Pigeon Flocks Research Articles

Case Study and Attempt of Treatment of Mycobacteriosis Caused by Mycobacterium avium in a Parental Flock of Meat-Breed Pigeons

Mycobacteriosis caused by Mycobacterium avium subsp. avium was observed in a parental loft of 70 meat-breed pigeons. It was decided to undertake treatment as the birds represented a substantial value to the owner. A multiagent therapy using azithromycin, marbofloxacin, and ethambutol was administered. After 4 mo of therapy, the desired results were not obtained. At the end of treatment, the birds were in poor general condition, with white blood cells above 20 g/L, and after clutching, 2-yr-old and older birds were euthanatized. Overall, postmortem lesions were found in 17 out of 49 necropsied individuals. Slide agglutination tests with a M. avium subsp. avium lysate were conducted in all examined pigeons. In 28 pigeons, blood count was conducted once a month during therapy, while in 24 pigeons, a tuberculin sensitivity test was conducted before the planned euthanatization. The tuberculin sensitivity test did not prove useful in the diagnosis of ill individuals. Slide agglutination yielded positive results in only four birds, all of which also had postmortem lesions. Blood count in a large number of cases allowed distinguishing between ill and healthy individuals, which was used for subsequent selection. The comparison of cultured strains with the (CCG)4-based PCR method showed the variation of M. avium isolates up to a maximum of 30%. The described case proves that the treatment of mycobacteriosis in pigeon flocks is not effective, mainly due to the high resistance to M. avium subsp. avium. In addition, therapy may contribute to an even greater increase in mycobacterial resistance to antibiotics, which may pose a potential risk to public health.

Fatal systemic non-albicans candidiasis with concurrent Hemoproteus columbae infection in a white pigeon flock

Fatal systemic non-albicans candidiasis with concurrent Hemoproteus columbae infection in a white pigeon flock

Leadership Hierarchy-based Formation Control via Adaptive Chaotic Pigeon-inspired Optimization

Abstract Formation control of multi-agent systems (MASs) is a significant research subject in the field of cooperative control. In this paper, we propose a novel consensus-based formation control approach with minimal resource cost and excellent adaptability for second-order nonlinear multi-agent systems. Specifically, an improved constrained adaptive chaotic pigeon-inspired optimization algorithm (ACPIO) is proposed for tuning parameters, which promotes the automation of controller design and alleviates the workload of conventional designer. Moreover, a variant of pinning control method integrating with hierarchical leadership model of pigeon flocks is introduced, which achieves excellent adaptability and reduces computational complexity simultaneously. Additionally, sufficient conditions are derived for achieving the desired formation pattern based on Lyapunov stability theory and matrix theory. Numerical simulation results demonstrate the feasibility and effectiveness of the proposed method for formation control of second-order nonlinear MASs.

Molecular and Virulence Characterization of Newcastle Disease Virus in Fowls and Pigeons From Jammu, India

Occurrence of Newcastle disease (ND) and characterization of the Avian Paramyxovirus-1 (APMV-1) amongst backyard fowls (Gallus gallus domesticus) and pigeon (Columba livia domestica) was studied. ND was suspected in two fowl flocks (100% morbidity, 86% mortality) and six pigeon flocks (21.68% morbidity, 14.16% mortality) with respiratory and/or enteric clinical signs in fowls and predominantly neurological signs in pigeons was observed. Cloacal swabs, tissue lysates or infected allantoic fluid could haemagglutinate (HA) chicken erythrocytes and pigeon convalescent serum inhibited haemagglutination (antibody titres >1/16). A 534 bp product was amplified from clinical samples and infected allantoic fluids by Reverse Transcriptase PCR (RT-PCR) targeting a partial Fusion protein gene including its cleavage site. The fowl and pigeon isolate was found to be velogenic and lentogenic respectively by virulence characterization. Fowl isolate grown in chicken embryonated eggs (CEE) showed 10-8.68 Embryo Infectious Dose (EID50) with a Mean Death Time (MDT) of 51.43 h and the Intra-Cerebral Pathogenicity Index (ICPI) in day-old chicks was 1.51. Pigeon isolate had corresponding values of 10-7.20 EID50, MDT of 92.00 h and ICPI of 0.43. Deduced amino acid sequence at Fusion protein cleavage site showed 112R-R-R-K-R*F117 velogenic motif for the fowl isolate and 112G-R-Q-G-R*L117 lentogenic motif for the pigeon isolate. Both isolates were found to be 84.1% related phylogenetically, while fowl isolate clustered with genotype XIII, the pigeon isolate clustered with genotype II and vaccine strains of APMV-1. This is the first instance of APMV-1 characterization in the region with the possibility of a vaccine spill over in pigeons.

