Passer Montanus Research Articles

Variation in corticosterone response and corticosteroid binding‐globulin during different breeding sub‐stages in Eurasian tree sparrow (Passer montanus)

In free-living animals, it has been well demonstrated that the intensity of the adrenocortical response to acute restraint stress can vary with reproductive investment during breeding. The parental care hypothesis posits that the stress response is negatively correlated with parental investment in avian species. To further test this hypothesis, we examined changes in both free and total corticosterone (CORT) at baseline and stress-induced levels (maximal CORT) and corticosteroid-binding globulin (CBG) capacities, in both sexes of a multi-brooded Eurasian tree sparrows (Passer montanus), during the nest building, the early nestling, the later egg-laying, and the later nestling stages. Our results showed Eurasian tree sparrows did not exhibit any differences between sexes in CORT and CBG levels during the egg-laying or nestling stages. Both sexes had lowered CBG capacities and females exhibited lower maximal CORT during the early compared to later nestling stages. In addition, both sexes had lower maximal free CORT levels during the nest building stage than those of the early nestling stages, and males expressed higher total maximal CORT levels than females during nest building stage. The variation in CORT response and CBG levels during different breeding sub-stages in Eurasian tree sparrow may correlate with their energetic situations and parental investments. J. Exp. Zool. 325A:75-83, 2016. © 2015 Wiley Periodicals, Inc.

House SparrowsPasser domesticusand Tree SparrowsPasser montanus: Fine-Scale Distribution, Population Densities, and Habitat Selection in a Central European city

Abstract. Populations of House and Tree Sparrows have rapidly declined in various breeding habitats throughout their European distribution range; however, the strongest decline was recorded within urban environments. In our study we investigated fine-scale distribution, population densities and habitat selection of both sparrow species within a 200 × 200 m squares in a medium sized city (Ceske Budějovice, Czech Republic) during the breeding season. The total population density of House and Tree Sparrow was 11.7 and 2.8 individuals/10 ha; however the densities of both sparrow species markedly differed among various urban units. The highest density of House Sparrow was recorded in residential areas (33.3 ind./10 ha) and Tree Sparrows were mostly found in garden colonies (10.3 ind./10 ha). After removing spatial effects, we found that numbers of both sparrows were negatively correlated with area of artificial surfaces (e.g. pavements, streets, railway networks or parking spaces) and positively correlated wit...

Campylobacter jejuni and Campylobacter coli in wild birds on Danish livestock farms.

BackgroundReducing the occurrence of campylobacteriosis is a food safety issue of high priority, as in recent years it has been the most commonly reported zoonosis in the EU. Livestock farms are of particular interest, since cattle, swine and poultry are common reservoirs of Campylobacter spp. The farm environment provides attractive foraging and breeding habitats for some bird species reported to carry thermophilic Campylobacter spp. We investigated the Campylobacter spp. carriage rates in 52 wild bird species present on 12 Danish farms, sampled during a winter and a summer season, in order to study the factors influencing the prevalence in wild birds according to their ecological guild. In total, 1607 individual wild bird cloacal swab samples and 386 livestock manure samples were cultured for Campylobacter spp. according to the Nordic Committee on Food Analysis method NMKL 119.ResultsThe highest Campylobacter spp. prevalence was seen in 110 out of 178 thrushes (61.8 %), of which the majority were Common Blackbird (Turdus merula), and in 131 out of 616 sparrows (21.3 %), a guild made up of House Sparrow (Passer domesticus) and Eurasian Tree Sparrow (Passer montanus). In general, birds feeding on a diet of animal or mixed animal and vegetable origin, foraging on the ground and vegetation in close proximity to livestock stables were more likely to carry Campylobacter spp. in both summer (P < 0.001) and winter (P < 0.001) than birds foraging further away from the farm or in the air. Age, fat score, gender, and migration range were not found to be associated with Campylobacter spp. carriage. A correlation was found between the prevalence (%) of C. jejuni in wild birds and the proportions (%) of C. jejuni in both manure on cattle farms (R2 = 0.92) and poultry farms (R2 = 0.54), and between the prevalence (%) of C. coli in wild birds and the proportions (%) of C. coli in manure on pig farms (R2 = 0.62).ConclusionsThe ecological guild of wild birds influences the prevalence of Campylobacter spp. through the behavioural patterns of the birds. More specifically, wild birds eating food of animal or mixed animal and vegetable origin and foraging on the ground close to livestock were more likely to carry Campylobacter spp. than those foraging further away or hunting in the air. These findings suggest that wild birds may play a role in sustaining the epidemiology of Campylobacter spp. on farms.

