Daily Laying Time in Free‐Living European Starlings: Solar Noon,a Potential Synchronizer

Reproduction is generally controlled by important temporal constraints involving complex adaptive mechanisms. Birds, in temperate zones, present marked breeding seasonality as well as marked daily organization of reproductive behavior, especially laying. Intra‐specific variability and determinants of this pattern have been investigated mainly in domestic non‐passerine birds. The present study analyzed the daily temporal organization of laying in a free‐living species, the European starling, Sturnus vulgaris. Breeding in a starling colony was monitored for five consecutive years using a non‐invasive method (infrared video camera) to precisely estimate laying times. European starlings present a marked daily laying rhythm, ovipositions occurring only during a morning species‐specific temporal window. Inside this laying window, time intervals between successive eggs varied greatly among females. Contrary to many species, the light/dark cycle did not appear to control laying time in European starlings, but daily variations of the ultraviolet composition of the solar spectrum appeared to be a possible Zeitgeber of this behavior.     

Daily organization of laying in Japanese and European quail: effect of domestication

In the present study, we aimed to examine the possible effects of domestication on the daily organization of laying in female quail. To achieve this we compared laying patterns in a laboratory strain of Japanese quail with those in European quail originating from a wild population. Under LD 14:10, the same specific laying window was observed, with ovipositions occurring mainly between 7 h and 15 h after lights on. Thus, domestication did not modify the specific daily organization of laying in females laying in the afternoon. Research about the functional value of this temporal organization in the field thus seems justified. At an individual level, two distinct laying profiles were recorded, as in a previous experiment on an industrial Japanese quail strain selected for meat and egg production. However, different frequencies were noted. Whereas stable profile females (laying at the same time each day) were predominant (80.4%, N=102) in the industrial Japanese quail strain, delayed profile females (laying successively later each day) appeared dominant in the European quail (81%, N=22). The Japanese quail from the laboratory strain constituted an intermediate group with a slight dominance of the stable profile (58.8%, N=17). Thus, domestication has changed the frequencies of the laying profiles, favoring stable females, which are the most productive birds. A model involving interaction between one circadian rhythm and one ultradian rhythm can explain the observed laying profiles.     

A case of cooperative breeding in the European Starling,Sturnus vulgaris

Cooperative breeding, where individuals other than the parents help to raise offspring, occurs in only ~9% of bird species. Although many starlings (Sturnidae) are cooperative breeders, the European starling (Sturnus vulgaris) has rarely been observed exhibiting this behavior. Only two other records exist, one of which was limited to a juvenile giving food to chicks that had already been collected by a parent (and hence providing limited help). Herein, we report a case of cooperative breeding by a juvenile European starling, which represents the second with any evidence of the juvenile collecting food independently and the first to document the extent of such help in the form of feeding rates. Over a period of at least 3 days, a juvenile starling assisted two parents to feed their second brood of the year, and it fed the chicks at the same rate as the adults (~3.5 feeds per hour). In considering potential explanations for this behavior, we conducted an ancestral state estimation of cooperative breeding across starlings and were able to eliminate the possibility that this is a rarely expressed behavior inherited from cooperatively breeding ancestors. Instead, we propose that our observations point to a behavioral innovation, which may be in response to environmental change such as climate change (which has previously been associated with cooperative breeding). Researchers working on birds should be alert to such behavior to determine whether this apparently new breeding strategy will increase as a potential adaptation to environmental change.     

Isolation and characterization of polymorphic microsatellite loci in the plural cooperatively breeding superb starling,Lamprotornis superbus

Superb starlings (Lamprotornis superbus) are separate nesting plural cooperative breeders endemic to East Africa that show high levels of reproductive conflict and low reproductive skew. I isolated 31 polymorphic microsatellite loci from the superb starling genome and characterized them in approximately 31 individuals. The numbers of alleles per locus ranged from two to 16 and observed heterozygosities ranged from 0.03 to 0.88. Many of these loci amplified in other passerine species including the European starling, Sturnus vulgaris, and a variety of other starlings and mockingbirds.     

THE WHISTLED SONGS OF THE EUROPEAN STARLING STURNUS VULGARIS AND THE SPOTLESS STARLING STURNUS UNICOLOR IN NORTH-EAST SPAIN

ABSTRACT

This paper describes the whistled songs of two allopatric populations of the European starling and spotless starling in NE Spain. The results show that European starlings in NE Spain sing the same whistled themes found earlier in other European populations and confirm the universal character of these themes. There are some differences between European starlings from NE Spain and other populations: rising phases appear for Inflection theme high-form, Inflection theme and Simple theme, and also differences of rate of emission appear for others (Rhythmic theme). Harmonic theme has not been found. Likewise, the first analysis of the spotless starling's whistled song shows that it shares the same general whistled song structure with the European starling; whistles have similar structural parameters (modulation, duration, frequency) and can be classified in the same categories or themes; a new theme appears, the Trilled theme, which has not been found to date in the European starling. Dialectal areas have been found in both species for the same themes (Inflection theme, Simple theme). The males of both studied populations have larger repertoires in comparison to other studied populations of the European starling.     

