Winter Flocks Research Articles

Genetic diversity of the critically endangered Blue‐crowned laughingthrush (Garrulax courtoisi)

AbstractTo evaluate the genetic quality and provide available management strategies for Blue‐crowned laughingthrush (BCLT), fifteen polymorphic microsatellite loci were developed and applied. The genetic diversity of wild individuals was indicated to be higher than the two captive populations. The average number of alleles (5.50 ± 0.317), the number of effective alleles (3.417 ± 0.222), observed heterozygosity (0.828 ± 0.04), and genetic differentiation index (0.028 ± 0.007) of 64 wild individuals showed high genetic diversity despite drastic bottleneck and low genetic differentiation. The number of effective migrants (22.737 ± 8.318) indicated the intriguing wintering grounds may be surrounded by the breeding sites where the syncheimadia occurred in Wuyuan. Efficient conservation, winter flocking, and cooperative breeding may facilitate gene exchange and inclusive fitness. We recommend that monitoring concentrated distribution areas for BCLT should be strengthened, and geographical barriers, interference types, and the inner mechanism of distribution patterns should be further explored.

Measurement of Dynamic Electric Consumption Trend in a Broiler House in Arkansas

Highlights We quantified the diurnal and seasonal electric load pattern during four consecutive growouts of heavy broilers over an 11-month period on a commercial farm. Consumption was measured separately for ventilation fans, lights, feed motors, well pump motors and radiant tube heater blowers. Ventilation fans were the largest consumer of energy and the largest contributor to peak demand on the farm. Average monthly electric demand ranged from 31% to 77% of the corresponding monthly peak demand, calculated from the largest 15-min period. The electricity cost of raising heavier-weight broiler chickens is higher in the summer ($22 per 1,000 kg live weight) than in the winter ($5 per 1,000 kg live weight). Abstract. Characterizing electric energy use in a commercial broiler house—partitioned by bird age, season, and electric load type—can provide engineers with insight for designing energy conservation practices, as well as help to analyze and design on-site renewable energy production sub-systems. This study monitored electric energy consumption in a commercial broiler house in Arkansas, raising heavy broilers (with a capacity of 17,000 birds) during an 11-month period that included four, 8-week flocks. Average electricity use (RMS voltage and current) was measured at a sampling interval of 5 min for all of the major load types, including ventilation, lighting, feed motors, and well-water pump motor. Results indicated that electric consumption for ventilation fans was the greatest load, accounting for over 88% of the total. The endwall fans (for tunnel ventilation) contributed to the peak electric demand (VA) in nine of the 11 months. Over the 11-month monitoring period, broiler chicken production had an average electric energy consumption (per unit live-weight mass produced) of 43 kWh per metric ton of live weight (in a winter flock) to 184 kWh per metric ton (in a summer flock). The corresponding electric costs were $5 per metric ton and $22 per metric ton in winter and summer flocks, respectively (based upon an electricity unit cost of $0.12/kWh). Keywords: Electricity demand, Energy efficiency, Poultry housing.

The Effect of Season on the Performance, Health, and Welfare of Broilers

The research was carried out on 80 broiler flocks (Ross 308) raised during the winter, spring, summer, and autumn seasons in commercial enterprises in Uşak City Center and its districts engaged in contract farming. Broiler flocks were examined weekly during the 0-42 day growth period for body weight, weight gain, feed consumption, feed conversion ratio, mortality and EPEF. The 42-day-old broiler was scored for FPD and HB. The season significantly impacted the broiler flock's performance and the birds' prevalence with FPD and HB under commercial conditions. Spring and autumn flocks showed higher performance than winter and summer flocks. The prevalence of birds with foot pad burn and hock burn was highest in winter flocks and lowest in summer flocks. These findings indicate that seasons can significantly impact broiler farms' economic performance and bird welfare. As a result, obtaining further information about the positive and negative effects of seasons on broilers can promote production and provide critical data to encourage innovative strategies for sustainable flock management and improve broiler industry compliance with animal welfare standards.

Feather corticosterone reveals that urban great tits experience lower corticosterone exposure than forest individuals during dominance-rank establishment.

