An evaluation of techniques to control problem bird species on landfill sites

Zoonotic potential of urban wildlife faeces, assessed through metabarcoding

Monitoring zoonoses in urban environments is of great relevance, where the incidence of certain pathogens may be higher and where population density makes the spread of any contagious disease more likely. In this study we applied a metabarcoding approach to study potentially zoonotic pathogens in faecal samples of 9 urban vertebrate species. We applied this methodology with two objectives. Firstly, to obtain information on potential pathogens present in the urban fauna of a large European city (Madrid, Spain) and to determine which are their main reservoirs. In addition, we tested for differences in the prevalence of these potential pathogens between urban and rural European rabbits, used as ubiquitous species. Additionally, based on the results obtained, we evaluated the effectiveness of metabarcoding as a tool for monitoring potential pathogen. Our results revealed the presence of potentially zoonotic bacterial genera in all studied host species, 10 of these genera with zoonotic species of mandatory monitoring in the European Union. Based on these results, urban birds (especially house sparrows and pigeons) and bats are the species posing the greatest potential risk, with Campylobacter and Listeria genera in birds and of Chlamydia and Vibrio cholerae in bats as most relevant pathogens. This information highlights the risk associated with fresh faeces from urban wildlife. In addition, we detected Campylobacter in >50 % of the urban rabbit samples, while we only detected it in 11 % of the rural rabbit samples. We found that urban rabbits have a higher prevalence of some pathogens relative to rural rabbits, which could indicate increased risk of pathogen transmission to humans. Finally, our results showed that metabarcoding can be an useful tool to quickly obtain a first screening of potentially zoonotic organisms, necessary information to target the monitoring efforts on the most relevant pathogens and host species.

Environmental Conditions and Vehicle Disturbance Influence Stress Behaviors in a Working Harris's Hawk (Parabuteo unicinctus)

Harris's hawk (Parabuteo unicinctus) is used for pest control, as their presence can deter wild birds such as gulls. Working Harris's hawk on UK waste sites is permitted in accordance with regulations and legislation. This study investigated the general environment of a waste site compound yard where a single Harris's hawk was flown for pest control. The hawk's behaviors were evaluated in an ethogram, alongside environmental measures, and disturbance levels. Data was analyzed using Generalised Linear Latent Variable Models (GLLVM) to elucidate the effects of disturbance and environment on hawk behaviors. Results suggested cloudy conditions encouraged grooming responses that were normal and relaxed in their nature. Rain, sun and wind conditions increased recognized stress behaviors. Frequency of disturbance by construction vehicles inside the compound increased stress behaviors, such that keepers are recommended to revise welfare conditions. Increased stress behaviors by birds worked in dynamic environments like waste recycling yards could potentially elicit damaging illness such as feather breaking behavior. Reducing stress factors for Harris's hawk in industrial working yards combined with amending husbandry practices will improve welfare for the species.

Bird flight behavior, collision risk and mitigation options at high-speed railway viaducts

High-speed railway (HSR) networks are rapidly expanding and are predicted to continue to grow over coming decades. However, there is scant knowledge of their environmental impacts. Their possible effects on bird mortality, particularly at viaducts, gives especial cause for concern. This work presents the results of a nine-month monitoring of bird activity in the vicinity of three HSR viaducts in Central Spain. The study focused on the effects of the infrastructure regarding bird frequentation of the site and on bird flight activity in the danger zone for collision with passing trains. The findings show (i) that bird communities may differ markedly between sites and (ii) that bird activity increases near the railway together with changes in relative species abundances. Furthermore, (iii) birds show a significant tendency to avoid flying across the danger zone, but (iv) all kinds of birds are at a real risk of collisions with trains at viaducts. The greatest danger is at viaduct extremes rather than in their central section, particularly during gusts of wind and for small or medium-sized birds. It also appears that relatively low viaducts might pose greater risk. In practical terms, these results (i) emphasise the need for thorough prior prospection of bird species present, and their flight patterns, where new viaducts are to be built, (ii) show that there is a real risk of bird collisions with trains at viaducts, which should be mitigated, with particular attention due to viaduct extremes and areas where their height is not much above the surrounding vegetation and (iii) strongly indicate the need to minimise viaduct features that may attract birds to them, for example as potential nest sites.

