Sit-and-wait for large prey: foraging strategy and prey choice of White-tailed Eagles

Nadjafzadeh, Mirjam; Hofer, Heribert; Krone, Oliver

doi:10.1007/s10336-015-1264-8

Cited by 42 publications

(48 citation statements)

References 42 publications

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“…The results for each dietary level are consistent with previous conventional diet studies (Nadjafzadeh et al . , ). A diet study on Bonelli's Eagles Aquila fasciata also documented an agreement between a conventional pellet analysis and SIAR (Resano‐Mayor et al .…”

Section: Discussionmentioning

confidence: 97%

“…We used a priori knowledge of the diet and food availability of White‐tailed Eagles in northeastern Germany obtained in a detailed analysis of food remains, pellet and stomach contents, and simultaneous monitoring of prey populations (Nadjafzadeh et al . , ) to select the most likely food sources. These comprised five fish and six waterfowl species, which would be captured alive by White‐tailed Eagles, and five game mammal species representing ingested carrion (Table ).…”

Section: Methodsmentioning

confidence: 99%

“…, Nadjafzadeh et al . ). Thirdly, lead poisoning is a major cause of death in White‐tailed Eagles (Krone et al .…”

mentioning

confidence: 99%

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Spatial, seasonal and individual variation in the diet of White‐tailed Eagles Haliaeetus albicilla assessed using stable isotope ratios

Nadjafzadeh

Voigt

Krone

2015

Ibis

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Many raptor species are considered to be generalists, taking a range of prey species. However, longitudinal dietary records are often scarce, although necessary for characterizing niche width of species at population and individual levels. Quantifying raptor diets at large spatio-temporal scales is often necessary for refining conservation efforts, although it can be particularly difficult and may involve a great effort by conventional means. Therefore, we adopted the analysis of stable isotopes in tissues of predators and their potential food sources as a complementary methodology for assessing animals' diet. We examined the isotopic composition (d 13 C and d 15 N) of White-tailed Eagles Haliaeetus albicilla from Germany, Finland and Greenland to detect patterns of dietary variation and quantify diet composition. The isotopic analysis included liver and muscle samples from Eagles of the three populations together with 16 potential food sources in the German population. Our results suggested dietary differences between German and Greenlandic Eagles, in accordance with the availability of freshwater and marine habitats in each population. Within the German population, we found seasonal shifts in isotopic ratios, suggesting the birds responded to temporal changes in food availabilities, and agerelated isotopic differences, indicating different diets in adults and juveniles. Isotopic values of liver and muscle tissues collected from the same animal showed intra-individual short-term changes in the German and Finnish but not Greenlandic population. This suggests that local feeding niches of this generalist predator may vary with local food supplies, which determines the niche width (from generalist to specialist) at the individual level. Our results also revealed that game mammal carcasses constitute an important food source (29.5% of diet) for the German Eagle population during the winter half-year corresponding to the hunting season. This result is of relevance to management and conservation because the White-tailed Eagle and other raptor species are affected by the ingestion of lead ammunition from shot mammalian carcasses.

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Section: Discussionmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

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Spatial, seasonal and individual variation in the diet of White‐tailed Eagles Haliaeetus albicilla assessed using stable isotope ratios

Nadjafzadeh

Voigt

Krone

2015

Ibis

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“…Neither length of the breeding season nor maximum altitude explained variations in the intensity of broodmate aggression when life history predictors were included in the models, again suggesting that effects of the location of breeding habitat were indeed affecting reproductive effort, and not broodmate aggression directly. An alternative explanation is that raptor species relying on more agile prey require considerable time and practice to improve foraging skills during their juvenile life (Edwards, 1989;Nadjafzadeh, Hofer, & Krone, 2015;Rutz, 2012;Rutz, Whittingham, & Newton, 2006), compared with species hunting for less agile prey (e.g., American kestrels Hunting success (and provisioning rates) was lower in species hunting for more agile prey, but it was unrelated to the intensity of broodmate aggression.…”

Section: Broodmate Aggression As a Trait Linked To A Slow Life-histmentioning

confidence: 99%

“…Moreover, lower provisioning rates in these species may be actually compensated by the fact that more agile prey are typically of a larger relative size (von Schantz & Nilsson, 1981;Toland, 1986). An alternative explanation is that raptor species relying on more agile prey require considerable time and practice to improve foraging skills during their juvenile life (Edwards, 1989;Nadjafzadeh, Hofer, & Krone, 2015;Rutz, 2012;Rutz, Whittingham, & Newton, 2006), compared with species hunting for less agile prey (e.g., American kestrels Falco sparverius, Varland, Klass, & Loughin, 1991). This may have a profound impact on life history parameters, particularly by reducing the prebreeding/adult survival ratio (Ashmole, 1963;Wiens, Noon, & Reynolds, 2006) and increasing age at first breeding (Krüger, 2005(Krüger, , 2007, that is, slowing down a species' life history pace.…”

Section: Broodmate Aggression As a Trait Linked To A Slow Life-histmentioning

confidence: 99%

Broodmate aggression and life history variation in accipitrid birds of prey

Redondo

Romero

Dı́az-Delgado

et al. 2019

Ecology and Evolution

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Aggressive sibling competition for parental food resources is relatively infrequent in animals but highly prevalent and extreme among certain bird families, particularly accipitrid raptors (Accipitriformes). Intense broodmate aggression within this group is associated with a suite of traits including a large adult size, small broods, low provisioning rates, and slow development. In this study, we apply phylogenetic comparative analyses to assess the relative importance of several behavioral, morphological, life history, and ecological variables as predictors of the intensity of broodmate aggression in 65 species of accipitrid raptors. We show that intensity of aggression increases in species with lower parental effort (small clutch size and low provisioning rates), while size effects (adult body mass and length of nestling period) are unimportant. Intense aggression is more closely related to a slow life history pace (high adult survival coupled with a restrained parental effort), rather than a by‐product of allometry or food limitation. Consideration of several ecological variables affecting prey abundance and availability reveals that certain lifestyles (e.g., breeding in aseasonal habitats or hunting for more agile prey) may slow a species’ life history pace and favor the evolution of intense broodmate aggression.

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Driving forces behind the fluctuating growth of the number of successful nests in an inland population of white‐tailed eagles in Hokkaido, Japan

et al. 2022

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This study aimed to describe the change in the number of successful nests of the white-tailed eagle, Haliaeetus albicilla, for 25 years along the Teshio River (100 km), Japan, which is a new habitat for this endangered species and identify factors driving the number of nests. The number of nests grew from two to nine. The logistic function fitted in well with the growth, and the capacity of the study area sustaining the successful nests was estimated at 6.5. The precipitation in January and April explained the deviation of the observed values from the model prediction. In particular, heavy rain in April was associated with low numbers. Forty-six nest remains were collected from 17 nest locations. Twelve genera of birds, six genera of mammals, and four

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Sit-and-wait for large prey: foraging strategy and prey choice of White-tailed Eagles

Cited by 42 publications

References 42 publications

Spatial, seasonal and individual variation in the diet of White‐tailed Eagles Haliaeetus albicilla assessed using stable isotope ratios

Spatial, seasonal and individual variation in the diet of White‐tailed Eagles Haliaeetus albicilla assessed using stable isotope ratios

Broodmate aggression and life history variation in accipitrid birds of prey

Driving forces behind the fluctuating growth of the number of successful nests in an inland population of white‐tailed eagles in Hokkaido, Japan

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