Starlings Sturnus Vulgaris Research Articles

Changing demography and population decline in the Common Starling Sturnus vulgaris: a multisite approach to Integrated Population Monitoring

Understanding demography is critical for understanding the causes underlying population declines, and for initiating and monitoring policies to reverse them. A method of fitting demographic models directly to avian count data recorded at a sample of census sites is described. The model is applied to national and regional counts of Common Starling Sturnus vulgaris in Britain for the period 1965–2000. Starlings have declined markedly during this time and are now on the list of birds of highest conservation concern. Although there have been small changes in various aspects of breeding success over this time, the analysis shows that these are unlikely to have made much impact on the long‐term status of the species. By incorporating estimates of survival, based upon recoveries of ringed birds, the model suggests that the pronounced national decline in Starling numbers since a period of stability in the 1970s is most likely to be due to changes in the survival of first‐year birds. This narrows the candidate range of environmental factors which might influence the decline and implicates changes in resource availability.

Long-term trends in first arrival and first egg laying dates of some migrant and resident bird species in northern Italy

Climate change is affecting the phenology of seasonal events in Europe and the Northern Hemisphere, as shown by several studies of birds' timing of migration and reproduction. Here, we analyse the long-term (1982-2006) trends of first arrival dates of four long-distance migratory birds [swift (Apus apus), nightingale (Luscinia megarhynchos), barn swallow (Hirundo rustica), and house martin (Delichon urbicum)] and first egg laying dates of two migrant (swift, barn swallow) and two resident species [starling (Sturnus vulgaris), Italian sparrow (Passer italiae)] at a study site in northern Italy. We also addressed the effects of local weather (temperature and precipitation) and a climate index (the North Atlantic Oscillation, NAO) on the interannual variability of phenological events. We found that the swift and the barn swallow significantly advanced both arrival and laying dates, whereas all other species did not show any significant temporal trend in either arrival or laying date. The earlier arrival of swifts was explained by increasing local temperatures in April, whereas this was not the case for arrival dates of swallows and first egg laying dates of both species. In addition, arrival dates of house martins were earlier following high NAO winters, while nightingale arrival was earlier when local spring rainfall was greater. Finally, Italian sparrow onset of reproduction was anticipated by greater spring rainfall, but delayed by high spring NAO anomalies, and swift's onset of reproduction was anticipated by abundant rainfall prior to reproduction. There were no significant temporal trends in the interval between onset of laying and arrival in either the swift or the barn swallow. Our findings therefore indicate that birds may show idiosyncratic responses to climate variability at different spatial scales, though some species may be adjusting their calendar to rapidly changing climatic conditions.

Crop use by introduced bird species in winter in relation to crop structure and seed resources

Capsule Most species preferred to forage in grassland where seed resources were more abundant and the vegetation was uniform in height but heterogeneous in density. Aim To determine the influence of crop composition and structure, and seed food resources on the distribution of introduced bird species on New Zealand farmland in winter. Methods Birds were counted on 90 ha of mixed cropping farmland during mid- and late-winter periods, 2004. The presence or absence of six introduced species (Blackbird Turdus merula, Skylark Alauda arvensis, House Sparrow Passer domesticus, Goldfinch Carduelis carduelis, Yellowhammer Emberiza citrinella and Starling Sturnus vulgaris) in fields was investigated in relation to crop composition and structure and seed abundance. Results Species–habitat associations varied over time and between species. Blackbird, House Sparrow, Yellowhammer and Starling were associated more frequently with grassland than arable crops during at least one survey. Seed abundance was a significant predictor of the occurrence of all species except House Sparrow, while crop structure was a predictor of only Goldfinch, Yellowhammer and Starling occurrence. Conclusion During the winter, the distribution of six introduced bird species in the lowland cropping area was related to habitat composition, vegetation structure, and seed food resources. The preference for grassland habitats was probably determined by the vegetation structure and seed resources in these areas. The trend for increased use of supplementary animal feed in livestock farming in New Zealand may help sustain introduced bird populations. A larger-scale study is needed to investigate the generality of the species–habitat associations detected in this study at the landscape scale.