L-band radar quantifies major disturbance of birds by fireworks in an urban area

Fireworks and other pyrotechnics are acknowledged as sources of disturbance to wildlife, with evidence that many species react adversely to their sight and sound at discharge. However, how firework releases impact wildlife within a city landscape is poorly understood. Here, we explore the effect of fireworks on urban birds using an L-band staring radar (90-degree sector out to a 5 km range) to capture bird activity derived from flight tracks (i.e. 3D visualisation of individual flying birds built from radar detections) within the city of Birmingham, UK. Comparing the tracks between baseline periods with no fireworks and periods where fireworks are commonly discharged using a null model indicated that birds flew at higher elevations during firework periods (standardised effect sizes of 17.11, 26.54 and 5.83, for Diwali, Bonfire Night, and New Year's Eve, respectively). Birds also flew in more significant numbers (standardised effect sizes of 23.41, 7.98 and 7.19 for Diwali, Bonfire Night, and New Year's Eve, respectively). Therefore, bird activity was elevated during firework events at a time of night when many would otherwise be roosting. Such disturbance may have implications for avian biology since large public firework events occur at colder times of the year in the UK when birds have elevated thermoregulatory costs.

Deterrence of birds with an artificial predator, the RobotFalcon

Collisions between birds and airplanes can damage aircrafts, resulting in delays and cancellation of flights, costing the international civil aviation industry more than 1.4 billion US dollars annually. Driving away birds is therefore crucial, but the effectiveness of current deterrence methods is limited. Live avian predators can be an effective deterrent, because potential prey will not habituate to them, but live predators cannot be controlled entirely. Thus, there is an urgent need for new deterrence methods. We developed the RobotFalcon, a device modelled after the peregrine falcon, and tested its effectiveness to deter flocks of corvids, gulls, starlings and lapwings. We compared its effectiveness with that of a drone, and of conventional methods routinely applied at a military airbase. The RobotFalcon scared away bird flocks from fields immediately, and these fields subsequently remained free of bird flocks for hours. The RobotFalcon outperformed the drone and the best conventional method at the airbase (distress calls). Importantly, there was no evidence that bird flocks habituated to the RobotFalcon over the course of the fieldwork. We conclude that the RobotFalcon is a practical and ethical solution to drive away bird flocks with all advantages of live predators but without their limitations.

Is the Hitchcock Story Really True? Public Opinion on Hooded Crows in Cities as Input to Management

Simple Summary

Human-wildlife conflicts are a novel topic in urban environments. The recent increase in hooded crows in cities across Europe has increased the frequency of such conflicts, and in some places, the control of crow populations has become a necessity and a hotly debated issue. We surveyed the attitude of people towards hooded crows using an online questionnaire developed to assess their knowledge of crows and which control method is acceptable to most people in Hungary. Many respondents had experience with hooded crows and agreed that their high numbers can cause problems. Most people expressed their willingness to learn about the crows and their management yet did not wish to get directly involved in management activities, which they believed should be the responsibility of professionals. In addition, most people supported the use of non-invasive or less harmful control methods and opposed more intrusive or destructive ones. These results clearly express the difficulty in identifying the most suitable and tolerable way to manage urban crow populations and thus address emerging human-wildlife conflicts in urban environments.

