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Muscular stomach or gizzard is one of the most important parts of gastrointestinal tract in birds for mechanical and chemical digestion and can vary depending on the bird's eating habits. In the present study, the morphology of muscular stomach in common kestrel, steppe eagle, golden eagle and imperial eagle has been investigated and compared. Materials & Methods: In this study, common kestrel (n=4), steppe eagle (n=5), golden eagle (n=4) and imperial eagle (n=6) which died because of broken leg and wing, sent to the faculty of veterinary science at Bu-Ali Sina University of Hamadan. The gizzard samples were fixed in 10% formalin buffer solution and the histological process was carried. Finally, H&E, Masson's trichrome, Orcein and PAS staining were utilized. Results: The most important difference between the stomach of steppe, golden, and imperial eagles and common kestrel was the lack of keratinous layer in the surface of stomach in eagles. The histological structure of stomach in imperial eagle was more similar to that of steppe eagle. The differences of the stomach of imperial eagle were due to the presence of a thick muscle layer in several different rows with different directions in comparison with steppe and golden eagles. Conclusions: It can be concluded that, the structure of muscular stomach in common kestrel was similar to gizzard, while the stomach in three species of eagles did not have a keratinous layer. [ABSTRACT FROM AUTHOR]

Short-toed Eagle Circaetus gallicus is the only snake eagle that nests in the Palearctic. Its diet has been studied in several European countries and it is essentially based on reptiles. The aims of this work were to characterise the feeding habits of Short-toed Eagle breeding in the Tolfa Mountains (Central Italy) including a comparison of the diet with that of other populations. Moreover, we assessed changes in the diet of the former population using published data collected more than 35 years ago. We monitored five nests and three roosts between 2020 and 2021. Using camera traps and the collection and analysis of feeding remains, a total of 247 prey items were identified. The diet of the sampled nests/individuals was clearly snake-based (93.5% of prey spectrum). We found no significant differences between the diet of nestlings and adult individuals. The main prey was the Western Whip Snake Hierophis viridiflavus (83% of snakes captured), probably due to its high availability in the environment and its average size, which is positively selected by the Short-toed Eagle. Long-term comparison with previous data shows an over time contraction of the diet breadth with a relative increase of Western Whip Snake compared to other prey. The same pattern is observed in long-term studies on the snake community of our study area and is probably linked to both local anthropogenic impacts and global warming, which tend to favour thermophilic and generalist snake species During the reproductive period our population showed a narrower diet breadth when compared to the diet of other Mediterranean sites, but a similar overall structure, with a comparable frequency of snakes. The populations with the wider diet breadth are those located in areas with a greater abundance of thermophilic snake species of medium to large size, such as France, Spain and Greece. [ABSTRACT FROM AUTHOR]

During the chick-rearing period, strategies of prey provisioning can have a decisive impact on several reproductive aspects .Adults can maximise their foraging effort by increasing the number of fish-prey brought to the nest per unit time and/or by catching moreenergetic prey, i .e .larger prey or prey with relatively higher caloric values. The CommonKingfisher (Alcedo atthis) is a fish-eating predator normally breeding in freshwater habitats .We collected data on fish-prey proportions found at nests (n= 10) and determined thecaloric content of such fish-prey (6 species overall) in rivers in northern Iberia. The proportion of each fish-prey species in the nest was not correlated with the proportion oflipids, proteins or carbohydrates, nor with its caloric content .Furthermore, the most energetic prey was not the most commonly consumed, illustrating the fact that the CommonKingfisher does not fish for the most energetic prey during the chick-rearing period. [ABSTRACT FROM AUTHOR]

Animal home ranges are typically characterized by their size, shape and a given time interval and can be affected by many different biotic and abiotic factors. Understanding of animal movements and assessing the size of their home ranges are essential topics in ecology and necessary for effective species protection, especially concerning birds of prey. Using radio-telemetry (VHF; 2.1 g tail-mounted tags) we studied the movements of two Tengmalm's owl (Aegolius funereus) males during the breeding season 2008 in a mountain area of Central Europe (the Czech Republic, the Jizera Mountains: 50° 50' N, 15° 16' E). We determined their average nocturnal hunting and diurnal roosting home range sizes. The mean hunting home range size calculated according to the 90% fixed kernel density estimator was 251.1 ± 43.2 ha (± SD). The mean roosting home range size calculated according to the 1 00% minimum convex polygon method was 57.9 ± 1 5.8 ha (± SD). The sizes of hunting home ranges during breeding in this study coincide with those previously reported by other studies focusing on Tengmalm's owl males. However, we found the roosting home ranges were smaller in size compared to those previously reported. This result was most probably connected with different habitat structure in our study area, which was severally damaged by air-pollution in the past, thus probably offering fewer suitable hiding-places, for instance from predators. We found the roosting locations were concentrated in the oldest and densest Norway spruce forest patches. We emphasize that these parts of forest stands require the highest possible protection in our study area. [ABSTRACT FROM AUTHOR]

Avian communal roosts provide insight into evolution and serve as focal points for conservation. Nonbreeding Crested Caracaras (Caracara cheriway; hereafter caracaras) use communal roosts, but evolutionary implications have not been explored. Though nonbreeding caracaras are nonmigratory, the scientific literature fails to explain seasonal differences in their movement and survival concurrent with seasonal consistency in their habitat and social ecology. In the Social Refuge–Territory Prospecting hypothesis we propose, socially subordinate nonbreeding caracaras precluded from breeding by habitat limitation use communal roosts as social refuges to avoid aggression from dominant territory holders during nonbreeding seasons, and engage in territory prospecting during breeding seasons. Communal roosts thus become central places from which to forage not for food, but for a breeding territory. Because foraging gains are stored as remembered information, competition costs resulting from public information are preempted. For the Social Refuge–Territory Prospecting hypothesis to be valid, two criteria need to be met. First, communal roost use needs to be higher during nonbreeding seasons. Second, a measure of fitness needs to be used to evaluate the hypothesis as an evolutionarily stable strategy. To meet these criteria, in this study we report that numbers of nonbreeding caracaras using a communal roost in Florida are higher during nonbreeding seasons (mean = 111.8 individuals / night) than during breeding seasons (mean = 60.7 individuals / night) as counted from August 2006–April 2009 (n = 407 counts). We also compare differential survival by season from previous work to demonstrate that by limiting exploratory movements to times when prospecting is most informative, nonbreeding caracaras balance maximizing survival against the likelihood of securing a breeding territory. Our hypothesis provides a unifying explanation for otherwise unexplained paradoxes in the ecology of nonbreeding caracaras, and may be useful in guiding conservation and expanding our understanding of the ecology of other communally roosting birds. [ABSTRACT FROM AUTHOR]

