Moult Patterns Research Articles

Extent and symmetry of tail moult in Amur Falcons

Amur Falcons Falco amurensis undergo one of the most extreme migrations of any raptor, crossing the Indian Ocean between their Asian breeding grounds and non-breeding areas in southern Africa. Adults are thought to replace all their flight feathers on the wintering grounds, but juveniles only replace some tail feathers before migrating. We compare the extent and symmetry of flight feather moult in a large sample of Amur Falcons killed at communal roosts during two hailstorms in KwaZulu-Natal, South Africa in March 2019, shortly before their northward migration. Most adults had completed replacing their remiges, with only a few still growing 1–3 feathers (mainly secondaries), but most were still growing their tail feathers. Juveniles only replaced tail feathers. Moult typically was distal from the central rectrices, but 25% of adults and 1% of juveniles replaced the outer tail first, and a few individuals exhibited other moult patterns (simultaneous moult across the tail, or among the inner and outer feathers). These different moult strategies were independent of sex. Adults that replaced the outer tail first typically had replaced a greater proportion of the rectrices (mean ± SD; 0.81 ± 0.19) than adults starting from the central tail (0.17 ± 0.08). Proportionally fewer distal moulting adults were killed on 9 March than 21 March, resulting in the average proportion of rectrices replaced by adults decreasing between the two storm events from 0.52 ± 0.26 to 0.43 ± 0.23. By comparison, juvenile tail moult increased from 9 March (0.34 ± 0.18) to 21 March (0.40 ± 0.15). Overall, the probability of replacement for T1 was similar for adults (0.82) and juveniles (0.83), but adults were more likely to have replaced T2–6 (0.40–0.45) than juveniles (0.18 for T2 and 0.04–0.07 for T3–6). Asymmetry in tail moult was greater at T1 for adults (15%) than juveniles (10%), but asymmetry for T2 to T6 was greater in juveniles (3–10%) than adults (1–4%), especially given the greater probability of feather replacement in adults. Despite these differences, the degree of asymmetry was less than expected by random replacement across all rectrices in both age classes. Interestingly, moult tended to be more advanced on the left than right side of the tail. The extent of tail moult was correlated with body condition in adults and juveniles, suggesting that moult pattern might be used as an indicator of fitness in falcons.

Feathers accurately reflect blood mercury at time of feather growth in a songbird

Methylmercury (MeHg) is a globally distributed pollutant that can negatively affect wildlife. Bird feathers are often used as a monitoring tool of contaminant exposure, but variability in total mercury (THg) content in flight feathers has raised concerns over their utility. The objective of this study was to quantify blood and feather THg depuration through the progression of primary feather molt in order to clarify the relationship between blood and feather mercury concentration, and test the reliability of feather THg measurements as a monitoring tool in wild songbirds. Song sparrows (Melospiza melodia) were experimentally exposed to dietary MeHg and their blood and primary feather THg concentrations were measured during exposure and post-exposure periods of three months each. A rapid decrease in feather and blood THg concentration through molt progression was observed. Primary feather THg content was higher in feathers grown during the MeHg exposure period compared to those grown during the post-exposure period. Primary feather THg concentration was highly correlated with blood THg measured at the time of feather growth (R = 0.98), indicating that, although THg concentration is variable among flight feathers, this reflects temporally sequential molting patterns and declining blood concentration during depuration. Primary flight feathers thus provide an accurate and useful tool for estimating the mercury burden of birds at the time a chosen feather was grown, and have the potential to be an effective and reliable biomonitoring tool for species with well-characterized molt patterns.

Padrões de Muda em Trilobitas do Devoniano da Bacia do Paraná

In general, trilobites had their moulting performed by the breakdown of the librigena, a region (more external) situated on the cephalon of those animals. However, phacopid (calmonid and homalonotid) trilobites from the Paraná Basin have shown a Salterian moulting pattern, differing from the other trilobites. This moult pattern consisted of the separation of all the cephalon to the thorax. So, this paper intends to demonstrate information regarding preservation standards resulting from behavior(moult) of trilobites from the Paraná Basin, as found in the literature specialized and studied scientific collections.