Abstract

In recent years, the Hooded crow (Corvus cornix) has become one of the most successful wild bird species in urban environments across Europe. Hooded crows can cause several problems in cities, including trash scattering, noise disturbance, and aggressive behavior toward humans or pets, and they can be potential vectors of pathogens. To find effective solutions, the public has to be involved in the decision-making process in urban planning management, managed by the city administration. In this study, we surveyed the attitude of people in Hungary towards crows and crow management by collecting information using an online questionnaire containing 65 questions published in 14 Facebook groups. We found that many people were familiar with corvid species and had personal experience with them. In most cases, these experiences were not negative, so the crows were not or only rarely perceived to cause problems to people, such as aggressive behavior, damage to cars or stealing something. Most respondents recognized that the presence of large numbers of hooded crows is a problem to be solved and acknowledged that they do not know how to resolve it. The majority of people expressed their interest in raising public awareness of crows but not in their management actions, which they believe should be implemented by experts. Most respondents preferred passive, harmless methods. More direct methods such as egg/chick removal from the nest, control by trapping, poisoned baits or firearms, or oral contraceptives were the least acceptable. These results express the difficulty in identifying a control method for managing hooded crow populations that is both acceptable to most people and effective at the same time. This study demonstrates the importance of involving public opinion in wildlife management and providing more information to citizens to reduce human-crow conflicts.

Viral Metagenomics Reveals Widely Diverse Viral Community of Freshwater Amazonian Lake

Despite the importance of understanding the ecology of freshwater viruses, there are not many studies on the subject compared to marine viruses. The microbiological interactions in these environments are still poorly known, especially between bacteriophages and their host bacteria and between cyanophages and cyanobacteria. Lake Bologna, Belém, capital of the Brazilian State of Pará, is a water source that supplies the city and its metropolitan region. However, it remains unexplored regarding the contents of its virome and viral diversity composition. Therefore, this work aims to explore the taxonomic diversity of DNA viruses in this lake, especially bacteriophages and cyanophages, since they can act as transducers of resistance genes and reporters of water quality for human consumption. We used metagenomic sequencing data generated by previous studies. We analyzed it at the taxonomic level using the tools Kraken2, Bracken, and Pavian; later, the data was assembled using Genome Detective, which performs the assembly of viruses. The results observed here suggest the existence of a widely diverse viral community and established microbial phage-regulated dynamics in Lake Bolonha. This work is the first ever to describe the virome of Lake Bolonha using a metagenomic approach based on high-throughput sequencing, as it contributes to the understanding of water-related public health concerns regarding the spreading of antibiotic resistance genes and population control of native bacteria and cyanobacteria.

GPS tracking reveals landfill closures induce higher foraging effort and habitat switching in gulls

BACKGROUND

Landfills are a major subsidy for some animals, with implications for their life history and demography. Gulls feed extensively on food from landfills and closures are expected to have ecological consequences, but how this influences movement ecology is virtually unknown.

METHODS

We used GPS-tracking to quantify foraging behaviour and habitat choice of lesser black-backed gulls (Larus fuscus) breeding at two colonies before and after closure of two nearby landfills.

RESULTS

Following closure, gulls from both colonies travelled further and for longer to forage. Gulls also changed habitat selection, although this differed by colony - birds from one colony shifted to agricultural habitats, while at the other, increased their use of urban areas. These behavioural responses had no effect on adult body condition but hint at potential direct effects of higher foraging costs and indirect impacts by shifting to new habitats.

CONCLUSIONS

Our results demonstrate how landfill availability influences gull foraging movements and habitat selection. We also emphasize the value of biologging to detect rapid behavioural responses in contrast to more conventional demographic approaches, which is especially important for animals that spend the majority of their lives away from direct observation.

