary feathers as well as in the 1st, 3rd, 5th, 7th and 10th primaries of 12 birds found freshly dead in the same breeding colony. After breeding, all tracked birds moved east of the Svalbard Archipelago and subsequently migrated to the Labrador Sea. Thereafter, birds showed individual variation in migration strategies: 3 travelled to the NE Atlantic, whereas the others remained in the Labrador Sea until the end of the wintering period. Changes in stable isotope signatures from the 1st to the 10th primary feathers corresponded well to the sequence of movements during migration and the area in which we inferred that each feather was grown. Thus, by combining information on moult patterns and tracking data, we demonstrate that stable isotope analysis of feathers can be used to trace migratory movements of seabirds.

Body feathers as a potential new biomonitoring tool in raptors: A study on organohalogenated contaminants in different feather types and preen oil of West Greenland white-tailed eagles ( Haliaeetus albicilla)

We investigated the variation in concentrations and profiles of various classes of organohalogenated compounds (OHCs) in different feather types, muscle tissue and preen oil from 15 white-tailed eagle ( Haliaeetus albicilla) carcasses from Greenland. The influence of moult patterns and potential external contamination onto the feather surface was examined, while the present study is also the first to investigate the use of body feathers for OHC monitoring. Concentrations of sum polychlorinated biphenyls (PCBs) in feathers from white tailed eagles ranged from 2.3 ng/g in a primary wing feather to 4200 ng/g in body feathers. Using 300 mg of body feathers, almost 50 different OHCs could be quantified and median concentrations in body feathers were 10 fold higher than concentrations in tail feathers (rectrices) or primary wing feathers. Body feathers could be very useful for biomonitoring taking into account their easy sampling, short preparation time and high levels of OHCs. In addition, the effects of confounding variables such as feather size, moult and age are also minimised using body feathers. Correlations with concentrations in muscle tissue and preen oil were high and significant for all feather types ( r ranging from 0.81 to 0.87 for sum PCBs). Significant differences in concentrations and profiles of OHCs were found between different primary feathers, indicating that the accumulation of OHCs in feathers varies over the moulting period (maximum three years). Washing of feathers with an organic solvent (acetone) resulted in a significant decrease in the measured concentrations of OHCs in feathers. However, our results indicated that preen oil is probably not the only contributor to the external contamination that can be removed by washing with acetone. Possibly dust and other particles may be of importance and may be sticking to the preened feathers. Rectrices washed only with water showed high and significant correlations with concentrations in muscle and preen oil as well. Washing with acetone therefore does not seem to be of great influence when relating to internal tissue concentrations. We recommend washing feathers only with distilled water in order to remove dirt and dust particles before analysis.

Moult pattern of primaries and secondaries in Eagle Owls <em>Bubo bubo</em>

Myting av vingefjaer ble studert hos 42 hubroskinn med kjent alder. I sitt andre levear starter hubroene med a myte de tre innerste armsvingfjaerene (S13-15). Neste sommer fortsetter armsvingfjaermytingen utover fra disse, samtidig med at handsvingfjaer P7 mytes. Mange fugler skifter ogsa handsvingfjaer P6 og P8 dette aret. I sin tredje vingefjaermyting (fjerde kalenderar) kan hubroene felle de siste armsvingfjaerene, men de beholder som regel de innerste 2-3 (4) handsvingfjaerene som juvenile. Til og med etter sin fjerde vingefjaermyting i femte kalenderar kan noen hubroer ha noen, eller i det minste en, juvenil vingefjaer tilbake. Siden noen hubroer likevel kan ha skiftet alle juvenile vingefjaer ved fjerde svingfjaermyting, bor hubroer ikke aldersbestemmes pa grunnlag av mytemonster hoyere enn 5K+ pa hosten og 6K+ om varen. Skandinaviske hubroer ser ut til a skifte vingefjaer i langsommere tempo enn andre store ugler.

