Dynamics of West Nile Virus Persistence in House Sparrows (Passer domesticus)

West Nile Virus (WNV) is now endemic throughout North America, with annual recurrence dependent upon successful overwintering when cold temperatures drive mosquito vectors into inactivity and halt transmission. To investigate whether avian hosts may serve as an overwintering mechanism, groups of eight to ten House Sparrows were experimentally infected with a WN02 genotype of WNV and then held until necropsy at 3, 5, 7, 9, 12, 15, or 18 weeks post-infection (pi) when they were assessed for the presence of persistent infection. Blood was collected from all remaining birds every two weeks pi, and sera tested for WNV RNA and WNV neutralizing antibodies. West Nile virus RNA was present in the sera of some birds up to 7 weeks pi and all birds retained neutralizing antibodies throughout the experiment. The detection of persistently infected birds decreased with time, from 100% (n = 13) positive at 3 weeks post-infection (pi) to 12.5% (n = 8) at 18 weeks pi. Infectious virus was isolated from the spleens of birds necropsied at 3, 5, 7 and 12 weeks pi. The current study confirmed previous reports of infectious WNV persistence in avian hosts, and further characterized the temporal nature of these infections. Although these persistent infections supported the hypothesis that infected birds may serve as an overwintering mechanism, mosquito-infectious recrudescent viremias have yet to be demonstrated thereby providing proof of principle.     

Individual and Sex Differences in Habituation and Neophobia in House Sparrows (Passer domesticus)

Heterogeneity in the environment favours foragers that are flexible (phenotypically plastic). However, consistent individual differences in behaviour (personality), such as in risk‐taking, might affect an individual's ability to find food, avoid predators and adjust to new conditions. It is now well known that personalities exist in many taxa, but much less is known about individual variation in plasticity. We measured the tendency to begin foraging across different levels of risk in house sparrows (Passer domesticus), using a behavioural reaction norm framework to simultaneously assess personality and plasticity. We asked whether individuals were consistently different across risk levels, and whether they differed in habituation and neophobia, both of which were treated as cases of plasticity. We found that males habituated more than females by beginning to feed sooner after repeated instances of a human disturbance in the presence of an initially unfamiliar object. Individuals of both sexes also exhibited consistent differences across trials, but did not differ in the rate of habituation beyond the difference between the sexes. When a novel object was placed in the foraging area, both sexes exhibited similar degrees of neophobia by delaying feeding. The magnitude of this change varied among birds, indicating individual differences in neophobia. Our results indicate that both personality and individual variation in plasticity exist but should be treated as independent phenomena. The presence of variation in plasticity implies that the raw material necessary for selection on neophobia exists, and that if heritable, plasticity in risk‐taking across contexts could evolve.     

Learning to Choose Among Social Foraging Strategies in Adult House Sparrows (Passer domesticus)

Social foragers may be regarded as being engaged in a producer–scrounger game in which they can search for food independently or join others who have discovered food. Research on the producer–scrounger game has focused mainly on the different factors influencing its evolutionarily stable strategy (ESS) solution, but very little is known about the actual mechanisms that shape players' decisions. Recent work has shown that early experience can affect producer–scrounger foraging tendencies in young house sparrows and that in nutmeg mannikins learning is involved in reaching the ESS. Here, we show that direct manipulation of the success rate experienced by adult sparrows when following others can change their strategy choice on the following day. We presented to live sparrows an experimental regime, where stuffed adult house sparrows in a feeding position were positioned on a foraging grid that included two reward regimes: a positive one, in which the stuffed models were placed near food, and a negative one, in which the models were placed away from food. There was a significant increase in joining behavior after the positive treatment (exhibited by 84% of the birds), but no change after the negative treatment. Further analysis demonstrated that sparrows more frequently used the strategy with which they were more successful (usually joining) and that differences in strategy use were correlated with differences in success. These results suggest that adult birds can monitor their success and learn to choose among social foraging strategies in the producer–scrounger game.     

