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Advancing breeding phenology is a commonly observed response to climate warming among bird species, potentially in response to shifts in the phenology of key resources. However, for migratory birds breeding at high latitudes, their capacity to breed earlier may be constrained by the time available between arrival on the breeding grounds and nesting, especially for later‐arriving individuals. This may have consequences for productivity, as early laying is often linked to higher breeding success, particularly in such seasonal environments. We investigated how migratory arrival timing influences subsequent timing of breeding, in particular whether the time between arrival and laying (arrival–laying gap) varies with arrival date, and if later‐arriving individuals are able to catch up with early‐arriving conspecifics. We tracked individual Icelandic Black‐tailed Godwit Limosa limosa islandica with GPS and PTT tags for one to two complete breeding seasons between 2013 and 2022. After arrival in Iceland, most Godwits visited their breeding territory within 5 days, though this interval was longer for earlier‐arriving birds. The total gap between arrival and laying was also longer for earlier‐arriving birds, such that laying date did not vary significantly with arrival date. These results suggest that, despite individual consistency in migratory phenology, subsequent timing of nesting is probably influenced by other factors, such as mate arrival timing and/or annual variation in environmental conditions. Regular pre‐nesting visits to the breeding territory may indicate that Godwits are able to monitor such factors closely and to nest early when conditions allow, but a larger sample of individuals and years is needed to assess whether early‐arriving individuals contribute disproportionately to population‐level advances in breeding phenology. Widespread tracking with high temporal and spatial resolution helps improve our understanding of phenological variation during the breeding season and its consequences for productivity and variation in juvenile phenology. [ABSTRACT FROM AUTHOR]

Long‐distance migratory species often include multiple breeding populations, with distinct migration routes, wintering areas and annual‐cycle timing. Detailed knowledge on population structure and migratory connectivity provides the basis for studies on the evolution of migration strategies and for species conservation. Currently, five subspecies of Bar‐tailed Godwits Limosa lapponica have been described. However, with two apparently separate breeding and wintering areas, the taxonomic status of the subspecies L. l. taymyrensis remains unclear. Here we compare taymyrensis Bar‐tailed Godwits wintering in the Middle East and West Africa, respectively, with respect to migration behaviour, breeding area, morphology and population genetic differentation in mitochondrial DNA. By tracking 52 individuals from wintering and staging areas over multiple years, we show that Bar‐tailed Godwits wintering in the Middle East bred on the northern West‐Siberian Plain (n = 19), while birds from West Africa bred further east, mostly on the Taimyr Peninsula (n = 12). The two groups differed significantly in body size and shape, and also in the timing of both northward and southward migrations. However, they were not genetically differentiated, indicating that the phenotypic (i.e. geographical, morphological and phenological) differences arose either very recently or without current reproductive isolation. We conclude that the taymyrensis taxon consists of two distinct populations with mostly non‐overlapping flyways, which warrant treatment as separate taxonomic units. We propose to distinguish a more narrowly defined taymyrensis subspecies (i.e. the Bar‐tailed Godwits wintering in West Africa and breeding on Taimyr), from a new subspecies (i.e. the birds wintering in the Middle East and breeding on the northern West‐Siberian Plain). [ABSTRACT FROM AUTHOR]

Occurring across Eurasia, the Black‐tailed Godwit Limosa limosa has three recognized subspecies, melanuroides, limosa and islandica from east to west, respectively. With the smallest body size, melanuroides has been considered the only subspecies in the East Asian‐Australasian Flyway. Yet, observations along the Chinese coast indicated the presence of distinctively large individuals. Here we compared the morphometrics of these larger birds captured in northern Bohai Bay, China, with those of the three known subspecies and explore the genetic population structuring of Black‐tailed Godwits based on the control region of the mitochondrial genome (mtDNA). We found that the Bohai Godwits were indeed significantly larger than melanuroides, resembling limosa more than islandica, but with relatively longer bills than islandica. The level of genetic differentiation between Bohai Godwits and the three recognized subspecies was of similar magnitude to the differentiation among previously recognized subspecies. Based on these segregating morphological and genetic characteristics, we propose that these birds belong to a distinct population, which may be treated and described as a new subspecies. [ABSTRACT FROM AUTHOR]

GLO:K8N/01jan21:ibi12883-fig-0001.jpg PHOTO (COLOR): . gl Theunis Piersma's contribution to ornithology goes far beyond his 500 plus peer-reviewed scientific papers and 14 books, generally focused on migratory birds, to his role in their conservation including via innovative use of the arts as well as influencing policies and management prescriptions. For approaching four decades Theunis has been a mainstay of the International Wader Study Group (IWSG), serving 15 of those years as Vice-Chair. The strength and breadth of Theunis' work within ornithology makes him an outstandingly deserving recipient of the BOU Goldman Salvin Prize, and for it to be awarded during his beloved International Wader Study Group's 50th anniversary conference is a fitting and fine tribute to an exceptional ornithologist. [Extracted from the article]