Seasonal patterns of breeding, moulting, and body mass variation in Pyrenean Common Crossbills Loxia curvirostra curvirostra

The aim of this study was to investigate the relationship between breeding, moulting and fuel load of Common Crossbills Loxia curvirostra curvirostra inhabiting a Scots pine Pyrenean forest. Data were collected from two locations (Sierra de Uztarroz and Bigüezal) in northern Iberia by systematic mist netting between 2000 and 2008. Breeding females were detected in most months of the year except June, October and November, and with two main peaks, one in late winter (March), and another in the summer (August). Between years, reproduction was more variable in some months than in others, particularly in summer months. This suggests that breeding during the summer was more likely to be influenced by external factors and relatively opportunistic compared to winter breeding. Moulting adults of both sexes were captured during almost every month with a unimodal pattern peaking in June, similar to the pattern described for Mediterranean Crossbills. Moulting did not overlap with breeding, and our data do not support suspended moult patterns. Mean fat scores overall were low and, as was the case for body mass, showed little month-to-month variation.

Age structure and age-related differences in molt status and fuel deposition of Dunlins during the nonbreeding season at Chongming Dongtan in east China

Although most shorebirds exhibit deferred migration and deferred breeding during their first summer, Dunlins (Calidris alpina) migrate to breeding areas and breed during their first summer. First-year and adult Dunlins should, therefore, have similar fueling and molt patterns if energetic and physiological constraints are responsible for deferred migration. From 2006 to 2008, we examined the age structure of Dunlins during the nonbreeding season at Chongming Dongtan, an estuarine wetland in the Yangtze River estuary in east China, and examined the effects of date, age, and molt status on fuel deposition during migration and during the winter. The Dunlin population at Chongming Dongtan was composed primarily of first-year birds. Most adults and first-year birds arrived together in late August. Regression analyses indicated that age, date, and molt status affected fuel deposition (as indicated by body mass) of Dunlins. Adults had significantly greater fuel deposits than first-year Dunlins near the end of northward migration (May: adults 70.8 ± 6.4 g, first-year 63.8 ± 8.0 g) and at the start of southward migration (September: adults 50.2 ± 6.1 g, first-year 47.2 ± 4.9 g). Adults also had significantly higher fuel deposition rates than first-year Dunlins during northward migration. Nonetheless, first-year Dunlins migrate and breed in their first summer. Thus, other factors, such as migration distance and body size, may be more important in determining if first-year shorebirds defer migration during their first spring and summer. During boreal spring and autumn, first-year Dunlins in active body molt had greater body mass than those that had not initiated body molt or those in suspended molt, and premigratory fuel deposits for northward migration were greatest after prealternate molt was completed. These results suggest that body molt requires additional fuel deposits and imposes a constraint on fuel deposition for migratory flights. ©2011 The Authors. Journal of Field Ornithology

The first record of a female hybrid between the Common Nightingale (Luscinia megarhynchos) and the Thrush Nightingale (Luscinia luscinia) in nature

Understanding the mechanisms causing reproductive isolation between incipient species can give important insights into the process of species origin. Here, we describe a record of a hybrid female between two closely related bird species, the Common Nightingale (Luscinia megarhynchos) and the Thrush Nightingale (L. luscinia). These species are separated by incomplete prezygotic isolation, and the occurrence of fertile hybrid males in nature has been documented before. Our record represents the first genetically confirmed evidence of the occurrence of hybrid females between these two species in nature. Although the hybrid female was captured in the peak of the breeding season in suitable habitat, it did not show any sign of reproductive activity, suggesting that it was sterile. This observation together with previous experimental work in captivity suggests that hybrid female sterility plays an important role in reproductive isolation in nightingales. Unexpectedly, the hybrid female had highly developed fat reserves and was in the process of moulting, which in nightingales normally occurs approximately 1 month later. This unusual moult pattern could contribute to lower fitness of hybrid females and thus to speciation in nightingales.

