House Sparrows Passer Domesticus Research Articles

It's cool to be stressed: Body surface temperatures track sympathetic nervous system activation during acute stress.

The acute stress response can be considered the primary evolutionary adaptation to maximise fitness in the face of unpredictable environmental challenges. However, the difficulties of assessing physiology in natural environments mean comparatively little is known about how response variation influences fitness in free-living animals. Currently, determining acute stress physiology typically involves blood sampling or cardiac monitoring. Both require trapping and handling, interrupting natural behaviour, and potentially biasing our understanding toward trappable species/individuals. Importantly, limits on repeated sampling also restrict response phenotype characterisation, vital for linking stress with fitness. Surface temperature dynamics resulting from peripheral vasomotor activity during acute stress are increasingly promoted as alternative physiological stress indicators, which can be measured non-invasively using infrared thermal imaging, overcoming many limitations of current methods. Nonetheless, which aspects of stress physiology they represent remains unclear, as the underlying mechanisms are unknown. To date, validations have primarily targeted the hypothalamic-pituitary-adrenal axis, when the sympathetic-adrenal-medullary (SAM) system is likely the primary driver of vasomotor activity during acute stress. To address this deficit, we compared eye and bill region surface temperatures - measured using thermal imaging - with SAM system activity - measured as heart-rate-variability via electrocardiogram telemetry - in wild-caught captive house sparrows (Passer domesticus), during capture and handling. We found lower body surface temperatures were associated with increased sympathetic nervous system activation. Consequently, our data confirm body surface temperatures can act as a proxy for sympathetic activation during acute stress, providing potentially transformative opportunities for linking the acute stress response with fitness in the wild.

Early-life telomeres are influenced by environments acting atmultiple temporal and spatial scales.

An individual's telomere length early in life may reflect or contribute to key life-history processes sensitive to environmental variation. Yet, the relative importance of genetic and environmental factors in shaping early-life telomere length is not well understood as it requires samples collected from multiple generations with known developmental histories. We used a confirmed pedigree and conducted an animal model analysis of telomere lengths obtained from nestling house sparrows (Passer domesticus) sampled over a span of 22 years. We found significant additive genetic variation for early-life telomere length, but it comprised a small proportion (9%) of the total biological variation. Three sources of environmental variation were important: among cohorts, among-breeding attempts within years, and among nestmates. The magnitude of variation among breeding attempts and among nestmates also differed by cohort, suggesting that interactive effects of environmental factors across time or spatial scales were important, yet we were unable to identify the specific causes of these interactions. The mean amount of precipitation during the breeding season positively predicted telomere length, but neither weather during a given breeding attempt nor date in the breeding season contributed to an offspring's telomere length. At the level of individual nestlings, offspring sex, size and mass at 10 days of age also did not predict telomere length. Environmental effects appear especially important in shaping early-life telomere length in some species, and more focus on how environmental factors that interact across scales may help to explain some of the variation observed among studies.

Changes in hypothalamic–pituitary–adrenal axis function, immunity, and glucose during acute Plasmodium relictum infection in house sparrows (Passer domesticus)

Hosts of the same species vary in physiological responses to the same parasite, and some groups of individuals can disproportionately affect disease dynamics; however, the underlying pathophysiology of host-parasite interactions is poorly understood in wildlife. We tested the hypothesis that the hypothalamic–pituitary–adrenal (HPA) axis mediates host resistance and tolerance to avian malaria during the acute phase of infection by evaluating whether individual variation in circulating glucocorticoids predicted resistance to avian malaria in a songbird. We experimentally inoculated wild-caught house sparrows (Passer domesticus) with naturally sourced Plasmodium relictum and quantified baseline and restraint-induced circulating corticosterone, negative feedback ability, cellular and humoral immune function, and baseline and restraint-induced glycemia, prior to and during acute malaria infection. During peak parasitemia, we also evaluated the expression of several liver cytokines that are established pathological hallmarks of malaria in mammals: two pro-inflammatory (IFN-γ and TNF-α) and two anti-inflammatory (IL-10 and TGF-β). Although most of the host metrics we evaluated were not correlated with host resistance or tolerance to avian malaria, this experiment revealed novel relationships between malarial parasites and the avian immune system that further our understanding of the pathology of malaria infection in birds. Specifically, we found that: (1) TNF-α liver expression was positively correlated with parasitemia; (2) sparrows exhibited an anti-inflammatory profile during malaria infection; and (3) IFN-γ and circulating glucose were associated with several immune parameters, but only in infected sparrows. We also found that, during the acute phase of infection, sparrows increased the strength of corticosterone negative feedback at the level of the pituitary. In the context of our results, we discuss future methodological considerations and aspects of host physiology that may confer resistance to avian malaria, which can help inform conservation and rehabilitation strategies for avifauna at risk.

