Response Of Birds Research Articles

Interactive effects of rising temperatures and urbanisation on birds across different climate zones: A mechanistic perspective.

Climate change and urbanisation are among the most pervasive and rapidly growing threats to biodiversity worldwide. However, their impacts are usually considered in isolation, and interactions are rarely examined. Predicting species' responses to the combined effects of climate change and urbanisation, therefore, represents a pressing challenge in global change biology. Birds are important model taxa for exploring the impacts of both climate change and urbanisation, and their behaviour and physiology have been well studied in urban and non-urban systems. This understanding should allow interactive effects of rising temperatures and urbanisation to be inferred, yet considerations of these interactions are almost entirely lacking from empirical research. Here, we synthesise our current understanding of the potential mechanisms that could affect how species respond to the combined effects of rising temperatures and urbanisation, with a focus on avian taxa. We discuss potential interactive effects to motivate future in-depth research on this critically important, yet overlooked, aspect of global change biology. Increased temperatures are a pronounced consequence of both urbanisation (through the urban heat island effect) and climate change. The biological impact of this warming in urban and non-urban systems will likely differ in magnitude and direction when interacting with other factors that typically vary between these habitats, such as resource availability (e.g. water, food and microsites) and pollution levels. Furthermore, the nature of such interactions may differ for cities situated in different climate types, for example, tropical, arid, temperate, continental and polar. Within this article, we highlight the potential for interactive effects of climate and urban drivers on the mechanistic responses of birds, identify knowledge gaps and propose promising future research avenues. A deeper understanding of the behavioural and physiological mechanisms mediating species' responses to urbanisation and rising temperatures will provide novel insights into ecology and evolution under global change and may help better predict future population responses.

Dietary 1,3-β-Glucans Affect Growth, Breast Muscle Composition, Antioxidant Activity, Inflammatory Response, and Economic Efficiency in Broiler Chickens.

Recently, researchers have been intensively looking for novel, safe antibiotic alternatives because of the prevalence of many clinical and subclinical diseases affecting bird flocks and the risks of using antibiotics in subtherapeutic doses as feed additives. The present study intended to evaluate the potential use of 1,3-β-glucans (GLC) as antibiotic alternative growth promotors and assessed the effect of their dietary inclusion on the growth performance, carcass traits, chemical composition of breast muscles, economic efficiency, blood biochemical parameters, liver histopathology, antioxidant activity, and the proinflammatory response of broiler chickens. This study used 200 three-day-old ROSS broiler chickens (50 chicks/group, 10 chicks/replicate, with an average body weight of 98.71 ± 0.17 g/chick). They were assigned to four experimental groups with four dietary levels of GLC, namely 0, 50, 100, and 150 mg kg-1, for a 35-day feeding period. Birds fed diets containing GLC showed an identical different growth rate to the control group. However, the total feed intake (TFI) increased quadratically in the GLC50 and GLC100 groups as compared to that in the control group. GLC addition had no significant effect on the weights of internal and immune organs, except for a decrease in bursal weight in the GLC150 group (p = 0.01). Dietary GLC addition increased the feed cost and total cost at 50 and 100 mg kg-1 doses. The percentages of n-3 and n-6 PUFA in the breast muscle of broiler chickens fed GLC-supplemented diets increased linearly in a dose-dependent manner (p < 0.01). The serum alanine aminotransferase (ALT) level and the uric acid level were quadratically increased in the GLC150 group. The serum levels of total antioxidant capacity, catalase, superoxide dismutase, interleukin-1β, and interferon-gamma linearly increased, while the MDA level decreased in the GLC-fed groups in a dose-dependent manner. Normal histological characterization of different liver structures in the different groups with moderate round cells was noted as a natural immune response around the hepatic portal area. The different experimental groups showed an average percentage of positive immunostaining to the proinflammatory marker transforming growth factor-beta with an increase in the dose of GLC addition. The results suggest that GLC up to 100 mg kg-1 concentration can be used as a feed additive in the diets of broiler chickens and shows no adverse effects on their growth, dressing percentage, and internal organs. GLC addition in diets improves the antioxidant activity and immune response in birds. GLC help enrich the breast muscle with n-3 and n-6 polyunsaturated fatty acids.