Starling foraging success in relation to agricultural land-use

Changes in agricultural land-use have been suggested to contribute to the decline of several bird species through negative effects on their food supply during breeding. One important change in land-use has been loss of pastures, especially permanent pastures. In this study we investigated how different forms of agricultural land-use affected foraging success of a declining bird species, the European starling Sturnus vulgaris . We let caged starlings forage in different forms of agricultural fields and determined time spent foraging and foraging success. The starlings' activity level (time spent actively foraging) as well as the number of prey caught per time unit was strongly related to the abundance of prey in soil samples. Also the body mass change during the experiment was positively related to activity level and prey capture rate. We found consistent differences in foraging variables between habitats. In spring sown grain starlings were least active and found fewer prey items at a lower rate than in any other habitat. The other three habitats differed less, but in general mowed hay fields appeared slightly more valuable than the cultivated and natural pastures. We did not find any differences between natural and cultivated pastures in foraging variables. Thus, starling foraging success is higher in grass-covered fields than in cultivated fields, but the management of the grass-covered fields mattered less. The results are consistent with starlings having higher population densities and breeding success in areas with higher availability of pasture. We suggest that the physical structure of the habitat (sward height) and moisture may be additional variables that need to be taken into account to explain starling breeding density and success in the agricultural landscape.     

Ontogeny of the rhythmic melatonin production in a precocial and an altricial bird,the Japanese quail and the European starling

A distinct daily rhythm of melatonin production was found in the pineal gland of both precocial Japanese quail (Coturnix coturnix japonica) and altricial European starling (Sturnus vulgaris) during the first day of postembryonic life. Rhythmic melatonin production was reflected in a rhythmic profile in the general circulation. Significant day-night differences in melatonin content were also observed in the eyes of Japanese quail.The amplitude of the rhythm in the quail pineal gland increased steadily during the first two weeks of postem-bryonic life. A transient increase in maximum melatonin concentration was observed at the end of the first week of life in the plasma but not in the pineal gland of quail suggesting that a metabolizing pathway or a changed ocular contribution may influence the melatonin profile in the circulation and its availability to other tissues. There was no delay in the postembryonic development of melatonin rhythmicity in the altricial starling in comparison with the precocial quail. The amplitude of the plasma melatonin rhythm did not increase over the first week of life in starlings as it did in quail and the only significant increase was found between 6- and 17-day old starlings.In general, the development of the rhythm resulted from an increase of dark-time values. The day-time concentrations were low in all age groups of both species. A one-hour light pulse suppressed the high dark-time melatonin concentrations in 1-, 7- and 14-day old Japanese quail as well as in 7- and 14-day old European starlings. The manner in which the rhythm develops suggests that the circadian pacemaker(s) as well as the mechanisms of photoreception and entrainment are developed in hatchlings of both species in spite of their otherwise different developmental strategies.     

同域分布下丝光椋鸟与灰椋鸟的繁殖行为

2011年3—6月,通过悬挂巢箱人工招引丝光椋鸟(Sturnus sericeus)及同域分布下的灰椋鸟(Sturnus cineraceus),并对其繁殖生态进行了初步研究。共设置椋鸟式巢箱40个,其中椋鸟的入住率是84.6%,营巢成功率是51.5%,利用摄像机对其中3巢丝光椋鸟与3巢灰椋鸟进行了系统的繁殖行为观察。结果显示:丝光椋鸟窝卵数为6～7枚,灰椋鸟窝卵数5～7枚,后者的卵显著大于前者;丝光椋鸟的育雏期(20d)较灰椋鸟(16d)长,且亲鸟的递食率明显较高;育雏期丝光椋鸟亲鸟的警戒频次也明显高于灰椋鸟。因此,相比于灰椋鸟,丝光椋鸟具有更完善的育雏行为机制。另外,本文还首次报道了丝光椋鸟的种内巢寄生现象。     

Efficacy of European starling control to reduce <Emphasis Type="Italic">Salmonella enterica</Emphasis> contamination in a concentrated animal feeding operation in the Texas panhandle