Highlights • The paper describes a computational model of prey pursuit in echolocating bats, the only mammals to hunt on the wing. • In contrast to earlier work, we model head movements observed in bats. • The responsiveness of the gaze direction allows bats to pursue and capture insects using reactive control. Abstract Echolocating bats are the only mammals engaging in airborne pursuit. In this paper, we implement a reactive model of sonar based prey pursuit in bats. Our simulations include a realistic prey localization mechanism as well as a model of the bat’s motor behavior. In contrast to previous work, our model incorporates bats’ ability to execute rapid saccadic scanning motions keeping the prey within its field of view. Decoupling the flight direction from the gaze direction allows our model to capture erratically moving prey using reactive control. We conclude that the rapid shifts in gaze direction allow bats to deal with the narrow field of view provided by their sonar system. [ABSTRACT FROM AUTHOR]

The human-wildlife conflict between beekeeping and wild birds is complicated, and further detailed studies are needed for a deeper understanding of the role and possible impact of predation by wild birds on honey production and bee colony health. Another potentially negative effect of birds on bees could be the dissemination of pathogens, such as Nosema ceranae. However, other important aspects of the complex relationship between bees and wild birds should be considered. First, honey bees have developed behavioural defences against the pressure of native predatory birds. Second, the ethology of some of these predators is fascinating like the interesting mutualistic relationship established between the so-called honeyguides and beekeepers. Finally, predatory birds could be important in the biocontrol of other bee enemies such as the invasive Asian hornet. Taking these additional aspects into consideration would provide a better insight into the conflict between wild animal conservation and human activity. [ABSTRACT FROM AUTHOR]

ABSTRACT: White‐tailed sea eagles (Haliaeetus albicilla) exhibit one of the highest mortality rates at wind power plants (WPPs) among raptor species in Europe, but data on circumstances of collision and behavioral response to WPPs are scarce. We analyzed the effect of WPPs on movement patterns of sea eagles in Germany with satellite telemetry. We analyzed ranging behavior and environmental parameters that influence the behavioral flight response to WPPs using multiple regression models. During 2003 through 2009 we radio‐tracked 25 white‐tailed sea eagles in northern Germany (8 territorial, 7 non‐territorial, 10 young eagles marked as nestlings). Mean home range sizes of territorial eagles varied with individuals tracked and the estimation method applied, ranging from 2.7 km2 to 669.7 km2. Sex or breeding status did not influence home range size. Ranging behavior varied between individuals and was correlated with habitat quality (i.e., nest distance to nearest water source and to anthropgogenic structure) and weather conditions. Among the 9 territorial eagles, only 1 individual resided within the officially proposed 3‐km minimum safety distance between nest and planned WPP. However, others frequently moved >3 km away from their nests, leaving the proposed safety area. One eagle inhabiting a territory within intensively cultivated landscape frequently approached a WPP and did not alter its movement patterns near the WPP compared to control areas. We identified several features visited by the eagles (e.g., perches, small lakes). To mitigate the collision risk of eagles, the recommended safety radius of 3 km between nest and WPP should become an international standard with a safe flight corridor to feeding grounds. To avoid frequent collisions at the population scale with WPPs, it is important to construct WPPs only outside the main distribution areas of white‐tailed sea eagles. © 2018 The Wildlife Society. [ABSTRACT FROM AUTHOR]

Most raptor species rely on perches for hunting, resting, preening, and roosting, and in many agricultural areas the availability of adequate perches can limit raptor abundance and diversity. This has negative implications for both raptor conservation and for the provisioning of natural pest control services for farmers. Installing artificial perches on agricultural lands can therefore benefit both raptors and farmers, but perches must be installed in optimal locations to maximize raptor use and minimize unnecessary costs to farmers. We monitored raptor use of artificial perches in a California vineyard over winter using remote photography to compare two sets of perch types: perches at the top versus perches at the bottom of a steep hill, and perches located among trees versus perches located in an open area. We found that raptors preferred perches on hilltops over perches at the base of hills, and that raptors seem to prefer perches in open habitat over perches located adjacent to trees, although a small sample size for this comparison limited our analysis. [ABSTRACT FROM AUTHOR]

Global urbanization is rapidly increasing, specifically within Africa. However, the effects of these processes on Africa's wildlife are largely unexplored. For many species, the effects are detrimental, whereas others are able to colonize these human-altered environments and can even thrive. Raptors are positioned at the top of the food chain and therefore particularly susceptible to environmental changes, and yet they are increasingly associated with urban areas. Given that adaptations to cope with urban stressors may differ from those occurring in more natural habitats, we might expect that directional selection in urban areas could account for phenotypic divergence between urban and rural individuals. This might include selection for different plumage coloration, which could be facilitated in color polymorphic species because no additional mutations are required to create variation. Color polymorphism is common in raptors, with 22% of the Accipitridae family being polymorphic. In this study, we focus on Black Sparrowhawks ( Accipiter melanoleucus) in Cape Town, South Africa. We explore whether the morphs are distributed differently along an urban-rural gradient and thus show a local adaptation. Using a long-term study (16 yr), we also investigate whether morph was related to the timing of breeding and breeding performance along the urban gradient. We found no differences of the morph distribution or of their breeding performance in relation to levels of urbanization. Our study represents the first to examine the breeding distribution of a polymorphic raptor in relation to urbanization and one of the first to explore avian productivity in relation to urbanization in Africa. [ABSTRACT FROM AUTHOR]