A case study on Salmonella enterica serovar Typhimurium at a dairy farm associated with massive sparrow death.

Background Salmonella enterica Typhimurium (S. Typhimurium) is the most common cause of bovine salmonellosis in Japan and where it is also cause of salmonellosis in wild birds. In 2008, a postpartum cow at a dairy farm developed diarrhea caused by S. Typhimurium. The herd was extensively surveilled for Salmonella sp. and we characterized bacterial isolates from this and other cows to determine the source of infection.ResultsEight isolates of S. Typhimurium from cattle were identified as phage type DT40 and showed a 100 % similarity by pulsed-field gel electrophoresis and the same or similar multiple-locus variable-number tandem-repeat analysis profiles as those of S. Typhimurium isolated from dead sparrows (Passer montanus) collected at Asahikawa in 2006. S. Typhimurium DT40 was considered to be a major cause of high sparrow mortality in Hokkaido in 2005–2006 and 2008–2009, suggesting that DT40 maintained in sparrows was transmitted to cattle.Conclusions S. Typhimurium DT40 may be transmitted from sparrows to dairy cattle.

Experimental infection of highly and low pathogenic avian influenza viruses to chickens, ducks, tree sparrows, jungle crows, and black rats for the evaluation of their roles in virus transmission

Highly pathogenic avian influenza viruses (HPAIVs) have spread in both poultry and wild birds. Determining transmission routes of these viruses during an outbreak is essential for the control of avian influenza. It has been widely postulated that migratory ducks play crucial roles in the widespread dissemination of HPAIVs in poultry by carrying viruses along with their migrations; however close contacts between wild migratory ducks and poultry are less likely in modern industrial poultry farming settings. Therefore, we conducted experimental infections of HPAIVs and low pathogenic avian influenza viruses (LPAIVs) to chickens, domestic ducks, tree sparrows, jungle crows, and black rats to evaluate their roles in virus transmission. The results showed that chickens, ducks, sparrows, and crows were highly susceptible to HPAIV infection. Significant titers of virus were recovered from the sparrows and crows infected with HPAIVs, which suggests that they potentially play roles of transmission of HPAIVs to poultry. In contrast, the growth of LPAIVs was limited in each of the animals tested compared with that of HPAIVs. The present results indicate that these common synanthropes play some roles in influenza virus transmission from wild birds to poultry.

Molecular cloning and 3D structure prediction of myoglobin and cytoglobin in Eurasian Tree Sparrow Passer montanus

In vertebrates, myoglobin (Mb) and cytoglobin (Cygb) are closest relatives in the family of globins, which are heme-containing proteins that can bind gaseous molecules. Mb acts not only as an O2 transporter but also a nitric oxide (NO) scavenger in cardiac and striated muscle. Cygb has been suggested to play important functions in lipid-based signaling processes, defense against reactive oxygen species (ROS), and nitric oxide (NO) metabolism, and it is present in a variety of cell types. However, little information about the structures and functions of Mb and Cygb is known in birds. Here, we cloned the full-length open reading frames (ORFs) of the two globins in Eurasian Tree Sparrow (Passer montanus). The Mb ORF cDNA contains 465 base pairs (bp) encoding 154 amino acids (aa), and the Cygb ORF cDNA contains 540 bp encoding 179 aa. Our results show that the amino acid sequences and three-dimensional (3D) structures of Mb and Cygb are highly conserved in vertebrate species. Interestingly, two specific substitutions were detected in Cygb compared with other vertebrates, which resulted in slight variation of the 3D conformation (e.g., distance between Tyr H16 and Lys G8, the strength of hydrogen bonds, and angles between the G–H helices). Our results may contribute to further understanding the structures, properties, and functions of Mb and Cygb as well as the potential mechanisms of oxygen utilization pathways in vertebrates.