Inferring causal relationship in coordinated flight of pigeon flocks.

Collective phenomenon of natural animal groups will be attributed to individual intelligence and interagent interactions, where a long-standing challenge is to reveal the causal relationship among individuals. In this study, we propose a causal inference method based on information theory. More precisely, we calculate mutual information by using a data mining algorithm named "k-nearest neighbor" and subsequently induce the transfer entropy to obtain the causality entropy quantifying the causal dependence of one individual on another subject to a condition set consisting of other neighboring ones. Accordingly, we analyze the high-resolution GPS data of three pigeon flocks to extract the hidden interaction mechanism governing the coordinated free flight. The comparison of spatial distribution between causal neighbors and all other remainders validates that no bias exists for the causal inference. We identify the causal relationships to establish the interaction network and observe that the revealed causal relationship follows a local interaction mode. Interestingly, the individuals closer to the mass center and the average velocity direction are more influential than others.

Verification of a UAV swarm flight simulating the passive inertial emergency obstacle avoidance behavior of a pigeon flock

In this paper, the passive inertial emergency obstacle avoidance behavior of pigeons is studied and applied to the coordinated flight verification of an unmanned aerial vehicle (UAV) swarm. Pigeons in nature dynamically adjust their routes during flight. When they encounter obstacles, emergency behaviors are generated; i.e., they change the current direction passively, get cross obstacles toward the largest gap between obstacles, and thus complete obstacle avoidance. Prior to the flight verification, the design of the UAV swarm system architecture is explained. Further, two scenarios of static emergency obstacle avoidance on the ground and with moving obstacles in the air are set up. The corresponding timing sequence diagrams and flight path diagrams are also given.

A case of Amidostomosis in a racing pigeon (Columba livia) in Greece

A dead pigeon (Columba livia) was submitted to the Unit of Avian Medicine, Clinic of Farm Animals, Faculty of Veterinary Medicine, Aristotle University of Thessaloniki, Greece. It derived from a pigeon flock consisted of approximately 100 racing birds of various ages between 4 months to 5 years old. The flock was kept on a terrace indoors in 4 cages of 3 m2 each. Near this flock, there were also two other pigeon flocks in a distance of 20 and 30 meters, respectively. The pigeons’ health problem had been present in this flock for approximately 3 years before this delivery. Lack of appetite, poor growth of young birds, weakness, depression, vomiting, diarrhea and emaciation were the most important clinical signs of the pigeons in the flock. During necropsy, discoloration and atrophy of liver, spleen and kidneys, edema of gizzard, necrosis in the koilin layer of the gizzard and under this, presence of small parasites, dilatation in the anterior small intestine (duodenum, jejunum) and finally hemorrhagic content in the second half of the small intestine and the rectum were observed. According to the findings of the postmortem and laboratory examination, amidostomosis was determined to be the cause of the pigeon’s death. Although pigeon infection by Amidostomum spp. is reported around the world, so far, amidostomosis has not been reported in pigeons in Greece. Pigeon owners should take all the appropriate treating and managing measures to control the spread of this parasite and its consequences on their flocks.

High prevalence of Sarcocystis calchasi in racing pigeon flocks in Germany.

The apicomplexan parasite Sarcocystis calchasi (Coccidia: Eimeriorina: Sarcocystidae) is the causative agent of Pigeon Protozoal Encephalitis (PPE) and infects birds of the orders Columbiformes, Piciformes and Psittaciformes. Accipiter hawks (Aves: Accipitriformes) are the definitive hosts of this parasite. Infections of S. calchasi have been detected in Germany, the United States and Japan. However, the prevalence of the parasite in racing pigeon flocks has not yet been determined. Here, the first cross-sectional prevalence study to investigate S. calchasi in pigeon racing flocks was accomplished including 245 pigeon flocks across Germany. A total of 1,225 muscle biopsies, were taken between 2012 and 2016 and examined by semi-nested PCR for S. calchasi DNA targeting the ITS gene. Additionally, a questionnaire on construction of the aviary as well as management and health status of the flock was conducted. In 27.8% (95% C.I. = 22.3–33.8%) of the flocks, S. calchasi DNA was detected in at least one pigeon. Positive flocks were located in 15 out of 16 federal states. A significant increase of infected racing pigeons was seen in spring. Half-covered or open aviary constructions showed a trend of increase of the prevalence rate, while anti-coccidian treatment and acidified drinking water had no effects. The high prevalence and the geographical distribution of S. calchasi suggest a long-standing occurrence of the parasite in the German racing pigeon population. For pigeons presented with neurological signs or other symptoms possibly related to PPE, S. calchasi should be considered as a potential cause throughout Germany.