Urban waste no replacement for natural foods—Marabou storks in Botswana

We compared diets of marabou storks Leptoptilos crumenifer foraging from urban landfills and natural areas in northern Botswana using stable isotope analyses and inductively coupled plasma mass spectrometry on moulted feathers. There were significant differences in the diet of marabous foraging from natural areas compared to urban waste sites, reflected by lower δ13C and less enriched δ15N concentrations in those feeding at landfills, suggesting a shift in trophic niche. Feathers from birds foraging at landfills also had significantly higher concentrations of chromium, lead, nickel, and zinc and lower levels of cadmium and potassium than feathers sampled from natural areas. We also analysed marabou regurgitant (42 kg, naturally expelled indigestible food resources) from the Kasane landfill site. More than half was plastic, with single regurgitants weighing up to 125 g. Urban waste stored in open air landfills is altering some marabou diets, affecting their natural trophic niche, resulting in the consumption (and regurgitation) of large amounts of plastic, and exposing marabou to potentially chronic levels of trace metals. Despite the marabou’s apparent resilience to this behavioural shift, it could have long-term effects on the population of the marabou stork, particularly considering Botswana has some of the few regular marabou breeding colonies in southern Africa.

Eutrophication forcings on a peri-urban lake ecosystem: Context for integrated watershed to airshed management

Peri-urban lakes increasingly experience intensified anthropogenic impacts as watershed uses and developments increase. Cultus Lake is an oligo-mesotrophic, peri-urban lake near Vancouver, British Columbia, Canada that experiences significant seasonal tourism, anthropogenic nutrient loadings, and associated cultural eutrophication. Left unabated, these cumulative stresses threaten the critical habitat and persistence of two endemic species at risk (Coastrange Sculpin, Cultus population; Cultus Lake sockeye salmon) and diverse lake-derived ecosystem services. We constructed water and nutrient budgets for the Cultus Lake watershed to identify and quantify major sources and loadings of nitrogen (N) and phosphorus (P). A steady-state water quality model, calibrated against current loadings and limnological data, was used to reconstruct the historic lake trophic status and explore limnological changes in response to realistic development and mitigation scenarios. Significant local P loadings to Cultus Lake arise from septic leaching (19%) and migratory gull guano deposition (22%). Watershed runoff contributes the majority of total P (53%) and N (73%) loads to Cultus Lake, with substantial local N contributions arising from the agricultural Columbia Valley (41% of total N load). However, we estimate that up to 66% of N and 70% of P in watershed runoff is ultimately sourced via deposition from the nutrient-contaminated regional airshed, with direct atmospheric deposition on the lake surface contributing an additional 17% of N and 5% of P. Thus, atmospheric deposition is the largest single source of nutrient loading to Cultus Lake, cumulatively responsible for 63% and 42% of total N and P loadings, respectively. Modeled future loading scenarios suggest Cultus Lake could become mesotrophic within the next 25 years, highlighting a heightened need for near-term abatement of P loads. Although mitigating P loads from local watershed sources will slow the rate of eutrophication, management efforts targeting reductions in atmospheric-P within the regional airshed are necessary to halt or reverse lake eutrophication, and conserve both critical habitat for imperiled species at risk and lake-derived ecosystem services.

Seabirds and marine plastic debris in the northeastern Atlantic: A synthesis and recommendations for monitoring and research

Marine plastic pollution is an increasing, and global, environmental issue. Numerous marine species are affected by plastic debris through entanglement, nest incorporation, and ingestion, which can lead to lethal and sub-lethal impacts. However, in the northeastern Atlantic Ocean, an area of international importance for seabirds, there has been little effort to date to assess information from studies of wildlife and plastic to better understand the spatiotemporal variation of how marine plastic affects different seabird species. To improve our understanding of seabirds and marine plastic in this region, we completed a synthesis of the published and grey literature to obtain information on all known documented cases of plastic ingestion and nest incorporation by this group. We found that of 69 seabird species that commonly occur in the northeastern Atlantic, 25 had evidence of ingesting plastic. However, data on plastic ingestion was available for only 49% of all species, with 74% of investigated species recorded ingesting plastic. We found only three published studies on nest incorporation, for the Northern Gannet (Morus bassanus) and Black-legged Kittiwake (Rissa tridactyla). For many species, sample sizes were small or not reported, and only 39% of studies were from the 21st century, whilst information from multiple countries and years was only available for 11 species. This indicates that we actually know very little about the current prevalence of plastic ingestion and nest incorporation for many species, several of them globally threatened. Furthermore, in the majority of studies, the metrics reported were inadequate to carry out robust comparisons among locations and species or perform meta-analyses. We recommend multi-jurisdictional collaboration to obtain a more comprehensive and current understanding of how marine plastic is affecting seabirds in the northeastern Atlantic Ocean.