Population Structure of the Blue Crab Callinectes sapidus in the Maryland Coastal Bays

The population structure of the blue crab Callinectes sapidus was examined in the Maryland Coastal Bays (MCB) from 2014 to 2016. Crabs were sampled from April to December of each year. Size–frequency distributions showed a strong seasonal cycle, with small crabs being abundant in April, increasing in size through September, with adult crabs observed in the highest proportions from August through October of each year. A subsample of crabs was assayed for hemolymph ecdysone concentrations to examine molting patterns in field-collected blue crabs. Molting was observed throughout the sampling season, peaking in April for immature crabs, with lows in all size classes occurring in October. The mean size at maturity (L50) for females collected in this study was 116 mm carapace width (CW), which is comparable to that reported for the lower Chesapeake Bay (CB) and suggests crabs in the MCB are not significantly smaller as previously thought; however, large crabs (>127 mm CW) appear to make up a smaller proportion of the total population in the MCB than in CB. Ovigerous females were observed at two distinct locations depending on the season, with 13/15 (86.7%) in southern Chincoteague Bay in April and May and 24/41 (58.5%) nearest to the Ocean City Inlet in July and August, indicating two potentially distinct spawning grounds and periods. This work suggests that blue crab reproductive success and general population trends are similar across both systems, with fishing pressure or disease in the MCB potentially explaining the low abundance of adult male crabs.

Complex postbreeding molt strategies in a songbird migrating along the East Asian Flyway, the Pallas's Grasshopper Warbler Locustella certhiola.

Molt strategies have received relatively little attention in current ornithology, and knowledge concerning the evolution, variability and extent of molt is sparse in many bird species. This is especially true for East Asian Locustella species where assumptions on molt patterns are based on incomplete information. We provide evidence indicating a complex postbreeding molt strategy and variable molt extent among the Pallas's Grasshopper Warbler Locustella certhiola, based on data from six ringing sites situated along its flyway from the breeding grounds to the wintering areas. Detailed study revealed for the first time that in most individuals wing feather molt proceeds from the center both toward the body and the wing‐tip, a molt pattern known as divergent molt (which is rare among Palearctic passerines). In the Russian Far East, where both breeding birds and passage migrants occur, a third of the adult birds were molting in late summer. In Central Siberia, at the northwestern limit of its distribution, adult individuals commenced their primary molt partly divergently and partly with unknown sequence. During migration in Mongolia, only descendantly (i.e., from the body toward the wing‐tip) molting birds were observed, while further south in Korea, Hong Kong, and Thailand the proportion of potential eccentric and divergent feather renewal was not identifiable since the renewed feathers were already fully grown as expected. We found an increase in the mean number of molted primaries during the progress of the autumn migration. Moderate body mass levels and low‐fat and muscle scores were observed in molting adult birds, without any remarkable increase in the later season. According to optimality models, we suggest that an extremely short season of high food abundance in tall grass habitats and a largely overland route allow autumn migration with low fuel loads combined with molt migration in at least a part of the population. This study highlights the importance of further studying molt strategy as well as stopover behavior decisions and the trade‐offs among migratory birds that are now facing a panoply of anthropogenic threats along their flyways.

Describing the growth and molt of modern domestic turkey (Meleagris gallopavo) primary wing feathers.

The use of feathers as noninvasive physiological measurements of biomarkers in poultry research is expanding. Feather molting patterns and growth rates, however, are not well described in domestic poultry. These parameters could influence the measurement of these biomarkers. Therefore, the objective of this study was to describe the juvenile primary feather molting patterns and feather growth rates for domestic turkeys. The 10 primary wing feathers of 48 female turkeys were measured weekly from week 1 (0 d of age) to week 20. Feathers were manually measured, and the presence or absence of each primary feather was recorded weekly. Generalized linear mixed models were used to investigate if feather growth differed between the primary feathers. The molting of the juvenile primary feathers followed a typical descending pattern starting with P1 (5 wk of age), while P9 and P10 had not molted by the end of the study (20 wk of age). The average feather growth rate was 2.4 cm/wk, although there was a significant difference between the 10 primary feathers (P < 0.0001, 2.1 to 2.8 cm/wk). Over time, feather growth followed a pattern where the growth rate reaches a peak and then declines until the feather is molted. The results of this study provide a critical update of patterns of molting and feather growth in primary wing feathers of modern turkeys. This can have implications for the interpretation of physiological biomarkers, such as the longitudinal deposition of corticosterone, in the feathers of domestic turkeys.