Brief exposure to captivity in a songbird is associated with reduced diversity and altered composition of the gut microbiome.

The gut microbiome is important for host fitness and is influenced by many factors including the host's environment. Captive environments could potentially influence the richness and composition of the microbiome and understanding these effects could be useful information for the care and study of millions of animals in captivity. While previous studies have found that the microbiome often changes due to captivity, they have not examined how quickly these changes can occur. We predicted that the richness of the gut microbiome of wild-caught birds would decrease with brief exposure to captivity and that their microbiome communities would become more homogeneous. To test these predictions, we captured wild house sparrows (Passer domesticus) and collected fecal samples to measure their gut microbiomes immediately after capture ("wild sample") and again 5-10 days after capture ("captive sample"). There were significant differences in beta diversity between the wild and captive samples, and captive microbiome communities were more homogenous but only when using nonphylogenetic measures. Alpha diversity of the birds' microbiomes also decreased in captivity. The functional profiles of the microbiome changed, possibly reflecting differences in stress or the birds' diets before and during captivity. Overall, we found significant changes in the richness and composition of the microbiome after only a short exposure to captivity. These findings highlight the necessity of considering microbiome changes in captive animals for research and conservation purposes.

House Sparrows Vary Seasonally in Their Ability to Transmit West Nile Virus.

AbstractSeasonality in infectious disease prevalence is predominantly attributed to changes in exogenous risk factors. For vectored pathogens, high abundance, activity, and/or diversity of vectors can exacerbate disease risk for hosts. Conversely, many host defenses, particularly immune responses, are seasonally variable. Seasonality in host defenses has been attributed, in part, to the proximate (i.e., metabolic) and ultimate (i.e., reproductive fitness) costs of defense. In this study, our goal was to discern whether any seasonality is observable in how a common avian host, the house sparrow (Passer domesticus), copes with a common zoonotic arbovirus, the West Nile virus (WNV), when hosts are studied under controlled conditions. We hypothesized that if host biorhythms play a role in vector-borne disease seasonality, birds would be most vulnerable to WNV when breeding and/or molting (i.e., when other costly physiological activities are underway) and thus most transmissive of WNV at these times of year (unless birds died from infection). Overall, the results only partly supported our hypothesis. Birds were most transmissive of WNV in fall (after their molt is complete and when WNV is most prevalent in the environment), but WNV resistance, WNV tolerance, and WNV-dependent mortality did not vary among seasons. These results collectively imply that natural arboviral cycles could be partially underpinned by endogenous physiological changes in hosts. However, other disease systems warrant study, as this result could be specific to the nonnative and highly commensal nature of the house sparrow or a consequence of the relative recency of the arrival of WNV to the United States.

Varying intensities of chronic stress induce inconsistent responses in weight and plasma metabolites in house sparrows (Passer domesticus).

