Starlings Sturnus Research Articles

The Phenomenon of Synchronous Food Intake in Starlings (Sturnus vulgaris) under the Conditions of Isolation from Each Other.

The dynamics of body temperature was used to determine the food intake synchronization in starlings located at a distance of 105 km from each other. Thermal accumulators were implanted intraperitoneally to the birds; the birds had free access to food or were kept under the conditions of food deprivation. It was found that food intake moments significantly more often coincided with an accuracy of up to a minute even in the birds separated by a considerable distance. The difference in time of sunrise of a few minutes, as well as the conditions of constant lighting did not affect the synchronism of food intake. On the basis of the data obtained, it can be assumed that there is a certain external factor, probably of an electromagnetic nature, which synchronizes the functional activity of the body, including food intake.

Bird ringing and nest recording in Britain and Ireland in 2018

ABSTRACT This is the 82nd annual report of the British Trust for Ornithology’s Ringing Scheme, incorporating the report of the Nest Record Scheme and covering work carried out and data processed in 2018. We reviewed the literature on tracking devices to assess the impact of their use on individual birds. More than 3400 studies were identified, the first dating back to the early 1960s. The ecological questions being studied varied, with migration being the most common study subject. The frequency of effects was significantly related to attachment type and the likelihood of adverse effects was related to device weight. The proportion of studies reporting adverse effects has declined over time and the research highlighted the need for systematic documentation of potential effects. NRS and CES data were used in a collaborative study which investigated mismatches between the timing of breeding for 21 British songbirds and the availability of food for their chicks. Results indicate that birds did breed later in warmer springs relative to the timing of spring; however, this did not have a significant impact on long-term breeding success. In 2018, 135 CE sites submitted data. Long-term (1984–2017) declines in abundance were observed in six migrant, one partial migrant and three resident species while long-term increases in abundance continue to be recorded in two short-distance migrants and four resident species. Seven species are exhibiting significant long-term declines in productivity; only two species, Reed Warbler Acrocephalus scirpaceus and Chaffinch Fringilla coelebs, are exhibiting a significant long-term increase in productivity. Long-term trends in survival indicate increases for 12 species and declines for eight. Compared to the five-year mean (2013–17), the abundance of 14 species decreased significantly in 2018 with five species being recorded in lower numbers than in any previous year since CES monitoring began. No significant increases in abundance were recorded. Productivity increased significantly for six migrant and four resident species in 2018 and decreased for only two species (both residents). Significant declines in survival rates were observed in 10 species in 2018 compared to the five-year mean. The number of Retrapping Adults for Survival submissions fell slightly in 2018 to 190; eight projects ran for the first time. In total, 58 species were monitored, with Pied Flycatcher Ficedula hypoleuca (23 projects), House Sparrow Passer domesticus (18), Starling Sturnus vulgaris (17), Sand Martin Riparia riparia (13) and Reed Warbler (10) the most-studied species. A total of 982 858 birds were ringed during the year, comprising 170 619 nestlings, 465 610 first-year birds, 319 955 adults (birds in their second calendar year or older) and 26 674 birds whose age could not be determined. In addition, there were 236 314 recaptures of ringed birds at or near the ringing site. In total, 54 324 recoveries (birds found dead, recaptured or resighted at least 5 km from the place of ringing) of BTO-ringed birds were reported in 2018. The Appendix highlights a selection of recoveries that have extended our knowledge of movements, as well as longevity records established during the year. A total of 38 269 NRS submissions were received in 2018, the lowest total since 2009. Mean laying dates for four species were significantly earlier than the five-year mean (2013–17) with eight of the 52 species analysed laying significantly later. Eight species displayed a significant increase in breeding success (fledglings per breeding attempt) in 2018 compared to the five-year mean, with one decreasing significantly. Permits or licences to disturb breeding birds on Schedule 1 of the Wildlife and Countryside Act 1981 (as amended), were prepared and issued to 502 ringers and nest recorders in 2018. During 2018, the use of special methods was authorised for 557 marking projects, 66 trapping projects and 52 sampling projects.