Although the consequences of urbanization for the physiological health of animals are the focus of much active research, an overlooked aspect is how physiology could be indirectly modulated by the urban environment via changes in intraspecific behavioural interactions, particularly among gregarious species. Both urbanization and the establishment, as well as maintenance, of hierarchical rank position are processes that could incur physiological stress. Measurements of glucocorticoids (GCs) in relation to urbanization, however, have yielded inconsistent results. In most cases, GCs have been measured in blood, offering only a 'snapshot' of an animal's current physiological state. Because circulating GCs are incorporated into growing feathers or hair, measurements of feather/hair GCs offer a longer term measure of stress exposure reflecting the whole period of feather/hair growth. During two calendar years, we collected tail feathers from 188 urban and forest great tits (P. major) across multiple sampling sites and analysed corticosterone (CORT-the main GC in birds) levels, reflecting CORT exposure during the extended period in late summer and early autumn when great tits moult and winter flocks are formed. Urban individuals exhibited consistently lower feather CORT (fCORT) levels than forest birds indicating lower overall exposure to CORT during this period. The lower fCORT levels in urban individuals could represent an adaptation to cope with the more challenging urban environment, physiological constraints on stress axis function or a trade-off between the ability to respond to stressors and predation risk during moult. Despite the expectation that CORT responses to urbanization are highly context-dependent, the spatial consistency of our results and agreement with a multi-population study of fCORT in European blackbirds (Turdus merula) suggests a generalization of the effect of urbanization on CORT exposure during post-breeding moult (i.e. not site- or species-specific).

Winter distribution and migratory strategies of Eurasian Spoonbills (Platalea leucorodia) from the Pannonian breeding population: are they long-distance migrants?

In this paper, the wintering characteristics of the Eurasian Spoonbills (Platalea leucorodia) breeding in the Carpathian Basin (Pannonian population) were analysed. The data of 305 wintering Spoonbills marked with colour-rings in Hungary was used. A significant part, 80% of the Spoonbills, wintered in Africa, while 20% spent the winter in Europe and only two birds in the Asian part of western Turkey. The most important wintering sites were in the central part of North Africa (in Algeria, Libya, but mainly Tunisia) and Italy. The tidal area in the Gulf of Gabes in Tunisia was the most important area where a significant proportion, 65% of all wintering Spoonbills, spent the winter. This study provided new evidence of Spoonbills occurring in Saharan wetlands (Chott Tindla in Algeria) in winter. 2% of the resighted Spoonbills were reported from the wetlands of the Sahel in Sudan, Nigeria, Niger, Mali, Mauritania, and Senegal. European winterers were mainly found in Italy and, to a lesser extent, in the Balkans and the Carpathian Basin. The mean distance between the natal colonies and the wintering areas was 1,535 km. Spoonbills migrated in a south-southwestern direction (mean: 213°) to reach their wintering sites. In the Hungarian population, most specimens (94%) were short-distance migrants (wintered north of 22°N), 2% were long-distance migrants, and 4% were residents. However, the proportions of the residents and short-distance migrants are supposed to be overestimated and the proportion of the long-distance migrants is likely to be underestimated due to the lack of observation effort in sub-Saharan Africa. However, based on the winter census data and the proportion of ringed individuals of Hungarian origin in the wintering flocks, I estimated that the lack of observation effort would only slightly modify the result. There were two shifts in migratory strategies on an individual level: a resident Spoonbill became a short-distance migrant, and a short-distance migrant became a long-distance migrant by a following winter. While most of the East Atlantic Spoonbills are long-distance migrants, the results of this study indicate that most birds in the Pannonian population are likely to be rather short-distance migrants. The results of the GPS tracking also confirm that most Pannonian Spoonbills are short-distance migrants and support the main conclusion of this paper.