Using community photography to investigate phenology: A case study of coat molt in the mountain goat (Oreamnos americanus) with missing data.

Participatory approaches, such as community photography, can engage the public in questions of societal and scientific interest while helping advance understanding of ecological patterns and processes. We combined data extracted from community‐sourced, spatially explicit photographs with research findings from 2018 fieldwork in the Yukon, Canada, to evaluate winter coat molt patterns and phenology in mountain goats (Oreamnos americanus), a cold‐adapted, alpine mammal. Leveraging the community science portals iNaturalist and CitSci, in less than a year we amassed a database of almost seven hundred unique photographs spanning some 4,500 km between latitudes 37.6°N and 61.1°N from 0 to 4,333 m elevation. Using statistical methods accounting for incomplete data, a common issue in community science datasets, we identified the effects of intrinsic (sex and presence of offspring) and broad environmental (latitude and elevation) factors on molt onset and rate and compared our findings with published data. Shedding occurred over a 3‐month period between 29 May and 6 September. Effects of sex and offspring on the timing of molt were consistent between the community‐sourced and our Yukon data and with findings on wild mountain goats at a long‐term research site in west‐central Alberta, Canada. Males molted first, followed by females without offspring (4.4 days later in the coarse‐grained, geographically wide community science sample; 29.2 days later in our fine‐grained Yukon sample) and lastly females with new kids (6.2; 21.2 days later, respectively). Shedding was later at higher elevations and faster at northern latitudes. Our findings establish a basis for employing community photography to examine broad‐scale questions about the timing of ecological events, as well as sex differences in response to possible climate drivers. In addition, community photography can help inspire public participation in environmental and outdoor activities specifically with reference to iconic wildlife.

Split moult: time constraints or endogenous strategy?

Plumage renewal is an important process in the avian yearly cycle, yet knowledge about the factors that shape moult strategies is far from complete. A varying proportion of individuals of several Palaearctic passerine species divide their flight‐feather moult between breeding and wintering areas. Here we focus on split moult, which includes retaining some or all the secondary feathers during the main moult period (interrupted moult) and later renewal of these feathers (complementary moult), after migration or breeding. We built a large moult database (213 species, 64 076 individuals) to describe split moult pattern in Palaearctic passerines, identify its frequency and test whether it is more common in long‐distance migrants than in short‐distance migrants and sedentary species. We found that first‐year individuals, tested shortly after the main moult period, exhibited interrupted moult, yet individuals tested later in the annual cycle also retained non‐moulted secondaries. In contrast, in most species, adults tested later in the annual cycle had fully renewed flight‐feathers. This would suggest that age may be a factor associated with the probability of exhibiting split moult, as this strategy was more common in adults than in first‐year birds. Furthermore, we found that interrupted and split moults occur more often among long‐distance migrants than among sedentary or short‐distance migrants. Our results probably imply that the split flight‐feather moult is not initiated in the first winter of the bird's life, as has been suggested in previous studies. In addition, the occurrence of split moult among long‐distance migrants in which the main moult takes place during the winter and among sedentary or short‐distance migratory species, suggests that split moult probably does not represent an evolutionary transition between summer and winter moult; in both species groups, an evolutionary transition towards winter moult is probably impossible. Based on our findings, we suggest that split moult may be a moult strategy that allows birds to cope with time and energy constraints during the main moult period by retaining part of their flight‐feathers and resuming their moult later in the yearly cycle.

Temporal and spatial differences in the post-breeding behaviour of a ubiquitous Southern Hemisphere seabird, the common diving petrel.