Exotic parrots breeding in urban tree cavities: nesting requirements, geographic distribution, and potential impacts on cavity nesting birds in southeast Florida

BackgroundExotic parrots have established breeding populations in southeast Florida, including several species that nest in tree cavities. We aimed to determine the species identity, nest site requirements, relative nest abundance, geographic distribution, and interactions of parrots with native cavity-nesting bird species.MethodsWe searched Miami-Dade County, Florida, and nearby areas for natural cavities and holes excavated by woodpeckers, recording attributes of potential nest trees. We inspected all cavities with an elevated video inspection system to determine occupancy by parrots or other birds. We mapped nearly 4000 citizen science observations of parrots in our study area corresponding to our study period, and used these to construct range maps, comparing them to our nesting observations.ResultsNot all parrots reported or observed in our study area were actively breeding. Some parrots were observed at tree cavities, which previous studies have suggested is evidence of reproduction, but our inspections with an elevated video inspection system suggest they never initiated nesting attempts. Several parrot species did successfully nest in tree cavities, Red-masked Parakeets (Psittacara erythrogenys) and Orange-winged Parrots (Amazona amazonica) being the most common (n = 7 and 6 nests, respectively). These two parrots had similar nesting requirements, but Orange-winged Parrots use nests with larger entrance holes, which they often enlarge. Geographic analysis of nests combined with citizen science data indicate that parrots are limited to developed areas. The most common parrots were less abundant cavity nesters than the native birds which persist in Miami’s urban areas, and far less abundant than the invasive European Starling (Sturnus vulgaris).ConclusionsExotic parrots breeding elsewhere in the world have harmed native cavity-nesting birds through interference competition, but competitive interference in southeast Florida is minimized by the urban affinities of parrots in this region. The relative abundance and geographic distribution suggest that these parrots are unlikely to invade adjacent wilderness areas.

Reproductive Biology of the Syrian Woodpecker Dendrocopos syriacus —A Case Study from Southwestern Iran

In the springs of 2016–2017, 42 nests of the Syrian Woodpecker Dendrocopos syriacus were surveyed in 400 ha of the mountainous region of southwestern Iran. Egg laying began in late March. Clutch size was between three and five eggs (mean: 4±0.6, median: 4, N=26). The incubation period varied from nine to 13 days (mean: 10.7±1.2 days). Hatching most often occurred in the last two weeks of April. The number of eggs that hatched in successful nests (N=25) was 2–5 (mean: 3.6±0.9), and hatching percentage (N=26) was 66.4%. The duration of the nestling period was 25–28 days (mean: 25.9±0.05 days), with fledging dates ranging from 7 May to 29 June, with most chicks fledging in mid-May. The number of fledglings from successful nests (N=19) was 1–5 (mean: 3.2±1.1), whereas the mean number of fledglings from all nests (N=35) was 1.7±1.8. The percentage of successful nests (at least one fledged young, N=19) was 54.3%. European Starlings Sturnus vulgaris caused the failure of two nests in 2016 and 12 nests in 2017, resulting in nesting success of 81.3% in 2016 but only 31.6% in 2017. The overall duration of breeding varied from 38 to 44 days (mean: 40.4±1.8 days).

Assessment of Avifaunal Diversity in Riverine and Urban Areas of Layyah along the River Indus, Punjab-Pakistan

Layyah City is located along the River Indus and provides rich habitat for a wide range of resident and migratory bird species. The present study documents for the first time the avifaunal diversity and abundance of urban and riverine sites of Layyah. Potential habitats around the city were identified and three study sites were selected, one in each of the main habitat types. A total of 223 species was recorded: 92 residents, 87 winter visitors, 42 passage migrants and two new records from the area. A Shannon Wiener Index of 4.36 indicates that the area has a high level of biodiversity. Of the species recorded, 16 are included in the IUCN Red list as vulnerable (N=6), near threatened (N=9) or endangered (N=1). The most abundant species were House Crow Corvus splendens, House Sparrow Passer domesticus, Common Myna Acridotheres tristis and Common Starling Sturnus vulgaris. Two species, Houbara or McQueen's Bustard Chlamydotis macqueenii and Black-headed Ibis Threskiornis melanocephalus were recorded for the first time from the area. Potential threats to the avian diversity of the area are hunting, habitat loss, and pollution.

Habitat-mediated breeding performance of Lewis's Woodpeckers (Melanerpes lewis) in British Columbia.