The molecular basis of differential host responses to avian influenza viruses in avian species with differing susceptibility.

Highly pathogenic avian influenza (HPAI) viruses, such as H5N1, continue to pose a serious threat to animal agriculture, wildlife and to public health. Controlling and mitigating this disease in domestic birds requires a better understanding of what makes some species highly susceptible (such as turkey and chicken) while others are highly resistant (such as pigeon and goose). Susceptibility to H5N1 varies both with species and strain; for example, species that are tolerant of most H5N1 strains, such as crows and ducks, have shown high mortality to emerging strains in recent years. Therefore, in this study we aimed to examine and compare the response of these six species, to low pathogenic avian influenza (H9N2) and two strains of H5N1 with differing virulence (clade 2.2 and clade 2.3.2.1) to determine how susceptible and tolerant species respond to HPAI challenge. Birds were challenged in infection trials and samples (brain, ileum and lung) were collected at three time points post infection. The transcriptomic response of birds was examined using a comparative approach, revealing several important discoveries. We found that susceptible birds had high viral loads and strong neuro-inflammatory response in the brain, which may explain the neurological symptoms and high mortality rates exhibited following H5N1 infection. We discovered differential regulation of genes associated with nerve function in the lung and ileum, with stronger differential regulation in resistant species. This has intriguing implications for the transmission of the virus to the central nervous system (CNS) and may also indicate neuro-immune involvement at the mucosal surfaces. Additionally, we identified delayed timing of the immune response in ducks and crows following infection with the more deadly H5N1 strain, which may account for the higher mortality in these species caused by this strain. Lastly, we identified candidate genes with potential roles in susceptibility/resistance which provide excellent targets for future research. This study has helped elucidate the responses underlying susceptibility to H5N1 influenza in avian species, which will be critical in developing sustainable strategies for future control of HPAI in domestic poultry.

Effect of Licorice Essential Oil (Glycyrrhizaglabraglabra) on Performance and Some Biochemical Parameters of Broiler Chickens.

Due to its beneficial components, such as glycyrrhizin, licorice is regarded a medicinal and fragrant plant. This research was designed to investigate the efficacy of licorice essential oil as an alternative to chemical antibiotics on broiler production, carcass features, cellular and humoral safety, and numerous biochemical variables in broiler blood serum. A total of 160 day-old broiler chicks were assigned to four treatment groups using a totally randomized approach. Each treatment consisted of 4 replicates, with 10 chicks in each replication. The experimental treatments included a control group, a group receiving an elemental diet containing 0.1% licorice essential oil, a group receiving an elemental diet containing 0.2% licorice essential oil, and a group receiving an elemental diet containing 0.3% licorice essential oil. Broilers had ad libitum access to feed and water in accordance with a three-phase feeding schedule consisting of a starter, grower, and finisher diet. There was no statistically significant difference (P>0.05) in body weight, feed intake, or feed conversion ratio between birds given the control or essential oil licorice at various stages of the experiment. However, birds receiving 0.1% licorice essential oil had a lower gallbladder relative weight and 0.3% licorice essential oil had less abdominal fat than the control group (P<0.05). Blood glucose, cholesterol, and LDL concentrations all fell considerably in licorice essential oil-treated birds relative to controls (P<0.05). The cellular immune response of birds fed licorice-containing diets did not differ from that of control birds (P>0.05), however there was a significant difference in the humoral immune response at 0.1% licorice essential oil compared to the control group (P<0.05). In overall, the results of this experiment demonstrated that incorporating licorice essential oil into a bird's diet improves its health and safety.