Infaunal molting in Trilobita and escalatory responses against predation

Research Article| May 01, 2011 Infaunal molting in Trilobita and escalatory responses against predation Juan J. Rustán; Juan J. Rustán * CICTERRA -CIPAL (Centro de Investigaciones en Ciencias de la Tierra–Centro de Investigaciones Paleobiológicas, CONICET–Universidad Nacional de Córdoba), Avenida Vélez Sársfield 299, C.P. 5000 Córdoba, Argentina *E-mail: jjrustan@conicet.gov.ar. Search for other works by this author on: GSW Google Scholar Diego Balseiro; Diego Balseiro CICTERRA -CIPAL (Centro de Investigaciones en Ciencias de la Tierra–Centro de Investigaciones Paleobiológicas, CONICET–Universidad Nacional de Córdoba), Avenida Vélez Sársfield 299, C.P. 5000 Córdoba, Argentina Search for other works by this author on: GSW Google Scholar Beatriz Waisfeld; Beatriz Waisfeld CICTERRA -CIPAL (Centro de Investigaciones en Ciencias de la Tierra–Centro de Investigaciones Paleobiológicas, CONICET–Universidad Nacional de Córdoba), Avenida Vélez Sársfield 299, C.P. 5000 Córdoba, Argentina Search for other works by this author on: GSW Google Scholar Rodolfo D. Foglia; Rodolfo D. Foglia CICTERRA -CIPAL (Centro de Investigaciones en Ciencias de la Tierra–Centro de Investigaciones Paleobiológicas, CONICET–Universidad Nacional de Córdoba), Avenida Vélez Sársfield 299, C.P. 5000 Córdoba, Argentina Search for other works by this author on: GSW Google Scholar N. Emilio Vaccari N. Emilio Vaccari CICTERRA -CIPAL (Centro de Investigaciones en Ciencias de la Tierra–Centro de Investigaciones Paleobiológicas, CONICET–Universidad Nacional de Córdoba), Avenida Vélez Sársfield 299, C.P. 5000 Córdoba, Argentina Search for other works by this author on: GSW Google Scholar Geology (2011) 39 (5): 495–498. https://doi.org/10.1130/G31879.1 Article history received: 04 Nov 2010 rev-recd: 07 Jan 2011 accepted: 12 Jan 2011 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Juan J. Rustán, Diego Balseiro, Beatriz Waisfeld, Rodolfo D. Foglia, N. Emilio Vaccari; Infaunal molting in Trilobita and escalatory responses against predation. Geology 2011;; 39 (5): 495–498. doi: https://doi.org/10.1130/G31879.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The outstanding fossil record of trilobites contrasts with our limited knowledge of their lifestyles and strategies. Aspects such as infaunalism and behavioral defensive skills in this group have yet to be demonstrated conclusively. We report new insights based on a striking sclerite configuration exhibited by three phacopid trilobite species, part of a late Silurian–Early Devonian Paciphacops (Paciphacops) Maksimova, 1972, lineage. An unusual molt pattern provides compelling evidence of infaunal behavior, which accounts for a hiding, antipredatory adaptation. In addition, strengthening of the exoskeleton and acquisition of spines indicate an evolutionary trend toward morphological defensive strategies. Both trends in active and passive traits are considered escalatory in nature, thus providing unequivocal support for understanding the ecological role of trilobites as a main prey group in the context of the global diversification of predators recorded during middle Paleozoic time. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Moult pattern of primaries and secondaries during first and second flight feather molt in Great Grey Owls Strix nebulosa

Great Grey Owls start flight feather moult when in their second year. Moult was studied on outspread wings of 58 individuals in the collections at Naturhistoriska Riksmuseet in Stockholm. The owls always moulted the innermost secondaries in their first moult, and usually at least two primaries, most often P5 and P6. After this moult, birds had 11–17 juvenile feathers left in each wing, of a total of 21 flight feathers. In their second flight feather moult, birds shed primaries outwards and inwards from the primaries moulted during the first moult. A variable number of secondaries outwards from S10 and S11 were moulted. All birds retained at least one juvenile feather, always P1. The number of juvenile flight feathers after the second moult was 1–6. The collection held no individuals known to be in their third flight feather moult. Thus it was not possible to determine whether birds in this age group could be aged by the wing moult pattern. Great Grey Owls with no juvenile flight feathers should thus be classified as 4C+ in autumn, and 5C+ in spring.

