Effects of supplementary feeding on interspecific dominance hierarchies in garden birds

In Situ Provisioning Wildlife with Food, Water, or Shelter after Bushfires: Using a One Welfare Framework to Guide Responses

Australia's 2019-2020 bushfires had a devastating impact on animals, humans, and ecosystems. They also demonstrated the lack of evidence or guidance for wildlife provisioning in response to severe fire events when volunteers and wildlife organisations rose to respond. In addition, the unprecedented scale and intensity of the fires and an absence of institutional support for wildlife provisioning meant that well-intentioned interventions were largely uncoordinated and lacked clear short-term, mid-term, and long-term objectives. Fundamentally, a lack of consensus was revealed on whether any such interventions are advisable. Given the strong evidence indicating that future bushfire seasons will become longer and more intense in Australia and elsewhere, the welfare and survival of millions of wild animals are at risk every year. Understanding the impacts of supplementary resource interventions and contributing to the development of best practice information is crucial to inform the response to the next major fire event. Here, we contextualize the arguments for and against provisioning within a 'One Welfare' framework that recognizes that animal welfare, biodiversity, and the environment are intertwined with human welfare and community resilience. We propose that the One Welfare approach can facilitate appropriate consideration of the extant scientific and lay literature; local legislation; views of stakeholders; emerging data; and modelling from historic fire events. As a further step, we see merit in engaging with wildlife provisioners and the broader conservation community to build an evidence base for future wildlife provisioning activities. From an informed position, we can encourage beneficial interventions and reduce the risk of negative outcomes. Finally, we propose controlled experiments (e.g., using hazard reduction burns), ongoing data collection using emergent technology, and longitudinal analysis to address shifting research priorities as the climate changes. We conclude that the ordered collection of the necessary evidence relevant to each of the three stakeholder groups in the One Welfare framework has the greatest potential to support an informed policy platform on wildlife provisioning across Australia that is feasible, legal, and sustainable.

Habitat quality, urbanisation & pesticides influence bird abundance and richness in gardens

Gardens are regularly portrayed as green oases, refuges for wildlife that has been displaced from the countryside by intensive farming practices which have reduced habitat availability. Pesticides are also commonly used in urban areas, but few studies have investigated their impacts. In this study, we explored how bird richness and abundance in gardens across the UK are influenced by habitat quality, urbanisation level and pesticide practices. To achieve this, we collaborated with the British Trust for Ornithology (BTO) which runs Garden Birdwatch, a citizen-science-based garden bird recording scheme. Participants in the study were asked to complete a questionnaire about their pesticide practice. From the 615 gardens that provided useful data, we found that 32.2 % applied pesticides in their gardens and that glyphosate comprised 53.3 % of these applications. We found that bird abundance and species richness was lower in suburban compared to rural gardens but positively influenced by measures of garden quality and by surrounding habitat quality. We show that there was an interaction between the habitat quality of the surrounding area and pesticide use: negative effects of pesticides on species richness were more pronounced in gardens in areas of high habitat quality compared to those surrounded by poor habitat. We found that pesticide use, and particularly glyphosate and metaldehyde, negatively predicted the abundance of house sparrows, a fast-declining bird species. The average house sparrow abundance was 12.1 % lower in gardens applying any pesticide, 24.9 % lower with glyphosate, and 38.6 % lower with metaldehyde. Overall, our study shows that garden bird abundance and richness is strongly influenced by both extrinsic and intrinsic factors, and suggests that garden management, particularly regarding pesticide use, has a significant effect on bird life.

Invited review: Social dominance in dairy cattle: A critical review with guidelines for future research

Cattle are gregarious animals able to form social relationships. Dominance is one of the most widely studied social behaviors of dairy cattle, especially cows confined indoors. However, much of the past dairy cattle research has used an unstandardized approach, differing in definitions and conceptual understanding of dominance, as well as their methods of data collection and dominance calculation. The first of the 3 aims of this review is to evaluate how dominance relates to the social behavior of housed dairy cows. Cows engage in agonistic interactions to establish and reinforce dominance relationships. An individual's dominance is influenced by intrinsic characteristics, such as personality, and extrinsic factors, including group composition. When competing for resources, agonistic interactions can also be influenced by individual motivational differences, such as hunger, which may diminish the role of dominance in regulating competition. Our second aim is to critically review methods used to assess dominance in cows. This includes discussions on the effect of time and location of data collection on measured values as well as the viability and limitations of some dominance calculation methods. We propose that different methodologies lend themselves to different types of research questions. For example, the use of data stream-based methods that consider the sequence of interactions are useful for estimating how dominance fluctuates with changing conditions and can be used in a dynamically changing group. In contrast, matrix-based methods that aggregate social interactions may be best for identifying the social position of individuals and understanding how social characteristics influence the attributes of a stable hierarchy. Our third aim is to discuss the future of dominance research. We use a flowchart to illustrate guidelines for a more standardized approach to measuring dominance in cattle. We also identify areas in need of further conceptual clarification, suggest practical applications of dominance when managing dairy cattle, and discuss some limitations of dominance research.