NESTLING IMMUNOCOMPETENCE IS AFFECTED BY CAPTIVITY BUT NOT INVESTIGATOR HANDLING

Abstract Environmental conditions during the neonatal period can affect the growth, physiology, behavior, and immune function of birds. In many avian studies the nestling environment includes investigator handling of young, which may be stressful. While neonatal handling is known to affect the adult phenotype in rats, the effects of handling on development have rarely been examined in wild birds. We examined the effect of short, repeated periods of neonatal handling on avian growth and immune system development. We subjected American Kestrels (Falco sparverius) and European Starlings (Sturnus vulgaris) to 15 min of daily investigator handling throughout the nestling period, while controls remained undisturbed. Immediately prior to fledging we assessed cutaneous immunity, humoral immunity, mass, and degree of fluctuating asymmetry. Daily handling did not significantly affect any of these measurements. We also addressed the possibility that treatment differences would appear only when birds were challenged ...

SELENIUM ACCUMULATION IN EUROPEAN STARLINGS NESTING IN A SELENIUM-CONTAMINATED ENVIRONMENT

Abstract I compared selenium (Se) levels in blood, liver, egg, and diet samples from European Starlings (Sturnus vulgaris) nesting at Kesterson Reservoir, Merced County, California and the surrounding area. Concentrations were highest in adult and nestling blood (8.3 and 5.5 µg g−1, respectively), nestling liver (7.5 µg g−1), and eggs (4.6 µg g−1) from nest boxes in interior parts of Kesterson compared to those from the perimeter (adult and nestling blood = 4.0 and 1.4 µg g−1, respectively, nestling liver = 4.7 µg g−1, eggs = 2.8 µg g−1) and off-site (nestling blood = 3.8 µg g−1, liver = 4.3 µg g−1, egg = 2.7 µg g−1). No hatching failure or embryo effects were observed. Although I found strong positive relationships in Se levels among tissues and eggs, variability of dietary exposure and differences in depuration rates across tissues confounds prediction of Se concentration. Nevertheless, I found blood Se to be a good indicator of dietary exposure that can be sampled nondestructively.

SONG LEARNING AFTER ISOLATION IN THE OPEN-ENDED LEARNER THE EUROPEAN STARLING: DISSOCIATION OF IMITATION AND SYNTACTIC DEVELOPMENT

Abstract We performed two studies to test whether the ability of open-ended learners to acquire new songs as adults depends on their having learned normal songs as juveniles. European Starlings (Sturnus vulgaris) were kept in isolation for their first year. In the first study the birds were housed in a group with a wild-caught adult male following isolation. The subjects imitated each other but not the wild male and failed to develop normal phonology or syntax. In the second study each yearling was housed individually with a wild-caught adult male following isolation. These subjects developed good phonology and syntax but copied few or no song motifs from the wild adults. Taken together, the two studies indicate that starlings are capable of imitating new motifs and of acquiring species-typical phonology and syntax after a year of isolation. The contrasting results of the two studies suggest that imitation and the development of syntax are independent processes subject to different influences.

Kinetics of primary antibody responses to sheep red blood cells in birds: a literature review and new data from great tits and European starlings

Abstract Measuring the primary antibody immune response to an injection with sheep red blood cells (SRBC) is a routine application in poultry science. Recently, this technique is also becoming an increasingly popular tool to investigate humoral immunocompetence in free-living birds in studies of ecological immunology and immunotoxicology. However, an extensive search of the literature revealed that many of these studies have been measuring the primary immune response to SRBC without verifying first when maximum levels of antibodies are reached in the bird species under study. In addition, most studies assessed antibody titres to SRBC approximately 6 days after their inoculation assuming a similar pattern as found in poultry. We tested this assumption of a uniform pattern of kinetics of the primary humoral immune response to SRBC across bird species and investigated it in detail in two important model species, namely the great tit Parus major and the European starling Sturnus vulgaris. In general, the pattern was found to be the same in both passerine species and strongly resembled the pattern observed in chickens. Maximum antibody levels (the plateau phase) were reached on, respectively, day 5 and day 6 (with day of inoculation = day 0) of the immune response in the great tit and the starling and lasted for 3 days in both species. We found no effects of age, sex or time spent in captivity. Furthermore, our findings suggest that antibody levels to SRBC should not be obligatory assessed during the plateau phase of maximum antibody levels although it still remains most accurate to do so or at least shortly before or after it. Overall, we conclude that antibody levels have been reliably assessed in most avian studies using this technique.