Social Control and Physiological Cost of Cheating in Status Signalling Male House Sparrows (Passer domesticus)

Flock-forming passerines often use plumage characteristics to signal their social dominance. While the benefits to signal dominance seem obvious, costs associated with status signalling are ambiguous. The social control hypothesis predicts that individuals of high social status – with large badges – are involved in more social interactions with individuals of similar badge size. Cheaters are therefore exposed to increased risk of fighting with high quality individuals and the costs associated with enhanced fights with dominant males are supposed to outweigh the benefits of cheating. We tested the social control hypothesis in male house sparrows ( Passer domesticus ), by observing social interactions in captive flocks and determining dominance relationships. Two low status individuals within each flock had the size of their badge experimentally increased and the interactions involving experimental and control birds were recorded. We also assessed the potential physiological cost of cheating in terms of enhanced levels of the stress hormone, corticosterone. Dominance was significantly positively correlated with badge size, but not with other morphological traits. We found little support for the social control hypothesis. Birds did not have significantly more interactions with individuals of similar badge size, before the manipulation. Similarly, after the experimental increase in badge size, experimental birds did not tend to have more encounters with large-badged males. Experimental birds with enlarged badges won more fights compared with prior to the manipulation, suggesting that badge size is used as a signal of social dominance even in small and stable flocks. Finally, corticosterone levels in the blood did not increase significantly after the manipulation of badge size, suggesting that there is no measurable cost, resulting from stress, in cheaters.     

Photoperiodic control of testicular regression and moult in male House Sparrows Passer domesticus

Testis size, bill colour and moult were monitored in male House Sparrows Passer domesticus kept under a natural daylength regime between February and November. On three occasions (at the summer solstice, 25 days later and 39 days later), groups of birds were transferred to a daylength of 18 h of light and 6 h of darkness per day (18L: 6D), the natural daylength at the solstice. In birds under natural daylengths, the testes had regressed significantly by 2 5 days after the solstice. In those transferred to 18L:6D at the solstice, the onset of regression was delayed by about 4 weeks. Transfer to 18L: 6D after the solstice did not cause recrudescence; the testes continued to regress. In birds transferred to 18L: 6D at the solstice, moult was delayed by 4 weeks and progressed more slowly. These results suggest that photoperiodically induced gonadal regression in this species contains elements characteristic of both absolute and relative photorefractoriness.     

Prevalence and Genetic Characterization of Toxoplasma gondii in House Sparrows (Passer domesticus) in Lanzhou,China

The prevalence of Toxoplasma gondii infection in birds has epidemiological significance because birds are indeed considered as a good indicator of environmental contamination by T. gondii oocysts. In this study, the prevalence of T. gondii in 313 house sparrows in Lanzhou, northwestern China was assayed by the modified agglutination test (MAT). Antibodies to T. gondii were positive in 39 (12.46%) of 313 samples (MAT titer ≥ 1:5). Tissues of heart, brain, and lung from the 39 seropositive house sparrows were tested for T. gondii DNA, 11 of which were found to be positive for the T. gondii B1 gene by PCR amplification. These positive DNA samples were typed at 9 genetic markers, including 8 nuclear loci, i.e., SAG1, 5''- and 3''-SAG2, alternative SAG2, SAG3, GRA6, L358, PK1, c22-8 and an apicoplast locus Apico. Of them, 4 isolates were genotyped with complete data for all loci, and 2 genotypes (Type II variants; ToxoDB #3 and a new genotype) were identified. These results showed that there is a potential risk for human infection with T. gondii in this region. To our knowledge, this is the first report of T. gondii seroprevalence in house sparrows in China.     