En Sudamérica, los corredores migratorios que utilizan las aves rapaces son en gran parte desconocidos, lo que obstaculiza el estudio y la conservación eficientes de estas especies. Realizamos un esfuerzo sistemático diurno para estimar el flujo migratorio durante el otoño austral en la pre-cordillera y cordillera de los Andes en el extremo norte de Chile. Elegimos esta región debido a que es el área más estrecha entre la costa del Océano Pacífico y la sección más ancha de la parte alta de la cordillera de los Andes y en base a datos de ubicación precisos de un individuo de Buteo albigula proporcionados por transmisores satelitales GPS. En este estudio documentamos la composición de especies, la fenología, y la abundancia promedio de aves rapaces migratorias, usando dos puntos de observación diferentes, registrando un total de 719 individuos de dos especies principales. Geranoaetus polyosoma representó el 58% de todos los individuos, migrando a una tasa promedio de 2.6 ± 0.6 aves/h. B.albigula fue menos común, con un promedio de 1.8 ± 0.5 aves/h. Empleando estimaciones conservadoras, este corredor es utilizado por 3-30% de la población biogeográfica estimada a nivel global de B. albigula y un porcentaje desconocido, pero superior al 4% de la población de G. polyosoma. Nuestros resultados documentan un mayor flujo migratorio de aves rapaces en comparación con estudios previos de conteos migratorios australes, lo que apoya la importancia de este corredor, al menos para estas dos especies. [Traducción de los autores editada] [ABSTRACT FROM AUTHOR]

We assessed the ability of southern house wrens ( Troglodytes aedon musculus) to recognize and discriminate different birds of prey. We exposed nesting birds to stuffed specimens of two sympatric predator species, the chimango caracara ( Milvago chimango, a nest predator) and the roadside hawk ( Buteo magnirostris, a predator of adults and nests), and to a dummy of a non-sympatric predator, the double-toothed kite ( Harpagus bidentatus, a predator of adults). Nesting wrens avoided going into their nest or took a longer time to resume their parental duties when exposed to the predators than when they were exposed to a control dummy ( Chrysomus ruficapillus, a sympatric blackbird). Nest avoidance was higher when birds were exposed to the roadside hawk but no differences were detected when exposed to the chimango caracara or the double-toothed kite. The results indicate that southern house wrens are able to recognize a predator, responding in a graded manner. Our findings support the hypothesis that southern house wrens exhibit a threat-sensitive response during breeding. Also, individuals were able to recognize the unknown predator but failed to correctly assess the threat level represented by it. We propose that correct assessment of threat level by house wrens requires direct experience with the predator, which might mediate in the modulation of the response. [ABSTRACT FROM AUTHOR]

The objective of this paper was to identify the main factors that explain the greater part of variation in bird of prey species richness (BPSR) along latitudinal gradient, particularly from Northern Europe to South Africa. For this purpose we used 26 environmental variables grouped according to the main hypotheses proposed to explain the regional variability in species richness. Because the relationship between species richness and environmental variables vary with spatial scale, we used two type of grain size (100 km x 100 km and 200 km x 200 km). To link explanatory environmental variables to BPSR, for each grain size, we used two multiple regression methods: a global model, the Ordinary Least Squares (OLS and a local model, the Geographically Weighted Regression (GWR). Further, we designed 11 different models based on combination of the environmental variables, both for OLS and GWR methods, in order to select the best one. For OLS method, variation in BPSR across the study area was best predicted by total model (all variables), both for finer (R2 adjusted = 0.712; AICc = 22394.89 and coarser spatial scales (R2 adjusted = 0.804; AICc = 4888.98). For GWR method, the (climate + habitat heterogeneity) model was the best model regarding variation explaination and model performances, both for finer (R2 adjusted = 0.953; AICc = 16890.49 and coarser (R2 adjusted = 0.958; AICc = 3909.18) resolutions. The GWR regression models performed better than OLS models in explaining variation in BPSR, the improvement of models performance was evident.In our study, both regression methods and analysis of variance partitioning lead to the conclusion that climate (particularly PC2) and habitat heterogeneity (particularly HABNB) were the most influental factors in determining BPSR at the spatial scales analyzed in this study. [ABSTRACT FROM AUTHOR]

El término rapaz, utilizado hoy en día ampliamente a través de diversas disciplinas más allá de la ciencia y la naturaleza, tiene orígenes que convergen hasta el Proto-Indo-Europeo (PIE), una lengua hipotética anterior a la mayoría de las lenguas del mundo. Se piensa que la raíz PIE postulada para h1rep representaba la acción de 'agarrar' o 'desplumar'. La raíz PIE se convirtió en Latín Clásico (75 AEC-3 EC) en la raíz verbal rap- y produjo la base de numerosas palabras, incluyendo rapaz. El camino léxico para rapaz en el inglés moderno siguió al menos tres rutas independientes y ha deambulado a través del latín, inglés medio, alemán y francés antes de establecerse en nuestro actual léxico del inglés moderno. Rapaz ha tomado significados más allá de su raíz original, incluyendo 'robar, saquear, llevarse, incautar, forzar y violar'. Todas ellas han contribuido a la estigmatización de la naturaleza de estos depredadores. La amplitud de significados puede ser atribuida a la licencia poética por parte de los autores latinos antiguos. Las primeras referencias vinieron de trabajos de literatura y poesía del Latín Clásico, seguido de la migración como un término latino hacia la religión y la jurisprudencia desde los primeros días de la Cristiandad, y finalmente hasta el inglés comenzando a finales del siglo XIV, y en la taxonomía a comienzos del siglo XIX. [Traducción del equipo editorial] [ABSTRACT FROM AUTHOR]