Rock Sandpipers Calidris ptilocnemis have the most northerly non‐breeding distribution of any shorebird in the Pacific Basin (upper Cook Inlet, Alaska; 61°N, 151°W). In terms of freezing temperatures, persistent winds and pervasive ice, this site is the harshest used by shorebirds during winter. We integrated physiological, metabolic, behavioural and environmental aspects of the non‐breeding ecology of Rock Sandpipers at the northern extent of their range to determine the relative importance of these factors in facilitating their unique non‐breeding ecology. Not surprisingly, estimated daily energetic demands were greatest during January, the coldest period of winter. These estimates were greatest for foraging birds, and exceeded basal metabolic rates by a factor of 6.5, a scope of increase that approaches the maximum sustained rate of energetic output by shorebirds during periods of migration, but far exceeds these periods in duration. We assessed the quality of their primary prey, the bivalve Macoma balthica, to determine the daily foraging duration required by Rock Sandpipers to satisfy such energetic demands. Based on size‐specific estimates of M. balthica quality, Rock Sandpipers require over 13 h/day of foraging time in upper Cook Inlet in January, even when feeding on the highest quality prey. This range approaches the average daily duration of mudflat availability in this region (c. 18 h), a maximum value that annually decreases due to the accumulation of shore‐fast ice. Rock Sandpipers are likely to maximize access to foraging sites by following the exposure of ice‐free mudflats across the upper Cook Inlet region and by selecting smaller, higher quality M. balthica to minimize foraging times. Ultimately, this unusual non‐breeding ecology relies on the high quality of their prey resources. Compared with other sites across their range, M. balthica from upper Cook Inlet have relatively light shells, potentially the result of the region's depauperate invertebrate predator community. Given the delicate balance between environmental and prey conditions that currently make Cook Inlet a viable wintering area for Rock Sandpipers, small variations in these variables may affect the suitability of the site in the future. [ABSTRACT FROM AUTHOR]

Sexual size dimorphism ( SSD) is common in birds and has been linked to various selective forces. Nevertheless, the question of how and when the sexes start to differentiate from each other is poorly studied. This is a critical knowledge gap, as sex differences in growth may cause different responses to similar ecological conditions. In this study, we describe the sex-specific growth - based on body mass and five morphometric measurements - of 56 captive Black-tailed Godwit Limosa limosa limosa chicks raised under ad libitum food conditions, and conclude that all six growth curves are sex-specific. Females are the larger sex in terms of body mass and skeletal body size. To test whether sex-specific growth leads to sex-specific susceptibility to environmental conditions, we compared the age-specific sizes of male and female chicks in the wild with those of Black-tailed Godwits reared in captivity. We then tested for a relationship between residual growth and relative hatching date, age, sex and habitat type in which the wild chicks were born. Early-hatched chicks were relatively bigger and in better condition than late-hatched chicks, but body condition and size were not affected by natal habitat type. Female chicks deviated more negatively from the sex-specific growth curves than male chicks for body mass and total-head length. This suggests that the growth of the larger females is more susceptible to limiting environmental conditions. On average, the deviations of wild chicks from the predicted growth curves were negative for all measurements, which suggests that conditions are limiting in the current agricultural landscape. We argue that in estimating growth curves for sexually dimorphic species, it is critical first to make accurate sex and age determinations. [ABSTRACT FROM AUTHOR]

Effective conservation of endangered species requires a solid understanding of the demographic causes of population change. Bird populations breeding on agricultural grasslands have declined because their preferred habitat of herb-rich meadows has been replaced by grassland monocultures. The timing of agricultural activities in these monocultural grasslands is critical, as they often coincide with the nesting phase of breeding birds. Here, we aim to identify the effect of habitat management and targeted nest protection on nest survival of Black-tailed Godwits Limosa limosa in the Netherlands, a population that has shown a 70% reduction in breeding population size since the 1970s. To protect nests in monocultures from destruction, farmers are paid to either delay mowing or leave a patch of unmown grass around the nest, a patch which in practice varied in size. In herb-rich meadows, which are typically managed for bird conservation purposes, mowing occurs after hatching. Nest survival declined as the season advanced, more steeply on monocultures than on meadows. Targeted nest protection was only partially successful, as nest predation was considerably higher on mown grassland monocultures with small unmown patches around the nest than in mown monocultures with large unmown patches and in unmown fields. Increased predator densities over the years have been suggested as an important cause of the trend towards lower nest survival, but here we show that nest survival was higher on herb-rich meadows than on monocultures, and similar to the 1980s. It thus seems that increased predator densities are an increased threat during the egg stage only if habitat quality is low. High-quality habitat in the form of herb-rich meadows therefore provides a degree of protection against predators. [ABSTRACT FROM AUTHOR]