One of the biggest unanswered questions in the field of stress physiology is whether variation in chronic stress intensity will produce proportional (a gradient or graded) physiological response. We were specifically interested in the timing of the entrance into homeostatic overload, or the start of chronic stress symptoms. To attempt to fill this knowledge gap we split 40 captive house sparrows (Passer domesticus) into four groups (high stress, medium stress, low stress, and a captivity-only control) and subjected them to six bouts of chronic stress over a 6-month period. We varied the number of stressors/day and the length of each individual bout with the goal of producing groups that would experience different magnitudes of wear-and-tear. To evaluate the impact of chronic stress, at the start and end of each stress bout we measured body weight and three plasma metabolites (glucose, ketones, and uric acid) in both a fasted and fed state. All metrics showed significant differences across treatment groups, with the high stress group most frequently showing the greatest changes. However, the changes did not produce a consistent profile that matched the different chronic stress intensities. We also took samples after a prolonged recovery period of 6 weeks after the chronic stressors ended. The only group difference that persisted after 6 weeks was weight-all differences across groups in metabolites recovered. The results indicate that common blood metabolites are sensitive to stressors and may show signs of wear-and-tear, but are not reliable indicators of the intensity of long-term chronic stress. Furthermore, regulatory mechanisms are robust enough to recover within 6 weeks post-stress.

Eating in the city: Experimental effect of anthropogenic food resources on the body condition, nutritional status, and oxidative stress of an urban bioindicator passerine.

Urban areas provide a constant and predictable supply of anthropogenic processed food. The House Sparrow (Passer domesticus Linnaeus, 1758), a declining urban bioindicator species, has recently been reported to have a high level of oxidative stress, with urban diet or pollutants proposed as the potential cause. In this study, we aimed to experimentally determine the effects of two urban trophic resource types (bar snack food leftovers and pet food) on sparrows' physical condition, plasma biochemical nutritional parameters, and blood oxidative status in captivity. To exclude the potential previous effect of urban pollutants, 75 House Sparrows were captured from a rural area in SE Spain and kept in outdoor aviaries. Individuals were exposed to one of three diet treatments: control diet (fruit, vegetables, poultry grain mixture), bar snack diet (ultra-processed snacks), or cat food diet (dry pellets) for 20 days. Blood samples were collected before and after diet treatments to analyze the relative change rates of 12 variables, including physical condition, nutritional status, and oxidant-antioxidant status. A principal component analysis was run to identify gradients of variables covariation, and Generalized Linear Mixed Models were used to determine the effect of diets on each selected PC and on raw variables. The bar snack diet led to signs of anemia and malnutrition, and females tended to lose body condition. The cat food diet increased oxidative stress indicators and protein catabolism. Unbalanced urban diets can affect the body condition and nutritional physiology of House Sparrows and may also induce oxidative stress despite the absence of environmental pollution.

Formation of the avifauna of the Zaryadye Park (Moscow) in 2018-2022

The article presents the results of a five-year monitoring of the bird population in the new Zaryadye Park (Moscow) and a forecast for the further development of their communities. The basis of the population of the park is, on the one hand, numerous urban species, such as the house sparrow Passer domesticus and the rock dove Columba livia, and, on the other hand, single migratory species, including those protected in Moscow. Of the 50 species noted in Zaryadye, 13 species reliably nest, and another 4 probably nest. In the future, as the forest stand matures, both new migratory and nesting species may appear in the park.

High epigenetic potential protects songbirds against pathogenic Salmonella enterica infection

ABSTRACT Animals encounter many novel and unpredictable challenges when moving into new areas, including pathogen exposure. Because effective immune defenses against such threats can be costly, plastic immune responses could be particularly advantageous, as such defenses can be engaged only when context warrants activation. DNA methylation is a key regulator of plasticity via its effects on gene expression. In vertebrates, DNA methylation occurs exclusively at CpG dinucleotides and, typically, high DNA methylation decreases gene expression, particularly when it occurs in promoters. The CpG content of gene regulatory regions may therefore represent one form of epigenetic potential (EP), a genomic means to enable gene expression and hence adaptive phenotypic plasticity. Non-native populations of house sparrows (Passer domesticus) – one of the world's most cosmopolitan species – have high EP in the promoter of a key microbial surveillance gene, Toll-like receptor 4 (TLR4), compared with native populations. We previously hypothesized that high EP may enable sparrows to balance the costs and benefits of inflammatory immune responses well, a trait critical to success in novel environments. In the present study, we found support for this hypothesis: house sparrows with high EP in the TLR4 promoter were better able to resist a pathogenic Salmonella enterica infection than sparrows with low EP. These results support the idea that high EP contributes to invasion and perhaps adaptation in novel environments, but the mechanistic details whereby these organismal effects arise remain obscure.

