Foraging behavior of the lesser kestrel under the Movement Ecology paradigm revealed using biologgers

Programa de Doctorado en Estudios MedioambientalesThe recent revolution of biologging technology has provided novel insights into free-ranging animal ecology with an unprecedented spatiotemporal resolution. As a consequence, literature on animal movement has vastly increased. This is the breeding ground over which Movement Ecology has arisen as a new discipline to unify all movement research under a common framework. Accordingly, Movement Ecology states that individual movement results from the interaction between four elements: individual state or motivation (why to move), motion abilities (how to move), navigation capacities (when and where to move), and external factors (both biotic and abiotic). This paradigm stresses the necessity to evaluate these elements in order to get a comprehensive understanding of the movement path. Thus, the Movement Ecology aims to answer old ecological questions and also to generate new ones thanks to the application of the latest technological advances to research on movement. The lesser kestrel (Falco naumanni) is a small insectivorous falcon that breeds in colonies across the Palearctic and winters in Africa. This species suffered a severe world population decline during the second half of the 20th century because of the agricultural intensification. The lesser kestrel has been well-studied during the breeding period, especially in its foraging ecology and mainly focusing on habitat selection and diet. In this PhD thesis, we investigated the foraging ecology of the lesser kestrel from the perspective of Movement Ecology by deploying high-frequency GPS and tri-axial accelerometers dataloggers on 35 individual lesser kestrels at two breeding colonies during four consecutive breeding seasons in southern Spain. Among external factors influencing movement, wind has been reported as one of the most important for flying animals. For this reason, we evaluated the influence of both wind speed and direction on lesser kestrel decisions about which direction to head when leaving the breeding colony to forage throughout the breeding season (Chapter One). We did not find any strong effect of wind conditions on lesser kestrel flights probably due to the prevailing winds registered in the study area that were weak and constant in direction. However, we found that kestrels show a uniform distribution of foraging trip departure directions when foraging early in the breeding season, which seems to be related to more exploratory flights when prey abundance is low and individuals have little knowledge about prey spatial distribution. Meanwhile, at the end of the breeding season kestrels concentrate their departure directions towards high-quality foraging areas when preferred prey abundance, individual experience, and energy demand derived from rearing the offspring are higher. Therefore, individual internal factors (mostly navigation capacities) appear to guide kestrel decision about departure directions of foraging trips, with little effect of external factors like wind. In some species with biparental care each member of the breeding pair cooperates by assisting its partner in every reproductive task, whereas in others each parent specializes in different tasks. The latter case is known as reproductive role specialization. In role-specialized species, such as the lesser kestrel, it is expected that sex will be an important motivational element that influence movement behavior in order to satisfy the temporally dynamic requirements during reproduction. We analyzed the effect of role specialization of the lesser kestrel on its foraging movement patterns throughout the breeding season (Chapter Two). Overall, we found differences in foraging movements between sexes in accordance with the general trend of raptor role specialization. Males fly larger daily distances and perform higher number of shorter foraging trips per day than females being the main responsible for provisioning tasks. Meanwhile, lesser kestrel females tend to stay longer than males at the colony through the day, which agrees with being the main responsible for nest protection, egg incubation and chick brooding. Furthermore, the lesser kestrel shows a sexual spatial segregation, with females constantly flying towards foraging areas located farther from the colony than males. This might be the result from an adaptive foraging strategy based on role specialization in order to avoid prey depletion in the surroundings of the colony and reduce intersexual competition between members of the breeding pair to be successful in reproduction. Most avian species move by flying and they can do it either through flapping, which requires muscles to convert chemical energy into work, or through soaring-gliding, which harvests kinetic energy from moving air masses to replace muscle work. We studied the flight strategy of the lesser kestrel during foraging trips and the effect of solar radiation (as a proxy for thermal updrafts) on several foraging trip parameters during the breeding season (Chapter Three). Surprisingly, we found that the lesser kestrel, which has been traditionally considered as a flapping raptor, relies heavily on thermal soaring during foraging trips, especially at higher values of solar radiation. Individuals fly at slower speeds at higher altitudes and reach farther distances from the colony during foraging trips with thermal soaring events in comparison to those without them. This guides to a circadian pattern of lesser kestrel foraging behavior: individuals fly by flapping their wings towards foraging areas located closer to the colony when thermals are weak or absent, whereas they fly towards foraging areas farther away by soaring on thermals as soon as they are formed. Theoretical flight models indicate that, given the lesser kestrel preference for feeding on large grasshoppers and considering the average distance traveled along the trips, foraging by flapping their wings would result in a negative energy balance for the family group. Apart from tracking devices, a series of animal-borne biological sensors has been developed to help fully understand individual movement, perhaps being accelerometers the most widely used devices nowadays. Tri-axial accelerometers measure body acceleration across three spatial axes at high temporal resolutions (typically 10 Hz or more). On the one hand, tri-axial accelerometry helps inferring animal behavior with no need of direct observation and, on the other hand, it has been also proved to be an effective methodology to measure animal energy expenditure. In Chapter Four, we built a behavioral classification model based on tri-axial accelerometer and GPS data for the lesser kestrel. Then, we investigated the effect of internal (breeding phenology, role specialization) and external factors (prey availability, weather conditions) on the behavioral time and energy budget of the lesser kestrel during the day in general and when foraging in particular. Our behavioral classification model performs well when classifying free-ranging lesser kestrel behaviors. Flapping and hovering flights require more energy than soaring-gliding flights, and these flight behaviors consume more energy than stationary (incubating/brooding and perching) behaviors. The daily time and energy budget of the lesser kestrel is mostly determined by behavior-specific costs and the role specialization between sexes. Lesser kestrels gradually replace flapping with soaring-gliding during commuting flights as solar radiation increases, that is, as thermal updraft gets stronger. Lesser kestrels also progressively substitute perching (i.e., sit-and-wait hunting strategy) with hovering flights (i.e., active hunting strategy) at the foraging patch as wind speed increases, that is, as they experience stronger lifts to be aloft. However, kestrels seem to decide which hunt strategy to use regarding the activity level of the preferred prey, which is influenced by air temperature. Thus, individuals increase the use of hovering flights as air temperature, and prey activity level, also increase. Overall, our results support predictions derived from the optimal foraging theory and suggest that the lesser kestrel prioritizes saving energy than time when foraging throughout the breeding season. This PhD thesis fills a gap of knowledge about the foraging behavior of the lesser kestrel through using the newest biologging technology, and so it has helped to understand better the lesser kestrel ecology during the breeding period.Universidad Pablo de Olavide. Departamento de Biología Molecular e Ingeniería Bioquímic