Live-fly experimentation for pigeon-inspired obstacle avoidance of quadrotor unmanned aerial vehicles

In this paper, we applied a pigeon-inspired obstacle-avoidance model to the flight of quadrotor UAVs through environments with obstacles. Pigeons bias their flight direction by considering the largest gap and minimum required steering. Owing to the similarities between pigeon flocks and UAV swarms in terms of mission requirements, the pigeon-inspired obstacle-avoidance model is used to control a UAV swarm so that it can fly through a complex environment with multiple obstacles. The simulation and flight results illustrate the viability and superiority of pigeon-inspired obstacle avoidance for quadrotor UAVs.

Molecular characterization of two novel sub-sublineages of pigeon paramyxovirus type 1 in China.

Pigeon paramyxovirus type 1 (PPMV-1) infection is enzootic in pigeon flocks and poses a potential risk to the poultry industry in China. To gain insight into the biological characteristics and transmission routes of circulating PPMV-1 in pigeons, 13 PPMV-1 isolates from domestic pigeons isolated during 2011-2015 in Guangxi province, China, were characterized using a pathogenicity assessment and phylogenetic analysis. All PPMV-1 isolates were mesogenic or lentogenic strains and had a mean death time (MDT) in 9-day-old SPF chicken embryos and a intracerebral pathogenicity index (ICPI) values of 54-154h and 0.00-0.90, respectively. Analysis of the F and HN gene sequences of the PPMV-1 isolates and the Newcastle Disease (ND) vaccine strain La Sota, revealed that the nucleotide sequence similarity of the F and HN genes were all < 85% between the PPMV-1 isolates and La Sota, significantly lower than those > 98% among the PPMV-1 isolates. The amino acids sequence of the F protein at the cleavage site of the 13 PPMV-1 isolates was 112RRQKR↓F117, characteristic of virulent Newcastle disease virus (NDV). All 13 isolates were classified as sublineage 4b by phylogenetic analysis and evolutionary distances, based on the F gene sequences. It was also found that the 13 isolates were divided into two novel sub-groups of sublineage 4b, sub-sublineages 4biig and 4biih. Since these two novel sub-sublineages had two different geographic sources, we speculated that they represent two different transmission routes of PPMV-1 in China. Phylogenetic analysis of these isolates will help to elucidate the sources of the transmission and evolution of PPMV-1 and may help to control PPMV-1 infection in the pigeon industry in China.

A multi-objective pigeon-inspired optimization approach to UAV distributed flocking among obstacles

Unmanned aerial vehicle (UAV) flocking control with obstacle avoidance is a many-objective optimization problem for centralized algorithms. A UAV flocking distributed optimization control frame is designed to render the many-objective optimization problem into a multi-objective optimization solved by a single UAV. For different objectives, two kinds of criteria are raised to guarantee flight safety: the hard constraints that must be satisfied and the soft ones that will be optimized. Considering the restrictions of onboard computing resources, multi-objective pigeon-inspired optimization (MPIO) is modified based on the hierarchical learning behavior in pigeon flocks. On such a basis, a UAV distributed flocking control algorithm based on the modified MPIO is proposed to coordinate UAVs to fly in a stable formation under complex environments. Comparison experiments with basic MPIO and a modified non-dominated sorting genetic algorithm (NSGA-II) are carried out to show the feasibility, validity, and superiority of the proposed algorithm.

Phoretic dispersal influences parasite population genetic structure.