Platypus (Ornithorhynchus anatinus) body size, condition and population structure in Tasmanian river catchments: variability and potential mucormycosis impacts

Context Despite widespread interest in platypus (Ornithorhynchus anatinus) conservation, it is unclear how their fundamental morphometric and demographic characteristics differ over a range of scales. This hampers impact assessments and understanding of platypus ecology. Although the ulcerative fungal disease mucormycosis has infected platypuses in Tasmania for three decades, its population level impacts and conservation significance remain unknown. Aims This study examined morphometric and demographic patterns in Tasmanian platypuses to provide a basis for investigating impacts of mucormycosis or other anthropogenic disturbances. It also sought to identify important spatial scales of natural variability and the magnitude of seasonal variation in platypus body size, condition and population structure. The hypothesis of higher mucormycosis prevalence and mortality in adult males was also investigated. Methods Extensive live-trapping surveys were conducted from January 2008 to July 2009 in 75 streams and 18 river catchments across Tasmania including King Island. The sex, age, body size, tail volume index, health and moult condition of 195 individuals were assessed, and population age and sex structures characterised. Sampling focussed on assessing variability within and between river catchments and compared populations in river catchments with contrasting disease status. Key results Differences in platypus morphometrics within and between catchments and seasonal moulting patterns were detected. Adult males had higher fat stores than adult females, especially during winter. This study also provided the first evidence of population level consequences of disease in platypuses. The demographic group most commonly affected by mucormycosis was confirmed to be adult males. Differences in male age structure among catchments of varying disease status were consistent with the hypothesis of higher adult male mortality rates and turnover in currently affected catchments. Conclusions More than 25 years after mucormycosis was first detected in Tasmanian platypuses, the disease continues to play a low-level, ongoing role in affected populations. Implications The present study provides the first systematic multi-scale spatial investigation of platypus mucormycosis, which contributes to unravelling the epidemiology of the disease and detecting its impacts. By identifying the magnitude and important scales of morphometric and demographic differences in Tasmanian platypuses the study also assists researchers choose comparable demographic groups and spatial scales for meaningful comparisons in future impact studies.

Pattern of Post-Juvenile Moult in Common Snipe (Gallinago Gallinago) and Its Implications for Ageing of the Species

External ageing of Common Snipe (Gallinago gallinago) still engenders considerable problems. To improve precision of age determination on the basis of plumage characteristics a scheme of post-juvenile moult was investigated in approximately 1200 first-year Common Snipes caught during autumn migration in central Poland. Post-juvenile moult was commenced from body feathers followed by moult of rectrices, lesser/median wing coverts and tertials. Moult sequence showed high inter-individual variability and was started in rectrices (36.9%), wing coverts (25.3%), tertials (8.4%) or simultaneously in several of these tracts of feathers (29.4%). Moult of rectrices was finished before completion of moult of wing coverts and tertials. Moult of tertials finished as the last from all age-indicative tracts of feathers. Consequently, tertials were suggested as the most useful for ageing of first-year Common Snipes in an advanced stage of moult. There was no case of moult of the outermost tertial in first-year birds. The second tertial from distal side of wing was moulted as the last one within this tract of feathers and thereby should be of special interest during plumage examination.