Dimensionamento da viga principal de uma ponte rolante

Pontes Rolantes são equipamentos utilizados no transporte e elevação de cargas, geralmente com altas capacidades e elevados ciclos de trabalho. Trata-se de uma estrutura, normalmente instalada dentro de edificações, sendo possível movimentar cargas, materiais, equipamentos entre outros, nas direções longitudinal, transversal e vertical. Este trabalho apresenta o projeto e dimensionamento da viga principal de uma ponte rolante univiga para aplicação na indústria metal-mecânica. O procedimento de cálculo estrutural é baseado na norma NBR 8400 e NBR 8800. A NBR 8400 estabelece os critérios mínimos para o dimensionamento de equipamentos para transporte e elevação de carga, e a NBR 8800 define os requisitos mínimos para o projeto de estruturas de aço. Após o dimensionamento e análise estrutural seleciona-se o perfil comercial W360x39 (fabricante Gerdau) para a viga principal da ponte rolante. Por fim, realiza-se uma análise de elementos finitos utilizando o software Autodesk Inventor, onde se observa que os níveis de tensão e deflexão estrutural são valores dentro dos limites estabelecidos pelos órgãos normativos.Overhead Cranes are equipments used for the transporting and lifting of loads, generally with high capacities and high working cycles. It is a structure, normally installed inside buildings, that is able to move loads, materials, equipments and others, in the longitudinal, transversal and vertical directions. This work presents the project and sizing of the main beam of a uni-beam overhead crane used in the metal-mechanical industry. The structural calculation procedure is based on NBR 8400 and NBR 8800. The NBR 8400 establishes the minimum criterias for the sizing of equipments for transporting and lifting loads, and the NBR 8800 defines the minimum requirements for the design of steel structures. After the sizing and structural analysis, it is selected the commercial profile W360x39 (made by Gerdau) as the main beam of the overhead crane. Then, it is analyzed the finite elements using the software Autodesk Inventor, where we can check that the tension and deflexion levels of the structure are within the limits established by the normative regulation used in this study