Dispersal is a fundamental component of the life history of most species. Dispersal influences fitness, population dynamics, gene flow, genetic drift and population genetic structure. Even small differences in dispersal can alter ecological interactions and trigger an evolutionary cascade. Linking such ecological processes with evolutionary patterns is difficult, but can be carried out in the proper comparative context. Here, we investigate how differences in phoretic dispersal influence the population genetic structure of two different parasites of the same host species. We focus on two species of host-specific feather lice (Phthiraptera: Ischnocera) that co-occur on feral rock pigeons (Columba livia). Although these lice are ecologically very similar, "wing lice" (Columbicola columbae) disperse phoretically by "hitchhiking" on pigeon flies (Diptera: Hippoboscidae), while "body lice" (Campanulotes compar) do not. Differences in the phoretic dispersal of these species are thought to underlie observed differences in host specificity, as well as the degree of host-parasite cospeciation. These ecological and macroevolutionary patterns suggest that body lice should exhibit more genetic differentiation than wing lice. We tested this prediction among lice on individual birds and among lice on birds from three pigeon flocks. We found higher levels of genetic differentiation in body lice compared to wing lice at two spatial scales. Our results indicate that differences in phoretic dispersal can explain microevolutionary differences in population genetic structure and are consistent with macroevolutionary differences in the degree of host-parasite cospeciation.

Intermittence and connectivity of interactions in pigeon flock flights

Collective circular motion is a common yet spectacular behavior of pigeon flocks. Efficient and robust inter-individual communication is required for flock coordination during this widely-spreaded movement pattern. When a flock hovers near the home loft, the rotational direction undergoes regular spontaneous variations. Based on intensive analyses of high spatial-temporal resolution GPS data, we quantified the intensity of velocity alignment among different individuals in terms of their velocity fluctuations. It is found that pigeon flocks employ an intermittent interaction (alignment) mechanism, where intra-group information transmission is not required at every instant. However, the union of the topologies of several consecutive interaction networks always keeps connected. This biological observation strongly suggests the presence of a jointly connected topology in pigeon flocks, which helps substantially reduce the communication and/or information processing requirements while retaining the agility and stability of the group. Finally, we conducted extensive investigation on the interaction mechanism as well as the spontaneous changes in rotational direction of pigeon flocks. These results shed some light onto the coordination mechanism exploration of bird flocks’ collective motions.

Multiple UAV distributed close formation control based on in-flight leadership hierarchies of pigeon flocks

Owing to the similarity between bird flocks and unmanned aerial vehicle (UAV) swarms among intelligence, autonomy and local interactions, the collective motion mechanisms in bird flocks have reference significance for the design of distributed control algorithms for multiple UAVs. In this paper, a pigeon flocking model is proposed based on the in-flight leadership hierarchy in pigeon flocks. Graph theory is adopted to describe the transformation process from an arbitrary connected topology to the leadership hierarchy required for a line formation. The leader–follower relations are defined as the guidance from leaders to followers on the relative positions. On the basis of the pigeon flocking model, a distributed close formation control method to coordinate multiple UAVs to fly in a line close formation is presented. The simulation results based on the UAV close formation model, modified by the additional nonlinear aerodynamic interactions, are elaborated to show the feasibility and validity of our proposed method.

Anisotropic interaction rules in circular motions of pigeon flocks: An empirical study based on sparse Bayesian learning.

Coordination shall be deemed to the result of interindividual interaction among natural gregarious animal groups. However, revealing the underlying interaction rules and decision-making strategies governing highly coordinated motion in bird flocks is still a long-standing challenge. Based on analysis of high spatial-temporal resolution GPS data of three pigeon flocks, we extract the hidden interaction principle by using a newly emerging machine learning method, namely the sparse Bayesian learning. It is observed that the interaction probability has an inflection point at pairwise distance of 3-4 m closer than the average maximum interindividual distance, after which it decays strictly with rising pairwise metric distances. Significantly, the density of spatial neighbor distribution is strongly anisotropic, with an evident lack of interactions along individual velocity. Thus, it is found that in small-sized bird flocks, individuals reciprocally cooperate with a variational number of neighbors in metric space and tend to interact with closer time-varying neighbors, rather than interacting with a fixed number of topological ones. Finally, extensive numerical investigation is conducted to verify both the revealed interaction and decision-making principle during circular flights of pigeon flocks.

Distributed UAV flocking control based on homing pigeon hierarchical strategies

The recent boom of animal collective motion investigation has attracted many researchers to the field of applying such intelligence to complicated distribute control problems in artificial systems, such as autonomous unmanned aerial vehicle (UAV) flocking. In this paper, a distributed control framework inspired by homing pigeon hierarchical strategies is proposed to solve the UAV flocking problem. This new approach combines the advantages of velocity correlation, leader-follower interaction and hierarchical leadership network observed in pigeon flock with altitude consensus control algorithm used in UAV flocking. The flocking control algorithm is implemented to achieve a stable performance by controlling local position and velocity of each UAV. The practical dynamic and constraints of fix-wing UAV are also taken into account. The distributed flocking algorithms are tested in several simulation cases, which verify the effectiveness and applicability of the proposed control framework.