Background  

European starlings (Sturnus vulgaris) are an invasive bird species known to cause damage to plant and animal agriculture. New evidence suggests starlings may also contribute to the maintenance and spread of diseases within livestock facilities. Identifying and mitigating the risk pathways that contribute to disease in livestock is necessary to reduce production losses and contamination of human food products. To better understand the impact starlings have on disease transmission to cattle we assessed the efficacy of starling control as a tool to reduce Salmonella enterica within a concentrated animal feeding operation. We matched a large facility, slated for operational control using DRC-1339 (3-chloro-4-methylaniline hydrochloride, also 3-chloro p-toluidine hydrochloride, 3-chloro-4-methylaniline), with a comparable reference facility that was not controlling birds. In both facilities, we sampled cattle feed, cattle water and cattle feces for S. enterica before and after starling control operations.     

Habitat selection, diet and interspecific associations of the rufous-tailed weaver and Fischer's lovebird

We investigated habitat selection and diets of two co-occurring endemic bird species (rufous-tailed weaver, Histurgops ruficauda , Fischer's lovebird, Agapornis fischeri ) and four other species with which they associated in mixed feeding flocks (red-billed buffalo weaver, Bubalornis niger , white-headed buffalo weaver, Dinemellia dinemellii , superb starling, Lamprotornis superbus , and Hildebrandt's starling, Lamprotornis hildebrandti ) during the dry season in Serengeti National Park Tanzania. Mixed species flocks could facilitate food acquisition and/or act as anti-predator mechanisms. Five of the six species selected grassland habitat over Acacia habitat along transects. Analysis of species association, using Cole's coefficient of association, showed that both rufous-tailed weavers and superb starlings co-occurred with red-billed buffalo weavers. Superb starlings were negatively associated with Fischer's lovebird, Hildebrandt's starling and white-headed buffalo weavers. Diet analysis revealed that the rufous-tailed weaver, white-headed buffalo weaver, and red-billed buffalo weaver were generalists eating both insects and seeds, whereas Fischer's lovebird and superb starling were specialists, selecting only seeds and insects respectively. These data offer some support for the hypothesis that mixed species flocks facilitate mutual food searching.     

Age-dependent changes in plasma and brain cholinesterase activities of house wrens and European starlings

We determined age-dependent changes in plasma and brain cholinesterase (ChE) activity for two species of passerines: house wren (Troglodytes aedon) and European starling (Sturnus vulgaris, starling). In plasma from nestlings of both species, total ChE activity increased with age, acetycholinesterase (AChE, EC 3.1.1.7) activity declined rapidly immediately after hatching, and butyrylcholinesterase (BChE, EC 3.1.1.8) activity increased steadily. For both species, total ChE and BChE activities and the BChE:AChE ratio in plasma were significantly greater in adults than nestlings suggesting trends observed in nestlings continue post fledging. In older nestlings and adults, AChE activity in plasma was significantly greater and BChE:AChE ratio less in house wrens than starlings. For house wrens as compared with starlings, ChE activity in brain increased at a significantly greater rate with age in nestlings and was significantly greater in adults. However, ChE activity in brain was similar at fledging for both species suggesting that the increase in ChE in brain is more directly related to ontogeny than chronologic age in nestlings of passerines. For both species, ChE activity increased significantly with brain weight of nestlings but not adults. House wrens hold similar patterns of age-dependent change in ChE activity in common with starlings but also exhibit differences in AChE activity in plasma that should be considered as a factor potentially affecting their relative toxicologic response to ChE inhibitors.     

Dynamics of an immune response in house sparrows Passer domesticus in relation to time of day, body condition and blood parasite infection

European starlings ( Sturnus vulgaris ) introduced to North America compete with native cavity-nesting birds for nest sites. I examined whether natural selection could favour a strategy of delayed nesting in a population of northern flickers ( Colaptes auratus ), a native woodpecker, to reduce overlap in breeding phenology with starling competitors. I developed a mathematical model based on reproductive parameters for a population of flickers from central British Columbia, Canada. On average, 7% of flicker nests each year were usurped by starlings; daily probabilities of takeover declined through the season but were relatively low (1–2%). Flickers laid between 3 and 13 eggs and there was a negative correlation between clutch size and date. The probability of renesting after nest failure also declined during the season, but renesting intervals (2–19 days) were not associated with female age, or stage of nest loss. The model suggested that costs of delaying reproduction would outweigh benefits of an early start except when the probability of nest usurpation is very high (>75%) early in the season and declines rapidly through the summer. Thus, early laying dates should be favoured especially in northern latitudes where breeding seasons are short.     