A review of harvest and population monitoring methods for western wild turkeys

AbstractSeveral subspecies of wild turkey (Meleagris gallopavo) are managed throughout the western USA for wildlife viewing and hunting, including Merriam's (M. g. merriami), Rio Grande (M. g. intermedia), eastern (M. g. silvestris), and Gould's (M. g. mexicana) wild turkey. In addition to the variety of subspecies, the West also comprises a wide variety of occupied vegetative communities throughout an array of state and federal jurisdictions. In 1993, the Colorado Division of Wildlife published the Management Guidelines for Merriam's Wild Turkeys (Hoffman et al. 1993). Since that time, harvest and monitoring methods have evolved. Harvests are monitored through mandatory or voluntary phone surveys, online surveys, mail surveys, email surveys, mobile phone applications, field checks, and wing or foot collections. Populations are monitored through harvest indices, summer brood surveys, winter flock counts, winter classifications, summer classifications, presence‐absence surveys, camera traps, forward‐looking infrared, aerial surveys, telemetry, weather indices, citizen science reports, and a variety of modeling approaches. We provide a limited review highlighting the substantive strengths and challenges associated with each population monitoring technique to provide agencies and organizations involved in monitoring harvest and populations of turkeys with an overview to assist in selecting appropriate tools for use in their jurisdiction.

Low-Cost Solar Collectors to Pre-Heat Ventilation Air in Broiler Houses

The objective of the study was to evaluate the effect of a low-cost solar collector to pre-heat ventilation air in commercial broiler buildings on supplemental heating demand and air quality during the cold season. Six black fabric-based solar collectors of 36 m2 each were installed on the south-facing rooftop of a broiler house. The solar collectors provided fresh warm air into the house during the ON cycle of minimum ventilation and during the OFF cycle of minimum ventilation when the temperature under the collectors met certain criteria. The daily cumulative duration of solar collectors in operation averaged 125 and 133 min during the first two or four weeks of brooding in the fall and winter flocks, respectively. When in operation, the solar collectors were able to raise up to 20 K above the ambient temperature, reducing fuel usage by 7% in the fall and winter flocks. The greatest challenge of solar collector utilization was the collectors providing less than half of ventilation air during daytime due to not enclosing the fresh air inlets. The limited airflow capacity and limited activation of the solar collectors due to the existing minimum ventilation scheme is another reason for low heating fuel savings.

Mobbing behaviour in non-breeding flocks of a passerine bird in northern Patagonia

Abstract Animal cooperation occurs in both genetically related and unrelated groups of individuals, involving costs and benefits that have not been fully elucidated. For example, risky behaviour such as mobbing a predator would be selected if participants are genetic relatives because they share a fraction of their gene pool (i.e., kin selection or indirect benefits). However, in the absence of genetic relatedness, benefits can be achieved by direct benefits such as reciprocity or mutualism, among others. In this study we analyzed the cooperative mobbing behaviour in winter flocks of an endemic passerine of the austral temperate forests, the Thorn-tailed rayadito (Aphrastura spinicauda). We first tested whether the probability of and the latency to mobbing response differed depending on the acoustic stimulus perceived by the flock (i.e., conspecific mobbing calls vs. predator calls), and whether the intensity of the mobbing was related to the number of individuals and species participating. We found that flocks were more likely to approach the predator when the acoustic signal was a conspecific mobbing call than when it was the predator’s call, and that the intensity of mobbing increased with the number of participants. Secondly, we explored if the level of kinship within the group potentially played a role in the development of the mobbing behaviour. The proportion of close-relatives found in these flocks was low, and the within- and among-flock degree of kinship did not differ. This suggests that kin selection might not be related with the expression of mobbing behaviour in winter flocks.

Status, distribution and conservation of Kentish plover <em>Charadrius alexandrinus</em> (Aves, Charadriiformes) in Sicily