Pigeon interaction mode switch-based UAV distributed flocking control under obstacle environments

Unmanned aerial vehicle (UAV) flocking control is a serious and challenging problem due to local interactions and changing environments. In this paper, a pigeon flocking model and a pigeon coordinated obstacle-avoiding model are proposed based on a behavior that pigeon flocks will switch between hierarchical and egalitarian interaction mode at different flight phases. Owning to the similarity between bird flocks and UAV swarms in essence, a distributed flocking control algorithm based on the proposed pigeon flocking and coordinated obstacle-avoiding models is designed to coordinate a heterogeneous UAV swarm to fly though obstacle environments with few informed individuals. The comparative simulation results are elaborated to show the feasibility, validity and superiority of our proposed algorithm.

Phylogenetic and pathogenic characterization of a pigeon paramyxovirus type 1 isolate reveals cross-species transmission and potential outbreak risks in the northwest region of China.

Pigeon paramyxovirus type-1 (PPMV-1) is enzootic in pigeons, causing severe economic loss in the poultry industry in many countries. However, the exact epidemic process of PPMV-1 transmission is still unclear. In this study, we analyzed the complete genome of the PPMV-1/SX-01/15 isolate. Sequence results show that the virus genome contains 15,192 nucleotides, with the gene order 3'-NP-P-M-F-HN-L-5'. Phylogenetic analysis revealed that this genome belongs to subgenotype VIc in class II. The mean death time (MDT) and intracerebral pathogenicity index (ICPI) were 62.4 h and 1.13, respectively, indicating that this isolate is a mesogenic PPMV-1 strain. To our knowledge, this is the first report of a subgenotype VIc mesogenic PPMV-1 strain circulating in commercial pigeon flocks in the northwest region of China. In a comparative infection experiment, the morbidity and mortality rates were 100% and 80%, respectively, in 4-week-old pigeons, whereas they were 50% and 30%, respectively, in 5-week-old chickens. Furthermore, this virus caused severe neurological symptoms in a 4-week-old pigeon and mild neurological symptoms in a 5-week-old chicken. A histopathological examination of the brain showed a classical nonsuppurative encephalitis lesion. The pattern of viral shedding, and viral load, and virus distribution differed between infected chickens and pigeons. Genomic characteristics suggest that there was cross-species transmission of PPMV-1 subgenotype VIc in this region at least from the years 2006 to 2015.

New Pigeon Flocks Behavior Used for Multiple Robots Autonomous Formation

New Pigeon Flocks Behavior Used for Multiple Robots Autonomous Formation

PREVALENCE OF COLUMBID HERPESVIRUS INFECTION IN FERAL PIGEONS FROM NEW SOUTH WALES AND VICTORIA, AUSTRALIA, WITH SPILLOVER INTO A WILD POWERFUL OWL (NINOX STRUENA).

Columbid herpesvirus-1 (CoHV-1) is widespread in feral pigeons in North America and Europe. We used a PCR assay to detect CoHV-1 DNA in oral and cloacal tissues and oral swabs from naturally infected pigeons. Fifty-three feral pigeons from five flocks in Australia (n=3 from south-central Victoria and n=2 from Sydney) were examined for CoHV-1 DNA. We detected CoHV-1 DNA in oral mucosa and cloacal mucosa, with higher concentrations in the oral mucosa. The sensitivity of testing oral swabs was the same as testing the tissue, indicating that testing of oral swabs from live birds is an effective means of screening flocks for CoHV-1 infection. Infection was found in all five of the flocks examined and the prevalence of infection ranged from 70% to100%. Most positive birds could be detected with a single-amplification PCR, but a nested amplification was required to detect others. Oral swabs from Australian native doves and pigeons (n=18) and the introduced Collared Dove (Streptopelia chinensis; n=2) were also tested by the nested PCR and all were negative for CoHV-1 DNA. We describe a fatal infection of CoHV-1 in a wild Powerful Owl (Ninox strenua) that was observed feeding on feral pigeons. This is the first known case of CoHV-1 causing death in a wild bird of prey in Australia. Our data suggest that CoHV-1 is widespread in feral pigeon flocks in Australia but we did not find it in native doves and pigeons. Spillover into native avian predator species may be occurring.