THE EFFECT OF NEEM LEAVES EXTRACT AS IMMUNSTIMULANT BEFORE CHICKEN INFECTIOUS ANEMIA VACCINATION IN BROILERS

Chicken infectious anemia (CIA) has lately arisen as a major problem in poultry production due to poor growth, high mortalities. We successfully used PCR on seven flocks of chickens (three breeder and four broiler) in the Egyptian governorates of Dakahlia and Damietta to detect CIAV in tissues of probable CIAV-infected birds. Numerous substances, including triterpenoids and glycosides, are found in Neem and are assumed to be the source of its antiviral effects. All birds were randomly allocated into eight groups (n=20 each) for different treatments, including vaccination, feeding Neem 8%, feeding infected birds 8%, vaccination and infected birds, feeding infected birds 8%, and finally feeding infected birds 8% and vaccination. One-hundred and sixty birds were randomly divided into eight groups (n=20 each). The groups were differentially-treated as the followings; healthy birds, birds infected with CIAV, birds fed Neem 8%, infected birds fed Neem 8%, vaccinated birds, vaccinated and infected birds, birds fed Neem 8% and vaccinated, and finally the infected ones fed Neem 8% and vaccinated. The study is aimed to detect the immunostimulant effect of Neem leaves extract 8% on immune response post vaccination against CIAV in broilers. The group taken immunstimulant (Neem leaves extract 8%) along with vaccination increased immune response of birds since titers of the enzyme-linked immunosorbent assay were 15200 (P≤ 0.05) than the group valued 14732 of vaccination only. However, in groups (Neem vaccinated infected, infected and vaccinated infected) were 14663, 12600 and 12091 (P&lt;0.05, P&lt;0.05 and P&lt;0.01, respectively). Infected group exhibited indications of CIAV as despondency, while group vaccinated and treated with Neem leaves extract 8% appeared normal after challenging with CIAV. The hematocrit values of infected group and vaccinated treated infected group were 21 and 30, respectively. Histopathological changes in Neem vaccinated group after challenging with CIAV showed increasing in the thickness of both cortex and medulla of thymic lobules beside over population. In the latest group, bone marrow showed activation and proliferated hemopoitic elements with regenerative centers. We conclude that the combination of Neem leaves extracts 8% and CIAV vaccination is a potent antiviral and has immunstimulant properties during the production cycle of broilers.

Bird’s blood and feathers as bioindicators for the oxidative stress induced by metal(loid)s in polymetallic contaminated areas

Toxic metal(loid)s in polymetallic mining areas are very prominent environmental stressors and may lead to undesirable oxidative stress responses in wild birds. Finding an effective nondestructive bioindicator to monitor the toxic effects of oxidative stress induced by metal(loid)s exposure is vital for bird conservation in these areas. In this study, the contents of six metal(loid)s (Cu, Zn, Pb, Cd, Cr and As) in feathers and plasma and the levels of seven oxidative stress biomarkers (MDA, SOD, GST, GPX, CAT, GSH and GSSG) in plasma were measured and their correlations were investigated for three resident bird species (turtledove Streptopelia chinensis, sparrow Passer montanus and blackbird Turdus merula) in Tongling, a polymetallic contaminated mining area in eastern China. The contents of most metal(loid)s were high in our samples and they were positively correlated with each other in both feathers and plasma, except that the Cd content was negatively correlated with Zn in plasma. Also, the activity levels of oxidative stress biomarkers (MDA, SOD, GST, GPX and CAT) in plasma were positively correlated with each other. The Pearson correlation analysis showed that the first principal component of metal(loid)s in feathers was positively correlated with that in plasma. The canonical correlation analysis (CCA) indicated that the levels of oxidative stress biomarkers had positive correlations with the contents of As, Cr and Cd in feathers, and with the contents of As, Cr, Pb, and Zn in plasma. Compared with those in feathers, the metal(loid)s in plasma explained more of the total variance of the levels of oxidative stress and should be a good bioindicator. Due to the sampling convenience and no damages, we suggest that feathers may possibly be used as an auxiliary bioindicator for monitoring oxidative stress induced by metal(loid)s. This study supplements the information about selecting the bird-related nondestructive bioindicators as environment monitoring tool in polymetallic mining areas and provides a reference for bird conservation in similar areas.