The non-breeding period plays a major role in seabird survival and population dynamics. However, our understanding of the migratory behaviour, moulting and feeding strategies of non-breeding seabirds is still very limited, especially for small-sized species. The present study investigated the post-breeding behaviour of three distant populations (Kerguelen Archipelago, southeastern Australia, New Zealand) of the common diving petrel (CDP) (Pelecanoides urinatrix), an abundant, widely distributed zooplanktivorous seabird breeding throughout the southern Atlantic, Indian and Pacific oceans. The timing, geographical destination and activity pattern of birds were quantified through geolocator deployments during the post-breeding migration, while moult pattern of body feathers was investigated using stable isotope analysis. Despite the high energetic cost of flapping flight, all the individuals quickly travelled long distances (greater than approx. 2500 km) after the end of the breeding season, targeting oceanic frontal systems. The three populations, however, clearly diverged spatially (migration pathways and destinations), and temporally (timing and duration) in their post-breeding movements, as well as in their period of moult. Philopatry to distantly separated breeding grounds, different breeding phenologies and distinct post-breeding destinations suggest that the CDP populations have a high potential for isolation, and hence, speciation. These results contribute to improving knowledge of ecological divergence and evolution between populations, and inform the challenges of conserving migratory species.

Preformative molt in Neotropical Cardinalidae

Neotropical Cardinalidae consists of 40 species in 10 genera that have diversified across the Americas. We provide quantitative information on the preformative molt of 21 Cardinalidae species of seven genera, plus one Thraupidae species placed within Cardinalidae until recently. From 155 preformative molt cards, we calculated molt extent estimates, computed frequencies of molt patterns, and summarized observed frequencies of wing-feather replacement in wing diagrams. We found 17 species with partial preformative molts, four species with eccentric preformative molts (outer but not inner primaries replaced), and one species with a complete preformative molt. Preformative molt extent and patterns were similar within Cardinalidae genera, including genera with Nearctic representatives, such as the complete preformative molt of Northern Cardinal Cardinalis cardinalis or the eccentric molt of Passerina buntings. Our results cover an important gap in the knowledge of the natural history of Cardinalidae, generate important criteria to determine the age of Neotropical Cardinalidae, and provide essential information to test hypotheses on the ecology and evolution of molt in this passerine family.

Time available for moulting shapes inter- and intra-specific variability in post-juvenile moult extent in wheatears (genus Oenanthe)

Moult is a vital and endogenously controlled process in the avian life. However, birds may modulate their feather renovation properties, such as the extent of moult, based on exogenous factors. Despite the large body of knowledge about moult patterns, numerous questions remain unclear. In this study, we aimed to improve our knowledge about the factors that affect variation in the extent of the post-juvenile moult in passerines by performing inter- and intra-specific comparative analyses. We assessed the effect of internal and external factors on passerines’ moult by comparing post-juvenile moult extent among 16 wheatear species (genus Oenanthe) from the Palearctic Ecozone. The tested factors included migration distance used as a proxy of time available for moulting and habitat type. We also explored the relationship between the extent of the moult, migration distance, and sex in the Northern Wheatear Oenanthe oenanthe across a latitudinal gradient in Western Europe. The results indicate that post-juvenile moult extent in wheatears was negatively related to migration distance, such that species with shorter migration distances moult extensively compared to long-distance migratory species. In contrast, the extent of post-juvenile moult in the Oenanthe genus was not related to preferred habitat type (arid or non-arid) of the species. Migration distance was also related to post-juvenile moult extent in the Northern Wheatear, with fewer renewed feathers in northern populations. However, the extent of the post-juvenile moult did not differ between sexes. Thus, our results support that time constraints affect moult extent in long-distance migratory species and populations.