The Kentish Plover Charadrius alexandrinus is a sensitive species whose national breeding population has been undergoing a sharp decrease, up to 50%, in 2010 compared to the previous decade. Due to the lack of updated data and fragmented knowledge about its current status and distribution in Sicily, a specific and accurate monitoring of this species was carried out during the years 2018 and 2019. About 230 km of coastline and 64 UTM squares 10x10 km were investigated during the breeding seasons, and a total of 205-287 pairs have been estimated for the whole region, distributed in 41 UTM squares (including the island of Favignana). Pairs are mainly concentrated in the complex of “Saline di Trapani and Stagnone di Marsala” and along the sandy coast of Gulf of Gela, with a higher abundance along the southeast coast of the region. Breeding population showed a decrease of 18-28% in number of pairs in comparison to the last estimation of 250-400 pairs reported for the years 2009-2010. After the investigation of 108 km of coastline and 46 UTM squares, the Sicilian wintering population has been estimated at 376- 563 ind., with wintering flocks mainly concentrated in the wetlands of “Mazara del Vallo” and along the coasts of Syracuse and the Gulf of Gela. These updated estimates place Sicily as the second most important Italian region for the wintering of this species, just after Sardinia. For the first time, the data collected have made it possible to draw up qualitative-quantitative maps of C. alexandrinus distribution in Sicily, providing an important instrument for the management and planning of specific conservation actions, which should be based on habitat protection and implementation of appropriate artificial ecological niches.

Quantification and Trends of Antimicrobial Use in Commercial Broiler Chicken Production in Pakistan.

Antimicrobial resistance (AMR) is a global health challenge and antimicrobial use (AMU) in the livestock sector has been considered as one of the contributing factors towards the development of AMR in bacteria. This study summarizes the results of a point prevalence survey conducted to monitor farm-level AMU in commercial broiler chicken farms in Punjab and Khyber Pakhtunkhwa (KPK) provinces of Pakistan. A cross-sectional study was conducted to quantify AMU and to check seasonal variations of AMU in 12 commercial broiler chicken farms (six from each province) during the summer and winter seasons of the year 2020–2021. AMU was recorded using three AMU metrics: kg, mg per population correction unit (mg/PCU), and mg/kg of final flock weight. A total of 22 antimicrobial drugs (348.59 kg) were used for therapeutic or prophylactic purposes in surveyed broiler chicken farms. The total combined AMU for all the broiler chicken farms was 462.57 mg/PCU. The use of most of the antimicrobials increased during winter flocks compared to summer. The top three antimicrobial drugs used during the summer were neomycin (111.39 mg/PCU), doxycycline (91.91 mg/PCU), and tilmicosin (77.22 mg/PCU), whereas doxycycline (196.81 mg/PCU), neomycin (136.74 mg/PCU), and amoxicillin (115.04 mg/PCU) during the winter. Overall, 60% of the antibiotics used in broiler chicken were critically important antimicrobial classes (CIA) for human medicine as characterized by the World Health Organization. Our findings showed high AMU in broiler chicken production and a call for urgent actions to regulate CIA use in food animals in Pakistan. This baseline survey is critical for the design and implementation of a subsequent national level AMU surveys that can include additional farming types, animals’ species, and geographical locations over a longer period of time.

EFFECT OF DIFFERENT SEASONS ON GROWTH PERFORMANCE, IMMUNE RESPONSES AND ANTIOXIDANT STATUS OF BROILER CHICKENS

The current experiment was carried out in farm nearby Fayoum research station to study effect of different seasons on growth performance of broiler chicks and detect early indicators for supplementing broilers flocks with antioxidant and immune enhancer. Four flocks from Arbor Acres broiler chicks were reared during summer, autumn, winter, and spring seasons in open side system. Productive performance parameters, complete blood count, antibody titers against Newcastle (NDV), antibody titers against avian influenza (H5N1) and some antioxidant parameters were measured. The following results were obtained: Body weight and body weight gain recorded significantly the highest values during spring seasons but the highest (P≤0.05) feed intake value was recorded during winter seasons and the best feed conversion value was recorded during autumn (P≤0.05). Total leukocytes count, heterophilus (H), lymphocyte (L) and H/L ratio were not affected by different seasons. Antibody titers against NDV and H5N1 record the highest significant values during summer season while the worst significant antioxidant status recorded during summer season. In contrast during winter values of antibody titers against NDV and H5N1 were significantly the worst but antioxidant parameters recorded significantly the best values. The results of the current study suggested that during winter flocks may need double doses from NDV and H5N1vaccines. However, during summer and autumn seasons, increasing antioxidant supplementation in diets or even drinking water is recommended.