Reversing declines in farmland birds: How much agri‐environment provision is needed at farm and landscape scales?

Abstract Agri‐environment schemes (AES) are the primary policy mechanism for addressing farmland biodiversity declines across Europe. Despite previous studies on the impacts of AES on biodiversity, there is little empirical evidence on the scale of provision required to reverse declines. Across three regions of lowland England with contrasting farm systems (arable, pastoral, mixed), we estimated avian population growth rates (PGRs) on farmland with high AES provision (‘higher‐tier’: average bird‐friendly option cover = 7.4%), low AES provision (‘lower‐tier’: 2.3%) and no bird‐friendly AES (‘no AES’). Ten‐year PGRs were derived for 24 species and three multi‐species groups comprising farmland‐associated species (‘farmland birds’), species of conservation concern (‘priority birds’) and species restricted to farmland (‘specialist birds’). We used PGRs to simulate the proportion of the regional farmland landscape that would have to be assigned to higher‐ and lower‐tier agreements to stabilise or increase populations. In the arable and pastoral regions, 13/23 and 13/22 species, respectively, had more positive PGRs under higher‐tier AES than on no AES farmland (none had more negative PGRs), compared to 4/22 (positive) and 1/22 (negative) in the mixed region. Only two to four species per region exhibited more positive PGRs under lower‐tier AES compared to no AES farmland. Multi‐species PGRs in the arable and pastoral regions increased from no AES (strong decline), to lower‐tier (decline or stability) to higher‐tier (moderate or strong increase). There was no overall AES effect in the mixed region. To increase regional farmland bird populations by 10% over 10 years, 47% and 26% of the farmed landscape would need to be devoted to higher‐tier agreements in arable and pastoral landscapes respectively. This falls to 34% and 17% when higher‐tier is targeted at localities supporting higher abundances of target species, and to 29% and 10% when 30% of the farmed landscape is also devoted to lower‐tier. Priority and specialist birds require higher provision levels. Policy implications. Where farmland bird recovery is an AES objective, farms should prioritise higher‐tier agreement delivery over lower‐tier. Farmland bird responses to AES provision are likely to vary regionally, but careful targeting will reduce the amount needed in the landscape.

A comparative evaluation of transcriptome changes in lung and spleen tissues of chickens infected with velogenic and mesogenic Avian Orthoavulavirus 1

Newcastle disease is an acute, highly contagious disease responsible for severe economic losses to the poultry industry worldwide. Clinical assessment of different pathotypes of AOaV-1 strains is well-elucidated in chickens. However, a paucity of data exists for a comparative assessment of avian innate immune responses in birds after infection with two different pathotypes of AOaV-1. We compared early immune responses in chickens infected with a duck-originated velogenic strain (high virulent: genotype VII) and a pigeon-originated mesogenic stain (moderate virulent; genotype VI). Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) identified 4737 differentially expressed genes (DEGs) in the transcriptional profiles of lung and spleen tissues of chickens infected with both pathotypes. More DEGs were expressed in spleen tissue infected with velogenic strain compared to spleen or lung exposed to mesogenic strain. An enriched expression was observed for genes involved in metabolic processes and cellular components, including innate immune-associated signaling pathways. Most DEGs were involved in RIG-I, Toll-like, NF-Kappa B, and MAPK signaling pathways to activate interferon-stimulated genes (ISGs). This study provided a comparative insight into complicated molecular mechanisms and associated DEGs involved in early immune responses of birds to two different AOaV-1 strains.

Physiological response of quail birds supplemented with different forms of aloe vera under heat stress conditions

Physiological response of quail birds supplemented with different forms of aloe vera under heat stress conditions

Modeling the response of Japanese quail to arginine intake.

