Fly with me : algorithms and methods for influencing a flock

As robots become more affordable, they will begin to exist in the world in greater quantities. Some of these robots will likely be designed to act as components in specific teams. These teams could work on tasks that are too large or complex for a single robot - or that are merely more efficiently accomplished by a team - such as surveillance in a large building or product delivery to packers in a warehouse. Multiagent systems research studies how these teams are formed and how they work together. Ad hoc teamwork, a newer area of multiagent systems research, studies how new robots can join these pre-existing teams and assist the team in accomplishing its goal. This dissertation extends and applies research in ad hoc teamwork towards the general area of flocking, which is an emergent swarm behavior. In particular, the work in this dissertation considers how ad hoc agents - called influencing agents in this dissertation - can join a flock, be recognized by the rest of the flock as part of the flock, influence the flock towards particular behaviors through their own behavior, and then separate from the flock. Specifically, the primary research question addressed in this dissertation is How can influencing agents be utilized in various types of flocks to influence the flock towards a particular behavior? In order to address this research question, this dissertation makes six main types of contributions. First, this dissertation formalizes the problem of using influencing agents to influence a flock. Second, this dissertation contributes and analyzes algorithms for influencing a flock to a desired orientation. Third, this dissertation presents methods for determining how to best add influencing agents to a flock. Fourth, this dissertation provides methods by which influencing agents can join and then leave a flock in motion. Fifth, this dissertation evaluates some of the influencing agent algorithms on a robot platform. Sixth, although the majority of this dissertation assumes the influencing agents will join a flock that behaves similarly to European starlings, this dissertation also provides insight into when and how its algorithms are generalizable to other types of flocks as well as to general teamwork and coordination research. All of the methods presented in this dissertation are empirically evaluated using a simulator that can support large flocks.Computer Science

Potencial Impacts of Ecosystem Degradation on the Reproductive Biology and Behavior of Malawian Cichlids

The Rift Valley is a tropical region of eastern Africa characterized by its complex geological makeup consisting of tectonic plates that have driven the formation of some of the largest lakes in the world being Lake Malawi, Victoria, and Tanganyika. In turn, the formation of these amazing freshwater ecosystems has enabled the evolution, and radiation of thousands of species of fish from the family Cichlidae, which constitutes the most diverse group of vertebrates on the globe. However, because these ecosystems are also in regions with a high prevalence of anthropogenic activities they are threatened by biodiversity loss. In particular, Lake Malawi is a notable example as it is an extremely delicate ecosystem that is home to the greatest number and diversity of African cichlids while also being surrounded by countries with severe anthropogenic pressures associated with climate change and increased agricultural activity. With that being said, by conducting an extensive literature review and experimental data collection in the Cruz Lab this study looked at the potential impacts of ecosystem degradation on the reproductive biology and behavior of Malawian cichlids. In doing so, I found that ecosystem degradation could have a negative impact on the reproductive biology and behavior of Malawian cichlids by disrupting aspects of sexual selection, courtship, spawning, and juvenile development and rearing. These finding are significant as they imply that continued ecosystem degradation in Lake Malawi could lead to a reduction in the fitness of Malawian cichlids that could substantially reduce the size and diversity of the largest family of vertebrates in the world

Piling behaviour in Swiss layer flocks: Description and related factors

Smothering is a major concern within the Swiss layer industry as it can lead to a high number of animal losses. The underlying cause is piling behaviour (PB), a phenomenon where hens densely cluster together in the litter area. The aim of this study was to describe PB and events preceding PB. Furthermore, we investigated the relation of the number of piles, pile duration, and number of hens involved in a pile with time of day, flock colour, flock age, environmental factors, and flock responses to behaviour tests. We video recorded the corners of litter areas (floor) inside the barn and winter garden of 13 commercial Swiss layer flocks (5 white, 5 brown, 3 mixed layer hybrids), which were known to previously experienced problems with smothering. We recorded environmental data (air speed, spot temperature) in the observed corners and assessed flock-level responses to two behaviour tests (novel object test, stationary person test). From the video recordings, events preceding piling and piling characteristics were assessed at 20 and 30 weeks of age (w) at three times per day (0−5 h, >5-10 h, >10−15 h after lights on). Statistical analyses included generalized and linear mixed-effects models and Spearman correlations. Results showed that piling events were mainly preceded by single hen activities (77.9%) and non- hysterical mass movements (7.6%). More piles and the largest numbers of animals involved in piling occurred in white and brown flocks at >5−10 h after lights came on. The number of piles was lower and the number of involved animals and pile duration higher in 20 w compared to 30 w. No correlation was found between environmental factors and flock behaviour test responses with piling characteristics. Potential underlying causes for PB are numerous, though we provide and discuss likely mechanisms, including response facilitation, individual stimulus response, and anti-predation behaviour, based on our findings. Furthermore, PB could relate to diurnal behaviours, for example, dustbathing and hens laying floor eggs in the litter area