Avian behaviour changes in response to human activity during the COVID-19 lockdown in the United Kingdom

Human activities may impact animal habitat and resource use, potentially influencing contemporary evolution in animals. In the United Kingdom, COVID-19 lockdown restrictions resulted in sudden, drastic alterations to human activity. We hypothesized that short-term daily and long-term seasonal changes in human mobility might result in changes in bird habitat use, depending on the mobility type (home, parks and grocery) and extent of change. Using Google human mobility data and 872 850 bird observations, we determined that during lockdown, human mobility changes resulted in altered habitat use in 80% (20/25) of our focal bird species. When humans spent more time at home, over half of affected species had lower counts, perhaps resulting from the disturbance of birds in garden habitats. Bird counts of some species (e.g. rooks and gulls) increased over the short term as humans spent more time at parks, possibly due to human-sourced food resources (e.g. picnic refuse), while counts of other species (e.g. tits and sparrows) decreased. All affected species increased counts when humans spent less time at grocery services. Avian species rapidly adjusted to the novel environmental conditions and demonstrated behavioural plasticity, but with diverse responses, reflecting the different interactions and pressures caused by human activity.

Using Machine Learning to Identify Associations between the Environment, Occurrence, and Outcomes of Songbird Displacements at Supplemental Feeders

The context and outcome of aggressive interactions between individuals has important fitness consequences. Displacements—an aggressive interaction wherein one individual is chased from a location by another—also have implications for social hierarchy formation and geographic distribution in songbirds. Morphological correlates, like body size, and social correlates, such as dominance rank, have been shown to mediate displacements in songbirds. However, the role of the physical environment, namely temperature, humidity, and time of day, which may influence an individual’s energy needs and thus displacement motivation, has remained understudied. We monitored songbird feeding and displacement behaviors using computerized automated feeders. We observed asymmetric differences across species in displacement involvement. To identify the conditions of the social and physical environment that are associated with the occurrence and outcome of songbird displacements at supplemental feeders, we use the machine learning approach, random forest, which is a novel method to the fields of ornithology and animal behavior. From our random forest models, we found that the attributes of the physical environment (i.e., humidity and the time of day) are associated with the occurrence of a displacement event, whereas the attributes of the social environment (i.e., species of the displacer and displaced individuals) are associated with which species are involved. These results provide context to develop further observational and experimental hypotheses to tease apart the inner workings of these multifactorial behaviors on a larger scale and provide a proof of concept for our analytical methods in the study of avian behavior.

Hinfluences severe disease-mediated population declines in two of the most common garden bird species in Great Britain

The influence of supplementary feeding of wildlife on disease transmission and its consequent impacts on population dynamics are underappreciated. In Great Britain, supplementary feeding is hypothesised to have enabled the spread of the protozoan parasite, Trichomonas gallinae, from columbids to finches, leading to epidemic finch trichomonosis and a rapid population decline of greenfinch (Chloris chloris). More recently, chaffinch (Fringilla coelebs), has also declined markedly from the second to fifth commonest bird in Britain. Using citizen science data, we show that both declines were driven primarily by reduced adult survival, with the greatest reductions occurring in peri-domestic habitats, where supplementary food provision is common. Post-mortem examinations showed a proportional increase in chaffinch trichomonosis cases, near-contemporaneous with its population decline. Like greenfinches, chaffinches often use supplementary food, but are less associated with human habitation. Our results support the hypothesis that supplementary feeding can increase parasite transmission frequency within and between common species. However, the dynamics behind resultant population change can vary markedly, highlighting the need for integrating disease surveillance with demographic monitoring. Other species susceptible to T. gallinae infection may also be at risk. Supplementary feeding guidelines for wildlife should include disease mitigation strategies to ensure that benefits to target species outweigh risks.