Photoperiodic control of the termination of breeding and the induction ofmoult in House Sparrows Passer domesticus

Two photoperiodic mechanisms controlling gonadal regression in birds have been identified: absolute photorefractoriness, typical of species with short breeding seasons, where gonadal regression occurs spontaneously during long days, and relative photorefractoriness, where a decrease in daylength is required to induce regression. An experiment was designed to test whether these simply represent extremes of one underlying mechanism. Three groups of male House Sparrows Passer domesticus were transferred from a short photoperiod, 8 h of light: 16 h of darkness per day (8L:16D) to long photoperiods of either 18L:6D, 16L:8D or 13L:11D. Gonadal maturation rates were similar in all three groups; gonadal regression and moult began latest in the 13L:11D group. Four additional groups of sparrows were transferred from 8L:16D to 18L:6D and then transferred to either 13L: 11D or 16L:8D prior to, or shortly after, the onset of gonadal regression. The decrease in daylength prior to regression had no effect on the timing of regression but did advance the onset of moult. Decrease in daylength after the onset of regression increased the rate of regression and the rate of moult. Because a decrease in daylength did not affect the timing of regression, the data do not support the hypothesis that absolute and relative photorefractoriness represent extremes of a single underlying photoperiodic control mechanism. The adaptive significance of the effects of decreasing daylength on the rate of regression and moult is discussed.     

Factors affecting the abundance of House Sparrows Passer domesticus in urban areas of southeast of Spain

Capsule: House Sparrows Passer domesticus in the Valencian Community, where the species is declining, were more abundant in parks and urban areas where rubbish bins are available as a source of food. In heavy traffic areas, crowded streets and high-rise building zones, the species was less abundant.

Aims: To explore biotic and abiotic factors affecting the abundance of urban House Sparrows. To infer the causes that might explain the urban decline and to propose measures that might halt it and elevate population numbers.

Methods: The abundance of urban House Sparrows was analysed in relation to 17 landscape variables by carrying out 181 point counts (50 urban parks/38 schools/93 streets) per season across six locations and over five seasons (breeding and non-breeding seasons) in southeast Spain. Urban parks were also described by 21 additional variables. Hierarchical partitioning analyses were used to identify favoured or avoided urban factors by birds in each season.

Results: House Sparrows were most abundant in parks and other urban areas where rubbish bins were available as their foraging sites. The presence of rubbish bins, area and proximity to other parks favoured their abundance in parks. Furthermore, House Sparrows were less abundant in crowded streets, heavy traffic areas and high-rise buildings zones.

Conclusion: House Sparrows were present in high abundance where they feed but were scarce in polluted, crowded and heavily built-up areas of the city. Changes in the structure of these urban habitats may underlie the documented declines across Spain. Green urban planning and management are needed to ensure heterogeneous green areas with enough vegetation coverage to provide high availability of natural food versus anthropogenic food scraps. Sufficient numbers of buildings offering nest sites and reduced air pollution might ameliorate cities adequately to support larger populations of House Sparrows.     

Honest signalling,dominance hierarchies and body condition in House Sparrows Passer domesticus (Aves: Passeriformes) during acute coccidiosis

Parasitic infections may change the equilibrium between the costs and benefits of an animal for maintaining its status in a social group. Consequently, parasites may influence the social status of an animal in a group. The present study investigated whether acute infection with Isospora spp. has any effect on the social relationships (e.g. dominance hierarchy) of male house sparrows and how the infection influences their behaviour, immune status, and body condition. Furthermore, the study allowed us to examine how important the ‘badge of dominance’ is with respect to maintaining social status even when the actual condition is changing as a result of infection. The results obtained showed that an acute infection leads to changes in the dominance hierarchy of a social group and that body mass losses of birds depend on the achieved hierarchy status. A positive correlation between the badge size and male aggressiveness was only found during acute infection. In addition, we also found a relationship between cell‐mediated immune response and male aggressiveness during acute infection. This suggests that male badge size is not sufficient to maintain a given dominance position. On the other hand, badge size, a signal developed during the moult, appears to remain an informative and ‘honest’ signal several months later, reflecting the energy reserves of a bird faced with a demanding stressful situation such as acute infection. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 718–726.     

Does Male Badge Size Signal Status in Small Island Populations of House Sparrows,Passer domesticus?