Age structure in a newly established and increasing population: initially high proportion of young birds among nesting Great Grey Owls

The mechanisms behind expansions of the distribution of a bird species and the ensuing establishment of new populations are poorly known. The distribution of Great Grey Owl (Strix nebulosa) in the western Palearctic has generally expanded towards southwest during the past fifty years, and particularly so in Fennoscandia. In the past decade, the recorded breeding population in Norway, confined to Hedmark county bordering Sweden, increased from 1 pair in 2009 to > 100 pairs in 2017–2018, extending the southwestern border of the distribution > 100 km. We studied the age structure of this expanding population based on the molting pattern of the wing feathers of birds captured at the nest site for banding and of non-captured birds photographed in flight. In Fennoscandia the Great Grey Owl relies on shrews and microtine rodents, which usually fluctuate in 3–4 years cycles. The proportion of 1-year old birds among the nesting Great Grey Owls was higher in peak year two of each small mammal population cycle (2011, 2014 and 2018) than in peak year one (2010, 2013 and 2017), and was particularly high (77%) in 2011 when the owl population was far lower (22 nestings recorded) than in later corresponding years (64 nestings in 2014 and 103 in 2018). Thus, this population seems to have been founded to a large extent by birds nesting as 1 year olds, and most likely having dispersed from Sweden. The ability to determine the age of Great Grey Owls without having to capture them extended our data set, in particular for males, which are more reluctant to attack intruders at the nest site and, therefore, less likely to be captured for banding. Being able to age a bird without having to capture it is important, because trapping does not sample a bird population randomly.

Body Mass and Primary Molt Patterns of Greater Sage-Grouse in Colorado

Patterns in body mass and molt provide useful information about how birds interact with their environment and act as potential explanatory variables in behavioral and demographic differences among sex and age classes. We collected population data for Greater Sage-Grouse (Centrocercus urophasianus) in Jackson and Moffat counties, Colorado, from 1973 to 1993 prior to consideration of federal listing of the species under the Endangered Species Act. Using spotlights and long-handled nets, we located and captured Greater Sage-Grouse while they roosted (primarily at night). Each captured bird was banded and released near the site of capture. We recorded the molt status of the primary flight feathers (1–10) and measured body mass. Most birds were captured prior to and during breeding (March–May) and during the brood-rearing period (July–September). Replacement of primary (P) flight feathers was initiated in May, starting with the first primary (P1), and was completed at the last primary (P10) by late September for adult (ASY) and subadult (SY) males, and by October for hatch-year males (young of the year, HY). Adult and subadult females did not replace primary flight feathers until after nesting was completed, starting in June. Primaries 1–3 were replaced within a week of the hen leaving the nest site, with or without chicks. Primary replacement then was similar to that of adult and subadult males and was completed before early October. A few late-nesting hens retained P10 and P9 into early October. Young of the year rarely replaced juvenal P9 and P10 in the year of hatching. Body mass of males peaked (x = 3000 g for adults, and 2200 g for yearlings) in March–April when birds were primarily feeding on sagebrush and then decreased to late May and reached seasonal lows (x = 2200 g) in July–August. Mass of females peaked in April (x = 1640 g) and decreased to 1250 g in August.

Sequential Molt in a Feathered Dinosaur and Implications for Early Paravian Ecology and Locomotion

Feather molt is an important life-history process in birds, but little is known about its evolutionary history. Here, we report on the first fossilized evidence of sequential wing feather molt, a common strategy among extant birds, identified in the Early Cretaceous four-winged dromaeosaurid Microraptor. Analysis of wing feather molt patterns and ecological properties in extant birds imply that Microraptor maintained its flight ability throughout the entire annual cycle, including the molt period. Therefore, we conclude that flight was essential for either its daily foraging or escaping from predators. Our findings propose that the development of sequential molt is the outcome of evolutionary forces to maintain flight capability throughout the entire annual cycle in both extant birds and non-avialan paravian dinosaurs from 120 mya. VIDEO ABSTRACT.

MOULT RECORDS FOR TROPICAL BIRD SPECIES TRAPPED IN ANGOLA

Between 21and 27 July 2015, a total of 43 birds of 15 species were caught with mist nets at Kissikina, Malange, Angola. Thirty-two of those, of 11 different species, were moulting primaries and their moult was recorded. In this note we present the data collected hoping to add some information on the moult patterns of these species in this part of the world.