The presence of intraspecific competitors can increase foraging costs through exploitation of resources. Optimal foraging theory suggests that when the cost of pursuing one food type increases, alternative resources should be accepted. Accepting novel foods readily might put a competitor at an advantage over its more conservative rivals in the race for sufficient sustenance, but also opens it to the danger of poisoning by chemically protected food. Dietary conservatism is a foraging behaviour characterised by a prolonged avoidance of novel foods, long after neophobia (initial fear of novel objects) has been overcome, and so might be seen as a disadvantage to foragers in a competitive situation. There are two stable foraging strategies found within forager populations: 1) adventurous consumers (AC) which rapidly accept novel foods and 2) foragers showing dietary conservatism (DC). The expression of these two strategies may also vary with environmental conditions. The aim of this study was to investigate the effect of intraspecific competition on the levels of dietary conservatism displayed among wild caught blue tits Cyanistes caeruleus. Blue tits were offered items of both novel and familiar foods under two conditions: with a competitor and without. Our results showed that individuals who experienced competition incorporated the novel items into their diet faster than those who did not experience competition. This study demonstrates, for the first time, the degree of plasticity in the expression of the DC trait using wild birds in laboratory conditions. This plasticity represents a significant adaptation to reduce the costs of foraging conservatively when novel alternative resources should be accepted. [ABSTRACT FROM AUTHOR]

Raptors are exposed to a wide variety of human-related mortality agents, and yet population-level effects are rarely quantified. Doing so requires modeling vital rates in the context of species life-history, behavior, and population dynamics theory. In this paper, we explore the details of such an analysis by focusing on the demography of a resident, tree-nesting population of golden eagles (Aquila chrysaetos) in the vicinity of an extensive (142 km2) windfarm in California. During 1994–2000, we tracked the fates of >250 radio-marked individuals of four life-stages and conducted five annual surveys of territory occupancy and reproduction. Collisions with wind turbines accounted for 41% of 88 uncensored fatalities, most of which were subadults and nonbreeding adults (floaters). A consistent overall male preponderance in the population meant that females were the limiting sex in this territorial, monogamous species. Estimates of potential population growth rate and associated variance indicated a stable breeding population, but one for which any further decrease in vital rates would require immigrant floaters to fill territory vacancies. Occupancy surveys 5 and 13 years later (2005 and 2013) showed that the nesting population remained intact, and no upward trend was apparent in the proportion of subadult eagles as pair members, a condition that would have suggested a deficit of adult replacements. However, the number of golden eagle pairs required to support windfarm mortality was large. We estimated that the entire annual reproductive output of 216–255 breeding pairs would have been necessary to support published estimates of 55–65 turbine blade-strike fatalities per year. Although the vital rates forming the basis for these calculations may have changed since the data were collected, our approach should be useful for gaining a clearer understanding of how anthropogenic mortality affects the health of raptor populations, particularly those species with delayed maturity and naturally low reproductive rates. [ABSTRACT FROM AUTHOR]

Flying birds have been documented to respond in different ways to the presence of wind farms. Such responses are species- and site-specific, with wind farm design playing an important role. Between 2009 and 2014, the length of rows of wind turbines within our study area increased from 3·4 km to ∼7·5 km, and the total area occupied by wind farms increased from 6·47 km2 to 14·21 km2. This area is located on an important migratory corridor in southern Mexico., We used marine radar and hawk-watch monitoring stations to collect data during six consecutive autumn seasons from a single wind farm. We analysed the response of migrating raptors to the presence of two new wind farms by comparing the mean bearing of flight trajectories and the number of intersections km−1 of trajectories with wind farm areas between 2009-2011 and 2012-2014, representing the pre- and post-construction stages of the new wind farms., Mean raptor count was >600 000 individuals for the six seasons. The most abundant species were Turkey Vulture Cathartes aura, Swainson's Hawk Buteo swainsoni and Broad-winged hawk Buteo platypterus. Between 79% and 97% of migration occurred in October. Radar monitoring overlapped with the peak migratory activity each season., We observed significant differences between periods, involving more scattering in flight bearings and less intersections km−1 of trajectory in the post- than in the pre-construction period, implying an avoidance of the new wind farms., Synthesis and applications. We show that migrating raptors adjusted their flight trajectories to avoid new wind farms, but also discuss the extent and limitations of our findings. Our results from our hawk-watch monitoring station, which represent the first published account about the seasonality and intensity of raptor migration in the area, could be used by decision-makers for careful planning of future wind energy developments in the area. Our results might aid in the conservation of those species of raptors that migrate through the Isthmus of Tehuantepec. [ABSTRACT FROM AUTHOR]

Little is known of how territoriality of tropical forest raptors may be influenced by habitat reduction or fragmentation. We compared territory size and territorial defense behavior of Collared Forest-Falcons ( Micrastur semitorquatus) in four 2500-ha survey quadrants with differing percent cover of tropical moist forest in a modified landscape in east-central Mexico. We delineated territories of Collared Forest-Falcons using playbacks of a simulated intruder, and calculated territory size and core area size using GIS. We also measured latency, duration, and type of territorial response of falcons to playbacks. We estimated a mean territory size of 205.5 ± 98.7 ha for seven Collared Forest-Falcons, although territories were significantly larger in low-forest-cover landscapes (mean 288.6 ± 76.9 ha), compared to those with high forest cover (mean 143.1 ± 58.3 ha). Collared Forest-Falcons showed stronger territorial behavior when defending territories with greater forest cover, responding for a longer time (5.9 ± 3.3 min), and including vocalizations with flights toward the speaker, compared to territories with low forest cover, where falcons mainly vocalized for 2 ± 1.1 min. Our results suggest that the Collared Forest-Falcon is sensitive to the extent of forest cover in the landscape, compensating for reduced forest cover by expanding the area defended, but investing less in defense of this area. This may have long-term implications for the acquisition of resources such as nest sites, and population dynamics of Collared Forest-Falcons in areas of reduced forest cover. [ABSTRACT FROM AUTHOR]