Understanding how Japanese quails respond to arginine intake has been an objective that previous studies have not fulfilled. The main responses to be quantified include the arginine requirement for maintenance (mg/kg0.67) and egg mass production (mg/g). Quantifying maintenance and production relationships are essential steps for predicting animal response. The current study aimed to describe how quails respond to arginine intake and determine arginine requirements for maintenance and egg production in Japanese quails. The experiment was carried out in a completely randomized design, with seven treatments and seven replicates with individual birds as experimental units. The arginine levels were: 2.43, 3.64, 4.85, 6.07, 9.07, 12.13, and 14.56 g/kg. The experiment lasted for eight weeks. The variables analyzed were daily arginine intake, daily arginine deposition in eggs, and body weight. The data were analyzed using a mixed model, with the experimental unit being the random effect and the experimental levels of arginine as a fixed effect. When the effect of arginine levels was detected (P≤0.05), saturation kinetics and an exponential model with four parameters (monomolecular) were adopted. ANOVA results indicated that dietary arginine levels significantly affected (P<0.01) the analyzed variables. The formulation strategy of the experimental diets allowed amplitude in the dietary arginine levels, and according to bird responses, arginine was the limiting nutrient. The arginine requirement for body weight maintenance (BW0.67) was estimated to be 90 mg/kg BW0.67 by the monomolecular function. The requirement for egg mass (EM) production was estimated to be 25 mg/g per egg. A factorial model was parameterized as follows: daily arginine intake mg/bird = 90 × BW0.67 + 25 × EM ± 12 mg. The model was applied to data obtained from literature, and the resultant error was within the expected limit of 12 mg. The recommended daily arginine intake for the daily production of 11 g of egg and 180 g of BW was determined to be 304 mg/bird. The current study provides procedures that researchers can easily adopt.

Breeding bird abundance and species diversity greatest in high-severity wildfire patches in central hardwood forests

In 2016, mixed-severity wildfires in the southern Appalachians created a gradient of forest structures not typical following prescribed burns, providing a unique opportunity to study temporally dynamic conditions and breeding bird response. We measured forest structure and breeding bird communities across a fire-severity gradient in 3 burned and 3 unburned watersheds for 5 years (Y1-Y5). We categorized plots as unburned (NB), low- (L), moderate- (M), or high-severity (H) using a composite fire-severity index. Tree mortality increased with fire-severity category (FSC) and over time; by Y5, 7 % of trees in NB, 11 % in L, 38 % in M, and 71 % in H had died. Shrub recovery was rapid and most pronounced in H, exceeding other FSCs (70 % vs 21 %–44 %) by Y5. Total bird abundance, species richness, and diversity increased over time in H (by Y3) and M (by Y4); by Y5, these metrics were highest in H and twice as high in H as in NB. Low-severity wildfires had no detectable effects on birds. Abundance of 7 species was greatest in higher-severity FSCs; 11 species did not differ among FSC, although ovenbirds (Seiurus aurocapilla) indicated a trend of lower abundance in H. No species was limited to NB, L, or M, whereas disturbance-dependent indigo bunting (Passerina cyanea), chestnut-sided warbler (Setophaga pensylvanica), and eastern towhee (Pipilo erythrophthalmus) were primarily associated with H. Increased richness and diversity were associated with heavy tree mortality and subsequent shrub recovery in H, accompanied by an influx of disturbance-dependent species and positive or neutral responses by most other species. Results highlight the interrelated roles of fire severity and time in driving forest structure and breeding bird response. Breeding birds responded to high-severity burns similarly to silvicultural treatments with heavy canopy reduction documented in other studies, offering possible alternatives when managing for breeding bird diversity in hardwood forests.