Genetic relatedness and morphology as drivers of interspecific dominance hierarchy in hummingbirds

A dominance hierarchy is the set of ranks occupied by species within an assemblage. Species with a high position within the dominance hierarchy tend to dominate subordinate species in contests for access to resources. In hummingbirds, greater weight and wing disc loading have been associated with highest ranks within the dominance hierarchy. Nevertheless, the limit to which the difference between the weight of contending species represents a competitive advantage has not yet been determined. Here, we determined the dominance hierarchy of a hummingbird assemblage exploiting the most abundant floral resource (Palicourea padifolia, Rubiaceae) in a cloud forest of central Veracruz, Mexico. Specifically, we tested whether species weight and wing disc loading influence the dominance hierarchy. Additionally, we tested whether the flowers visited per foraging bout increases with species weight and dominance. We further tested whether weight, wing disc loading, and the genetic relatedness between contenders influenced the dominance relationships in species-pair interactions. Our results indicate that the hierarchy is positively influenced by weight. Hummingbirds visited similar number of flowers regardless their weight or their dominance. Nevertheless, the probability that the heaviest contender won contests was positively associated with the differences of weight and genetic relatedness between contenders. Contrarily, the probability that the contender with greatest wing disc loading won contests was positively associated with differences of weight and negatively associated with the relatedness between contenders. However, these models only explained between 22% and 34% of the variation, respectively. Our results demonstrate that the weight was the major contributor to high dominance values. However, future studies should include (1) the temporal variability of the weight and (2) experimental predictor variables such the burst power of the hummingbirds to evaluate its effects on the dynamics of dominance hierarchies in hummingbird assemblages. All the hummingbird species present in the studied assemblage have developed wide behavioral mechanisms that compensate their morphological differences, which allow them to coexist, even when they compete for the access to the same resource.

Effects of density, species interactions, and environmental stochasticity on the dynamics of British bird communities

Our knowledge of the factors affecting species abundances is mainly based on time‐series analyses of a few well‐studied species at single or few localities, but we know little about whether results from such analyses can be extrapolated to the community level. We apply a joint species distribution model to long‐term time‐series data on British bird communities to examine the relative contribution of intra‐ and interspecific density dependence at different spatial scales, as well as the influence of environmental stochasticity, to spatiotemporal interspecific variation in abundance. Intraspecific density dependence has the major structuring effect on these bird communities. In addition, environmental fluctuations affect spatiotemporal differences in abundance. In contrast, species interactions had a minor impact on variation in abundance. Thus, important drivers of single‐species dynamics are also strongly affecting dynamics of communities in time and space.

The association of social rank with paternity efficiency in competitive mating flocks of Zi goose ganders (Anser cygnoides L.)

The purpose of this study was to investigate the influence of social rank (SR) on paternity efficiency (PE) in competitive mating flocks of geese. Thirty ganders and 150 geese (Zi geese, Anser cygnoides L.) aged approximately one, were divided into 3 groups. Flock 1 included 10 ganders and 50 female geese, flock 2 included 11 ganders and 55 female geese, and flock 3 included 9 ganders and 45 female geese. The frequency of the agonistic behavioral interactions (ABI) of the ganders and mating activity (MA) were video recorded in each flock. The SR of each gander was determined by the frequency of ABI with a score of 1 to 3 (1 being the dominant and 3 the most subordinate). To clarify the difference between being dominant and submissive, we collapsed rank 2 and rank 3 into a “subordinate” category. In total, 280 eggs were collected, and 219 goslings were hatched. Parent–offspring relationships among 399 individuals from the 2 generations were identified via 20 microsatellite markers, and the PE of each gander was calculated. There was no significant difference in individual body weight and semen quality factor among the different SR groups (dominant and subordinate), and the SR of the ganders was significantly correlated to PE for the 3 flocks. Goslings of high-ranking ganders contributed 48.68% in flock 1, 37.50% in flock 2, and 47.62% in flock 3. Approximately 45% of all goslings were sired by the 7 dominant ganders of the 30 total ganders across the 3 flocks. As SR has been shown to be heritable in geese, the selection of high-ranking ganders might be an effective way to improve reproductive efficiency in commercial geese flocks.