Respiratory water loss during rest and flight in European Starlings (Sturnus vulgaris)

Respiratory water loss in Starlings (Sturnus vulgaris) at rest and during flight at ambient temperatures (T(amb)) between 6 and 25 degrees C was calculated from respiratory airflow and exhaled air temperature. At rest, breathing frequency f (1.4+/-0.3 Hz) and tidal volume Vt (1.9+/-0.4 ml) were independent of T(amb), but negatively correlated with each other. Mean ventilation at rest was 156+/-28 ml min(-1) at all T(amb). Exhaled air temperature (T(exh)) at rest increased with T(amb) (T(exh) = 0.92.T(amb)+12.45). Respiratory water loss at rest averaged 0.18+/-0.09 ml h(-1) irrespective of T(amb). In flying Starlings f was 4.0+/-0.4 Hz and independent of T(amb). Vt during flight averaged 3.6+/-0.4 ml and increased with T(amb) (Vt = 0.06.T(amb)+2.83) as, correspondingly, did ventilation. T(exh) during flight increased with T(amb) (T(exh) = 0.85.T(amb)+17.29). Respiratory water loss during flight (average REWL(f) = 0.74+/-0.22 ml h(-1)) was significantly higher than at rest and increased with T(amb). Our measurements suggest that respiratory evaporation accounts for most water loss in flying Starlings and increases more than cutaneous evaporation with rising ambient temperature.

Date of breeding of the starling Sturnus vulgaris in New Zealand is related to El Niño Southern Oscillation

Abstract: Weather and climatic conditions may impact on the timing of breeding in birds. We examined changes in the laying date of the starling Sturnus vulgaris at Lower Hutt, New Zealand in the period 1970–2003 and investigated possible relationships with the El Niño Southern Oscillation (ENSO). Laying dates (expressed both as first and modal dates for the local population) were significantly delayed over the study period, i.e. starlings tended to lay later. The timing of breeding was non‐linearly related to ENSO, with early laying associated with both low and high values of ENSO. We suggest that changes in laying dates varied with food availability, which fluctuated according to climatic events.

Avian translocations and disease; implications for New Zealand conservation

There is little published information on the pathogens present in New Zealand passerines. We report here on a preliminary survey of selected pathogens and haematology profiles for seven species in the Auckland region. Avian translocations are commonly used for the recovery of threatened species. Translocations may increase the risk of spreading disease to immunologically na�ve populations. It is therefore important to take every opportuntty to gather baseline disease data and test hypotheses associated with disease. Blood, cloacal and faecal samples were collected from Fernbird Bowdleria punctata, Tui Prosthemadera novaeseelandiae, Bellbird Anthornis melanura, Tomtit Petroica macrocephala, New Zealand Robin Petroica australis, Whitehead Mohua albicilla and Starling Sturnus vulgaris during four translocations to and from Tiritiri Matangi Island. Birds (n = 137) were also examined for external lesions typical of avian pox. Blood samples (n = 40) were screened by microscopy for Plasmodium spp., Atoxoplasma spp. and other blood parasites and a differential white blood cell count was made. Cloacal swabs (n = 38) were cultured for Yersinia spp., Salmonella spp. and Campyobaeter spp. Faecal samples were screened for coccidia spp. (n = 28). An unidentified coccidian sp. and a Haemoproteus sp. were detected in one Fembird and one robin respectively. No other organisms with the potential to cause disease were detected. Despite the effort required to complete disease screening, we argue that disease samples and baseline haematology normal values should be collected at an opportunities. We make recommendations for future disease screening, and discuss the importance and potential significance of disease to the conservation of New Zealand's biodiversity.