Tree cavities provide a critical resource for cavity-nesting animals, and high quality cavities can be difficult for animals to acquire in habitats where competition is high. We investigated the breeding performance of Lewis’s Woodpeckers in three habitat types in British Columbia, Canada in 2013 and 2014. We also assessed whether the number of nest competitors and cavity availability influenced the habitat specific breeding performance of this threatened cavity nesting species. We found that daily nest survival rate was lower in burned habitat (0.15 ± 0.08 (0.05–0.37)) than in live pine (0.72 ± 0.10 (0.51–0.87)) or cottonwood (0.69 ± 0.09 (0.51–0.83)) habitats. However, hatching success (the proportion of eggs that hatch) was lower in live pine habitat (0.59 ± 0.09 95% CI) than burned (0.77 ± 0.19 95% CI) or cottonwood (0.80 ± 0.07 95% CI) habitat, and the fledging success of successful nests in live pine and burned habitat (1.86 ± 0.31 and 1.88 ± 0.59 95% CI, respectively) was slightly lower than in cottonwood habitat (2.61 ± 0.45 95% CI). Consequently, Lewis’s Woodpeckers in cottonwood habitat produced more fledglings per nesting attempt (2.05 ± 0.49 95% CI) than in live pine (1.53 ± 0.35 95% CI) or burned (0.79 ± 0.49 95% CI) habitat. Habitats differed in the number of nesting competitors and the number of suitable cavities surrounding active Lewis’s Woodpecker nests. Our results showed that cavity density best explained breeding performance differences although the mechanisms remain unclear. There was no evidence that the number of heterospecific nest competitors, including the invasive European Starling (Sturnus vulgaris), explained or influenced Lewis’s Woodpecker breeding performance. Cavity density influenced the productivity of successful nests but did not explain habitat differences in hatching success or daily nest survival. Further work is required to understand the mechanistic basis for the habitat specific breeding performance of Lewis’s Woodpeckers. Habitat differences in breeding performance in British Columbia are not consistent with those in other regions, highlighting the importance of regionally-specific demographic data for managing species at risk.

Developmental history, energetic state and choice impulsivity in European starlings, Sturnus vulgaris

Impulsivity—the extent to which a reward is devalued by the amount of time until it is realized—can be affected by an individual’s current energetic state and long-term developmental history. In European starlings (Sturnus vulgaris), a previous study found that birds that were lighter for their skeletal size, and birds that had undergone greater shortening of erythrocyte telomeres over the course of development, were more impulsive as adults. Here, we studied the impulsivity of a separate cohort of 29 starlings hand-reared under different combinations of food amount and begging effort. The task involved repeated choice between a key yielding one pellet after 3 s and another key yielding two pellets after 8 s. Impulsivity was operationalised as the proportion of choices for the short-delay option. We found striking variation in impulsivity. We did not replicate the results of the previous study concerning developmental telomere attrition, though combining all the evidence to date in a meta-analysis did support that robustness of that association. We also found that early-life conditions and mass for skeletal size interacted in predicting impulsivity. Specifically, birds that had experienced the combination of high begging effort and low food amount were less impulsive than other groups, and the usual negative relationship between impulsivity and body mass was abolished in birds that had experienced high begging effort. We discuss methodological differences between our study and studies that measure impulsivity using an adjusting-delay procedure.

Effects of an introduced, novel prey on diet and reproduction in the diet-specialist European Starling (Sturnus vulgaris)

Diet specialization has important consequences for how individuals or species deal with environmental change that causes changes in availability of prey species. We took advantage of a “natural experiment” — establishment of a commercial insect farm — that introduced a novel prey item, black soldier flies (Hermetia illucens (Linnaeus, 1758)), to the diet-specialist European Starling (Sturnus vulgaris Linnaeus, 1758). We investigated evidence for individual diet specialization (IDS) and the consequences of diet specialization and exploitation of novel prey on breeding productivity. In all 4 years of our study, tipulid larvae were the most common prey item. Soldier flies were not recorded in diets in 2013–2014; however, coincident with the establishment of the commercial insect farming operation, they comprised 22% and 30% of all prey items in the diets of European Starling females and males, respectively, in 2015. There was marked individual variation in use of soldier flies (4%–48% and 2%–70% in females and males, respectively), but we found little evidence of dichotomous IDS, i.e., where only some individuals have a specialized diet. We found no evidence for negative effects of use of soldier flies on breeding productivity: brood size at fledging and chick quality (mass, tarsus length) were independent of the number and proportion (%) of soldier flies returned to the nest.