An avian dominance hierarchy at a supplemental water source in the Patagonian steppe

Birds often compete and engage in interspecific agonistic interactions for access to resources such as food and breeding territories. Based on the observed outcomes from such interactions (i.e., patterns of displacements) dominance hierarchies can be established. Knowing which species can outcompete others for essential resources allows researchers to make predictions about the broader ecological impacts of interspecific interactions. We constructed an interspecific dominance hierarchy of twelve avian species which visited an artificial water source in an arid region of coastal Patagonia, Argentina. Displacements were categorized into four types, based on the behaviors involved in the interaction, and we tested if they could predict the difference in dominance between the interacting species (the difference between calculated dominance coefficients for the two focal species). Indirect displacements, involving only the arrival of the dominant species to the water source without direct aggression toward the subordinate bird, occurred more frequently between species with a large difference in dominance. The most dominant bird observed was the kelp gull (Larus dominicanus), which, due to an increasing population and expanding range, in part due to food supplementation from fisheries waste, is likely to outcompete terrestrial and marine avian species for other scarce resources.

Any despot at my table? Competition among native and introduced bird species at garden birdfeeders in winter

Garden bird feeding constitutes a massive provision of food that can support bird communities, but there is a growing concern it might favour the establishment of exotic species that could be detrimental to others. How bird species compete with novel species for this anthropogenic food resources needs to be assessed. Here, we investigated competition in wintering bird communities at garden birdfeeders. We evaluated whether - and how much - bird access to resources is hampered by the presence of putative superior competing species, among which the Rose-ringed parakeet, the most abundant introduced species across Europe. Using the nation-wide citizen science scheme BirdLab, in which volunteers record in real-time bird attendance on a pair of birdfeeders during 5-minute sessions, we tested whether i) cumulative bird presence time and richness at birdfeeders, and ii) species probability of presence at birdfeeders, were influenced by three large species (the Eurasian magpie, the Eurasian collared-dove, and the Rose-ringed parakeet). Additionally, we assessed whether the Rose-ringed parakeet occupied resources significantly more than others. Presence of the Rose-ringed parakeet or the Eurasian collared-dove similarly reduced community cumulative presence time at birdfeeders, but only the dove reduced community richness. Each of the three large species influenced the presence of at least one of the six smaller species that could be separately modelled, but effects varied in strength and direction. The Rose-ringed parakeet and the Eurasian collared-dove were among the three species monopolising birdfeeders the longest, substantially more than the Eurasian magpie. Our findings confirm the competitive abilities of the large species studied, but do not suggest that garden bird feeding may alarmingly favour introduced species with detrimental effects on native species. Given the variability of large species' effects on small passerines, direct and indirect interactions among all species must be examined to fully understand the ecological net effects at stake.

Arboreal twig-nesting ants form dominance hierarchies over nesting resources

Interspecific dominance hierarchies have been widely reported across animal systems. High-ranking species are expected to monopolize more resources than low-ranking species via resource monopolization. In some ant species, dominance hierarchies have been used to explain species coexistence and community structure. However, it remains unclear whether or in what contexts dominance hierarchies occur in tropical ant communities. This study seeks to examine whether arboreal twig-nesting ants competing for nesting resources in a Mexican coffee agricultural ecosystem are arranged in a linear dominance hierarchy. We described the dominance relationships among 10 species of ants and measured the uncertainty and steepness of the inferred dominance hierarchy. We also assessed the orderliness of the hierarchy by considering species interactions at the network level. Based on the randomized Elo-rating method, we found that the twig-nesting ant species Myrmelachista mexicana ranked highest in the ranking, while Pseudomyrmex ejectus was ranked as the lowest in the hierarchy. Our results show that the hierarchy was intermediate in its steepness, suggesting that the probability of higher ranked species winning contests against lower ranked species was fairly high. Motif analysis and significant excess of triads further revealed that the species networks were largely transitive. This study highlights that some tropical arboreal ant communities organize into dominance hierarchies.

The composition of British bird communities is associated with long-term garden bird feeding

There is a multi-billion dollar global industry dedicated to feeding wild birds in residential gardens. This extraordinary boost to food resources is almost certainly reshaping entire bird communities, yet the large-scale, long-term impacts on community ecology remain unknown. Here we reveal a 40-year transformation of the bird communities using garden bird feeders in Britain, and provide evidence to suggest how this may have contributed to national-scale population changes. We find that increases in bird diversity at feeders are associated with increasing community evenness, as species previously rarely observed in gardens have increasingly exploited the growing variety of foods on offer over time. Urban areas of Britain are consequently nurturing growing populations of feeder-using bird species, while the populations of species that do not use feeders remain unchanged. Our findings illustrate the on-going, gross impact people can have on bird community structure across large spatial scales.

Garden bird feeding is a prolific human activity that provides a reliable foraging opportunity to wild birds. Here the authors use a 40-year data set to show that large-scale restructuring of garden bird communities and growth in urban bird populations can be linked to changing feeding practices.