Chronic exposure to tebuconazole alters thyroid hormones and plumage quality in house sparrows (Passer domesticus).

Triazoles belong to a family of fungicides that are ubiquitous in agroecosystems due to their widespread use in crops. Despite their efficiency in controlling fungal diseases, triazoles are also suspected to affect non-target vertebrate species through the disruption of key physiological mechanisms. Most studies so far have focused on aquatic animal models, and the potential impact of triazoles on terrestrial vertebrates has been overlooked despite their relevance as sentinel species of contaminated agroecosystems. Here, we examined the impact of tebuconazole on the thyroid endocrine axis, associated phenotypic traits (plumage quality and body condition) and sperm quality in wild-caught house sparrows (Passer domesticus). We experimentally exposed house sparrows to realistic concentrations of tebuconazole under controlled conditions and tested the impact of this exposure on the levels of thyroid hormones (T3 and T4), feather quality (size and density), body condition and sperm morphology. We found that exposure to tebuconazole caused a significant decrease in T4 levels, suggesting that this azole affects the thyroid endocrine axis, although T3 levels did not differ between control and exposed sparrows. Importantly, we also found that exposed females had an altered plumage structure (larger but less dense feathers) relative to control females. The impact of tebuconazole on body condition was dependent on the duration of exposure and the sex of individuals. Finally, we did not show any effect of exposure to tebuconazole on sperm morphology. Our study demonstrates for the first time that exposure to tebuconazole can alter the thyroid axis of wild birds, impact their plumage quality and potentially affect their body condition. Further endocrine and transcriptomic studies are now needed not only to understand the underlying mechanistic effects of tebuconazole on these variables, but also to further investigate their ultimate consequences on performance (i.e. reproduction and survival).

Effect of estradiol and predator cues on behavior and brain responses of captive female house sparrows (Passer domesticus).

The presence of predators can cause major changes in animal behavior, but how this interacts with hormonal state and brain activity is poorly understood. We gave female house sparrows (Passer domesticus) in post-molt condition an estradiol (n = 17) or empty implant (n = 16) for 1week. Four weeks after implant removal, a time when female sparrows show large differences in neuronal activity to conspecific vs. heterospecific song, we exposed birds to either 30min of conspecific song or predator calls, and video recorded their behavior. Females were then euthanized, and we examined neuronal activity using the expression of the immediate early gene (IEG) ZENK to identify how the acoustic stimuli affected neuronal activation. We predicted that if female sparrows with estradiol implants reduce neuronal activity in response to predator calls as they do to neutral tones and non-predatory heterospecifics, they would show less fear behavior and a decreased ZENK response in brain regions involved in auditory (e.g., caudomedial mesopallium) and threat perception functions (e.g., medial ventral arcopallium) compared to controls. Conversely, we predicted that if females maintain auditory and/or brain sensitivity towards predator calls, then female sparrows exposed to estradiol would not show any differences in ZENK response regardless of playback type. We found that female sparrows were less active during predator playbacks independent of hormone treatment and spent more time feeding during conspecific playback if they had previously been exposed to estradiol. We observed no effect of hormone or sound treatment on ZENK response in any region of interest. Our results suggest that female songbirds maintain vigilance towards predators even when in breeding condition.