We investigated the effects of body mass and latitude on primary moult duration from published data of migrating shorebirds that moult exclusively on the wintering grounds. Non-phylogenetic and phylogenetic models demonstrated that body mass and latitude correlate with moult duration in a non-additive way: the models predict different latitudinal relationships for smaller and larger shorebirds, and in the northern hemisphere, primary moult duration increased allometrically with body mass (exponent = 0.17), whereas in the southern hemisphere, primary moult duration was not correlated with body mass. If birds optimize feather quality and if slower moult yields sturdier feathers, the fast primary moult of northerly wintering shorebirds indicates additional selection pressures at work. [ABSTRACT FROM AUTHOR]

In many species, naïve first-time migrants undertake migration without adults, supposedly on the basis of a 'simple' vector programme that combines an innate directional preference with a temporal programme that specifies distance. In strongly dimorphic species in which the sexes show distinct ecological requirements, the innate mechanisms of navigation may be expected to diverge between males and females with respect to their specific destinations. Based on captures of juvenile Ruff Philomachus pugnax at a migratory stopover over 21 years, a correlation was found between the year-specific sex ratio and the global magnetic field disturbance during the 2 weeks prior to the peak of captures in that year. This suggests that males and females respond differently to geomagnetic disturbance with changes in either the direction of migration or the level of migratory activity, and implies sex-specificity in the use of their geomagnetic navigational 'toolbox'. [ABSTRACT FROM AUTHOR]

Recently, Schroeder et al. (2010, Ibis 152: 368-377) suggested that intronic variation in the CHD1-Z gene of Black-tailed Godwits breeding in southwest Friesland, The Netherlands, correlated with fitness components. Here we re-examine this surprising result using an expanded dataset (2088 birds sampled from 2004 to 2010 vs. 284 birds from 2004 to 2007). We find that the presence of the Z* allele (9% of the birds) is not associated with breeding habitat type, egg size, adult survival, adult body mass or adult body condition. The results presented here, when used in synergy with the previously reported results by Schroeder et al., suggest that there might be a tendency towards female adults with the Z* allele laying earlier clutches than adult females without the Z* allele. The occurrence of the Z* allele was also associated with a higher chick body mass and return rate. Chicks with the Z* allele that had hatched early in the breeding season were heavier at birth than chicks without the Z* allele and chicks with the Z* allele that had hatched late. Collectively, the results suggest that variation in the CHD1-Z gene may indeed have arisen as a byproduct of selection acting on females during the egg fase and on chicks during the rearing stages of the reproductive cycle. [ABSTRACT FROM AUTHOR]

Foraging birds can manage time spent vigilant for predators by forming groups of various sizes. However, group size alone will not always reliably determine the optimal level of vigilance. For example, variation in predation risk or food quality between patches may also be influential. In a field setting, we assessed how simultaneous variation in predation risk and intake rate affects the relationship between vigilance and group size in foraging Ruddy Turnstones Arenaria interpres. We compared vigilance, measured as the number of 'head-ups' per unit time, in habitat types that differed greatly in prey energy content and proximity to cover from which predators could launch surprise attacks. Habitats closer to predator cover provided foragers with much higher potential net energy intake rates than habitats further from cover. Foragers formed larger and denser flocks on habitats closer to cover. Individual vigilance of foragers in all habitats declined with increasing flock size and increased with flock density. However, vigilance by foragers on habitats closer to cover was always higher for a given flock size than vigilance by foragers on habitats further from cover, and habitat remained an important predictor of vigilance in models including a range of potential confounding variables. Our results suggest that foraging Ruddy Turnstones can simultaneously assess information on group size and the general likelihood of predator attack when determining their vigilance contribution. [ABSTRACT FROM AUTHOR]

The article focuses on the study which aims to understand how rice field conditions influence the bird community during the winter. Researchers analyzed bird densities in the rice field areas around the Tejo and the Sado estuaries, Portugal and related these to straw management and water level in the paddies. In the study, the water level in the fields also differs between paddies due to both rainfall and drainage with some fields completely drying out while others remaining moist and some with water in ditches, and others remaining flooded. It shows that he amount of water in the paddies was also included in the final fitted models for seven species with variable included in the final model.