POPULASI DAN HABITAT JALAK PUTIH (Sturnus melanopterus Daudin 1800) DI TAMAN NASIONAL BALI BARAT

Black-winged starling (Sturnus melanopterus Daudin 1800) has spread across West Bali National Park (WBNP). There are three subspecies of black-winged starling; Sturnus melanopterus tertius is distributed in the area of Bali, Sturnus melanopterus tricolor is distributed in East Java, and Sturnus melanopterus melanopterus is distributed in East Java and Madura. Status of black-winged starling was Critically Endangered in 2010. Therefore, this study aimed to (1) analyze the populations (numbers, sex ratio, and age structure) and analyze habitats of black-winged starling in West Bali National Park. Bird population was estimated by transect and concentration count method and black-winged starling habitat condition was identified using vegetation analysis. The result showed that the estimation of black-winged starling population were 35 individuals, sex ratio was 1:1, and all individuals were adults. The habitat which often used by black-winged starling was savanna as feeding area, drinking area, shelter area, and cover area. Keywords: black-winged starling, Bali barat, habitat, population

Birds trapped in telephone wiring system

[Six cases of birds trapped in telephone wires or in structures connected to telephone wires were signaled in the areas of Turin and Novara (Piedmont, N. W. Italy). The birds stayed hanging fatally either by chance or during a trophic activity. The species involved in the described episodes are five, but become eight when added to the ones subjects of previous signaling: Little bitten Ixobrychus minutus, Grey heron Ardea cinerea, Moorhen Gallinula chloropus, Barn owl Tyto alba, Little owl Athene noctua, Robin Erithacus rubecula, Starling Sturnus vulgaris, Hooded crow Corvus corone cornix.]
 [Article in Italian]

Developmental history and stress responsiveness are related to response inhibition, but not judgement bias, in a cohort of European starlings (Sturnus vulgaris)

Judgement bias tasks are designed to provide markers of affective states. A recent study of European starlings (Sturnus vulgaris) demonstrated modest familial effects on judgement bias performance, and found that adverse early experience and developmental telomere attrition (an integrative marker of biological age) both affected judgement bias. Other research has shown that corticosterone levels affect judgement bias. Here, we investigated judgement bias using a modified Go/No Go task in a new cohort of starlings (n = 31) hand-reared under different early-life conditions. We also measured baseline corticosterone and the corticosterone response to acute stress in the same individuals. We found evidence for familial effects on judgement bias, of a similar magnitude to the previous study. We found no evidence that developmental treatments or developmental telomere attrition were related to judgement bias per se. We did, however, find that birds that experienced the most benign developmental conditions, and birds with the greatest developmental telomere attrition, were significantly faster to probe the learned unrewarded stimulus. We also found that the birds whose corticosterone levels were faster to return towards baseline after an acute stressor were slower to probe the learned unrewarded stimulus. Our results illustrate the potential complexities of relationships between early-life experience, stress and affectively mediated decision making. For judgement bias tasks, they demonstrate the importance of clearly distinguishing factors that affect patterns of responding to the learned stimuli (i.e. response inhibition in the case of the Go/No Go design) from factors that influence judgements under ambiguity.

Physiological predictors of reproductive performance in the European Starling (Sturnus vulgaris)

BackgroundIt is widely assumed that variation in fitness components has a physiological basis that might underlie selection on trade-offs, but the mechanisms driving decreased survival and future fecundity remain elusive. Here, we assessed whether physiological variables are related to workload ability or immediate fitness consequences and if they mediate future survival or reproductive success. We used data on 13 physiological variables measured in 93 female European starlings (Sturnus vulgaris) at two breeding stages (incubation, chick-rearing), for first-and second-broods over two years (152 observations).ResultsThere was little co-variation among the physiological variables, either in incubating or chick-rearing birds, but some systematic physiological differences between the two stages. Chick-rearing birds had lower hematocrit and plasma creatine kinase but higher hemoglobin, triglyceride and uric acid levels. Only plasma corticosterone was repeatable between incubation and chick-rearing. We assessed relationships between incubation or chick-rearing physiology and measures of workload, current productivity, future fecundity or survival in a univariate manner, and found very few significant relationships. Thus, we next explored the utility of multivariate analysis (principal components analysis, Mahalanobis distance) to account for potentially complex physiological integration, but still found no clear associations.ConclusionsThis implies either that a) birds maintained physiological variables within a homeostatic range that did not affect their performance, b) there are relatively few links between physiology and performance, or, more likely, c) that the complexity of these relationships exceeds our ability to measure it. Variability in ecological context may complicate the relationship between physiology and behavior. We thus urge caution regarding the over-interpretation of isolated significant findings, based on single traits in single years, in the literature.