Epigenetic modification of the hypothalamic–pituitary–adrenal (HPA) axis during development in the house sparrow (Passer domesticus)

Epigenetic modifications such as DNA methylation are important mechanisms for mediating developmental plasticity, where ontogenetic processes and their phenotypic outcomes are shaped by early environments. In particular, changes in DNA methylation of genes within the hypothalamic–pituitary–adrenal (HPA) axis can impact offspring growth and development. This relationship has been well documented in mammals but is less understood in other taxa. Here, we use target-enriched enzymatic methyl sequencing (TEEM-seq) to assess how DNA methylation in a suite of 25 genes changes over development, how these modifications relate to the early environment, and how they predict differential growth trajectories in the house sparrow (Passer domesticus). We found that DNA methylation changes dynamically over the postnatal developmental period: genes with initially low DNA methylation tended to decline in methylation over development, whereas genes with initially high DNA methylation tended to increase in methylation. However, sex-specific differentially methylated regions (DMRs) were maintained across the developmental period. We also found significant differences in post-hatching DNA methylation in relation to hatch date, with higher levels of DNA methylation in nestlings hatched earlier in the season. Although these differences were largely absent by the end of development, a number of DMRs in HPA-related genes (CRH, MC2R, NR3C1, NR3C2, POMC)—and to a lesser degree HPG-related genes (GNRHR2)—predicted nestling growth trajectories over development. These findings provide insight into the mechanisms by which the early environment shapes DNA methylation in the HPA axis, and how these changes subsequently influence growth and potentially mediate developmental plasticity.

Abundance of Non-Native Birds in the City: Spatial Variation and Relationship with Socioeconomics in a South American City.

Cities commonly support a high abundance of non-native species that can affect both wildlife and human health; however, their distribution across the urban environment and their relationship with socioeconomics are not well documented. Here, we map the abundance of three non-native birds in a Latin American city-domestic pigeon (Columba livia f. domestica), house sparrow (Passer domesticus), and monk parakeet (Myiopsitta monachus)-and investigate the effect of socioeconomics on their abundance. We found that C. livia f. domestica exhibited a random distribution of abundance across the city but reached its greatest abundance in low-income areas. P. domesticus exhibited an aggregated distribution of abundance, being most abundant in the southern and western areas of the city and in low-income areas. M. monachus exhibited an aggregated distribution of abundance, being most abundant in the northeastern part of the city and reaching its greatest abundance in high-income areas. Low-income areas likely provide high abundance of food, shelter, and nesting sites for both C. livia f. domestica and P. domesticus, whereas high income areas have greater tree cover and larger trees in which M. monachus can build communal nests. Our study finds that the abundance of non-native birds varies across the city and between socioeconomic groups; therefore, targeted management is needed in different city zones to limit negative effects on native species and prevent zoonotic diseases.

Predation on a White-throated Clawed Gecko (Gonatodes albogularis fuscus) by the Tropical House Gecko (Hemidactylus mabouia) in Cuba

Substantial biodiversity declines, alterations in ecosystem functioning, and high monetary expenditures associated with the management, are among the main negative effects of biological invasions (Diagne et al. 2021). Invasive alien species, i.e. species that have successfully been introduced, established and spread beyond their native range, are expected to increase in number and impact worldwide as a result of international trade and climate change (Fournier et al. 2019; Diagne et al. 2021). Invasive species is the fourth most prevalent threat for world´s reptiles (Cox et al. 2022). Of the 21 reptiles that were brought to Cuba in the last several centuries, nine species have successfully colonized and are now considered invasive (Borroto-Páez et al. 2015), with three of them being house geckos of the genus Hemidactylus. The Tropical House Gecko (H. mabouia) is native to central Africa (Henderson and Powell 2009) and currently can be found in several areas around Cuba with populations appearing to increase rapidly (Díaz 2014), especially in urban areas. These large geckos (adult snout-vent length [SVL] = 61–75 mm) are mainly associated with human habitations, where they hide in cracks and other refuges. They feed mainly on insects, but other arthropods and even small vertebrates can be taken (Albuquerque et al. 2013; Lamb et al. 2021). The White-throated Clawed Gecko, Gonatodes albogularis fuscus is another lizard considered as an invasive species in Cuba by some authors (Borroto-Páez et al. 2015) and possibly native by others (Chaves et al. 2022). This species can be found in several sites around the Cuban archipelago living as a human commensal in houses, gardens, parks, and plantations (Díaz 2008). This diurnal gecko can reach 40 mm SVL (Schwartz and Henderson 1991) and the only known predator in Cuba is the House Sparrow (Passer domesticus; Bello 2000). Although the first introduced reptiles probably arrived to Cuba in the early 16th Century with the beginning of the slave trade (Borroto-Páez et al. 2015), little information has been published about the interactions among invasive reptile species and about the relations with the Cuban native reptiles (e.g. Armas and Iturriaga 2017; Borroto-Páez and Reyes 2019). In this note, we document interactions between two invasive lizard species and comment about possible negative effects of Hemidactylus mabouia on sympatric geckos living in human habitations. On 2 August 2020 at 1201 h, we found an adult individual Hemidactylus mabouia (about 75 mm SVL) swallowing an adult male Gonatodes albogularis fuscus (about 20 mm SVL). The observation was in a house´s courtyard in the residential neighborhood named Los Olmos in Santiago de Cuba city, Cuba. The predation event occurred on a wall, ca. 178 cm above the ground, the predator had captured the prey head-first and only the rear legs and tail were hanging from its mouth (Fig. 1).