Urban House Sparrow (Passer domesticus) populations decline in North America

House Sparrow (Passer domesticus) populations declined across much of their global range in the late 20th century. Most research examining this decline is conducted in the species' native European range, but Europe encompasses a small portion of the species' current distribution. House Sparrow population trends in the United States and Canada, and the potential mechanisms driving these trends, remain relatively unexplored. We use 21 years of data from Project FeederWatch, a large-scale citizen science project, to investigate House Sparrow population trends in North America. We found winter flocks in urbanized areas were larger than flocks in rural areas, with widespread spatial heterogeneity in local population trends. Despite greater abundance in developed areas, House Sparrow populations declined in developed areas from 1995 to 2016 while remaining stable in rural areas. House Sparrow population declines coincide with an increase in populations and expansion of the winter distributions of Accipiter hawks, which are known predators of House Sparrows. However, we do not find a direct connection between the presence of Accipiter hawks at count sites and House Sparrow population declines in winter. These results expand our knowledge of widespread House Sparrow declines to North America and provide context for continuing research on House Sparrow declines in the introduced range.

Contrasting effects of the onset of spring on reproductive success of Arctic-nesting geese

AbstractBreeding output of geese, measured as the proportion of juveniles in autumn or winter flocks, is lower in years with a late onset of spring in some species, but higher in at least one other species. Here we argue that this is because the timing of spring affects different stages of the reproductive cycle differently in different species. Because the effects on 2 different stages are opposite, the combined effects can result in either a positive or a negative overall effect. These stages are the pre-laying, laying, and nesting phase on the one hand; and the hatchling, fledgling, and juvenile phase on the other hand. The first phase is predominantly positively affected by an early snowmelt, with higher breeding propensity, clutch size, and nest success. The second phase in contrast is negatively affected by early snowmelt because of a mismatch with a nutrient food peak, leading to slow gosling growth and reduced survival. We argue that recognition of this chain of events is crucial when one wants to predict goose productivity and eventually goose population dynamics. In a rapidly warming Arctic, the negative effects of a mismatch might become increasingly important.

Costs and benefits of social connectivity in juvenile Greylag geese

Living in groups has various advantages and disadvantages for group members. We investigated the fitness consequences of early social connectivity (normalized Freeman degrees based on nearest neighbour data), physiology (levels of excreted corticosterone metabolites assayed from droppings), and agonistic interactions in a group of free-ranging greylag geese (Anseranser). Forty-four greylag geese below 3 years of age were observed in three different seasonal phases: during the re-aggregation of the flock in autumn, at the end of the winter and during the forthcoming breeding season. We show that corticosterone metabolite levels and initiated and received aggression increased with increasing social connectivity. Individuals had higher connectivity scores in the winter flock than during the mating and breeding seasons. One-year old juveniles were more connected than 2- and 3-year old individuals. In addition, we examined the link between social connectivity during early development and reproductive success several years later. We found that birds with greater connectivity early in life attempted to breed at a younger age. Furthermore, successful breeders with higher early connectivity scores had higher numbers of fledged goslings. Our results show that social context in early life stages may have long-term effects on individual fitness.

Nest Box Use for Winter Roosting within a Flock of Tits

Roosting in various shelters allows saving energy, especially in winter, thus hole nesting birds, like tits, search for places suitable to spend cold nights. Because the environment probably does not provide enough shelters for all birds from a winter flock to roost, a competition for best sites, as nest boxes, probably occurs. Therefore, the aim of this study was to describe the pattern of using the nest boxes by birds for roosting during three consecutive winter seasons and to determine the structure of a group of roosting birds in relation to the winter flock. Tits were captured and marked; daily controls of nest boxes were performed to find out which of them the tits used for roosting and subsequently, birds entering these boxes were caught at night. Great tits Parus major were the most abundant species roosting in the studied boxes with proportion of blue tits Cyanistes caeruleus differed between years. Young individuals prevailed among the birds roosting in nest boxes. However the age and sex structure of great tits roosting in nest boxes was similar to that observed in winter flocks, which was in contrast to earlier studies that found that the males and older individuals, high in the social hierarchy of the flock, will take over these boxes. The size of winter flock differs strongly among winters, thus it is possible that the level of competition for these roosting sites also varies between the years.