Pehkun kunnon vaikutus broilerin ja broileriemojen jalkapohjaterveyteen ja korotettujen ritilätasojen vaikutus broilerin jalkaterveyteen

Contact dermatitis in broilers is a multifactorial condition that is most commonly caused by poor litter quality or otherwise unsuitable material affecting the footpad or hock skin. Footpad health is mainly maintained by keeping litter in a dry and friable condition. Hence, footpad lesions reflect litter quality that, more widely, describes the housing conditions and bird health. The evaluation of the prevalence of contact dermatitis denotes a commonly accepted approach to assess the welfare of broiler flocks. However, there is lack of knowledge about footpad lesions in broiler breeders. Although numerous studies on the effect of litter materials on footpad condition have been conducted, experiments with peat are scarce. Also, knowledge of the influence of peat on hock burns and litter quality is lacking. Modern fast-growing broilers spend excessive time resting and this inactivity has been suggested to increase the incidence of impaired gait and leg disorders. Tibial dyschondroplasia (TD) is one of the most common leg pathologies in broilers. Perches or elevated platforms add complexity to the broilers’ environment and may stimulate locomotion. However, research on the use of elevated structures under commercial rearing conditions and possible benefits for broiler leg health is limited. This thesis provides descriptive information about contact dermatitis and breast blisters in broiler breeders throughout the production period with respect to litter condition. Secondly, the study compared the influence of peat bedding with wood shavings and ground straw (fine crushed straw) on contact dermatitis and plumage cleanliness in fast-growing broilers and litter condition in commercial broiler houses. Furthermore, the study examined the use of perches and elevated platforms by broilers, and the impact of the additional equipment on contact dermatitis, plumage cleanliness, walking ability, the occurrence of TD and litter conditions under intensive rearing circumstances. Litter condition in broiler and breeder houses was evaluated according to the Welfare Quality® (WQ) protocol for broiler chicken. Additionally, litter height was measured, and litter quality determined according to moisture, pH and ammonia content. Footpad condition was visually inspected with the WQ-scoring method (broilers), the official Finnish system (broilers) or employing a method modified from the official system (breeders). Hock skin lesions and plumage cleanliness were assessed according to the WQ-protocol. Broiler gait was scored before slaughter following the WQ-protocol. The severity of TD was determined. The use of perches and platforms was monitored by video recording. Additionally, farmers estimated the platform and perch usage twice a week throughout the growing period. The condition of breeder footpads deteriorated towards the end of the production period, with the occurrence of severe lesions reaching a maximum of 64% on average at slaughter. However, hock burns and breast blisters were rarely recorded. The litter layer became drier over time. Although dry and friable litter in breeder houses was associated with healthier footpads, other factors were of greater importance, as footpad lesions, particularly severe lesions, appeared more often towards slaughter age. Broiler footpads were generally in good condition at slaughter age, 80% of the birds having healthy footpads. In broilers, hock burns were more frequently detected than footpad lesions. Inferior footpad and hock skin health was scored on wood shavings rather than on peat, without differences in litter condition and moisture. Moreover, the lack of difference in moisture between ground straw and peat still resulted in poorer litter, footpad and hock skin condition on ground straw. Farms differed for footpad and hock burn condition, and litter quality. In risk analysis, the impact of farmer on contact dermatitis severity exceeded the effect of litter quality. The platforms were used frequently while only single birds used perches. The study indicated no effects of platform treatment on footpad and hock skin health, and litter condition. The birds with access to platforms, however, had enhanced leg health: mean gait score, the percentage of birds scored 3, and TD percentage and severity were lower for birds in platform-equipped houses. Access to platforms most likely enables more versatile movement, such as walking forward, up and down, grasping by feet, and jumping, which may promote leg health and gait. This was the first study to follow footpad health in broiler breeders through the whole production period. The results indicate the need for further investigation because good litter condition alone appears insufficient to keep breeder footpads healthy for their entire life. Further, this thesis provides new knowledge about the applicability of peat as broiler bedding. According to our results, regarding