Molecular Detection and Phylogenetic Analysis of Avian Haemosporidian Parasites in House Sparrows (Passer domesticus) of Western Iran.

House Sparrows (Passer domesticus) are ubiquitous wild birds and can be potential reservoirs of avian haemosporidians (vector-borne blood parasites) in their habitat. The Zagros Mountain range in western Iran is an important habitat of many endangered birds. To investigate the occurrence and molecular characterization of Haemoproteus and Plasmodium spp. in Kuhdasht County in the central western region of Zagros, blood samples from 60 House Sparrows were screened by microscopic examination and PCR. An overall prevalence of 6.6%, with a varied intensity of infection (1-198 parasites per 15,000 erythrocytes) for Haemoproteus spp. and no infection for Plasmodium spp., was observed by microscopy. One of the studied cytochrome b sequences was identical to the lineage PAHIS1, and the other sequence was a new lineage, PADOM41; both were extremely similar to Haemoproteus passeris. This is the first report on the molecular detection and characterization of Haemoproteus in passerines of Kuhdasht.

Nestling mouth colors mediate parental favoritism but do not influence detectability

AbstractYoung animals often solicit care from their parents using behaviors and morphologies collectively termed begging. Many nestling altricial birds add to their familiar postures and vocalizations by displaying colorful mouthparts, hypothesized to enhance their visual conspicuousness and/or be favored by choosy parents. We evaluated these two hypotheses with experimental manipulations of the flange tissue of house sparrow (Passer domesticus) nestlings. We allowed parents to interact with nestlings that appeared to have either carotenoid-rich or carotenoid-poor flanges, and then with nestlings that appeared similar in carotenoid-richness but differed in either brightness (total light reflected) or ultraviolet (UV) richness. These three features of flange color comprise much of the variation observed both within and among species. None of our three manipulations shaped parents’ ability to transfer prey efficiently to nestlings, a proxy for how visually detectable nestlings were. Parents preferentially allocated prey to nestlings that appeared carotenoid-rich, but did not bias allocation when we manipulated brightness or UV reflectance. These patterns suggest that nestlings displaying carotenoid-rich flanges benefit from parental favoritism, but that variation in brightness and UV reflectance do not independently shape parental care, at least within the range a house sparrow parent might encounter in nature. Efforts to understand mouth color in the context of offspring-parent communication and visual signal evolution may benefit from considering the component parts of color, as they may function, be constrained, and evolve independently.