Ecology and phylogeny of birds foraging at outdoor restaurants in Sweden.

BackgroundBirds frequently visit the outdoor serving areas of restaurants to feed on scraps of food and leftovers. Although this feeding association between humans and birds is widespread and could have significant effects, both positive and negative, for all taxa involved, the authors know of no published studies that have investigated restaurant bird communities. To lay the foundation for future research, the authors conducted a basic study of birds at 80 outdoor restaurants in Sweden, identifying which species and taxonomic clades of birds visited the restaurants and comparing restaurant birds in urban and rural environments.New informationThirteen species of birds visited the outdoor restaurants. Eight of these species were predominant, i.e. accounting for 51% or more of bird presence (sum of minutes of all individual birds) at one or more restaurants. Every restaurant studied had a predominant species, but species often differed from each other in frequency of predominance in different landscapes. No endangered species were seen visiting restaurants. However, three farmland bird species (House Sparrow Passer domesticus, White Wagtail Motacilla alba, Eurasian Tree Sparrow Passer montanus), whose numbers are reported to be declining in the countryside, were predominant at the majority of restaurants in rural areas, suggesting that rural restaurants might be able to contribute to the conservation of these species. The thirteen species of restaurant-visiting birds belonged to five monophyletic clades. Ninety percent of all restaurants had, as their predominant species, birds from either Clade A (Passeridae, Motacillidae, Fringillidae) or Clade C (Corvidae). Statistical testing revealed that Clade A and Clade C were distributed differently in environments along the urban-rural gradient. At all spatial scales measured, birds of Clade C were predominant at the majority of restaurants in urban areas, while birds of Clade A were the predominant clade at the majority of restaurants in rural areas. The authors use this evidence, and observations of birds foraging in association with other primates, to hypothesize that the outdoor serving areas of modern restaurants may be helping to preserve and nurture ancient human-bird symbioses that have been part of human ecology since antiquity.

Current Land Bird Distribution and Trends in Population Abundance Between 1982 and 2012 on Rota, Mariana Islands