Watershed Assessment with Beach Microbial Source Tracking and Outcomes of Resulting Gull Management

Total maximum daily load (TMDL) implementation at a southern California beach involved ultraviolet treatment of watershed drainage that provided >97% reduction in fecal indicator bacteria (FIB) concentrations. However, this pollutant control measure did not provide sufficient improvement of beach water quality, prompting further assessment. Investigation included microbial source tracking (MST) for human, gull, and canine fecal sources, monitoring of enterococci and fecal coliform, and measurement of chemical and physical water quality parameters for samples collected from watershed, groundwater, and beach sites, including a beach scour pond and tidal creek. FIB variability remained poorly modeled in regression analysis. However, MST revealed correlations between FIB and gull source tracking markers, leading to recommendations to manage gulls as a pollutant source. Beach conditions were followed for three years after implementation of a best management practice (BMP) to abate gulls using a falconry program for the beach and an upland landfill. The gull abatement BMP was associated with improved beach water quality, and this appears to be the first report of falconry in the context of TMDL implementation. Overall, MST data enabled management action despite an inability to fully model FIB dynamics in the coupled watershed-beach system.

A sonic net excludes birds from an airfield: implications for reducing bird strike and crop losses

Collisions between birds and aircraft cause billions of dollars of damages annually to civil, commercial, and military aviation. Yet technology to reduce bird strike is not generally effective, especially over longer time periods. Previous information from our lab indicated that filling an area with acoustic noise, which masks important communication channels for birds, can displace European Starlings (Sturnus vulgaris) from food sources. Here we deployed a spatially controlled noise (termed a "sonic net"), designed to overlap with the frequency range of bird vocalizations, at an airfield. By conducting point counts, we monitored the presence of birds for four weeks before deployment of our sonic net, and for four weeks during deployment. We found an 82% reduction in bird presence in the sonic net area compared with change in the reference areas. This effect was as strong in the fourth week of exposure as in the first week. We also calculated the potential costs avoided resulting from this exclusion. We propose that spatially controlled acoustic manipulations that mask auditory communication for birds may be an effective long term and fairly benign way of excluding problem birds from areas of socioeconomic importance, such as airfields, agricultural sites, and commercial properties.

The Efficiency of an Integrated Program Using Falconry to Deter Gulls from Landfills

Gulls are commonly attracted to landfills, and managers are often required to implement cost-effective and socially accepted deterrence programs. Our objective was to evaluate the effectiveness of an intensive program that integrated the use of trained birds of prey, pyrotechnics, and playback of gull distress calls at a landfill located close to a large ring-billed gull (Larus delawarensis) colony near Montreal, Quebec, Canada. We used long-term survey data on bird use of the landfill, conducted behavioral observations of gulls during one season and tracked birds fitted with GPS data loggers. We also carried out observations at another landfill located farther from the colony, where less refuse was brought and where a limited culling program was conducted. The integrated program based on falconry resulted in a 98% decrease in the annual total number of gulls counted each day between 1995 and 2014. A separate study indicated that the local breeding population of ring-billed gulls increased and then declined during this period but remained relatively large. In 2010, there was an average (±SE) of 59 ± 15 gulls/day using the site with falconry and only 0.4% ± 0.2% of these birds were feeding. At the other site, there was an average of 347 ± 55 gulls/day and 13% ± 3% were feeding. Twenty-two gulls tracked from the colony made 41 trips towards the landfills: twenty-five percent of the trips that passed by the site with falconry resulted in a stopover that lasted 22 ± 7 min compared to 85% at the other landfill lasting 63 ± 15 min. We concluded that the integrated program using falconry, which we consider more socially acceptable than selective culling, was effective in reducing the number of gulls at the landfill.