Although New Zealand's avifauna includes many unusual birds, species-level diversity within lineages is typically low. There are, however, several instances where different allied forms are recognized in each of the two main islands. Among them is the Kārearea Falco novaeseelandiae, which is the only surviving endemic raptor species in New Zealand. Recent analysis confirms it to be a distinct lineage in the global radiation of this genus and most closely related to the Aplomado Falcon Falco femoralis of South America. We examined body size metrics and neutral genetic markers in Kārearea sampled across New Zealand to assess subspecific variation within the species. We found strong evidence using linear modelling and Bayesian clustering for two distinct sizes within Kārearea, in addition to the recognized sexual dimorphism. The boundary between the size clusters coincides closely with the Cook Strait, a narrow seaway between the two largest islands. However, analysis of mitochondrial sequence data and nuclear microsatellites showed no compelling partitioning at neutral loci. These data suggest adaptive change along a stepped environmental cline. Lineage splitting in Kārearea has either yet to become apparent in the distribution of neutral genetic variation and/or regional adaptation is proceeding despite gene flow. [ABSTRACT FROM AUTHOR]

Raptors are always considered to have an extraordinary resolving power of their eyes (high visual acuity). Nevertheless, raptors differ in their diet and foraging tactics, which could lead to large differences in visual acuity. The visual acuity of an opportunist bird of prey, the Chimango caracara ( Mivalgo chimango ) was estimated by operant conditioning. Three birds were trained to discriminate two stimuli, a positive grey uniform pattern and a negative grating pattern stimulus. The visual acuity range from 15.08 to 39.83 cycles/degrees. When compared to other birds, they have a higher visual acuity than non-raptorial birds, but they have the lowest visual acuity found in bird of prey so far. We discuss this result in the context of the ecology of the bird, with special focus on it is foraging tactic. [ABSTRACT FROM AUTHOR]

Predatory species' usage of different prey types is affected by both prey availability and selectivity. The diet during the breeding season may affect the reproductive success of individual pairs. We studied the prey use of a small reversed size-dimorphic raptor, the Eurasian sparrowhawk Accipiter nisus, with respect to prey weight on two organizational levels. Using 13 years of data from southern Norway, we related reproductive output of individual breeding events to prey size taken. Further, we assessed the regional variation in prey usage between five Fennoscandian populations. This was done by fitting optimum-type functions to the prey species' numbers or relative predation risks. Pairs that successfully completed the season with more fledglings displayed less variation in prey size, suggesting a possible adaptive benefit of diet specialism, or possibly a correlative effect due to higher prey availability or lower female hunting effort. This finding contrasts with earlier raptor studies, which have suggested benefits of dietary (and hence nutritional) diversity. Indeed, our results might be limited to nutritionally substitutable prey items. We also found a tendency suggesting that older females raised more fledglings than 1-year-old females. In the population-level analysis, we found that optimum-type functions with constant width and spatially variable average best described the relationship between relative predation risk and log weight. This can reflect local conditions, such as prey availability. Our findings and new methodological tools could apply to a broader spectrum of predators. They also highlight the role of viewing usage or choice of prey at several spatial scales. [ABSTRACT FROM AUTHOR]

Diet studies present numerous methodological challenges. We evaluated the usefulness of commercially available trail-cameras for analyzing the diet of Northern Goshawks (Accipiter gentilis) as a model for nesting raptors during the period 2007–2011. We compared diet estimates obtained by direct camera monitoring of 80 nests with four indirect analyses of prey remains collected from the nests and surroundings (pellets, bones, feather-and-hair remains, and feather-hair-and-bone remains combined). In addition, we evaluated the performance of the trail-cameras and whether camera monitoring affected Goshawk behavior. The sensitivity of each diet-analysis method depended on prey size and taxonomic group, with no method providing unbiased estimates for all prey sizes and types. The cameras registered the greatest number of prey items and were probably the least biased method for estimating diet composition. Nevertheless this direct method yielded the largest proportion of prey unidentified to species level, and it underestimated small prey. Our trail-camera system was able to operate without maintenance for longer periods than what has been reported in previous studies with other types of cameras. Initially Goshawks showed distrust toward the cameras but they usually became habituated to its presence within 1–2 days. The habituation period was shorter for breeding pairs that had previous experience with cameras. Using trail-cameras to monitor prey provisioning to nests is an effective tool for studying the diet of nesting raptors. However, the technique is limited by technical failures and difficulties in identifying certain prey types. Our study also shows that cameras can alter adult Goshawk behavior, an aspect that must be controlled to minimize potential negative impacts. [ABSTRACT FROM AUTHOR]

ABSTRACT There is widespread evidence that multiple drivers of global change, such as habitat degradation, invasive species, and climate change, are influencing wildlife. Understanding how these drivers interact with and affect species may be difficult because outcomes depend on the magnitude and duration of environmental change and the life history of the organism. In addition, various environmental drivers may be evaluated and managed at different spatial scales. We used a historical dataset from 1991 to 1994 and current information from 2010 to 2012 to examine whether occupancy patterns of wintering raptors were consistent with regional changes in distribution or habitat conditions within a local management unit, the Morley Nelson Snake River Birds of Prey National Conservation Area (NCA). We predicted that if local populations reflected regional shifts, then rates of raptor occupancy within the NCA would be higher compared to historical estimates and birds would use different habitats compared to historical use. Alternatively, if local populations were determined by habitat conditions, then we predicted that occupancy rate of raptors within the NCA would be lower compared to historical estimates and current habitat use would be consistent with historical use. Results support the hypothesis that northward distributional shifts influenced wintering raptor populations in southwest Idaho to a greater extent than local habitat conditions. Wintering raptors had higher occupancy rates in 2010-2012 compared to 1991-1994, whereas invasive grasses have increased and native shrubs have decreased suggesting that habitat suitability for raptors has declined over time. On the species level, changes in habitat use were associated with greater increases in occupancy rates in 2010-2012 compared to 1991-1994. Organisms flexible in their habitat use may be better able to respond to continental forces driving distribution shifts. Conversely, habitat or prey specialists may be poorly equipped to handle such rapid, large-scale global change. Further, Grinnellian niche models predicting species response to change by mapping current habitat use to forecasted vegetation maps should consider plasticity in habitat use and changes in the cost-benefits of life-history strategies. © 2015 The Wildlife Society. [ABSTRACT FROM AUTHOR]