Number of neighbors instead of group size significantly affects individual vigilance levels in large animal aggregations

The group size effect states that animals living in groups gain anti‐predator benefits through reducing vigilance levels as group size increases. A basic assumption of group size effect is that all individuals are equally important for a focal individual, who may adjust its vigilance levels according to social information acquired from them. However, some studies have indicated that neighbors pose greater influences on an individual's vigilance decisions than other group members, especially in large aggregations. Vigilance has also been found to be directed to both predators (anti‐predation vigilance) and conspecifics (social vigilance). Central individuals might rely more on social vigilance than peripheral individuals. To test these hypotheses, we examined the effects of flock size, number of neighbors and position within a flock on vigilance and competition of greater white‐fronted goose Anser albifrons that form large foraging flocks in winter, controlling the effects of other variables (group identity, winter period and site). We found that individual vigilance levels were significantly affected by number of neighbors and position within a flock, whereas flock size showed no effect. Individuals devoted a large component of vigilance to nearby flock mates. Central individuals directed a relatively larger proportion of vigilance to monitor neighbors than peripheral ones, indicating that central individuals more relied on social information acquired from neighbors, possibly caused by the more blocked visual field of central individuals. Moreover, some social vigilance may function as conducting or preventing agonistic interactions since competition intensity was positively correlated with number of neighbors. Our study therefore demonstrate that the number of neighbors is more important than group size in determining individual vigilance in large animal groups. Further studies are still needed to unravel which neighbors pose greater influence on individual vigilance, and the factors that influence individuals to acquire information from their neighbors to adjust vigilance behaviors.

Longevity of Willow Tits (Poecile montanus): the significance of flock membership, social rank and body size

The Willow Tit Poecile montanus is highly sedentary and breeding pairs remain in their exclusive areas throughout the year. During the winter, these areas are defended by small, non-kin flocks, formed as the roaming yearlings become sedentary and join adults during late summer and autumn. Once established, stable social hierarchies are maintained in these flocks during the winter. The winter flocks consist normally of the socially dominant adult mated pair and two mated juvenile pairs, one higher-ranked and one lower-ranked. Individually colour-ringed juvenile Willow Tits were followed over years in subalpine forest in Norway from ringing in the autumn till they disappeared. None of the lower ranked birds survived their first winter, whereas only 4 of 71 higher-ranked juvenile pairs disappeared during this time. Half of the 71 pairs survived their first winter, about 25 % survived two winters, 8.5% survived three winters, and 5.6% survived four winters. Survival was similar for males and females. Alpha pairs remained mated and defended their common territory across years. Maximum age as revealed by ringing showed one female became six years old and two males ringed as adults were at least nine years old when last observed. The main factor associated with survival was early flock establishment that led to a high rank position among the juvenile flock members. Body size seemed insignificant. Birds that survived their first winter either succeeded to establish as territory owners or they were forced into the role as floaters and probably perished.

Evolution of resident bird breeding phenology in a landscape with heterogeneous resource phenology and carryover effects

It is generally expected that, in environments with pronounced seasonal resource peaks, birds’ reproductive success will be maximised when nestlings’ peak food demand coincides with the timing of high food availability. However in certain birds that stay resident over winter, earlier breeding leads juveniles to join the winter flock earlier, which by the prior residence effect increases their success in breeding territory competition. This trade-off between reproduction and competition may explain why, in certain species, breeding phenology is earlier and asynchronous with the resource. This study extends a previous model of the evolution of breeding phenology in a single habitat type to a landscape with two habitat types: ‘early’ and ‘late’ resource phenology. The offspring’s natal habitat type has a carryover effect upon their competitive ability regardless of which habitat type they settle in to potentially breed. We find that, when the difference in resource phenology between habitats is small (weak carryover effect), breeding phenology in the late habitat evolves to occur earlier and more asynchronously than in the early habitat, to compensate for the competitive disadvantage to juveniles raised there. However if the difference is large (strong carryover effect), then the reproductive cost of earlier breeding outweighs the benefit of the compensation, so instead breeding phenology in the late habitat evolves to become more synchronous with the resource. Recruitment is generally asymmetric, from early to late habitat type. However if the early habitat is less frequent in the landscape or produces fewer offspring, then the asymmetry is reduced, and if there is some natal habitat-type fidelity, then recruitment can have an insular pattern, i.e. most recruits to each habitat type come from that same habitat type. We detail the different scenarios in which the different recruitment patterns are predicted, and we propose that they have implications for local adaptation.