Impacts of Traffic Infrastructure on Urban Bird Communities: A Review

With increasing urbanization and related loss of biodiversity, it has become increasingly important to understand the determinants of biodiversity in cities, and to learn how we can maintain existing habitats and improve their quality for both wildlife and humans. Detrimental effects of urbanization on animals such as noise and light pollution, have frequently been reported, but comparatively little is known about the connection between different types of traffic infrastructure and their impacts on urban birds. Here, we provide an overview of the existing knowledge about bird responses to traffic-related stressors, and most importantly, we highlight that this aspect has not been satisfactorily investigated in urban environments. Therefore, we suggest suitable study systems and designs with which the effects of traffic infrastructure on bird communities in cities could be studied, and how biodiversity, in tandem with human wellbeing, in cities would benefit from improvements to the existing infrastructures. In doing so, we aim to strengthen the connection between human wellbeing and birds through research that will ultimately facilitate the development of sustainable cities.

Large-scale spatial variability in urban tolerance of birds.

Quantifying intraspecific and interspecific trait variability is critical to our understanding of biogeography, ecology and conservation. But quantifying such variability and understanding the importance of intraspecific and interspecific variability remain challenging. This is especially true of large geographic scales as this is where the differences between intraspecific and interspecific variability are likely to be greatest. Our goal is to address this research gap using broad-scale citizen science data to quantify intraspecific variability and compare it with interspecific variability, using the example of bird responses to urbanization across the continental United States. Using more than 100 million observations, we quantified urban tolerance for 338 species within randomly sampled spatial regions and then calculated the standard deviation of each species' urban tolerance. We found that species' spatial variability in urban tolerance (i.e. standard deviation) was largely explained by the variability of urban cover throughout a species' range (R2 =0.70). Variability in urban tolerance was greater in species that were more tolerant of urban cover (i.e. the average urban tolerance throughout their range), suggesting that generalist life histories are better suited to adapt to novel anthropogenic environments. Overall, species differences explained most of the variability in urban tolerance across spatial regions. Together, our results indicate that (1) intraspecific variability is largely predicted by local environmental variability in urban cover at a large spatial scale and (2) interspecific variability is greater than intraspecific variability, supporting the common use of mean values (i.e. collapsing observations across a species' range) when assessing species-environment relationships. Further studies, across different taxa, traits and species-environment relationships are needed to test the role of intraspecific variability, but nevertheless, we recommend that when possible, ecologists should avoid using discrete categories to classify species in how they respond to the environment.

Grassland restoration benefits declining farmland birds: A landscape-scale before-after-control-impact experiment

The decline of farmland bird populations starting in the 1980s has induced intense research on farmland biodiversity conservation in Europe. Although many studies assessing the effectiveness of agri-environmental schemes have concentrated on birds, farmland birds, surprisingly, have not yet been targeted directly by permanent, landscape-scale restoration of grassland ecosystems on former croplands in Europe. We compared farmland bird responses to grassland restoration by grass sowing, alfalfa sowing followed by spontaneous grassland recovery, and hay transfer (impact sites) with responses to extensive, low-intensity cropland cultivation (controls) in a Before-After-Control-Impact design, and also compared extensive croplands against a baseline reference of intensive croplands. Point counts in 69 sites on 910 ha in at least two years before and three years after the interventions showed that farmland bird species richness increased in both restored grasslands and in extensive croplands, whereas abundance and Shannon diversity increased only in restored grasslands but not in extensive croplands. Abundance increased in restored grasslands for five farmland species and two species of conservation importance, and in extensive croplands for one farmland and one species of conservation importance. Active restoration by grass sowing increased both species richness and diversity and active restoration by hay transfer increased abundance, while passive restoration targeting spontaneous grassland recovery after alfalfa sowing increased richness and abundance. Extensive croplands had four-five times more species and individuals than intensive croplands. Our results suggest that landscape-scale grassland restoration can locally reverse regional farmland bird declines and can thus be a promising tool in farmland biodiversity conservation.