Implications of Prebasic and a Previously Undescribed Prealternate Molt For Aging Rusty Blackbirds

Abstract. Aging birds often relies on differences in plumage between immatures and adults, and understanding these patterns can improve our ability to discern demographic patterns within populations. We investigated patterns of prebasic molt of the Rusty Blackbird (Euphagus carolinus) in fall at Whitehorse, Yukon Territory, and developed a new technique for aging based on characteristics of the head plumage acquired during prebasic molt. Furthermore, we investigated the possibility of a prealternate molt among wintering Rusty Blackbirds on the basis of captures in Mississippi and museum specimens from across the species' winter range. Finally, we examined how a prealternate molt might affect the aging of winter birds by plumage. Rusty Blackbirds completed their prebasic molt by the end of September, and immature birds had a more prominent eye ring and a paler chin than adults, allowing a reliable age determination. Previously, the Rusty Blackbird was thought to attain its breeding plumage through feather ...

Relationships among timing of moult, moult duration and feather mass in long‐distance migratory passerines

Moult is a costly but necessary process in avian life, which displays two main temporal patterns within the annual cycle of birds (summer and winter moult). Timing of moult can affect its duration and consequently the amount of material invested in feathers, which could have a considerable influence on feather structure and functionality. In this study, we used two complementary approaches to test whether moult duration and feather mass vary in relation to the timing of moult. Firstly, we conducted a comparative study between a sample of long‐distance migratory passerine species which differ in moult pattern. Secondly, we took advantage of the willow warbler's Phylloscopus trochilus biannual moult, for which it is well‐known that winter moult takes longer than summer moult, to assess between‐moult variation in feather mass. Our comparative analysis showed that summer moulting species performed significantly shorter moults than winter moulters. We also detected that feathers produced in winter were comparatively heavier than those produced in summer, both in between‐species comparison and between moults of the willow warbler. These results suggest the existence of a trade‐off between moult speed and feather mass mediated by timing of moult, which could contribute to explain the diversity of moult patterns in passerines.

Connectivity and Age Distribution of the Baltic Common GuillemotUria aalgePopulation: Evidence from Morphometry and Ringing Recoveries

In evolutionary ecology, environmental monitoring and conservation management, reliable information on phenotypic and demographic traits in marine seabirds is highly wanted, but difficult to acquire. Therefore, freshly dead Common Guillemots Uria aalge (n = 149) incidentally drowned in salmon drift gill nets in the Baltic Sea, during October—November, were studied. We noted age, sex, moult pattern and fat status, and took morphometric measurements to compare with data from the Northeast Atlantic population. Only minor phenotypic differences were found. The birds had slightly longer wings than expected at the latitude where they were collected, probably due to their newly grown primaries and/or observer differences, rather than a genetic divergence. The Baltic Guillemot appears not to be a distinct subspecies, but only the marginal member of a deme. Ringing recoveries also suggest intermittent exchange of birds between the Baltic and the North Sea. Young birds did not seem to be over-represented in gill net bycatches. Our found age distribution — with a heavy dominance of adult birds, but few immature/juveniles — deviated from that reported earlier, and suggests that the population is more vulnerable to adult mortality through bycatch in gill nets than previously believed.

Achieving luster: prenuptial molt pattern predicts iridescent structural coloration in Blue-black Grassquits

Colors in feathers are produced by pigment deposition or by nanostructures within barbs or barbules. In the absence of pigments or nanostructures, light is scattered incoherently, producing white coloration. Honest advertisement models predict that ornamental colors evolve if they reliably signal individual properties such as viability, health, or nutritional state. In this study, we tested if (1) iridescent structural and (2) unpigmented plumage coloration signal male quality in the Blue-black Grassquit (Volatinia jacarina). During three reproductive seasons, we captured males and measured morphological variables and nuptial plumage coverage, and collected feathers for spectrometry. We found that saturation of the iridescent coloration was positively related to relative molting speed, indicating that males investing more in prenuptial molt also produced more saturated, UV-shifted plumage. Body condition was not related to brightness or saturation of the iridescent plumage, and no male morphological attributes were associated with the white underwing patch coloration or size. Our results suggest that patterns of molt, and possibly feather growth, may affect the organization of optical nanostructures responsible for iridescent coloration, and that the ontogeny of iridescent plumage ornaments must be taken into account in hypotheses concerning honest advertisement of such signals. Thus, coloration in this species may reliably reflect energy allocation to molting, constituting an honest indicator of male quality, life history decisions, or endocrine state. To our knowledge, this is the first report of natural variation in molting pattern being associated with sexually-selected structural color plumage.