Sex‐specific patterns of fuelling and pre‐breeding body moult of Little Stints Calidris minuta in South Africa

The timing and duration of each stage of the life of a long‐distance migrant bird are constrained by time and resources. If the parental roles of males and females differ, the timing of other life stages, such as moult or pre‐migratory fuelling, may also differ between the sexes. Little is known about sexual differences for species with weak sexual dimorphism, but DNA‐sexing enables fresh insights. The Little Stint Calidris minuta is a monomorphic long‐distance migrant wader breeding in the Arctic tundra. Males compete for territories and perform elaborate aerial displays. Females produce two clutches a season. Each sex may be a bigamist and incubate one nest a season, each with a different partner. We expect that these differences in breeding behaviour entail different preparations for breeding by males and females, so we aimed to determine whether Little Stints showed any sex differences in their strategies for pre‐breeding moult and pre‐migratory fuelling at their non‐breeding grounds in South Africa. We used body moult records, wing length and body mass of 241 DNA‐sexed Little Stints that we caught and ringed between 27 January and 29 April in 2008–2018 at two neighbouring wetlands in North West Province, South Africa. For each individual we assessed the percentage of breeding plumage on its upperparts and took blood samples for DNA‐sexing. We calculated an adjusted Body Moult Index and an adjusted Wing Coverts Moult Index, then used the Underhill–Zucchini moult model to estimate the start dates and the rate of body moult in males and females. We estimated the changes in the sex ratio of the local population during their stay in South Africa, and also estimated the timing and rate of pre‐migratory fuelling and the potential flight ranges for males and females. The males started body moult on average on 7 February and the females on 12 February, but the sexes did not differ in their timing of wing covert moult, which started on average on 10 February. In January to mid‐February, males constituted c. 57% of the population, but their proportion declined afterwards, indicating an earlier departure than females. We estimated that both sexes began pre‐migratory fuelling on average on 15 March. The sexes did not differ in fuelling rate, but most females stayed at the non‐breeding site longer than the males, and thus accumulated more fuel and had longer potential flight ranges. These patterns of moult and fuelling suggest sex differences in preparations for breeding. We suggest that the males depart from South Africa earlier but with smaller fuel loads than the females to establish breeding territories before the females arrive. We conclude that for each sex the observed trade‐offs between fuelling and moult at the non‐breeding grounds are precursors to different migration strategies, which in turn are adaptations for their different roles in reproductive behaviour.

Sequential Moult in a Feathered Dinosaur: Implications for Early Paravian Locomotion and Ecology

Feather moult is an important life-history process in birds, but little is known about its evolutionary history. Here we report on the first fossilized evidence of sequential wing feather moult, a common strategy among extant birds, identified in the Early Cretaceous four-winged dromaeosaurid Microraptor. Analysis of wing feather moult patterns and ecological properties in extant birds imply that Microraptor maintained its flight ability throughout the entire annual cycle, including the moult period. Therefore, we conclude that flight was essential for either its daily foraging or escaping from predators. Our findings propose that the development of sequential moult is the outcome of evolutionary forces to maintaining flight capability throughout the entire annual cycle in both extant birds and non-avialan paravian dinosaurs from 120 million years ago.

Wing‐feather moult phenotypes differ between the preformative and prealternate episodes and along passerine phylogeny

Passerine wing‐feather moult has been studied historically in terms of its intensity, duration, timing and extent. However, little is known about variation of wing‐moult phenotypes (i.e. the identity of moulted wing feathers in a given individual) within species, among moult episodes and in relation to passerine phylogeny. Here we studied 5373 wing‐moult cards from 285 Holarctic and 155 Neotropical passerine species. Variation of moult phenotypes, although high, was far below that expected by chance, and the same phenotypes were repeated among individuals within and among species, suggesting the existence of shared mechanisms of moult control. We successfully classified moult phenotypes according to nine moult patterns described in the literature and found an uneven distribution between the preformative and the prealternate moult. Moult patterns were phylogenetically conserved for the preformative but not for the prealternate moult. Our results suggest differential seasonal control of bird moult with preformative moults being associated with (evolutionarily conserved) somatic demands, whereas prealternate moults are probably associated with (rapidly evolving) signalling functions.