footpad health, peat seems to be the optimal litter material for Finnish conditions. Furthermore, the study underlines the importance of farmer ability to manage litter conditions, regardless of the chosen litter material. Hock burn monitoring could represent a more sensitive indicator of litter condition and possibly also signal leg health status, therefore monitoring hock burns at slaughter should be considered. The advantages of traditional perches for broilers should be re-evaluated as they remained largely unused. However, the extensive use of platforms suggests that broilers are motivated to perch on elevated structures. Hence, platform availability could enhance their emotional wellbeing. Elevated platforms offering additional possibilities for locomotion seem promising because they show apparent potential to enhance leg health without compromising litter condition or footpad health. Based on all these findings, elevated platforms with ramps can be recommended as a way forward to enhance broiler welfare in commercial environments.Broilereiden jalkapohjien ja kintereiden iholla yleinen kontakti-ihottuma syntyy kosketuksesta huonokuntoiseen kuivikepohjaan tai muuten sopimattomaan pohjamateriaaliin. Tärkeimpänä ihovaurioita ennaltaehkäisevänä tekijänä pidetään hyväkuntoista ja kuivaa kuivikepohjaa eli pehkua. Jalkapohjavaurioiden arvostelua käytetään paitsi parven ja yksilön hyvinvoinnin myös kasvatusolosuhteiden onnistumisen arvioinnissa. Eri kuivikemateriaalien vaikutuksia jalkapohjaterveyteen on tutkittu runsaasti, mutta suomalaisen broilerituotannon yleisimmästä kuivikkeesta, turpeesta, on vähän tutkimustietoa. Broileriemojen jalkapohjaterveyttä on toistaiseksi tutkittu hyvin vähän. Nopea kasvu ja vähäinen liikunta huonontavat broilerin kävelykykyä ja altistavat jalkavioille, kuten esimerkiksi sääriluun kasvuruston luutumishäiriölle. Kasvattamoon sijoitetuilla orsilla on mahdollista parantaa broilerien liikkuvuutta. Tutkimustietoa tarvitaan siitä, miten linnut käyttävät orsia käytännön tilaolosuhteissa ja onko orsilla vaikutusta pehkun kuntoon, kontakti-ihottuman esiintymiseen ja jalkaterveyteen. Väitöskirjassa kartoitettiin ensimmäistä kertaa emojen jalkapohjaterveyttä ja kuivikepohjan kuntoa läpi koko tuotantokauden. Lisäksi selvitettiin, vaikuttaako kuivikemateriaalin valinta broilereiden jalkapohjatulehdusten ja kinnerpalamien esiintymiseen ja pehkun kuntoon. Kuivikkeista verrattiin turvetta kutteriin ja hienojakoiseen olkikuivikkeeseen. Väitöskirjassa tutkittiin lisäksi, miten broilerit käyttävät kasvattamoon sijoitettuja orsia ja ritilätasoja sekä näiden vaikutusta pehkun kuntoon, kontakti-ihottuman yleisyyteen ja jalkaterveyteen. Tutkituissa broileriemokanaloissa kuivikepohja pysyi koko tuotantokauden ajan hyvässä tai melko hyvässä kunnossa. Pehkun kosteus aleni tuotantokauden edetessä. Jalkapohjavauriot, varsinkin vakavat muutokset, yleistyivät iän myötä. Vakavia vaurioita todettiin teurasiässä keskimäärin 64 %:lla tutkituista broileriemoista. Vaikka huonokuntoisempi ja kosteampi kuivikepohja lisäsi jalkapohjavaurioiden määrää, tulosten perusteella näyttää siltä, että pelkästään kuiva ja irtonainen pehku ei riitä pitämään emojen jalkapohjia terveinä koko tuotantokautta. Tutkituissa broileriparvissa lintujen jalkapohjat olivat keskimäärin hyvässä kunnossa, terveiden jalkapohjien osuus oli noin 80 %. Kinnerpalamia esiintyi jalkapohjavaurioita enemmän, keskimäärin 32 %:lla linnuista. Vaikka turve- ja kutteripohjan kunto ja kosteus eivät eronneet, turpeella esiintyi vähemmän kontakti-ihottumaa. Olkikuivike- ja turvepehkun kosteudessa ei todettu eroa, mutta olkikuivikepohjan kunto oli huonompi ja kontakti-ihottumaa esiintyi sillä enemmän. Tilojen väliset erot olivat merkittäviä, joten tuottajan rooli olosuhteiden hallinnassa on keskeinen. Broilerit käyttivät rampillisia ritilätasoja mielellään, mutta orsien käyttö oli vähäistä. Ritilätasojen avulla näyttäisi olevan mahdollista parantaa broilereiden jalkaterveyttä: ritiläparvilla todettiin parempi kävelykyky, vähemmän ontuvia lintuja ja sääriluun kasvuruston luutumishäiriötä. Ritilöiden vaikutus pehkun ja jalkapohjien kuntoon näytti olevan hallittavissa oikeilla olosuhdesäädöillä. Kaikki tutkimukset tehtiin suomalaisilla tuotantotiloilla, joten tulosten käytännön merkitys on suuri. Tuottajien ja tutkijoiden innovatiivista yhteistyötä tarvitaan jatkossakin, jotta saataisiin selville mistä emojen jalkapohjamuutokset juontuvat ja millaisin keinoin jalkavaurioista päästään eroon. Turvepehkulla broilerilla kontakti-ihottumaa esiintyi vähemmän kuin kutterilla ja olkikuivikkeella, mutta tuottajan ammattitaidon merkitys oli kuitenkin kuivikemateriaalia suurempi. Broilerilla kinnerpalamat saattaisivat olla jalkapohjavaurioita herkempi mittari kertomaan pehkuolosuhteista tai esimerkiksi jalkaterveydestä, joten kinnerpalamien esiintymistä olisi hyvä seurata säännöllisesti. Koska broilerit käyttivät ritilöitä innokkaasti, ritilätasojen käytön edistäminen broilerikasvattamoissa olisi tutkimuksen perusteella suositeltavaa