The relationship between dominance and throat badge size, body size, and body condition was examined in three small island populations of house sparrows, Passer domesticus, on the coast of northern Norway. Individual dominance rank in males was determined by observation of agonistic interactions in an artificial observation cage (one replicate in Dec. and one in Mar. in two populations and one replicate in Mar. in the third population). Previous studies had indicated that badge size signals status in house sparrows. In this study, because of the small population sizes and stability in their membership, we expected that prior information about fighting ability would reduce the importance of badge size for the outcome of conflicts in favour of traits most directly associated with fighting ability. In two of five replicates, significant relationships were found between components of body size and dominance rank, but in opposite directions. The relationship between badge size and dominance rank was consistently positive, but non-significant. In a pooled sample of the three independent replicates, badge size was the best predictor of dominance, and no other variable explained any variance in dominance. However, the coefficient of determination was low and linearity of dominance hierarchies was poor. We therefore suggest that individual recognition may influence the dominance relationships.     

Nocturnal loss of muscle protein from House sparrows (Passer domesticus)

An overall loss of protein was considered to be the explanation for at least some of the observed loss of lean dry material from muscle of wild House sparrows overnight.     

Development of Badges of Status in Captive Male House Sparrows (Passer domesticus) in Relation to the Relative Ornamentation of Flock‐Mates

The development of quality signals is expected to be largely influenced by environmental conditions among which the social environment could be an important factor, particularly in gregarious animals. Here, we investigated the role of the presumed social environment on the development of badge size in moulting male House Sparrows (Passer domesticus) over a 3‐yr time span. House Sparrow badges are testosterone‐dependent ornaments that are typically argued to be ‘badges of status’ –that is, signals of competitive ability and aggression. Immediately prior to moult, we created several groups of males, either with similarly sized badges or with badges of different sizes, and we measured each male's badge size before and after moult. The former groups were presumed to have a less clear social hierarchy than the latter groups because of group members advertising relatively similar competitive ability (and thus were expected to more frequently challenge one another in order to establish dominance). Conversely, the latter groups were presumed to have relatively higher social stability because birds would less frequently encounter rivals advertising similar agonistic threat. We predicted in groups of birds with similarly sized badges, both (1) larger changes (i.e. increases or decreases) in badge sizes and (2) higher increases in between‐individual variation within groups. The first prediction was supported in one of the 3 yrs, but there was no support for the second prediction in any year. We conclude that social environment has an effect on the development of badges of status, but that it is highly contingent on the specific nature and timing of group interactions.     

Using non‐linear mixed effects models to identify patterns of chick growth in House Sparrows Passer domesticus

For many animals, adult size is an important determinant of fitness. Thus, after a period of food restriction, offspring often grow quickly to approach an optimal size. Offspring can approach an optimal size by increasing mass faster than the peak growth of offspring that do not delay development (compensatory growth) or by extending the period of rapid growth to reach an optimal size (catch‐up growth). Unfortunately, the most common statistical techniques make it difficult to differentiate alternative growth patterns among developing offspring. Here, I show how random effect estimates can be used to uncover important variation in growth in a short‐lived passerine, the House Sparrow Passer domesticus. Specifically, I show that much of the variation in offspring growth can be explained by differences in the timing of peak growth and in final adult size, both within a single population and within treatments of an experimental manipulation. These results suggest that much of the variation in offspring growth may be explained by factors other than growth rate. I also show that offspring that delay development either maintain slow but steady growth across development and reach a small adult size, or extend the period of rapid growth to reach an optimal size, indicative of catch‐up growth. This pattern of extending the period of rapid growth may allow offspring to minimize the cellular damage caused by compensatory growth but still maximize size‐related fitness benefits (e.g. increased survival and fecundity) prior to fledging.     