Captive European starlings (Sturnus vulgaris) in breeding condition show an increased cardiovascular stress response to intruders

European starlings (Sturnus vulgaris) alter their physiology and behavior between seasons, becoming territorial during the spring/summer and flocking during the fall/winter. We used captive male starlings in breeding (photostimulated to 18L : 6D) and nonbreeding (11L : 13D) conditions to determine whether changing physiology and behavior alters their reaction to crowding. One or five intruders entered a resident's cage without human disturbance. A subcutaneous heart rate transmitter recorded cardiovascular output in residents. Corticosterone and testosterone were measured in plasma samples taken before and after the intrusion. While corticosterone concentrations did not change, heart rate changed significantly, indicating that these responses can be regulated independently. Long-day birds showed a significantly elevated heart rate response to the single-bird intrusion compared to short-day birds. Whereas five intruders elicited an identical peak response in both groups, long-day birds also demonstrated an equivalent response to one intruder. In addition, one intruder induced longer elevation in heart rate for long-day birds. Male starlings in breeding condition, therefore, demonstrate an increased sensitivity to additional conspecifics. This seasonal shift in response suggests that a higher tolerance for intrusion (i.e., considering a nearby starling as less stressful) may facilitate flocking behavior, while a lower tolerance may aid in territoriality.     

Pollutants increase song complexity and the volume of the brain area HVC in a songbird

Environmental pollutants which alter endocrine function are now known to decrease vertebrate reproductive success. There is considerable evidence for endocrine disruption from aquatic ecosystems, but knowledge is lacking with regard to the interface between terrestrial and aquatic ecosystems. Here, we show for the first time that birds foraging on invertebrates contaminated with environmental pollutants, show marked changes in both brain and behaviour. We found that male European starlings (Sturnus vulgaris) exposed to environmentally relevant levels of synthetic and natural estrogen mimics developed longer and more complex songs compared to control males, a sexually selected trait important in attracting females for reproduction. Moreover, females preferred the song of males which had higher pollutant exposure, despite the fact that experimentally dosed males showed reduced immune function. We also show that the key brain area controlling male song complexity (HVC) is significantly enlarged in the contaminated birds. This is the first evidence that environmental pollutants not only affect, but paradoxically enhance a signal of male quality such as song. Our data suggest that female starlings would bias their choice towards exposed males, with possible consequences at the population level. As the starling is a migratory species, our results suggest that transglobal effects of pollutants on terrestrial vertebrate physiology and reproduction could occur in birds.     

Timing of photorefractoriness in the European starling: significance of photoperiod early and late in the reproductive cycle

In European starlings, as in many other birds inhabiting higher latitudes, gonads develop in response to the increasing daylengths in early spring. Later in the year, however, the hypothalamo-pituitary-gonadal axis becomes refractory to the previously stimulatory long photoperiods and the gonads regress in summer. The present study addresses the question of when during the gonadal growth phase photorefractoriness is determined. A 13-h photoperiod induces testicular development and subsequent testicular regression associated with refractoriness in male starlings. An 11-h photoperiod, in contrast, induces only testicular development, and photorefractoriness never develops. When starlings were transferred to an 11-h photoperiod, either 12 or 25 days following exposure to a 13-h photoperiod, their testes developed to full size, but remained large to the end of the experiment, i.e. refractoriness did not develop. The same was even true of most birds in a third group that were transferred to an 11-h photoperiod after 46 days of the 13-h photoperiod, when gonads had developed to near maximal size. These data show that, in contrast to some other species of passerine birds, the onset of photorefractoriness does not become fixed before the testes have undergone considerable development, and that the photoperiodic conditions experienced at the end of the testicular growth phase are still effective in determining the precise time of onset of photorefractoriness. It is suggested that this peculiarity of the starling is related to the fact that its gonadal development begins rather early in spring and, hence, under much shorter photoperiods than the other species studied.     

European starlings (Sturnus vulgaris) challenged with Escherichia coli O157 can carry and transmit the human pathogen to cattle