Observation of an Attempted Forced Copulation within a Captive Flock of Greater Flamingos (Phoenicopterus roseus)

Flamingos (Phoenicopteriformes) are obligate colonial species that nest in large colonies, with monogamous pairs rearing a single chick following a synchronised group courtship display. Within this relatively simplistic behavioural description, deviations from these social and reproductive norms are apparent. Same sex pairings, multi-bird relationships and extra pair copulations are documented in the literature. Flamingos display highly sexually selected characteristics of plumage colour, carotenoid accumulation and diversity of display movements that underpin mate choice decisions. The brightest birds in best body condition are more successful at breeding. Therefore, documented mate guarding of female birds by male partners, is a relevant response to maximise investment in a pair bond. Limited information that describes the action of forced copulation by the male flamingo and the response of the female bird is available in the literature. This paper describes an occurrence of an attempted forced copulation by an older male Greater Flamingo to a younger female bird. Such behaviour may be an artefact of the captive environment, and limited mate choice when compared to the sizes of wild flocks, or it could be regularly apparent in the wild and therefore worthy of more scrutiny and empirical study.

Temporal shifts in avian phenology across the circannual cycle in a rapidly changing climate: A global meta‐analysis

AbstractThe alteration of the timing of biological events is one of the best documented effects of climate change, with overwhelming evidence across taxa. Many studies have investigated the phenology of consumers, especially birds. However, most of these studies have focused on specific phenophases, whereas a global analysis of avian phenological trends during recent climate change across different phases of the circannual cycle is still lacking. Here, we performed a comprehensive meta‐analytic synthesis of the phenological responses (temporal shifts in days year−1) of birds across different phenophases (prebreeding migration, breeding, and postbreeding migration) by summarizing more than 5500 time series from 684 species from five continents during 1811–2018. Our results confirm that avian taxa have advanced prebreeding migration and breeding by ~2–3 days per decade, whereas no significant temporal changes in the timing of postbreeding migration were documented. Advancement in the timing of prebreeding migration and breeding strongly depended on migratory behavior, with the advance being the weakest for long‐distance migrants and the strongest for resident species. Diet generalists and primary consumers tended to advance prebreeding migration timing more than species with different dietary specializations. Increasing body size resulted in a larger advancement in the onset (but not in the mean date) of prebreeding migration and breeding, whereas phenological advances were larger in the northern than in the southern hemisphere. Our synthesis, covering most of the world, highlighted previously unappreciated patterns in avian phenological shifts over time, suggesting that specific life‐history or ecological traits may drive different responses to climate change.

Fear in urban landscapes: conspecific flock size drives escape decisions in tropical birds.

Human-induced disturbances affect animal behaviours such as anti-predatory responses. Animals in urban environments tend to exhibit a reduced escape response, measured as a shorter flight initiation distance (FID), compared to their rural counterparts. While FID has been evaluated in animals dwelling in contrasting habitats (e.g. urban versus rural), little is known about how this response varies within urban environments, especially in tropical cities. Here, we studied the FID of 15 resident bird species in Bogota, Colombia, at 22 sites grouped into four categories (natural sites, metropolitan parks, zonal parks and residential areas) that differed in landscape features and evaluated which factors affected the escape responses of birds. We showed that birds foraging in larger flocks are more tolerant when being approached but they do not seem to be influenced by other factors such as heterospecific flock size, noise levels, pedestrian density, predator density, natural cover or body length. Also, birds inhabiting residential areas and parks showed a shorter FID compared to birds in natural areas suggesting that they are more tolerant of human-related disturbances compared to their conspecifics that live in natural areas within the city. Our study shows important differences in bird anti-predatory responses within the city and suggests that social strategies (i.e. flocking patterns) may be a mechanism for adapting to human-induced disturbances in urban tropical environments.

Effect of Dietary Inclusion of Turmeric (Curcuma longa) and Garlic (Allium Sativum) Powders as Feed Additives on Growth Performance and Cell Mediate Immune Response of Broiler Chicken