Ranging behavior relates to welfare indicators pre- and post-range access in commercial free-range broilers.

Little is known about the effect of accessing an outdoor range on chicken welfare. We tracked individual ranging behavior of 538 mixed-sex Ross 308 chickens on a commercial farm across 4 flocks in winter and summer. Before range access, at 17 to 19 d of age, and post-range access, at 30 to 33 and 42 to 46 d of age in winter and summer flocks respectively, welfare indicators were measured on chickens (pre-range: winter N = 292; summer N = 280; post-range: winter N = 131; summer N = 140), including weight, gait score, dermatitis and plumage condition. Post-ranging autopsies were performed (winter: N = 170; summer: N = 60) to assess breast burn, leg health, and ascites. Fewer chickens accessed the range in winter flocks (32.5%) than summer flocks (82.1%). Few relationships between welfare and ranging were identified in winter, likely due to minimal ranging and the earlier age of post-ranging data collection compared to summer flocks. In summer flocks prior to range access, chickens that accessed the range weighed 4.9% less (P = 0.03) than chickens that did not access the range. Pre-ranging weight, gait score, and overall plumage cover predicted the amount of range use by ranging chickens in summer flocks (P < 0.01), but it explained less than 5% of the variation, suggesting other factors are associated with ranging behavior. In summer flocks post-range access, ranging chickens weighed 12.8% less than non-ranging chickens (P < 0.001). More range visits were associated with lower weight (P < 0.01), improved gait scores (P = 0.02), greater breast plumage cover (P = 0.02), lower ascites index (P = 0.01), and less pericardial fluid (P = 0.04). More time spent on the range was associated with lower weight (P < 0.01) and better gait scores (P < 0.01). These results suggest that accessing an outdoor range in summer is partly related to changes in broiler chicken welfare. Further investigations are required to determine causation.

Duet displays within a flock function as a joint resource defence signal in the red-crowned crane

Avian duets performed in an exclusive territory have been studied intensively. By contrast, only a few studies have been conducted on duets with multi-modal displays performed within a fission–fusion flock in which individuals can participate in face-to-face social interactions. Here, we examined the duet displays (DDs) of the red-crowned crane (Grus japonensis), an endangered species in Japan, in a wintering flock in which individuals gathered for artificially provisioned foods. We tested two hypotheses: that DDs function as a signal of joint resource defence and for pair bond maintenance. Our behavioural analyses showed that the total frequency of DDs within a flock was positively associated with the number of joining cranes. This result indicated that the change in within-flock competition positively affected DD performance because an increase in flock size can reduce the per capita gain of resources. At the individual level, pairs accompanying their young (families) performed DDs more frequently than pairs that did not have their young. To care for their young, access to food resources is thought to be more important for pairs accompanying their young than pairs that did not have young. This result suggests that the DDs reflected the motivation to compete for resources. The performance of DDs increased the probability of staying in a favourable area. These results support the hypothesis that DDs function as a signal of joint resource defence in the flock. This study provides rare data on the function of coordinated vocal displays within a flock of birds. Crane pairs perform duet displays (DDs) in a wintering flock. We mainly tested the hypothesis that DDs function as a joint resource defence signal. The change of overall competition positively affected the frequency of DDs, and the performance of DDs reflected the motivation to access food. The frequency of DDs was positively associated with the success of the food defence. This study provides rare data on the function of coordinated vocal displays within a group of birds.