云南普洱发现家麻雀

<正>2014年10月,在云南省普洱市思茅区、宁洱县等地多次发现集群的家麻雀(Passer domesticus),雌雄混群。雄鸟羽色与麻雀(P.montanus)相似,眼先、颏、喉部黑色,颊部灰白色,后颈部和颈侧栗褐色,翅上具两道淡色翼斑,下体棕白色。但家麻雀的雄鸟额部、头顶及枕部灰色,耳部无黑色斑块,上胸部黑色,与麻雀明显不同。     

The spread of the House Sparrow Passer domesticus in Bolivia

Bolivia lies within the Tropics and contains extremes from desert to jungle and from low to high altitudes. House Sparrows entered the south of Bolivia from Argentina about 1930 and have now spread to towns and villages scattered through about half of the country. These are principally in the semi-arid Andean descents of south and central Bolivia and in the lowlands in Santa Cruz city and certain nearby towns. In the high altiplano they have reached only two cities and are not numerous in either. They appear to be absent from the humid Andean slopes and from most of the eastern and northern lowlands, with the exception of two isolated towns which they could have reached either from Brazil or from elsewhere in Bolivia. House Sparrows do not occur away from human settlements in Bolivia.     

House sparrows (Passer domesticus) increase protein catabolism in response to water restriction

Birds primarily rely on fat for energy during fasting and to fuel energetically demanding activities. Proteins are catabolized supplemental to fat, the function of which in birds remains poorly understood. It has been proposed that birds may increase the catabolism of body protein under dehydrating conditions as a means to maintain water balance, because catabolism of wet protein yields more total metabolic and bound water (0.155·H(2)O(-1)·kJ(-1)) than wet lipids (0.029 g·H(2)O(-1)·kJ(-1)). On the other hand, protein sparing should be important to maintain function of muscles and organs. We used quantitative magnetic resonance body composition analysis and hygrometry to investigate the effect of water restriction on fat and lean mass catabolism during short-term fasting at rest and in response to a metabolic challenge (4-h shivering) in house sparrows (Passer domesticus). Water loss at rest and during shivering was compared with water gains from the catabolism of tissue. At rest, water-restricted birds had significantly greater lean mass loss, higher plasma uric acid concentration, and plasma osmolality than control birds. Endogenous water gains from lean mass catabolism offset losses over the resting period. Water restriction had no effect on lean mass catabolism during shivering, as water gains from fat oxidation appeared sufficient to maintain water balance. These data provide direct evidence supporting the hypothesis that water stress can increase protein catabolism at rest, possibly as a metabolic strategy to offset high rates of evaporative water loss.     

Changes in the House Sparrow Passer domesticus population in Valencia (Spain) from 1998 to 2008

Capsule The population of House Sparrow Passer domesticus has experienced a sharp decline in the municipality of Valencia.

Aims To investigate the population trends of House Sparrows.

Methods Between September 1998 and December 2008, House Sparrows were censused monthly in 22 urban parks covering a total of 118 ha. Additionally, birds in the wider urban landscape were censused in 24 plots of about 50 ha during the winter and spring of years 1998, 2003 and 2007.

Results The House Sparrow population experienced a significant decline of about 70% over 10 years in urban parks, with monthly peak values decreasing from about 2000 birds in 1998 to about 500 in 2008. Between 1998 and 2007, a significant decline was detected in the urban landscape mostly during the winter.

Conclusions Urban parks are a main feeding habitat for House Sparrows, and habitat structure of urban parks has remained similar throughout these years. Therefore, the decreasing number of sparrows recorded in parks probably reflects an overall population decline of the species in Valencia. This decline has coincided with high‐intensity urban development i.e. an increase in the building density and a reduction in the amount of wastelands and other feeding habitats. Thus, shortage of nest‐sites did not seem to be a limiting factor for the population, but a reduction of food availability may be partially responsible for the observed patterns.     

Diurnal variation in the distribution of lipid in the pectoralis muscle of the House sparrow (Passer domesticus)

The content and distribution of lipid in avian muscle were investigated on a diurnal basis. The results were discussed with reference to shivering and with respect to apparently conflicting findings obtained by previous workers on the effects of exercise and starvation on intracellular lipid in muscle fibres.