Aims: European starlings (Sturnus vulgaris) are an invasive species in the United States and are considered a nuisance pest to agriculture. The goal of this study was to determine the potential for these birds to be reservoirs and/or vectors for the human pathogen Escherichia coli O157:H7. Materials and Results: Under biosecurity confinement, starlings were challenged with various doses of E. coli O157:H7 to determine a minimum infectious dose, the magnitude and duration of pathogen shedding, and the potential of pathogen transmission among starlings and between starlings and cattle. Birds transiently excreted E. coli O157:H7 following low‐dose inoculation; however, exposure to greater than 10^5.5 colony‐forming units (CFUs) resulted in shedding for more than 3 days in 50% of the birds. Colonized birds typically excreted greater than 10³ CFU g^?1 of faeces, and the pathogen was detected for as long as 14 days postinoculation. Cohabitating E. coli O157:H7‐positive starlings with culture‐negative birds or 12‐week‐old calves resulted in intra‐ and interspecies pathogen transmission within 24 h. Likewise, E. coli O157:H7 was recovered from previously culture‐negative starlings following 24‐h cohabitation with calves shedding E. coli O157:H7. Conclusions: European starlings may be a suitable reservoir and vector of E. coli O157:H7. Significance and Impact of the Study: Given the duration and magnitude of E. coli O157:H7 shedding by European starlings, European starlings should be considered a public health hazard. Measures aimed at controlling environmental contamination with starling excrement, on the farm and in public venues, may decrease food‐producing animal and human exposure to this pathogen.     

Neural correlates of behavioural olfactory sensitivity changes seasonally in European starlings

Background

Possibly due to the small size of the olfactory bulb (OB) as compared to rodents, it was generally believed that songbirds lack a well-developed sense of smell. This belief was recently revised by several studies showing that various bird species, including passerines, use olfaction in many respects of life. During courtship and nest building, male European starlings (Sturnus vulgaris) incorporate aromatic herbs that are rich in volatile compounds (e.g., milfoil, Achillea millefolium) into the nests and they use olfactory cues to identify these plants. Interestingly, European starlings show seasonal differences in their ability to respond to odour cues: odour sensitivity peaks during nest-building in the spring, but is almost non-existent during the non-breeding season.

Methodology/Principal Findings

This study used repeated in vivo Manganese-enhanced MRI to quantify for the first time possible seasonal changes in the anatomy and activity of the OB in starling brains. We demonstrated that the OB of the starling exhibits a functional seasonal plasticity of certain plant odour specificity and that the OB is only able to detect milfoil odour during the breeding season. Volumetric analysis showed that this seasonal change in activity is not linked to a change in OB volume. By subsequently experimentally elevating testosterone (T) in half of the males during the non-breeding season we showed that the OB volume was increased compared to controls.

Conclusions/Significance

By investigating the neural substrate of seasonal olfactory sensitivity changes we show that the starlings'' OB loses its ability during the non-breeding season to detect a natural odour of a plant preferred as green nest material by male starlings. We found that testosterone, applied during the non-breeding season, does not restore the discriminatory ability of the OB but has an influence on its size.     

Azimuthal sound localization in the European starling (Sturnus vulgaris): II. Psychophysical results

Small songbirds have a difficult analysis problem: their head is small compared to the wavelengths of sounds used for communication providing only small interaural time and level differences. Klump and Larsen (1992) measured the physical binaural cues in the European starling (Sturnus vulgaris) that allow the comparison of acoustical cues and perception. We determined the starling’s minimum audible angle (MAA) in an operant Go/NoGo procedure for different spectral and temporal stimulus conditions. The MAA for broadband noise with closed-loop localization reached 17°, while the starling’s MAA for open-loop localization of broadband noise reached 29°. No substantial difference between open-loop and closed-loop localization was found in 2 kHz pure tones. The closed-loop MAA improved from 26° to 19° with an increase in pure tone frequency from 1 to 4 kHz. This finding is in line with the physical cues available. While the starlings can only make use of interaural time difference cues at lower frequencies (e.g., 1 and 2 kHz), additional interaural level difference cues become available at higher frequencies (e.g., 4 kHz or higher, Klump and Larsen 1992). An improvement of the starling’s MAA with an increasing number of standard stimulus presentations prior to the test stimulus has important implications for determining relative (MAA) localization thresholds.     

Ahemeral light regimens test the photoperiodic threshold of the european starling(Sturnus vulgaris)

Male European starlings(Sturnus vulgaris) were held for three consecutive photoperiod oscillations (ahemeral years) composed of 30-h day lengths, i.e., the daily light and dark each lasted three hours longer than under the natural daily photoperiod at latitude 38°N. These starlings had no gonad metamorphosis during the 45 actual months necessary to complete the three ahemeral photoperiod oscillations; nor did subsequent exposure to continuous illumination elicit gonad response. It is concluded that the daily duration of light and darkness (although certainly operant in controlling starling sexual cycles under temperate-zone photoperiod oscillations) is not the critical factor establishing a sexual cycle under the ahemeral regimen. Rather, it appears that this species must experience a daily duration of light of 12 hours or less (a definitive photoperiodic threshold) before photo-induction of a sexual cycle is possible.Presented at the Eighth International Congress of Biometeorology, 9–14 September 1979, Shefayim, Israel.     

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.