A Comparative Analysis of the Influence of Weather on the Flight Altitudes of Birds

Birds pose a serious risk to flight safety worldwide. A Bird Avoidance Model (BAM) is being developed in the Netherlands to reduce the risk of bird-aircraft collisions. In order to develop a temporally and spatially dynamic model of bird densities, data are needed on the flight-altitude distribution of birds and how this is influenced by weather. This study focuses on the dynamics of flight altitudes of several species of birds during local flights over land in relation to meteorological conditions. We measured flight altitudes of several species in the southeastern Netherlands using tracking radar during spring and summer 2000. Representatives of different flight strategy groups included four species: a soaring species (buzzard Buteo buteo), an obligatory aerial forager (swift Apus apus), a flapping and gliding species (blackheaded gull Larus ridibundus), and a flapping species (starling Sturnus vulgaris). Maximum flight altitudes varied among species, during the day and among days. Weather significantly influenced the flight altitudes of all species studied. Factors such as temperature, relative humidity, atmospheric instability, cloud cover, and sea level pressure were related to flight altitudes. Different combinations of factors explained 40%-70% of the variance in maximum flight altitudes. Weather affected flight strategy groups differently. Compared to flapping species, buzzards and swifts showed stronger variations in maximum daily altitude and f lew higher under conditions reflecting stronger thermal convection. The dynamic vertical distributions of birds are important for risk assessment and mitigation measures in flight safety as well as wind turbine studies.

Changes in circadian LH-secretion patterns and annual gonadal cycles in the male European starling (Sturnus vulgaris)

An analysis of the circadian and circannual patterns of luteinizing hormone (LH) secretion in male European starlings (Sturnus vulgaris) held in outdoor aviaries is presented. On the basis of six daily time points, eight calendar dates, and seven individuals per sampling unit, we present a mathematical model developed to compare the two temporal patterns of secretion, the circadian and the circannual one. The superposition of four orthonormal trigonometric base functions, plus a constant, is used to examine the daily fluctuations. The contribution of the second harmonic was not the same at each calendar date. From the subsequent regression functions, hourly estimates of LH concentration were calculated and used to construct circannual cubic splines and an LH(t,T) function over the whole year. The model features indicate strong circannual and circadian components in the data. In addition, there appear to be two daily time regions of LH secretion: morning and afternoon. In particular, the afternoon maxima occur during photorefractoriness and early gonadal development; the morning maxima at the onset of photoinduction and late gonadal development. At the peak of gonadal activity (end of April), the highest LH levels occur during the photic input phase. It appears, then, that the circadian acrophase of LH secretion in male starlings fluctuates over the annual cycle of gonadal activity in a highly predictive and biologically interpretable manner.

Brood size and environmental conditions sex-specifically affect nestling immune response in the European starling Sturnus vulgaris

Brood size and environmental conditions sex-specifically affect nestling immune response in the European starling Sturnus vulgaris

Mutual ornamentation, age, and reproductive performance in the European starling

Ornamental traits expressed in both sexes are widespread among birds. Many studies have indicated that male ornaments develop through sexual selection. Female ornaments may be correlated effects of selection on males or have signaling functions in their own right. In the facultatively polygynous starling Sturnus vulgaris, both sexes possess iridescent throat feathers, which are actively displayed during courtship by males. This paper investigates the reproductive correlates of throat feather ornaments in both sexes. Bird-perceived hue and components of feather length covaried strongly, and a summary variable (the first principal component [PC1]) was extracted using Principal component analysis. Sex and age-related differences were found for PC1. Positive assortative mating was found with respect to age and PC1. However, the relative influences of ornamentation and age on breeding variables were hard to separate, so effects may be related to other age-related variables. This provides a cautionary note for studies of ornamentation where age is unknown. However, we argue that throat feathers in starlings may signal age and age-related quality measures in both sexes. Older females with higher PC1 scores bred earlier and laid larger clutches with higher hatching success; older males with higher PC1 scores had higher chances of becoming polygynous and attracting high reproductive quality females. PC1 showed no relationship with parental care in either sex. Direct reproductive benefits for males and indirect genetic benefits for either sex may drive mate choice based on these age-related characters. However, only experimental manipulation can determine whether ornamentation signals quality variation within age classes. Key words: avian color vision, mutual sexual selection, ornamentation, plumage coloration, reproductive performance. [Behav Ecol]

Evidence for sexy sons in European starlings (Sturnus vulgaris)