Diet of Peregrine Falcons Falco peregrinus in the urban environment of Maribor (NE Slovenia)

Abstract The article presents dietary habits of the Peregrine Falcon in the urban environment of Maribor. The diet was studied with an analysis of prey remnants at the nesting site. In October 2015, prey remnants were collected after the nesting in and around the nest built on top of the grain storage silo. Prey remnants, mostly bones and feathers, were sorted into body parts: skull with the beak, wings, and legs. Wings were the most numerous remnants with 41.7%, followed by legs and skulls with 28.1% each. In total, 96 units of prey were found, belonging to five different species of birds. The number of specimens and biomass was dominated by Feral Pigeons Columba livia domestica with 64.6% in number and 89.5% in prey biomass. The second most frequent prey of falcons were Starlings Sturnus vulgaris.

Common Starling Sturnus vulgaris expansion in South Africa

The Common Starling Sturnus vulgaris has progressively expanded its range in South Africa since its introduction into Cape Town in the late 19th century. In the past few decades it has extended this range into Gauteng province. Using data from the Southern African Bird Atlas Project 2, this paper examines the spread and relative abundance changes for the species across South Africa over the past 10 years, with a detailed look at the recently-colonised Gauteng. Across South Africa, the Common Starling's distribution has shifted, and grown. As it spreads north along the coastline and northwards inland, some of the former range has been lost. In Gauteng, the species has shown a range and abundance expansion over the same period. If the observed trends are to continue, this species is likely to eventually become a prominent species across the entire country, and further north into the sub-region. However, the potential impact that this species has on indigenous avifauna is unknown and, in the face of rapid anthropogenic change, remains to be investigated.

Nesting pattern of birds in Jahangirnagar University Campus, Bangladesh

Based on a study on nesting behavior conducted in Jahangirnagar University Campus between 2009 and 2011 brief descriptions are given of nest site preferences in a diverse habitat, variation in nest shape against height above ground, and materials used for constructing nests in different tree species. The study found that April is the peak time for nesting due to food availability. High competition for tree holes as nest sites forced some species to build nests in unusual sites, for example Rose-ringed Parakeet Psittacula krameri , Asian Pied Starling Sturnus contra , Common Myna Acridotheres tristis , and Jungle Myna A. fuscus , Oriental Magpie-robin Copsychus saularis showed better adaptation to the campus environment than other birds. Predation risk was found to be higher for non-hole nests than for hole nests. To minimize predation pressure, birds were seen to adopt passive protection by making false nests and constructing well-camouflaged nests. Besides predation, human disturbance was observed on low height nests in roadside vegetation resulting in breeding failure. Reducing human disturbance is needed if birds are to achieve better reproductive success in the campus. The most commonly used trees were Albizia spp. (native or long naturalized species) whereas no nest was found in Eucalyptus spp . and only a few nests were found in Acacia moniliformes , both are exotic trees which have been planted in huge numbers in the campus, indicating that birds do not prefer exotic tree species for nesting. It is recommended to plant more native tree species, which may also help birds to nest in usual sites rather than unusual sites (such as electrical pillars, electrical boxes, air conditioner boxes, and building holes). Regular monitoring in support of native tree planting and raising awareness to reduce disturbance, could enhance the successful reproduction of birds in Jahangirnagar University Campus. Finally, an update to the avifauna of the campus is presented, with 17 species added in this study or from other recent reports, bringing the total to 195 species, including one globally ‘Near Threatened’ species, the Brown-winged Kingfisher Pelargopsis amauroptera .