A predator's body size correlates with its prey size. Change in the diet may call for changes in the hunting mode and traits determining hunting success. We explored long-term trends in sternum size and shape in the northern goshawk by applying geometric morphometrics. Tetraonids, the primary prey of the goshawk, have decreased and been replaced by smaller birds in the diet. We expected that the size of the goshawk has decreased accordingly more in males than females based on earlier observations of outer morphology. We also expected changes in sternum shape as a function of changes in hunting mode. Size of both sexes has decreased during the preceding decades (1962−2008), seemingly reflecting a shift in prey size and hunting mode. Female goshawks hunting also mammalian prey tend to have a pronouncedly ' Buteo-type' sternum compared to males preying upon birds. Interestingly, the shrinkage of body size resulted in an increasingly ' Buteo-type' sternum in both sexes. In addition, the sternum shape in birds that died accidentally (i.e., fit individuals) was more Buteo-type than in starved ones, hinting that selection was towards a Buteo-type sternum shape. We conclude that these observed patterns are likely due to directional selection driven by changes in the diet towards smaller and more agile prey. On the other hand, global warming is predicted to also cause a decrease in size, thus these two scenarios are inseparable. Because of difficulties in studying fitness-related phenotypic changes of large raptors in the field, time series of museum exemplars collected over a wide geographical area may give answers to this conundrum. [ABSTRACT FROM AUTHOR]

The article offers information about the importance of broadcasting calls using tapes or digital recorders and speakers in surveys on Peregrine Falcons scientifically termed as Falco peregrinus anatum. Topics discussed include importance of response to broadcast calls by diurnal raptors in Alaska, broadcasting calls may be helpful in locating the birds and territorial behavior of falcons. It further discusses the significance of sound intensity in showing interaction.

The article discusses the observations on the post-fledging period of a group of collared sparrowhawks, Accipiter cirrocephalus, that were conducted for 64 hours over 20 days in suburban Bunbaberg in Queensland. Topics discussed include the first sighting of the nest in a small exotic plantation behind a school in Bundaberg on August 29, 2012, the behaviour of the adult sparrowhawks and several incidents of parental prey deliveries to juvenile sparrowhawk.

The article discusses a study which used molecular dating and ancestral state reconstruction to infer the origins and evolutionary changes in migratory behavior and ancestral area reconstruction to investigate historical patterns of range evolution in accipitrid birds of prey, or Accipitriformes. Topics include the phylogeny and historical bigeography of diurnal birds of prey and the ecological and behavioral traits associated with migratoriness in the group.

Five juveniles of the imperial eagle were tracked during 2011-201 2. Movements were monitored in the western part of Slovakia and in the border area between Austria, Hungary and Slovakia. Three eagles came from the Záhorská nížina Lowlands and the others from the Malé Karpaty Mts and the Podunajská nížina Lowlands. Post-fledging movements were recorded in areas around the nests. Post-fledging areas covered a large territory (minimum convex polygons - 89, 941 , 969 km2). During the postfledging period the eagles carried out exploratory flights (1 2-33 km from the nest). One temporary settlement area (TSA) was identified in the border area between Austria, Hungary and Slovakia (minimum convex polygon - 68 km2). Two eagles with radio transmitters were recorded in this area. In the TSA and the post-fledging areas two habitat categories were dominant: arable land and forests. Heterogeneous agricultural areas were also important in the TSA (8%). [ABSTRACT FROM AUTHOR]

Although unconfirmed reports on the breeding of the eastern imperial eagle exist from as early as in 1 920s, the first confirmed breeding only took place in 1 998. Since then, 1-5 pairs have bred annually, chiefly in the South Moravia region (the Breclav, Znojmo and the Brno-venkov districts). Out of 37 breeding attempts, 26 (i.e. 70%) were successful, with 48 young reared. The paper summarizes some characteristics of the breeding biology (productivity, breeding losses, nesting tree species, nest height, nest turnover, minimum convex polygon of the nests [nesting trees] built by individual pairs) as well as ringing recoveries. Out of 42 ringed chicks, 39 fledged successfully and produced 3 recoveries (Slovakia - 2, Austria - 1 ). Three foreign ringed birds were also sighted in the Czech Republic. The most interesting case is the breeding of a 1 9-year-old female born in eastern Slovakia (distance 336 km), found via a photo of the ring (V. Gahura, 201 3). [ABSTRACT FROM AUTHOR]