Spatial ecology, phenological variability and moulting patterns of the Endangered Atlantic petrel Pterodroma incerta

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 40:189-206 (2019) - DOI: https://doi.org/10.3354/esr00991 ESR Special: Biologging in conservation Spatial ecology, phenological variability and moulting patterns of the Endangered Atlantic petrel Pterodroma incerta Marina Pastor-Prieto1,*, Raül Ramos1, Zuzana Zajková1,2, José Manuel Reyes-González1, Manuel L. Rivas1, Peter G. Ryan3, Jacob González-Solís1 1Institut de Recerca de la Biodiversitat (IRBio) and Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals (BEECA), Universitat de Barcelona, 08028 Barcelona, Spain 2Center for Advanced Studies of Blanes (CEAB-CSIC), 17300 Girona, Spain 3FitzPatrick Institute of African Ornithology, DST-NRF Centre of Excellence, University of Cape Town, Rondebosch 7701, South Africa *Corresponding author: marina.pastor6@gmail.com ABSTRACT: Insights into the year-round movements and behaviour of seabirds are essential to better understand their ecology and to evaluate possible threats at sea. The Atlantic petrel Pterodroma incerta is an Endangered gadfly petrel endemic to the South Atlantic Ocean, with virtually the entire population breeding on Gough Island (Tristan da Cunha archipelago). We describe adult phenology, habitat preferences and at-sea activity patterns for each phenological phase of the annual cycle and refine current knowledge about its distribution, by using light-level geolocators on 13 adults over 1-3 consecutive years. We also ascertained moulting pattern through stable isotope analysis (SIA) of nitrogen and carbon in feathers from 8 carcasses. On average, adults started their post-breeding migration on 25 December, taking 10 d to reach their non-breeding areas on the South American shelf slope. The pre-breeding migration started around 11 April and took 5 d. From phenological data, we found evidence of carry-over effects between successive breeding periods. The year-round distribution generally coincided with the potential distribution obtained from habitat modelling, except during the non-breeding and pre-laying exodus periods, when birds only used the western areas of the South Atlantic. Moulting occurred during the non-breeding period, when birds spent more time on the water, and results from SIA helped us to distinguish feathers grown around Gough Island from those grown in the non-breeding area. Overall, our results bring important new insights into the spatial ecology of this Endangered seabird, which should help improve conservation strategies in the South Atlantic Ocean. KEY WORDS: Atlantic petrel · Year-round movements · At-sea behaviour · Carry-over effects · Patagonian Shelf Full text in pdf format Supplementary material PreviousNextCite this article as: Pastor-Prieto M, Ramos R, Zajková Z, Reyes-González JM, Rivas ML, Ryan PG, González-Solís J (2019) Spatial ecology, phenological variability and moulting patterns of the Endangered Atlantic petrel Pterodroma incerta. Endang Species Res 40:189-206. https://doi.org/10.3354/esr00991 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 40. Online publication date: November 14, 2019 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2019 Inter-Research.

Ageing Northern Saw-Whet Owls (Aegolius acadicus) from Remigial Molt Patterns

We recorded molt patterns of migrant Northern Saw-whet Owls (Aegolius acadicus) at three locations in the Great Lakes region: Stevens Point, Wisconsin; Whitefish Point, Michigan; and Duluth, Minnesota. We then analyzed the molt patterns of recaptured birds that were banded in a previous season and originally classified as hatch-year birds (i.e., they had no remigial molt). Of these 286 known-age birds included in our analysis, 155 (54%) were second-year (SY), 72 (25%) were third-year (TY), 39 (14%) were fourth-year (4Y), 16 (6%) were fifth-year (5Y), three (1%) were sixth-year (6Y), and one (0.30%) was eighth-year (8Y). Using these known-age birds, we were able to identify definitive molt patterns for the SY and TY age classes. All 155 (100%) SY birds and 52 (72%) of the TY birds matched our ageing criteria. The remaining 28% of TY birds did not match our ageing criteria and were classified as after-second-year (ASY). Of the entire sample (n = 286), only three birds (1%) matched an incorrect age class, including one 4Y that matched the SY age class and two 5Y that matched the TY age class.