It is often assumed that strong selection pressures give rise to trade-offs between body condition and time in long-distance migrating birds. Birds that are‘behind schedule’ in fuel deposition or moult should delay departure, and this should result in a negative correlation between initial condition and departure date. We tested this hypothesis in the Great KnotCalidris tenuirostrismigrating from north-west Australia to eastern Asia en route to Siberia. Great Knot gain mass and moult into breeding plumage before leaving northern Australia in late March and early April, and fly 5400–6000 km to eastern China and Korea. We radiotracked 27 individuals (17 males and ten females) to determine departure dates; 23 migrated and four remained in Australia. We characterized body condition at capture using body mass, predicted pectoral muscle mass (based on ultrasound estimates of the size of the pectoral muscles) and breeding plumage scores. Residual condition indices were uncorrelated, indicating that at the individual level, variation in one fuelling component was not strongly associated with variation in the other components. Birds that did not depart had lower residual body mass and breeding plumage indices than those that did migrate; these four birds may have been subadults. Neither sex, size nor the condition indices explained variation in departure date of migrants. Reasons for this are explored. Departure dates for northward migrating waders indicate that the migration window (span over which birds depart) decreases with proximity to the northern breeding grounds. We suggest that migration schedules become tighter as birds get nearer to the breeding grounds. Thus the lack of a relationship between condition and departure date in Great Knots may reflect the fact that the departure episode under study is the first one in sequence and is still 4–8 weeks before breeding. [ABSTRACT FROM AUTHOR]

To test whether heat generated during locomotion substitutes for the thermoregulation cost, oxygen consumption of four post-absorptive temperate-wintering Knot Calidris canutus was measured at air temperatures of 25d̀C (thermoneutral) and 10d̀C (c. 10d̀ below the lower critical temperature) when the birds were at rest at night and during running on a treadmill. After allowing for body mass, the thermoregulation cost at 10d̀C was significantly lower in active birds compared with birds at rest. At rest, the birds spent, on average, 0.50 watt (W; range, 0.47-0.57 W) on thermoregulation. During exercise, this cost factor averaged 0.33 W (range, 0.25-0.42 W). The average difference in thermoregulation cost was 35% (ranging from 26% to 49% between individuals) and provides an estimate of the amount of substituted heat. A review of nine studies, all restricted to small birds, showed that substitution is a widespread phenomenon. The consequences of such partial substitution for the annual energetics of Knot wintering in the temperate Wadden Sea v tropical west Africa are examined. Compared with a previous additive model, the model which includes substitution (i.e. the use of heat produced during activity) reduces the differences in maintenance metabolism between the two wintering strategies by 17%, from 1.19 W to 0.99 W. [ABSTRACT FROM AUTHOR]

To test whether Knot Calidris canutus wintering in the tropics suffer higher rates of water loss through evaporation than do Knot wintering at temperate latitudes, we tried to develop a physically realistic model to predict evaporative heat loss from air temperature, wind and humidity. In separate experiments, involving respirometry and double-labelled water, we tried to estimate relevant parameters. In both sets of experiments, we were able to show significant effects of air temperature on evaporative water loss only. Knot which were able to eat and drink had an evaporative water loss three times that of postabsorptive Knot unable to drink when in a metabolic chamber. Water turnover rates of Knot feeding on bivalves under simulated field conditions were high and did not correlate with predicted evaporative water loss. Over 32 experimental bird-days, the average contribution of predicted evaporative water loss to daily water turnover was 20%. A comparison of predicted evaporative water loss in the north-temperate Dutch Wadden Sea and in the tropical Banc d'Arguin in Mauritania in midwinter showed that Knot wintering in the tropics may need only marginally more water for evaporative cooling than Knot wintering in the Dutch Wadden Sea. Knot foraging on intertidal invertebrates are able to maintain high water turnover rates with little need to drink seawater. [ABSTRACT FROM AUTHOR]

The fact that one cannot kill a bird twice makes it very difficult to determine the relative contributions of fat and non-fat components to increases in body mass before migratory flights in individual birds. Knowing the relative contributions of these components is of obvious energetic interest since fat yields about eight times as much energy as fat-free muscle tissue. Several recent studies have failed to demonstrate convincingly, due to flaws in their analyses, that fat-free mass in addition to fat is accumulated before long-distance flights. We point out that regressions of fat or the non-fat component on total body mass cannot yield reliable estimates of the composition of individual mass changes in view of inter-individual variation in structural size, reserve levels or timing of storage. We suggest that studies over time of synchronous populations or marked individuals will give better answers. A re-analysis of published data indicates the widespread existence of fat-free tissue deposition during migration, whereas in some species fat alone explained the increase in total body mass. Larger species tend to incorporate a relatively higher proportion of non-fat components when increasing in mass. However, the comparative data set is not yet of sufficient quality to allow general statements on why, and to what extent in different individuals and species, non-fat tissue in addition to fat is deposited before take-off on migratory flights. [ABSTRACT FROM AUTHOR]

The article discusses a case related to ornithology. In modern ornithology, the use of oral traditions as sources for fact-finding about birds is rare. Nevertheless, when it comes to reconstructing the abundance, distribution and life-history of extinct or nearly extinct bird species, anecdote and "oral" history may be an important source of information. The Slender-billed Curlew Numenius tenuirostris , which is now classified as of "critical" conservation status and as Europe's rarest bird species, is a case in point.