During the period 2008-201 3, 32 different breeding territories were occupied by eastern imperial eagles (EIEs). These territories were mainly distributed in two regions: the Dervent Heights/Yıldız Mts. and the area to the north of the Marmara sea coast. The nearest neighbour distance established was 4.2 km. The mean distance between pairs was 1 0.44±2.95 km. The mean value of breeding success for the period 2008-201 3, including 1 07 cases of incubation, was 1 .01±0.1 0. The mean breeding success of birds in the Marmara region (1 .05±0.78) was higher than that in the Dervent Heights/Yıldız Mts. (0.91±0.84). The present study on the diet of the EIE was based on the remains of 582 prey items of at least 70 taxa. Mammals were the most common group (46.5%), followed by birds (32.4%) and reptiles (20.3%). The white-breasted hedgehog (Erinaceus roumanicus) was the most common prey, followed by two tortoises - Hermann's tortoise (Eurotestudo hermanni) and the Greek tortoise (Testudo graeca) - which together accounted for a total of 1 4.4% of the prey caught. The prey species particularly represented in the food spectrum of the studied pairs were: the yellow-legged gull (Larus michahellis), the European souslik (Spermophilus citellus), the chicken (Gallus gallus f. domestica) and the white stork (Ciconia ciconia). These species together accounted for 67.8% of the prey caught. There was a statistically significant difference (Z=2.52, p=0.01 ) in the food preferences of the EIEs in the two studied regions. [ABSTRACT FROM AUTHOR]

Some of the known major bottlenecks on European flyways are yet insufficiently explored and require more intensive study. On the basis of raptor counts on the Vistula Spit (southern Baltic coast, Poland), from 15th August to 15th November 2008-2011, we consider this bottleneck to be important at a European scale. Every year we observed there almost 11,000 individuals of 22 raptor species. The flyway is especially important for Peregrine Falcons, Hen Harriers, Merlins and Eurasian Sparrowhawks. To analyse the species composition observed we related the mean annual number of raptors recorded on the Vistula Spit to the corresponding numbers at Falsterbo. The linear mixed model showed that the median migration date showed a significant effect on the species composition and the flight strategies a nearly significant effect. The southern Baltic coast seems to be the most important bottleneck in the autumn passage for late migrating raptors with flapping flight and differ in composition and numbers of species from the flyway at Falsterbo. [ABSTRACT FROM AUTHOR]

The article focuses on the observation towards the foraging, behaviour and nest-trees of the Brahminy Kite (Haliastur indus) in Darwin, Northern Territory. It highlights the territorial disputes between adult Kites and their method of capturing insects by crashing into trees. It also provides information on double-brooding among Brown Goshawks (Accipiter fasciatus).

The article presents a study on raptor migration at the Pelagie Islands. According to the author, the Pelagie Islands attract many migrants such as passerine moving between Europe and North Africa because of their strategic location. The author confirms that the southern Sicilian Channel is largely avoided by the larger soaring raptors although smaller species passed the islands regularly to help them cross the Sicilian Channel.

We compared scavenging bird abundance and diversity across 17 estuaries on the Central Coast of British Columbia, Canada in relation to landscape characteristics and biomass of spawning salmon and senescent and depredated salmon carcasses. We discovered that all metrics for spawning salmon and carcass biomasses were strong predictors of scavenger abundance and diversity. Specifically, Shannon's diversity, which emphasizes rare species richness, and total abundances of scavengers, corvids ( Corvus spp.), and small and large gulls ( Larus spp.) were most strongly predicted by total biomass of carcasses. In contrast, the abundance of bald eagles Haliaeetus leucocephalus was most strongly predicted by biomass of carcasses that had been killed or scavenged by other predators (mostly bears and wolves). Simpson's diversity, which emphasizes evenness of common species, was best predicted by total spawning salmon biomass. Estuary area also featured prominently among top predictors of most scavenger metrics. Our results suggest a link between terrestrial salmon predators and bald eagles, and that available salmon biomass is important for maintaining the abundance and diversity of scavenging birds that congregate at estuaries throughout the spawning season. [ABSTRACT FROM AUTHOR]

One of the most common explanations of the alternative nest-building behavior in raptors' population is the "Ectoparasite-avoidance'' hypothesis, which claims that switching to alternative nests each year reduces nests' parasites that could decrease their breeding success. Our aim was to investigate this hypothesis concerning the Judean Long-legged Buzzard (Buteo rufinus) and Short-toed Eagle (Circaetus gallicus) population, in Israel. Furthermore, we also investigated whether any specific parasites for each of these raptors' species actually exist. Thirty-one nests of Long-legged Buzzards (LLB) and 61 nests of Shorttoed Eagles (STE) were located and systematically examined during the period of February-September 2011, in an area of 450 km2 in the Judean Foothills, Israel. Nest material samples were collected from the center of the nest of 26 LLB and 45 STE nests. Four specimens of the Mallophaga Laemobothrion maximum were isolated from three nests of LLB and one male of Degeeriella leucopleura from a nest of STE. In addition, a hard tick larva (Rhipicephalus sp.), an argasid nymph (Argas sp.) and six specimens of dermanyssid mites were isolated from nests of STE. In 82.1% of the LLB nests, Coleoptera larvae and/or adults were found, most of them belonging to the families Scarabaeidae, Buprestidae, Elateridae and Dermestidae. In 89.8% of the STE nests, Coleoptera larvae and/or adults were found, most of them belonging to the families Buprestidae, Tenebrionidae, Curculionidae, Dermestidae, Elateridae, Coccinellidae and Chrysomelidae. The vast majority of the isolated beetles were damaged and in more or less small pieces. In addition, few specimens of silverfish (Lepismatidae), book lice (Psocidae), ants (Formicidae) and true flies (Muscidae), as well as spiders (Araneae), scorpions (Scorpionida) and pseudoscorpions (Pseudoscorpionida) were isolated from the nests of both species. Although nest parasites were actually found, in significant small numbers, we cannot support the "ectoparasite-avoidance" hypothesis in our study system. Furthermore, no species specific ectoparasites for either LLB or STE were found. [ABSTRACT FROM AUTHOR]

The level of fidelity to potential nest site in representatives of different bird of prey species (Falconiformes) has been studied as dependent on population density and land-use status of the nesting area (a specially protected natural area or unprotected forest area). Species with high and low parameters of nest site fidelity and occupancy have been distinguished. The former group includes the Common Buzzard ( Buteo buteo), Booted Eagle ( Hieraaetus pennatus), and White-tailed Sea Eagle ( Haliaeetus albicilla): no less than 60% of observed pairs have not changed their nest sites and nests during 5 years. The latter group includes the Common Kestrel ( Falco tinnunculus), European Honey Buzzard ( Pernis apivorus), and, at the nest level, Northern Goshawk ( Accipiter gentiles). [ABSTRACT FROM AUTHOR]