Пространственная структура колонии и особенности гнездования обыкновенного скворца (Sturnus vulgaris) и полевого воробья (Passer montanus) в зеленой зоне г. Энгельса

Пространственная структура колонии и особенности гнездования обыкновенного скворца (Sturnus vulgaris) и полевого воробья (Passer montanus) в зеленой зоне г. Энгельса

Lead Gunshot Ingestion By A Peregrine Falcon

Summary. Lead ammunition represents a source of poisoning for raptors eating game. Although the Peregrine Falcon Falco peregrinus commonly preys on gamebirds, only a few cases of lead poisoning have been recorded, probably owing to the lack of specific investigations. We document an adult female found dead with many lead shot in the digestive tract, mixed with the remains of a feral Pigeon Columba livia domestica and a European Starling Sturnus vulgaris. Concentrations in heart blood clot, liver, kidney and bone suggest that lead poisoning was not the ultimate cause of death. However, lead levels in the blood clot suggest that a small amount of lead may have been absorbed from the shot. The two prey species involved cannot be hunted in Italy but they are intensively shot all year round to prevent damage to crops. —Andreotti, A., Fabbri, I., Menotta, S. & Borghesi, F. (2018). Lead gunshot ingestion by a Peregrine Falcon. Ardeola, 65: 53–58.

Förändringar av häckfåglar på en sydsmåländsk gård från 1970- till 2010-talet

I compare the number of breeding birds of a 70 ha farm in a forest region of southern Sweden between the 1970s and the 2010s. The most important habitat change was replacement of 25 hectares 100 years old mixed forest by spruce plantation. Stands dominated by deciduous trees only grew older, and pastures were grazed by cattle both periods. More species decreased than increased, especially residents and tropical migrants decreased. For short distance migrants, the number of decreasing species were balanced by a similar number of increasing species. The density change of most species could be attributed to the replacement of the old mixed forest by the spruce plantation. Species preferring deciduous forest had much higher densities in the study plot than the regional averages. Two deciduous forest species, Pied Flycatcher Ficedula hypoleuca and Marsh Tit Poecile palustris declined strongly, the latter possibly due to competition from the increasing Blue Tit Cyanistes caeruleus. The Starling Sturnus vulgaris and the Tree Pipit Anthus trivialis stands out as drastically decreasing much more than local habitat changes can explain.

Factors determining presence of passerines breeding within White Stork Ciconia ciconia nests

Nests of White Stork Ciconia ciconia are commonly used by various passerines as nesting sites. In this study, we investigated factors determining presence and number of pairs of species breeding within White Stork nests in an extensive farmland in NE Poland. In 133 (57%) out of 233 White Stork nests, we found at least one breeding pair of passerine bird. These were from three species: House Sparrows Passer domesticus (68% of 133 nests with co-breeding), Tree Sparrows Passer montanus (65%), and Starlings Sturnus vulgaris (30%). The probability of breeding passerines within White Stork nests increased with increasing nest thickness, and was significantly higher in currently occupied nests. Sparrows were more likely to breed in White Stork nests located on electricity poles, situated closer to settlements and surrounded mainly by arable fields where meadows were not prevalent. In this paper, we show that White Stork nests are favorable nesting sites for passerines, as they are well insulated and provide an anti-predatory shield.

Intraclutch egg size variation is independent of ecological context among years in the European Starling Sturnus vulgaris

Female birds can potentially utilise various mechanisms, such as intraclutch egg size variation (ICESV), to modulate offspring quality. If this represents an ‘adaptive’ strategy allowing females to adjust reproductive effort after laying of the first egg, as information on resources becomes more predictable later in the laying sequence, then we would predict that ICESV would vary with ecological context, e.g. in ‘good’ versus ‘bad’ years. Here, in European Starlings (Sturnus vulgaris), we tested specific predictions that (1) females would lay relatively small last laid eggs in ‘poor’ years (with early laying and below-average breeding productivity); and (2) that ICESV would be lower in good years (late laying, above-average productivity) so that late-hatched chicks would not be disadvantaged. At the individual level we predicted (3) that repeatability of ICESV would be low if females adjusted this in relation to the environment in different years; and (4) that within-individual variation in ICESV should correlate with the number, and timing, of loss of chicks. Mean ICESV averaged −1.9% (measured as last egg mass relative to mean egg mass), typical of other hole-nesting passerines. However, our results did not support any of our hypotheses: (1) although there was annual variation in ICESV, in all years egg mass decreased through the laying sequence; (2) annual variation in ICESV was not consistent with variation in phenology or breeding productivity among years; (3) marked individual variation in ICESV (last laid egg varied from −20 to +10% relative to mean egg mass within clutches) was repeatable, i.e. individual females did not adjust ICESV in subsequent breeding attempts; and (4) variation in the magnitude of ICESV, alone and combined with hatching asynchrony, did not predict early brood loss. Our study suggests that ICESV is a relatively inflexible component of an individual female’s phenotype that might contribute to variation in individual quality.