Abstract The western Pacific island of Rota is the fourth largest human-inhabited island in the Mariana archipelago and designated an Endemic Bird Area. Between 1982 and 2012, 12 point-transect distance-sampling surveys were conducted to assess bird population status. Surveys did not consistently sample the entire island; thus, we used a ratio estimator to estimate bird abundances in strata not sampled during every survey. Trends in population size were reliably estimated for 11 of 13 bird species, and 7 species declined over the 30-y time series, including the island collared-dove Streptopelia bitorquata, white-throated ground-dove Gallicolumba xanthonura, Mariana fruit-dove Ptilinopus roseicapilla, collared kingfisher Todiramphus chloris orii, Micronesian myzomela Myzomela rubratra, black drongo Dicrurus macrocercus, and Mariana crow Corvus kubaryi. The endangered Mariana crow (x̄ = 81 birds, 95% CI 30–202) declined sharply to fewer than 200 individuals in 2012, down from 1,491 birds in 1982 (95% CI = 815–3,115). Trends increased for white tern Gygis alba, rufous fantail Rhipidura rufifrons mariae, and Micronesian starling Aplonis opaca. Numbers of the endangered Rota white-eye Zosterops rotensis declined from 1982 to the late 1990s but returned to 1980s levels by 2012, resulting in an overall stable trend. Trends for the yellow bittern Ixobrychus sinensis were inconclusive. Eurasian tree sparrow Passer montanus trends were not assessed; however, their numbers in 1982 and 2012 were similar. Occupancy models of the 2012 survey data revealed general patterns of land cover use and detectability among 12 species that could be reliably modeled. Occupancy was not assessed for the Eurasian tree sparrow because of insufficient detections. Based on the 2012 survey, bird distribution and abundance across Rota revealed three general patterns: 1) range restriction, including Mariana crow, Rota white-eye, and Eurasian tree sparrow; 2) widespread distribution, low abundance, including collared kingfisher, island collared-dove, white-throated ground-dove, Mariana fruit-dove, white tern, yellow bittern, black drongo, and Micronesian myzomela; and 3) widespread distribution, high abundance, including rufous fantail and Micronesian starling. The Mariana crow was dispersed around the periphery of the island in steep forested land-cover types. In contrast, the Rota white-eye was restricted to the high-elevation mesa. Only for the white-throated ground-dove was there a significant difference among cover types, with lower occupancy in open field than in forested areas. Vegetation was included in the best-fit occupancy models for yellow bittern, black drongo, Micronesian myzomela, and Micronesian starling, but vegetation type was not a significant variable nor included in the top models for the remaining five species: white tern, island collared-dove, Mariana fruit-dove, collared kingfisher, and rufous fantail. Given declining population trends, the Rota bird-monitoring program could benefit from establishing threshold and alert limits and identifying alternative research and management actions. Continued monitoring and demographic sampling, in conjunction with ecological studies, are needed to understand why most bird species on Rota are declining, identify the causative agents, and assess effectiveness of conservation actions, especially for the Mariana crow.

The complete mitochondrial genome of Spotted Munia Lonchura punctulata topela (Passeriformes: Estrildidae)

Spotted Munia Lonchura punctulata is a sparrow-sized estrildid finch native to tropical Asia. In this study, we used PCR-based method to determine the complete mitochondrial genome of Lonchura punctulata topela. The mitochondrial genome of Spotted Munia is a 16 824-bp circular molecule, which contains 37 typical mitochondrial genes (13 protein-coding genes, two rRNAs, and 22 tRNAs) and a 1247-bp A + T– rich region. The gene arrangement pattern is identical to Taeniopygia guttata and Passer montanus. All the start codons of PCGs are typical ATG, except for the COI and ND3 genes. TAN is the most frequent stop codon, and TAN and T– are also found very common. The non-coding region contains some inter-genic spacers and a control region. The phylogenetic trees from the Bayesian and neighbor-joining analyses, based on the complete mtDNA of 12 Passeriformes species, share similar topologies and high node support values. Lonchura punctulata topela has close relative with Taeniopygia guttata.

Complete mitochondrial genome of the Onychostruthus taczanowskii (Aves, Passeridae) and its phylogenetic analysis

The complete mitochondrial genome sequence of Onychostruthus taczanowskii consisted 16 917 bp, the genome harbored the same gene order with that of other birds, contained 13 protein-coding genes, 22 tRNAs, 2 rRNAs and 1 non-coding control region. The all tRNAs formed typical cloverleaf secondary structures, except tRNASer (AGN) and tRNAPhe. The control region was located between tRNAGlu and tRNAPhe with 1310 bp in length, which consist of three domains: highly variable domain I, central conserved domain II and conserved sequence domain III. According to the phylogenetic analysis, Onychostruthus taczanowskii had a closer relationship with Pyrgilauda ruficollis, and Passer montanus were sister to them.

Radioactive contamination of nest materials of the Eurasian Tree Sparrow Passer montanus due to the Fukushima nuclear accident: The significance in the first year

The 2011 Fukushima nuclear accident contaminated large areas of eastern and northeastern Japan, releasing vast amounts of radiation. Here we investigated radioactive contamination of the nest materials of the Eurasian Tree Sparrow Passer montanus from the breeding season of 2011 directly after the accident to the next breeding season of 2012 at two sites. In Tokyo (222 km southwest of the plant), ambient dose rates in the nestboxes were lower than those in Ibaraki (175 km southwest of the plant), where the levels of 2011 were higher than those of 2012. Further, the amount of radioactive Cs in each nest increased with the increase in nest weight, with a higher increment at Ibaraki than at Tokyo. These data suggested higher nest contamination levels in the breeding season directly after a nuclear accident than in later seasons, and an increment of nest contamination levels via nest materials of birds.