Generating self-organizing collective behavior using separation dynamics from experimental data

Mathematical models for systems of interacting agents using simple local rules have been proposed and shown to exhibit emergent swarming behavior. Most of these models are constructed by intuition or manual observations of real phenomena, and later tuned or verified to simulate desired dynamics. In contrast to this approach, we propose using a model that attempts to follow an averaged rule of the essential distance-dependent collective behavior of real pigeon flocks, which was abstracted from experimental data. By using a simple model to follow the behavioral tendencies of real data, we show that our model can exhibit emergent self-organizing dynamics such as flocking, pattern formation, and counter-rotating vortices. The range of behaviors observed in our simulations are richer than the standard models of collective dynamics, and should thereby give potential for new models of complex behavior.Comment: Submitted to Chao

Heterogeneous structure in mixed-species corvid flocks in flight

Flocks of birds in flight represent a striking example of collective behaviour. Models of self-organization suggest that repeated interactions among individuals following simple rules can generate the complex patterns and coordinated movements exhibited by flocks. However, such models often assume that individuals are identical and interchangeable, and fail to account for individual differences and social relationships among group members. Here, we show that heterogeneity resulting from species differences and social structure can affect flock spatial dynamics. Using high-resolution photographs of mixed flocks of jackdaws, Corvus monedula, and rooks, Corvus frugilegus, we show that birds preferentially associated with conspecifics and that, like high-ranking members of single-species groups, the larger and more socially dominant rooks positioned themselves near the leading edge of flocks. Neighbouring birds showed closer directional alignment if they were of the same species, and neighbouring jackdaws in particular flew very close to one another. Moreover, birds of both species often flew especially close to a single same-species neighbour, probably reflecting the monogamous pair bonds that characterize these corvid social systems. Together, our findings demonstrate that the characteristics of individuals and their social systems are likely to result in preferential associations that critically influence flock structure

The Welfare of Animals in the Chicken Industry

More than 8.5 billion chickens are slaughtered for meat production in the United States every year. Raised in industrial production systems, these animals experience crowded indoor confinement, unnatural lighting regimes, poor air quality, stressful handling and transportation, and inadequate stunning and slaughter procedures. Because they are selectively bred for rapid growth, broiler chickens are prone to a variety of severe skeletal and metabolic disorders that can cause suffering, pain, and even death. Broiler breeders, the parent birds of chickens raised for meat, are subjected to severe feed restriction, and males may undergo painful toe and beak amputations, performed without pain relief. Scientific research on the behavior and welfare of broiler chickens demonstrates that these are substantial and important issues. Rapid and immediate reform is needed to improve the welfare of chickens raised for meat