The study was conducted during 2019 at the Faculty of Veterinary Sciences &amp; Animal Husbandry, Sher-e-Kashmir University of Agricultural Sciences &amp; Technology-Jammu, India to investigate the effect of dietary inclusion of garlic, turmeric and their combinations on performance of broilers (Cobb strain). 240-day old unsexed broiler chicks were procured, weighed and randomly divided into 5 dietary treatments (n=48): antibiotic (C), 1% turmeric (T1), 1% garlic (T2), 0.6% turmeric±0.4% garlic (T3), 0.6% garlic±0.4% turmeric (T4) replicated 4times (12 birds / replicate). The diets formulated were isocaloric and isonitrogenous. Experimental trial lasted for 42 days. Feed consumption of broilers on weekly basis showed non-significant variation during first two weeks, but at 3rd week, feed intake was higher (p&lt;0.05) in antibiotic growth promoter supplemented group than garlic supplemented groups. Weekly body weight and body weight gain during the entire trial did not differ except at week 1. Average weekly FCR was similar (P&gt;0.05) throughout the experimental trial of different dietary treatments, but was numerically better in garlic fed group. Weekly PER showed no difference. Average CMI response of broiler birds was statistically higher (p&lt;0.05) in T1 than T4 with intermediate values in C, T2 and T3 at 24 hours, indicating that turmeric has immunomodulatory properties. But, at 48 and 72 hours, there was no difference found in CMI response. The mean values of cell mediated immune response showed no significant difference. It was concluded that turmeric and garlic powder supplementation (@ 1%) either alone or in combination may substitute antibiotics without any adverse effect.

Breeding-bird assemblages of calcareous grasslands and heathlands provide evidence for Common juniper (Juniperus communis) as a keystone species

Relative to their biomass or abundance, keystone species have a disproportionate effect on many other organisms. Common juniper (Juniperus communis) is an evergreen shrub that has significant impacts on microclimate, composition of plant assemblages and herbivorous insects. However, J. communis is currently not considered a keystone species. The present study aims to provide deeper insights into the potential importance of juniper as a keystone species in its two main habitats: calcareous grasslands and heathlands. The response of breeding birds to the occurrence of Common juniper was highly similar in both habitat types. Plots with the presence of J. communis had a higher species richness and density of all and shrub-nesting species than absence plots. Additionally, presence plots exhibited a higher density (calcareous grasslands) or richness (heathlands) of threatened species than absence plots. Overall, the occurrence of scattered juniper shrubs boosted species richness and abundance of breeding birds. Responsible for this pattern were (i) the general increase in structural complexity and (ii) two (genuine) properties of the tall, evergreen shrub in particular: dense growth and prickly leaves. Due to the latter, the shrubs provide nesting sites that are strongly sheltered against predation and adverse weather. However, juniper shrubs have also an important function as song posts and perches for hunting. Additionally, the usually scattered distribution of juniper shrubs ensures a maximum territory density in calcareous grasslands and heathlands. Our study provides evidence that J. communis should be considered a keystone species in both habitat types of European conservation concern.

Species-specific song responses emerge as a by-product of tuning to the local dialect

Oscine birds preferentially respond to certain sounds over others from an early age, which focuses subsequent learning onto sexually relevant songs.1,2,3 Songs vary both across species and, due to cultural evolution, among populations of the same species. As a result, early song responses are expected to be shaped by selection both to avoid the fitness costs of cross-species learning4 and to promote learning of population-typical songs.5 These sources of selection are not mutually exclusive but can result in distinct geographic patterns of song responses in juvenile birds: if the risks of interspecific mating are the main driver of early song discrimination, then discrimination should be strongest where closely related species co-occur.4 In contrast, if early discrimination primarily facilitates learning local songs, then it should be tuned to songs typical of the local dialect.5,6,7 Here, we experimentally assess the drivers of song discrimination in nestling pied flycatchers (Ficedula hypoleuca). We first demonstrate that early discrimination against the songs of the closely related collared flycatcher (F.albicollis) is not strongly affected by co-occurrence. Second, across six European populations, we show that nestlings' early song responses are tuned to their local song dialect and that responses to the songs of collared flycatchers are similarly weak as to those of other conspecific dialects. Taken together, these findings provide clear experimental support for the hypothesis that cultural evolution, in conjunction with associated learning predispositions, drives the emergence of pre-mating reproductive barriers.