The “sexy son” hypothesis suggests that females obtain future fitness benefits from mating with polygynous males through the inheritance by their sons of traits contributing to mating success. We tested this hypothesis in the facultatively polygynous European starling (Sturnus vulgaris) in two ways. We first compared sons of monogynous and polygynous free-living males for their abilities in nest site acquisition and female-directed behaviors in controlled aviary tests. We then investigated eggs laid in monogynous and polygynous matings for concentrations of maternal steroid hormones that could affect behavioral differentiation of sons. Sons of polygynous fathers defended more nest boxes and produced more courtship song than sons of monogynous fathers. Mean concentrations of maternal androstenedione (A4), 5α-dihydrotestosterone (DHT), testosterone (T), and 17β-estradiol (E) in yolks were not affected by mating status. However, the within-clutch pattern of A4 depended on mating status, with higher concentrations in last than in first eggs of clutches of monogynous but not polygynous matings. These results suggest that (1) sons may inherit from their fathers behavioral qualities for the successful acquisition of nest sites and attraction of mates; (2) differential exposure to maternal steroid hormones during development in the egg is unlikely the cause of the behavioral differences between adult sons of monogynous and polygynous fathers; and (3) females adjust the within-clutch pattern of androgen to mating status, possibly in response to the expected contribution of their mate to nestling care.

Evaluating the Breeding Bird Survey for producing national population size and density estimates

Capsule The BBS has potential for producing better estimates of habitat-specific densities and population sizes for many UK bird populations than those available previously. Aims To examine the use of the Breeding Bird Survey (BBS) in providing unbiased national population and habitat-specific density estimates of British birds. Methods Line transect data collected by volunteers in 1998 from 2287 1-km squares across the UK were analysed using distance sampling methods to calculate habitat-specific density and abundance estimates. For each species, the habitat-specific decline in detectability with distance from a transect line was modelled and applied at a regional level to incorporate variation in sampling intensity in different areas of the country. Results National population and density estimates calculated here were at a magnitude expected for at least seven species in this study. However, national population size estimates were higher than expected for Starling Sturnus vulgaris, House Sparrow Passer domesticus, Blackbird Turdus merula, Greenfinch Carduelis chloris, Jackdaw Corvus monedula, Whitethroat Sylvia communis, Woodpigeon Columba palumbus and Linnet Carduelis cannabina and lower than expected for Skylark Alauda arvensis, Dunnock Prunella modularis, Song Thrush Turdus philomelos and Corn Bunting Miliaria calandra. These differences are likely to be related to differences in sampling design and survey methods. For example, Starling, House Sparrow, Blackbird, Jackdaw, Greenfinch and Wood Pigeon, which have considerable populations in urban areas, were undoubtedly underestimated by the Common Birds Census (CBC). The counts of species that flock during the breeding season, or are not strongly territorial (e.g. Linnet, Jackdaw and Wood Pigeon) could be biased if detectability is strongly related to flock size. National population estimates of Skylark and Corn Bunting are lower than those based on CBC, but higher, or similar, to targeted national surveys of these species. Possible reasons for the differences between these estimates are considered. Conclusions This study highlights the strength of the BBS over previous data sources in producing national estimates of density and abundance at the habitat and national level. More research on the sex ratio and status of birds counted during surveys, and on the reliability of the detectability functions derived from distance sampling is needed to improve the interpretation of population estimates derived from BBS data.

Are the Low Protein Requirements of Nectarivorous Birds the Consequence of Their Sugary and Watery Diet? A Test with an Omnivore

Nectar-feeding birds have remarkably low nitrogen requirements. These may be due either to adaptation to a low-protein diet or simply to feeding on a fluid diet that minimizes metabolic fecal nitrogen losses. We measured minimal nitrogen requirements (MNR) and total endogenous nitrogen loss (TENL) in the omnivorous European starling Sturnus vulgaris, fed on an artificial nectar-like fluid diet of varying concentrations of sugar and protein. The MNR and TENL of the birds were similar and even slightly higher than allometrically expected values for birds of the starlings' mass (140% and 103%, respectively). This suggests that the low measured nitrogen requirements of nectar-feeding birds are not simply the result of their sugary and watery diets but a physiological adaptation to the low nitrogen input. We also measured the effect of water and protein intake on the nitrogenous waste form in the excreta and ureteral urine in European starlings. Neither high water intake nor low protein intake increased the fraction of nitrogen excreted as ammonia. Ammonia was excreted at consistently low levels by the starlings, and its concentration was significantly higher in ureteral urine than in excreta. We hypothesize that ureteral ammonia was reabsorbed in the lower intestine, indicating a postrenal modification of the urine.