Dramatic improvements in beach water quality following gull removal

Gulls are often cited as important contributors of fecal contamination to surface waters, and some recreational beaches have used gull control measures to improve microbial water quality. In this study, gulls were chased from a Lake Michigan beach using specially trained dogs, and water quality improvements were quantified. Fecal indicator bacteria and potentially pathogenic bacteria were measured before and during gull control using culture methods and quantitative polymerase chain reaction (qPCR). Harassment by dogs was an effective method of gull control: average daily gull populations fell from 665 before to 17 during intervention; and a significant reduction in the density of a gull-associated marker was observed (p < 0.001). Enterococcus spp. and Escherichia coli densities were also significantly reduced during gull control (p < 0.001 and p = 0.012, respectively for culture methods; p = 0.012 and p = 0.034, respectively for qPCR). Linear regression results indicate that a 50% reduction in gulls was associated with a 38% and 29% decrease in Enterococcus spp. and E. coli densities, respectively. Potentially human pathogenic bacteria were detected on 64% of days prior to gull control and absent during gull intervention, a significant reduction (p = 0.005). This study demonstrates that gull removal can be a highly successful beach remedial action to improve microbial water quality.

Birds flee en mass from New Year's Eve fireworks

Anthropogenic disturbances of wildlife, such as noise, human presence, hunting activity, and motor vehicles, are becoming an increasing concern in conservation biology. Fireworks are an important part of celebrations worldwide, and although humans often find fireworks spectacular, fireworks are probably perceived quite differently by wild animals. Behavioral responses to fireworks are difficult to study at night, and little is known about the negative effects fireworks may have on wildlife. Every year, thousands of tons of fireworks are lit by civilians on New Year's Eve in the Netherlands. Using an operational weather radar, we quantified the reaction of birds to fireworks in 3 consecutive years. Thousands of birds took flight shortly after midnight, with high aerial movements lasting at least 45 min and peak densities measured at 500 m altitude. The highest densities were observed over grasslands and wetlands, including nature conservation sites, where thousands of waterfowl rest and feed. The Netherlands is the most important winter staging area for several species of waterfowl in Europe. We estimate that hundreds of thousands of birds in the Netherlands take flight due to fireworks. The spatial and temporal extent of disturbance is substantial, and potential consequences are discussed. Weather radar provides a unique opportunity to study the reaction of birds to fireworks, which has otherwise remained elusive.

Murid stress odours: a review and a ‘low tech’ method of collection

Stress cues can affect the welfare of animals in close proximity and are possibly useful non-invasive indicators of the emitters’ welfare. To facilitate their study in murids, we tested whether rats’ stress odours could be collected and stored using an enfleurage-type technique. ‘Donor’ rats were individually exposed to a compound stressor (carried circa 75 m inside a novel container, then euthanised with rising carbon dioxide) while on blotting paper dotted with melted vegetable lard. These sheets were sealed, left at room temperature for 2-5 h, and then ‘bioassayed’ by a blind observer for their effects on conspecifics. Compared with control sheets (exposed to unstressed rats, to CO2 alone, or untreated), stress-exposed sheets significantly affected the unconditioned behaviour of 16 pairs of detector rats trained to enter an arena from their home cage to obtain sucrose. When used to line this arena, the stress-exposed sheets significantly increased: i) rats’ latencies to eat, to place front feet into, and to completely step into the arena and ii) shuttling movements between arena and home cage. These pilot data thus suggest that odours produced by stressed rats can be simply and successfully collected and stored for several hours, though certain potential confounds (eg urine volume) may conceivably be alternative explanations for the observed effects. Future work should control for urine volume, and assess whether fat is needed for optimal odour absorption by paper and for how long sheets can be stored at various temperatures. Much fundamental work is also still needed on the nature, functions, and sources of stress odours.