A Survey of Artificial Neural Network in Wind Energy Systems

Wind energy has become one of the most important forms of renewable energy. Wind energy conversion systems are more sophisticated and new approaches are required based on advance analytics. This paper presents an exhaustive review of artificial neural networks used in wind energy systems, identifying the methods most employed for different applications and demonstrating that Artificial Neural Networks can be an alternative to conventional methods in many cases. More than 85% of the 190 references employed in this paper have been published in the last 5 years. The methods are classified and analysed into four groups according to the application: forecasting and predictions; design optimization; fault detection and diagnosis; and optimal control. A statistical analysis of the current state and future trends in this field is carried out. An analysis of each application group about the strengths and weaknesses of each ANN structure is carried out. A quantitative analysis of the main references is carried out showing new statistical results of the current state and future trends of the topic. The paper describes the main challenges and technological gaps concerning the application of ANN to wind turbines, according to the literature review. An overall table is provided to summarize the most important references according to the application groups and case studies

Barrier crossings and winds shape daily travel schedules and speeds of a flight generalist

External factors such as geography and weather strongly affect bird migration influencing daily travel schedules and flight speeds. For strictly thermal-soaring migrants, weather explains most seasonal and regional differences in speed. Flight generalists, which alternate between soaring and flapping flight, are expected to be less dependent on weather, and daily travel schedules are likely to be strongly influenced by geography and internal factors such as sex. We GPS-tracked the migration of 70 lesser kestrels (Falco naumanni) to estimate the relative importance of external factors (wind, geography), internal factors (sex) and season, and the extent to which they explain variation in travel speed, distance, and duration. Our results show that geography and tailwind are important factors in explaining variation in daily travel schedules and speeds. We found that wind explained most of the seasonal differences in travel speed. In both seasons, lesser kestrels sprinted across ecological barriers and frequently migrated during the day and night. Conversely, they travelled at a slower pace and mainly during the day over non-barriers. Our results highlighted that external factors far outweighed internal factors and season in explaining variation in migratory behaviour of a flight generalist, despite its ability to switch between flight modes.Peer reviewe

Gone with the wind: Seasonal trends in foraging movement directions for a central-place forager

Lesser kestrels Falco naumanni are migratory central-place foragers that breed in dynamic arable landscapes. After arriving from migration, kestrels have no knowledge of the distribution of crops, and consequently prey, around their colony. The energy demand of pairs increases as breeding season progresses, but at the same time prey abundance, and their knowledge on prey distribution, also increases. Wind can have a strong influence on flight cost and kestrels should try to reduce energy expenditure when possible. When prey abundance is low, kestrels have little knowledge of prey distribution, and pairs have no chicks, they could reduce foraging flight cost by leaving the colony with tailwinds. When prey is abundant, knowledge on prey distribution has increased, and chick demand is high, kestrels should fly to the most favorable foraging patches. We analyzed foraging trips directions in a lesser kestrel colony along the breeding season and in relation to wind speed and direction. We recorded 664 foraging trips from 19 individuals using GPS-dataloggers. We found that outward flights direction changed from uniform to a concentrated distribution along the season, as prey abundance and individual experience increased. We also found a temporal trend in the angular difference between outward flights and wind directions, with low values early in the season and then increasing as expected, but again low values at the end, contrary to expectation. Results suggest changes in kestrels foraging strategy along the season in relation to wind. Kestrels depart more with tailwinds in exploratory flights early in the season, while there is a spurious coincidence in direction to preferred foraging patches and dominant wind direction at the endPeer reviewe

A few long versus many short foraging trips: different foraging strategies of lesser kestrel sexes during breeding