FEMALE SONG IN EUROPEAN STARLINGS: SEX DIFFERENCES, COMPLEXITY, AND COMPOSITION

Abstract While male song and its functions have been well studied, female song has often been overlooked. In this study, we provide a detailed description of the spontaneous female song in a well-studied northern temperate songbird, the European Starling (Sturnus vulgaris). We compared the song organization, complexity, and composition of female and male starlings housed in large outdoor aviaries. Overall, the general organization was similar in both sexes, and some females sang complex song bouts of more than 30 seconds of uninterrupted song. Although some females were capable of singing the four phrase-type categories typically found in male song bouts (whistle, variable, rattle, and high-frequency phrase types), a significantly lower proportion of females sang all four categories of phrase type as compared to males. Our results also revealed large individual variation in song characteristics among females: repertoire size varied between 11 and 36 phrase types, while average song bout length ranged betw...

The effects of habitat structure on predation risk of birds in agricultural landscapes

It has been suggested that increased predation rates may rival habitat alteration as a causal agent in farmland bird population declines. Such a view may be over‐simplistic, however, as changes in habitat structure may influence habitat selection and foraging efficiency through their influence on perceived and actual predation risk. We review evidence from the literature on the effects of habitat structure on predation risk of foraging and nesting birds and apply these principles to investigate the likely effects on the 20 species that comprise the UK Government's ‘Farmland Bird Index’. Shorter vegetation is likely to enhance foraging efficiency and reduce predation risk (when ground foraging) for 15 of the 20 species. However, within grassland systems longer vegetation is known to enhance food supplies (e.g. Tipulid larvae and voles) of several farmland bird species and so mosaics of short and long vegetation may provide the optimum conditions for most species (e.g. LapwingVanellus vanellus, StarlingSturnus vulgaris, Barn OwlTyto alba). Agricultural intensification has encouraged uniform dense swards, thus reducing habitat diversity, and agri‐environment schemes that provide heterogeneous sward structure may thus facilitate farmland bird conservation. Intensification has also resulted in less dense hedgerows; although a reversal of this trend may improve foraging efficiency for many species, it may be detrimental to a smaller number of species that prefer shorter, less dense hedges for nesting. Before these tentative conclusions can be confirmed, more research is required that considers how the effects of habitat structure on individuals is likely to translate into population‐level impacts.

What factors determine where invertebrate‐feeding birds forage in dry agricultural grasslands?

Increases in the intensity of the management of agricultural grasslands over the past 50 years have reduced plant species diversity in swards and increased uniformity in structure through changes in fertilizer regimes, grazing and mowing practices. These factors, as well as increased disturbance and trampling, have reduced the number and diversity of forbs and thus the diversity and abundance of invertebrates, in particular of foliar species. Associated with these changes in management, there has been a large decline in the abundance of many species of farmland birds in pastoral areas and more local extinctions compared with arable areas. To understand the impact of these management changes on bird populations, and design measures to reverse the declines, it is necessary to identify the key factors influencing bird usage of fields. We review results from five studies, which have related fertilizer and grazing management to bird usage of grass fields. Species that fed on soil invertebrates tended to show a positive response to the amount of nitrogen fertilizer added and increased grazing pressure, although there was a high degree of correlation between these two variables. In summer, many species, including corvids, Common Blackbird Turdus merula, Common Starling Sturnus vulgaris, Pied Wagtail Motacilla alba and Hedge Accentor Prunella modularis, showed a negative relationship with sward height, and in winter more species showed a positive relationship with bare ground. Taller sward heights are associated with a greater abundance and diversity of bird invertebrate food resources, and accessibility of food items or a lower risk of predation (actual or perceived) are likely to be the reasons for birds choosing to forage on shorter swards and in areas with more bare ground. Birds feeding on soil invertebrates were found to be generally tolerant of modern management practices that maintain short swards short, as accessibility to the soil has been increased. Species that feed on foliar invertebrates or forb seeds have been affected negatively by modern grassland agricultural practices.