Flight Feather Molt of Turkey Vultures

We document the molt sequence of flight feathers in Turkey Vultures (Cathartes aura) based on studies of captive and wild birds, and examination of museum specimens. We found an unusual pattern of primary replacement, which appears to be a modified form of Staffelmauser, or stepwise wing molt. A Staffelmauser-like strategy for replacement of the secondaries is also described. These patterns of feather replacement appear to be adaptations to maintain flying performance while replacing all primaries and most secondaries during each molt. To what extent molt patterns in Turkey Vultures reflect convergent adaptation for flight, rather than ancestral characters useful for phylogenetic studies, remains unknown.

Organochlorines, brominated flame retardants and mercury levels in six seabird species from the Gulf of St. Lawrence (Canada): Relationships with feeding ecology, migration and molt

Concentrations of organochlorines (OCs), brominated flame retardants (BFRs) and mercury (Hg) were measured in eggs of six seabird species breeding in the Gulf of St. Lawrence, Canada. Stable nitrogen ( δ 15N) and carbon ( δ 13C) isotopes were used as ecological tracers to measure trophic level and connectivity with benthos, respectively. Concentrations, patterns as well as ecological tracers varied significantly between species. The sum of polychlorinated biphenyls (ΣPCBs) was the most important group measured in all seabird species based on concentration followed generally by the sum of chlorinated pesticides (ΣCPs), the sum of brominated flame retardants (ΣBFRs) and finally total Hg (THg). ΣPCBs, ΣCPs and ΣBFRs increased with trophic level, whereas THg did not. Only ΣBFRs increased with a higher connectivity with the benthos. Seabird species resident to the Great Lakes-St. Lawrence ecosystem showed higher Hg and BFR levels than migratory species. Molt patterns were used to explain variations of contaminant levels.

Timing of primary wing moult in sexually dimorphic passerines from the Western Cape, South Africa

SAFRING ringing data was used to investigate the differences in the timing and duration of primary wing moult between males and females of sexually dimorphic passerines from the Western Cape, South Africa. In the sunbirds, weavers and canaries that were considered, the males generally started moult before the females, whereas this was not so for other species. In the species where males started moult before the females, the standard deviation of the start of moult was generally smaller in the males and the males generally took longer to moult. These differences in the patterns of moult are discussed in the context of differences in parental care between males and females of each species and within their taxonomic groups.

Population dynamics and morphological variability of Calanus euxinus in the Black and Marmara Seas

Temporal and spatial changes in abundance, prosome length, oil sac volume, molting patterns and morphometric parameters were studied in Calanus euxinus from the Black and Marmara Seas. In the south‐western part of the Black Sea and deep shelf zone near Sinop the abundance of C. euxinus was high during the whole studied period (2000–2005), with a maximum 23,400 ind m−2 in March 2004. In the Marmara Sea near the Prince Islands in the deep zone the mean annual abundance of C. euxinus was 47 times lower than in the deep zone of the Black Sea (during 2000–2007). However, this parameter reached a significant magnitude of 12,264 ind m−2 in spring in Izmit Bay. During the warm season, C. euxinus are rare in the Marmara Sea. The high temperature and salinity accelerate development in this species; therefore, preadults and adults possess reduced prosome length and oil sac volume. In the cold period in the Marmara Sea the size and lipid content in late copepodite stages increase, especially in Izmit Bay. Similar size of eggs, prosome length of early copepodite stages in the Black and Marmara Seas indicate that the C. euxinus population in the Marmara Sea originates from the individuals penetrating from the Black Sea through the Bosphorus.