Do rufous common cuckoo females indeed mimic a predator? An experimental test

Received 2 February 2015; revised 31 March 2015; accepted for publication 31 March 2015The similarity of common cuckoos Cuculus canorus to raptors is accepted as a classic example of predator mimicry.However, cuckoo females are polymorphic: grey females are similar to sparrowhawks Accipiter nisus, while rufousfemales were assumed to mimic kestrels Falco tinnunculus. Previous evidence based on dummy experiments withgrey females consistently showed that both hosts and non-hosts recognize this brood parasite by its yellow eye andbarred underparts. However, these traits are absent in kestrels. Host responses also do not covary geographicallywith local abundance of supposed models (sparrowhawks/kestrels). These patterns cast doubts on the kestrel-mimicry hypothesis. Here, we show experimentally for the first time that small birds that are unsuitable as hostsindeed do not mistake rufous cuckoos for kestrels: both tree sparrows Passer montanus and house sparrowsP. domesticus feared grey cuckoos (similarly to sparrowhawks and kestrels) but ignored rufous cuckoos (similarlyto innocuous Eurasian collared doves Streptopelia decaocto). These results provide further support for the hawk-mimicry hypothesis, but reject the kestrel-mimicry hypothesis. Colour polymorphism in birds is determinedgenetically, follows simple Mendelian rules and affects only colour but not patterns. These facts and strikingsimilarities between plumages of rufous females and cuckoo fledglings suggest that the rufous morph is simply acolour alternative to the grey morph, did not evolve to mimic kestrels and might have arisen throughpaedomorphic retention of juvenile plumage to adulthood (neoteny). Research on the genetic, developmental andmechanistic basis of cuckoo plumage polymorphism will be especially revealing. © 2015 The Linnean Society ofLondon, Biological Journal of the Linnean Society, 2015, 00: 000–000.

Structural variations and their adaptive significances in the bones of some migratory and resident birds

We investigated variations in the shape and size of some bones and their adaptive significances in both sexes of the migratory yellow breasted bunting (Emberiza aureola Pallas, 1773) and resident house sparrow (Passer domesticus Linnaeus, 1758) and tree sparrow (Passer montanus Linnaeus, 1758). Measurements of the large bones like skull, beak, orbit, sternum, coracoid, scapula, femur, tibiotarsus, humerus and metatarsus were recorded to find out variations in their measurements. The skull, cranial and sternum indices were also calculated. An attempt was also made to correlate the structural differences of these bones between migratory and nonmigratory species and also between sexes with their adaptive significances. Principal component analysis indicated 84.79% of the total variance. Discriminant function analysis shows distinct separation in the bone lengths between the resident and migratory birds while there was little overlap between the sexes. The proportion of original grouped cases correctly classified was found to be 95.0%. Migratory bunting showed significantly longer sternum, tibiotarsus, femur and humerus beside a higher sternum when compared to those of resident sparrows. On the other hand, beak width, sternum width and indices of cranium and sternum, were more in resident sparrows. Thus, our studied birds seem to possess species specific adaptations by modifying their bones to fit their modes of living and conditions for better endurance and performance.

