Northward Summer Migration of Red-Tailed Hawks Fledged from Southern Latitudes

Bloom, Peter H.; McCrary, Michael D.; Scott, James M.; Papp, Joseph M.; Sernka, Karyn J.; Thomas, Scott E.; Kidd, Jeff W.; Henckel, Edmund H.; Henckel, Judith L.; Gibson, Marjorie J.

doi:10.3356/jrr-14-54.1

Cited by 14 publications

(21 citation statements)

References 42 publications

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“…This is consistent with these birds ranging more widely than do territorial birds (a pattern that is observed elsewhere; Miller et al 2016). Likewise, there is evidence that younger, non-territorial birds of many species are more likely to make migratory or pseudo-migratory movements even when they are from putatively 'sedentary' populations (Bloom et al 2015). Such migratory movements involve being in motion and are often faster than local movements (Wheat et al 2017).…”

Section: Internal Statesupporting

confidence: 71%

Relevance of individual and environmental drivers of movement of Golden Eagles

Sur

Duerr²,

Bell³

et al. 2019

Ibis

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An animal's movement is expected to be governed by an interplay between goals determined by its internal state and energetic costs associated with navigating through the external environment. Understanding this ecological process is challenging when an animal moves in two dimensions and even more difficult for birds that move in a third dimension. To understand the dynamic interaction between the internal state of an animal and the variable external environment, we evaluated hypotheses explaining association of different covariates of movement and the trade‐offs birds face as they make behavioural decisions in a fluctuating landscape. We used ~870 000 GPS telemetry data points collected from 68 Golden Eagles Aquila chrysaetos to test demographic, diel, topographic and meteorological hypotheses to determine (1) the probability that these birds would be in motion and (2), once in motion, their flight speed. A complex and sometimes interacting set of potential internal and external factors determined movement behaviour. There was good evidence that reproductive state, manifested as age, sex and seasonal effects, had a significant influence on the probability of being in motion and, to a lesser extent, on speed of motion. Likewise, movement responses to the external environment were often unexpectedly strong. These responses, to northness of slope, strength of orographic updraft and intensity of solar radiation, were regionally and temporally variable. In contrast to previous work showing the role of a single environmental factor in determining movement decisions, our analyses support the hypothesis that multiple factors simultaneously interact to influence animal movement. In particular they highlighted how movement is influenced by the interaction between the individual's internal reproductive state and the external environment, and that, of the environmental factors, topographic influences are often more relevant than meteorological influences in determining patterns of flight behaviour. Further disentangling of how these internal and externals states jointly affect movement will provide additional insights into the energetic costs of movement and benefits associated with achieving process‐driven goals.

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Section: Internal Statesupporting

confidence: 71%

Relevance of individual and environmental drivers of movement of Golden Eagles

Sur

Duerr²,

Bell³

et al. 2019

Ibis

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“…For other raptors that migrate long distances, strategies may differ between juveniles and adults of the same species (Maransky andBildstein 2001, Håke et al 2003). Juvenile Red-tailed Hawks migrated from California whereas adult hawks from the same populations were generally nonmigratory, possibly a result of climate change, seasonal prey availability, and adult dominance (Bloom et al 2015).…”

Section: Discussionmentioning

confidence: 99%

“…When juvenile hawks disperse longer distances due to wide spacing or seasonality of habitats, their first-year movements may gradate into migration (Newton 2008). For juvenile migrant raptors, lack of experience and different life needs compared to adult hawks may influence their migration timing and patterns, and locations of settlement areas until the time of their recruitment into nesting populations (Bildstein et al 1984, Ferrer 1993, Bloom et al 2015. Different patterns and areas of use may affect age-specific survival and thus be important to conservation needs of immature hawks (Mañosa et al 1998, McIntyre et al 2006, Cadahia et al 2010, Hunt et al 2017.…”

Section: Migración Del Primer Año Y Fidelidad a La Región De Nacimienmentioning

confidence: 99%

“…Other studies on Buteo hawks have documented age differences in migration trajectories important to differential distribution and habitat use. Fledgling Red-tailed Hawks in California, USA, for example, dispersed toward the north whereas adults from the same population generally remained sedentary (Bloom et al 2015). Differences were potentially due to effects of climate change, seasonal prey availability, and adult dominance.…”

Section: Migración Del Primer Año Y Fidelidad a La Región De Nacimienmentioning

confidence: 99%

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First-Year Migration and Natal Region Fidelity of Immature Ferruginous Hawks

Watson

Banasch

Byer

et al. 2019

Journal of Raptor Research

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“…Red‐tailed hawks have a continent‐wide distribution in North America (Preston and Beane ), and different subpopulations exhibit a wide variety of migratory behaviors (Bloom et al. ). Thus, the birds potentially affected by wind facilities in California likely include in‐state, year‐round residents, as well as migrant, dispersers, and nomadic individuals from in‐ or out‐of‐state.…”

Section: Applicationmentioning

confidence: 99%

Assessing population‐level consequences of anthropogenic stressors for terrestrial wildlife

et al. 2020

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Human activity influences wildlife. However, the ecological and conservation significances of these influences are difficult to predict and depend on their population-level consequences. This difficulty arises partly because of information gaps, and partly because the data on stressors are usually collected in a count-based manner (e.g., number of dead animals) that is difficult to translate into rate-based estimates important to infer population-level consequences (e.g., changes in mortality or population growth rates). However, ongoing methodological developments can provide information to make this transition. Here, we synthesize tools from multiple fields of study to propose an overarching, spatially explicit framework to assess population-level consequences of anthropogenic stressors on terrestrial wildlife. A key component of this process is using ecological information from affected animals to upscale from count-based field data on individuals to rate-based demographic inference. The five steps to this framework are (1) framing the problem to identify species, populations, and assessment parameters; (2) field-based measurement of the effect of the stressor on individuals; (3) characterizing the location and size of the populations of interest; (4) demographic modeling for those populations; and (5) assessing the significance of stressor-induced changes in demographic rates. The tools required for each of these steps are well developed, and some have been used in conjunction with each other, but the entire group has not previously been unified together as we do in this framework. We detail these steps and then illustrate their application for two species affected by different anthropogenic stressors. In our examples, we use stable hydrogen isotope data to infer a catchment area describing the geographic origins of affected individuals, as the basis to estimate population size for that area. These examples reveal unexpectedly greater potential risks from stressors for the more common and widely distributed species. This work illustrates key strengths of the framework but also important areas for subsequent theoretical and technical development to make it still more broadly applicable.

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Northward Summer Migration of Red-Tailed Hawks Fledged from Southern Latitudes

Abstract: BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.

Cited by 14 publications

References 42 publications

Relevance of individual and environmental drivers of movement of Golden Eagles

Relevance of individual and environmental drivers of movement of Golden Eagles

First-Year Migration and Natal Region Fidelity of Immature Ferruginous Hawks

Assessing population‐level consequences of anthropogenic stressors for terrestrial wildlife

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