House sparrows exhibit individual differences in generalization when confronted with different novel stimuli

AbstractGeneralization refers to the process by which animals assign different stimuli into cognitive categories based on their similarity/dissimilarity to previously experienced stimuli. Stimuli that strongly deviate from previous experience may be avoided due to their novelty (i.e., neophobia), while stimuli that are sufficiently similar to a known/recognized cue may elicit the same response as that cue (i.e., generalization). While generalization has been widely researched, few studies have examined among‐individual variance in its expression. Our study quantified among‐individual variation in neophobia and generalization in house sparrows (Passer domesticus) by placing a series of different objects next to each subject's food source on successive days and measuring the subject's latency to approach the food source in the presence versus absence of each object. Similar to previous work, we found that house sparrows are neophobic on average and exhibit significant among‐individual variance in neophobia. More interestingly, we found that the neophobic response declined across presentations of different novel objects. This implies that the sparrows generalized some aspect(s) of the objects. We also found significant among‐individual variance in the rate at which approach latency changed across this series, possibly reflecting individual differences in propensity to generalize. These results raise new questions about how neophobia, habituation, and generalization are linked and about the potential for selection to act on these traits under different ecological conditions.

H7N9 influenza A virus transmission in a multispecies barnyard model

Influenza A viruses are a diverse group of pathogens that have been responsible for millions of human and avian deaths throughout history. Here, we illustrate the transmission potential of H7N9 influenza A virus between Coturnix quail (Coturnix sp.), domestic ducks (Anas platyrhynchos domesticus), chickens (Gallus gallus domesticus), and house sparrows (Passer domesticus) co-housed in an artificial barnyard setting. In each of four replicates, individuals from a single species were infected with the virus. Quail shed virus orally and were a source of infection for both chickens and ducks. Infected chickens transmitted the virus to quail but not to ducks or house sparrows. Infected ducks transmitted to chickens, resulting in seroconversion without viral shedding. House sparrows did not shed virus sufficiently to transmit to other species. These results demonstrate that onward transmission varies by index species, and that gallinaceous birds are more likely to maintain H7N9 than ducks or passerines.

Long-Term Population Trends of House Sparrow and Eurasian Tree Sparrow in Spain

Urban areas are constantly increasing, which can cause an effect in bird populations since human activities lead to nature alterations. Populations of House Sparrow (Passer domesticus) and Eurasian Tree Sparrow (Passer montanus) have been decreasing in Spain according to the latest national censuses in Spain. In this study, we tried to assess the population trend over more than two decades using ringing data from Spanish constant effort sites, as well as to determine the population and breeding success proxy in relation to habitat composition at landscape level. We analysed the data and confirmed the decreasing trend in the two species. However, Eurasian Tree Sparrow showed signs of increasing presence in urban areas. Furthermore, the productivity remained stable over sampling sites and years, meaning that the causes of the decreasing populations are affecting both adult and juvenile individuals.

House sparrows prioritize skin repair over constitutive innate immunity during long-term chronic stress.

The reactive scope model was created to address two major unanswered questions in stress physiology: how and when does the adaptive acute stress response turn into harmful chronic stress? Previous studies suggest that immunoenhancement should occur in reactive homeostasis (acute stress) and immunosuppression should occur in homeostatic overload (chronic stress). We used this dichotomy of immune function to further elucidate the transition from acute to chronic stress by treating house sparrows (Passer domesticus) with different intensities of chronic stress and then monitoring their immune function. By varying the number of stressors given per day and the length of chronic stress bouts over a period of 6 months, we produced four treatment groups: high, medium, and low stress, and captivity-only. We tracked immunity through the bacterial killing assay and monitored healing of a 4 mm skin biopsy punch. We hypothesized that higher-stress birds would repair their skin more slowly and have lower bacterial killing capacity. The opposite was true-high-stress birds initially repaired their skin fastest. Additionally, all birds dramatically reduced bacterial killing capacity after the biopsy and increased food-derived uric acid, suggesting increased energy acquisition and a shift in immune resources to a more immediate concern (healing). Once healing finished, only the high-stress birds were unable to recover circulating immune function, suggesting that the combination of high stress and an immune challenge pushed these birds into homeostatic overload. Prioritizing healing over other immunological processes might be the best defense for a bird in its natural habitat.