Testing optimal body mass theory: Evidence for cost of fat in wintering birds

Optimal body mass models for small wintering birds are central to animal ecology, and offer insights into maximizing individual fitness in a complex environment. Such models assume both costs and benefits of fat deposition, and consider how they affect winter survival probability. Hypothesized mass‐dependent costs of elevated fat include increased wing load and subsequent reduced ability to avoid predators, as well as increased predator exposure while feeding to fatten. A likely benefit of winter fat is increased fasting capacity during resource shortages. Here I test optimal body mass theory by searching for both cost and benefits of winter fattening, utilizing interspecific variation in winter fat in natural populations. If increased predation risk is a mass‐dependent cost of fattening, wintering birds occupying dense (closed) winter habitat offering low exposure to predators should show (1) higher fat reserves, and (2) higher wing load, than wintering birds occupying less dense (open) habitat offering less protection from predators. This prediction was tested in the two winters in south‐central Kansas, a north temperate region with winter precipitation falling as snow and low ambient winter temperatures. The predicted patterns in wing load and winter fat reserve were observed: with phylogeny controlled, both were significantly lower in two open cover species (Dark‐eyed Junco Junco hyemalis, American Tree Sparrow Spizella arborea) than in eight closed cover species (seven sparrow species in the genera Melospiza, Passerella, and Zonotrichia, and the Spotted Towhee Pipilo maculatus). Body mass increased with wing area at a greater rate in the closed than in the open cover group, indicating lower body‐size specific wing load in the latter group. With phylogeny controlled, fat level varied inversely with resource predictability among three winter foraging guilds occupying a vertical gradient of snowfall probability, indicating both costs and benefits exist in the study system.This study is the first to support the existence of fat cost with a positive fat‐cover relationship in natural populations. These results serve to verify the cost‐benefit approach widely taken by optimal body mass models, to studying the relationship between a surrogate fitness variable and factors affecting it in a variable winter environment.

Polybrominated diphenyl ethers in resident Eurasian Tree Sparrow from Shanghai: Geographical distribution and implication for potential sources

An investigation of polybrominated diphenyl ethers (PBDEs) in Eurasian Tree Sparrow (Passer montanus) samples (n=37) collected from different land use areas in Shanghai provided information about the levels, compositional patterns, geographical distribution, potential sources of PBDEs and the evaluation of contamination status in Shanghai. The concentrations of BDE 209 and Sum-PBDEs were within the range of 8.20–292.0ngg−1lw (median: 47.0ngg−1lw) and 33.16–375.63ngg−1lw (median: 78.7ngg−1lw), respectively. As the predominant individual congener, BDE 209 was detected in all samples with a mean percentage of 62.8%, followed by BDE 47, 99 and 100 sequentially. The geographical distribution of PBDEs in ETS muscles followed the order below: landfill>urban>industrial parks>suburban>rural>remote, indicating that Shanghai Laogang Municipal Landfill was an important emission source of PBDEs in Shanghai, and also the PBDE levels were in association with urbanization and industrialization. Compared with other regions, contamination status in Shanghai was relatively good with the exception of these high concentration areas. There was significant correlation (r2=0.89, P<0.01) between PBDEs concentrations in soil and ETS, indicating ETS could be used as a useful biomonitoring tool for PBDEs in Shanghai.

Winter density and habitat preferences of three declining granivorous farmland birds: The importance of the keeping of poultry and dairy farms

Populations of granivorous farmland birds have dramatically declined during recent decades in many European countries. Winter conditions and consequently, survival rates of farmland bird species during this critical period, are considered as one of the main causes of this negative trend. However, the importance of different habitat structures and connected food sources for successful overwintering in bird species has gained little attention so far in the Czech Republic. In this study we aimed to examine the role of habitat composition and food availability on winter distribution and abundance of three declining sedentary and granivorous bird species. During the winters 2009–2014, 149 villages in the Czech Republic were monitored for distribution and density of three farmland seed-eaters. House Sparrow was the most dominant species (88.6% of villages occupied; 4.32±4.67ind./100m of transect), followed by Tree Sparrow (67.1% villages occupied; 1.83±3.53ind./100m of transect) and Collared Dove (65.8% villages occupied; 0.72±1.51ind./100m of transect). Occurrence of House and Tree Sparrow was significantly affected by the number of instances of poultry keeping. In both species, occupied villages showed a higher number of instances of poultry keeping. We did not find any such significant relationship for Collared Dove. Density of House Sparrow was significantly higher in villages with dairy farms, but we failed to find this relationship for Tree Sparrow and Collared Dove. Habitat preferences were similar for all three studied species. They positively responded to the proportion of shrubs/trees, the keeping of poultry, dairy farms and they avoided houses, arable land and grasslands. We conclude that poultry keepings and dairy farms can be important for studied species during the winter since they offer high food availability and good protection against predators. This suggestion is supported by the fact that long-term population decline has coincided with a long-term reduction in the keeping of poultry and dairy farms in the Czech Republic during the last 50 years.