There is a debate on whether an influence of biotic interactions on species distributions can be reflected at macro-scale levels. Whereas the influence of biotic interactions on spatial arrangements is beginning to be studied at local scales, similar studies at macro-scale levels are scarce. There is no example disentangling, from other similarities with related species, the influence of predator-prey interactions on species distributions at macro-scale levels. In this study we aimed to disentangle predator-prey interactions from species distribution data following an experimental approach including a factorial design. As a case of study we selected the short-toed eagle because of its known specialization on certain prey reptiles. We used presence-absence data at a 100 km2 spatial resolution to extract the explanatory capacity of different environmental predictors (five abiotic and two biotic predictors) on the short-toed eagle species distribution in peninsular Spain. Abiotic predictors were relevant climatic and topographic variables, and relevant biotic predictors were prey richness and forest density. In addition to the short-toed eagle, we also obtained the predictor's explanatory capacities for 1) species of the same family Accipitridae (as a reference), 2) for other birds of different families (as controls) and 3) artificial species with randomly selected presences (as null models). We run 650 models to test for similarities of the short-toed eagle, controls and null models with reference species, assessed by regressions of explanatory capacities. We found higher similarities between the short-toed eagle and other species of the family Accipitridae than for the other two groups. Once corrected by the family effect, our analyses revealed a signal of predator-prey interaction embedded in species distribution data. This result was corroborated with additional analyses testing for differences in the concordance between the distributions of different bird categories and the distributions of either prey or non-prey species of the short-toed eagle. Our analyses were useful to disentangle a signal of predator-prey interactions from species distribution data at a macro-scale. This study highlights the importance of disentangling specific features from the variation shared with a given taxonomic level. [ABSTRACT FROM AUTHOR]

The article presents a study on the effect of phenological change on the spring and autumn migration of North American raptors. The researcher conducted the project in the Whitefish Point Bird Observatory and Hawk Ridge Bird Observatory in North America. He concludes the timing is earlier in spring and later in autumn.

The article examines the feeding and foraging behaviour of Australasian Bittern Botaurus poiciloptilus, a waterbird that is listed as endangered in Australia and New Zealand. As the bird forage during daylight hours, its primary prey species was the Growling Grass Frog Litoria raniformis. A description of the hunting behaviour of the waterbird and its manner of preparing the frogs for swallowing including dunking them in water before being swallowed is provided. It notes the significance of the predator-prey relationship between the Bittern and the Growling Grass Frog.

Intraguild predation, a form of omnivory that can occur in simple food webs when one species preys on and competes for limiting resources with another species, can have either a stabilizing effect (McCann and Hastings in Proc. R. Soc. Lond. B 264:1249-1254, ) or a destabilizing effect (Holt and Polis in Am. Nat. 149:745-764, ), depending on the assumptions of the system. Another type of behavior that has been observed in simple food web experiments (Murdoch in Ecol. Monogr. 39:335-354, ) is prey switching. Prey switching can occur when the predator prefers the most abundant prey. This has also been shown to be capable of having either a stabilizing effect or a destabilizing effect and even possibly lead to predator extinction (VanLeeuwen et al. in Ecology 88:1571-1581, ). Therefore, it is clear that incorporating prey switching into an intraguild predation model could lead to unexpected consequences. In this paper, we propose and explore such a model. [ABSTRACT FROM AUTHOR]

The article presents a report on a Harpy Eagle (Harpia harpyja) observed to be feeding on a brown-throated three-toed sloth (Bradypus variegates). Due to their secretive nature, very few studies have reportedly been made on the feeding behavior of Harpy Eagles. On February 24 to 27, 2010, a Harpy Eagle was observed feeding on a brown-throated three-toed sloth. It was the first of a non-scavenging raptor feeding for more than two days on prey.

The article analyzes the effects of wind conditions on raptor migratory patterns at the Strait of Messina, Southern Italy. It compares the migration of European Honey-buzzards and Circus spp. which can be found in abundance in the area. The birds were observed between Sicily and continental Italy and between Scilla and Villa S. Giovanni. Variables such as species, age and sex classes were observed. The study suggests that headwinds lead raptors to fly over land where they can exploit thermals and minimize risks associated with longer sea crossings.

The global growth of wind energy has outpaced our assessment of possible impacts on wildlife. There is a pressing need for studies with pre- and post-construction data to determine whether wind facilities will have detrimental effects on susceptible avian groups such as raptors. A pre- and post-construction study was conducted to determine the impact of a windfarm on the abundance and behaviour of raptors in Wisconsin, USA. Variation in abundance and behaviour was examined both within and among years and relative to selected spatial, temporal and weather covariates. Raptor avoidance rates and indices of collision risk were calculated. Raptor abundance post-construction was reduced by 47% compared to pre-construction levels. Flight behaviour varied by species, but most individuals remained at a distance of at least 100 m from turbines and above the height of the rotor zone. Turkey vultures Cathartes aura and red-tailed hawks Buteo jamaicensis displayed high-risk flight behaviours more often than all other raptor species, but also showed signs of avoidance. Red-tailed hawks were the only raptor species found dead beneath turbines during mortality searches. There were few observed mortalities and corrected mortality estimates were comparable to those from other windfarm studies. Synthesis and applications. The decline in raptor abundance post-construction together with other lines of evidence suggests some displacement from the windfarm project area. While certain species may be at risk, flight behaviour data and mortality estimates indicate that the majority of raptors may not be directly affected by the presence of turbines. The avoidance rates recorded in this study should be used to improve collision risk models, and both current and future windfarms should investigate avoidance behaviour post-construction. [ABSTRACT FROM AUTHOR]