[Background] In species with biparental care both members of the breeding pair cooperate to raise the offspring either by assisting each other in every reproductive task or by specializing in different ones. The latter case is known as reproductive role specialization. Raptors are considered one of the most role-specialized groups, but little is known about parental behavior away from the nest. Until the advent of biologgers, avian role specialization was traditionally studied with direct observations at the nest because of the difficulties of following and recording the behavior of free-ranging individuals. In this paper we analyze how the role specialization of the lesser kestrel (Falco naumanni) influences foraging movement patterns throughout the breeding season. We tracked 30 lesser kestrel breeders from two breeding colonies using high-frequency GPS-dataloggers during four consecutive breeding seasons.[Results] We found no differences between sexes in lesser kestrel foraging movements early in the breeding season before the formation of the breeding pair. However, we observed sexually distinct foraging movement strategies later in the breeding season once breeding pairs were formed. Lesser kestrel males performed a large number of short foraging trips while females made a few long ones. This maximized the provisioning rate by males to feed their mates and offspring. Meanwhile, lesser kestrel females spent more time at the colony than males in order to defend the nest, incubate the eggs and brood the nestlings. Females also helped their mates to provision the nestling once these had grown and required more food and less protection. Furthermore, lesser kestrels showed a sexual spatial segregation in foraging areas, with males foraging closer to the colony than females.[Conclusions] The lesser kestrel responds to changes in energy demand throughout the breeding season with its foraging movement strategy, but in a different way depending on parental sex. The sexual spatial segregation observed is likely to be the result of an adaptive foraging strategy based on role specialization to reduce prey depletion close to the colony and intersexual competition in order to improve breeding success.This study was funded by “HORUS” (ref: P09-RNM-04588), Consejería de Innovación, Ciencia y Empresa of the Junta de Andalucía, by “KESTREL-MOVE” (ref: CGL2016-79249-P), Ministerio de Economía y Competitividad MINECO, Spain (both projects received FEDER funds from the European Union), and by “Migratory decisions in a changing world: mechanisms and drivers of changing migratory behaviour”, NERC standard grants, United Kindgdom. J. Hernández-Pliego and C. Rodríguez were supported by JAE-predoc and a JAE-doc fellowships, respectively, co-funded by the Spanish National Research Council and the European Social Fund. The funders had no role in the design of the study and collection, analysis, and interpretation of data and in writing the manuscript

Effects of wind farms on Montagu's harrier (Circus pygargus) in southern Spain

© 2015 Elsevier Ltd. To study the potential impact of wind turbines and associated structures on Montagu's harriers Circus pygargus, we located 111 nests over five years (18-28 nests per year) and compared their distances to several features (natural and anthropogenic) between wind farm pre- and post-construction periods using a before-after (BA) study design. We analysed abundance and density of nests and colonies through the study period. We also fitted a predictive model of nest occurrence using distance-to-feature variables and habitat as predictors. Lastly, Montagu's harrier fatalities from collision with wind turbines were estimated. No differences were detected between pre- and post-construction periods in nest or colony abundances. We found that harriers nested closer to the locations of wind turbines and power lines after wind farm construction, although distance to closest track did not change. We detected a higher spatial aggregation of Montagu's harrier nests after wind farms were installed, when the distribution of nests was mostly explained by habitat and distance to the closest track. Distance to wind turbine was apparently not influential. Fatality through collision was relatively uncommon during the study period. Our findings demonstrate that the construction, operation and maintenance of wind farms did not seem to adversely affect Montagu's harrier nesting decisions in our study area. However, we encourage further studies including reproductive parameters and foraging strategies of Montagu's harrier to provide a complete investigation of potential impacts of wind farms on this species.Peer Reviewe

Why Do Kestrels Soar?

<div><p>Individuals allocate considerable amounts of energy to movement, which ultimately affects their ability to survive and reproduce. Birds fly by flapping their wings, which is dependent on the chemical energy produced by muscle work, or use soaring-gliding flight, in which chemical energy is replaced with energy harvested from moving air masses, such as thermals. Flapping flight requires more energy than soaring-gliding flight, and this difference in the use of energy increases with body mass. However, soaring-gliding results in lower speeds than flapping, especially for small species. Birds therefore face a trade-off between energy and time costs when deciding which flight strategy to use. Raptors are a group of large birds that typically soar. As relatively light weight raptors, falcons can either soar on weak thermals or fly by flapping with low energy costs. In this paper, we study the flight behavior of the insectivorous lesser kestrel (<i>Falco naumanni</i>) during foraging trips and the influence of solar radiation, which we have adopted as a proxy for thermal formation, on kestrel flight variables. We tracked 35 individuals from two colonies using high frequency GPS-dataloggers over four consecutive breeding seasons. Contrary to expectations, kestrels relied heavily on thermal soaring when foraging, especially during periods of high solar radiation. This produced a circadian pattern in the kestrel flight strategy that led to a spatial segregation of foraging areas. Kestrels flapped towards foraging areas close to the colony when thermals were not available. However, as soon as thermals were formed, they soared on them towards foraging areas far from the colony, especially when they were surrounded by poor foraging habitats. This reduced the chick provisioning rate at the colony. Given that lesser kestrels have a preference for feeding on large insects, and considering the average distance they cover to capture them during foraging trips, to commute using flapping flight would result in a negative energy balance for the family group. Our results show that lesser kestrels prioritize saving energy when foraging, suggesting that kestrels are more energy than time-constrained during the breeding season.</p></div