Effects on rural House Sparrow and Tree Sparrow populations by experimental nest-site addition

While rural House Sparrows (Passer domesticus) have declined in Sweden, the population of the related Tree Sparrow (P. montanus) has remained stable, suggesting that they are affected by different population regulating mechanisms. Here we investigated if the two species differ in degree of nest-site limitation. After conducting an initial survey of both species on farmsteads in southern Sweden, we supplemented a subset of farms with additional nest-boxes. The farmsteads were resurveyed 3–4 years later to compare any change in population sizes for the two species between farms with and without added nest-sites. We also considered the availability of other nest-sites by counting the number of tile-clad buildings on the farmsteads. We did not find any effect of adding nest-boxes on House Sparrow population sizes, but a significant increase in the population estimate of Tree Sparrows. The number of Tree Sparrows was related to the availability of tile-clad buildings, whereas no such relationship was found for House Sparrows. At low and intermediate population sizes, House Sparrow nest-box utilization declined with the number of tile-clad buildings, suggesting preference for nest-sites under tiles when available. Our results suggest that while Tree Sparrow populations in the southern Swedish farmland are nest-site limited, House Sparrow populations are mainly limited by other mechanisms. Our results suggest that nest-site limitation is unlikely to explain the stronger population decline in rural House Sparrows compared to Tree Sparrows and that nest-site addition is unlikely to be an efficient remedy for the rural House Sparrow decline.

Minimum mesh size of bird net entered by Eurasian Tree Sparrow, Passer montanus and digging behaviour

Minimum mesh size of bird net entered by Eurasian Tree Sparrow, Passer montanus and digging behaviour

冬期におけるスズメの住宅地利用と営巣場所への執着

冬期におけるスズメの住宅地利用と営巣場所への執着

Changes in phytohaemagglutinin skin-swelling responses during the breeding season in a multi-brooded species, the Eurasian Tree Sparrow: do males with higher testosterone levels show stronger immune responses?

Life-history theory assumes that the fitness costs of immunity may have negative effects on reproductive success. Similarly, the immunocompetence handicap hypothesis is based on findings that testosterone (T) has immunosuppressive effects, although the basis of this hypothesis has recently been challenged. As much of the work examining the relationship between T levels and immune function has been carried out in captive-housed species, these results may not accurately reflect the situation of animals living in natural environments. To better understand the relationship between plasma T levels and immune function, studies focusing on free-living animals are needed. A previous study by our group determined the changes in both baseline and stress-induced T levels in free-living Eurasian Tree Sparrows (Passer montanus) across different annual cycle stages. In this study, we further report the phytohaemagglutinin skin-swelling (PHA) immune response in this multi-brooded species during different breeding sub-stages, and then determine the relationships between the PHA response and both baseline and stress-induced T levels. Our results show that the PHA response varied across the different sub-stages and differed significantly between the first and second brood stage. Furthermore, T levels in male Tree Sparrows are positively correlated with the PHA response during the breeding season, whereas this relationship is negative in females, suggesting that the biological function of T differs between the sexes. Therefore, our results suggest that free-living animals have evolved the ability to orchestrate trade-offs between reproduction and immune functions based on changes in physiology and the environment, which should provide further opportunities to study the flexibility and plasticity of physiological and ecological adaptations in natural environments.