Characteristics of Bald Eagle Communal Roosts in the Klamath Basin, Oregon and California

Keister, George P.; Anthony, Robert G.

doi:10.2307/3808166

Cited by 15 publications

(19 citation statements)

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“…Other studies have shown roosts that vary from a single tree (Isaacs et al 1993) to a 254-ha forest patch (Keister and Anthony 1983), including roosts in North Carolina (1.3-5.0 ha; Chester et al 1990), Maryland (0.39-1.0 ha;Buehler et al 1991b), Florida (20 ha;Curnutt 1992), South Dakota (5 ha; Steenhof et al 1980), Montana (42 ha;Crenshaw and McClelland 1989), and Oregon (2.4-28.3 ha;Isaacs and Anthony 1987).…”

Section: Resultsmentioning

confidence: 97%

“…Variation in the relative significance of roosts has been noted in other study areas. Keister and Anthony (1983) collected pellets under six communal roosts in the Klamath Basin and found that nearly 49% of the total pellets were from a single roost and that more than 80% were from the two largest roosts. Although the range of use was narrower, Isaacs et al (1996) found that eagles wintering along the Upper John Day River in Oregon typically used small roosts that were an order of magnitude smaller than the largest roosts.…”

Section: Resultsmentioning

confidence: 99%

“…Feeding and roosting are exclusive activities, require different habitats, and are often separated by considerable distances (Swisher 1964, Edwards 1969, Keister and Anthony 1983. The distribution of communal roosts is believed to reflect a dynamic balance between the cost of travel to and from feeding areas, the relative profitability of feeding areas, and the energy savings achieved from roosting within protected microclimates (Stalmaster andGessaman 1984, Keister et al 1985).…”

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confidence: 98%

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Use of Satellite Transmitters to Delineate Bald Eagle Communal Roosts within the Upper Chesapeake Bay

Watts

Mojica

2012

Journal of Raptor Research

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 98%

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Use of Satellite Transmitters to Delineate Bald Eagle Communal Roosts within the Upper Chesapeake Bay

Watts

Mojica

2012

Journal of Raptor Research

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“…' During the daytime, bald eagles usually perch close to a food source if possible. It has been observed that bald eagles will most overnight in old-growth stands as far as 15 km (9.3 mi) from a food source in the Klamath Basin, even though closer stands of juniper and young Ponderosa pine were available (Keister and Anthony, 1983). Forest stand structure (i.e., uneven-aged and at least a temnant of the old-growth component) is an important habitat component for selection of communal night roosts (Anthony et al,, 1982).…”

Section: Habitat Characteristics Of Wintering Bald Eaglesmentioning

confidence: 99%

Klickitat Cogeneration Project : Final Environmental Assessment.

Partners¹

1994

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SUMMARY:To meet BPA's contxactual obligations to supply electrical power tp its customers, BPA proposes to acquire pwer generated by the Klickitat Cogeneration Project (Project). ' BPA has prepared an environmental assessment evaluating the proposed project. Based upon the analysis in the BA, BPA's proposed action is not a major Federal action significanfly affecting the quality of the human environment within the meaning of the National Envirohental Policy Act (NEPA) of 1969 for the following reasons: (1) the proposed project will not have a si@icant impact on land use, upland vegetation, wetlands, water quality, geology, soils, public health and safety, visual quality, and cultural resou mation and socioeconomics, and (2) hpac& to fi mhor, or sufficiently offset by m environmental impact statement @IS) is not required and BPA is issuing this FONSI. Land uses at the proposed Project site are characteristic of a partially to fully developed area. At the cogenemtion facility site, the land is zoned for heavy industry with an existing sawmill. The gas transmission loop line route parallels an existing @s line for much of its length, crossing midential land, pasture, croplands, and forest. Almost half of the land that would be affected by the gas spur line is currently in industrlaycommercial use. The additional space required for the proposed gas loop line would permanently convert 2.5 ha (6.4 ac) of pasture and forest lands to pss-covered project. Minor amounts of erosion and sedimentation would occuf during pipeline, substation, and power plant construction. This impact will be m h i z e d , however, by best management practices (BMPs) that include installation of erosion and sediment control featurn. In addition, construction will primarily take place during the dry season, and all disturbed areas along the pipeline ROW will be reseeded. Erosian and sedimentation will therefore be reduced to a level of non-significance. Water will be taken h m the Columbia River using an existing intake and fish Screens. Water w i l l be returned to the Columbia using e-g outfau and modified diffuser. Return water will, be of nearly identical composition and quantity as the river water itse€f, with the exception of a slight increase in chlorine, The concentrations of this chemical will be kept to within Washington state guidelines to protect river quality, and thus are not expected to have a significant impact. ADDRESS:The use of National Evlarine Fishery Service (NMFS) and Washingon Department of WiIdlife and Fisheries approved fish screefls and screen surface area to minimike intake velocity at the intake structure will prevent protected anadromous species and most other fish from being entrained, although some underyearling resident species and anadromous American shad might be small enough to get through the scrkns. These fish are currently not protected by screen requirements. Water tempemre would be returned at 8.3 "C (15 O F ) higher than the ambient water temperature at the diffuser. The diffuser structure y2l be e...

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“…Bald eagles ( Haliaeetus leucocephalus ) are highly social and nonbreeding individuals frequently utilize communal roosts that form around important feeding sites (McClelland , Isaacs and Anthony , Keister et al ). Investigations of eagle roosts have focused on the number of individuals using roosts (McClelland et al ), temporal patterns of roost use (Steenhof , Crenshaw and McClelland , Curnutt ), physical characteristics of roost structures (Hansen et al , Keister and Anthony , Chester et al , Stohlgren , Dellasala et al ), or landscape context of roost sites (Steenhof , Stalmaster and Gessaman , Keister et al , Buehler et al , Stahlecker and Smith ). Despite eagles regularly moving among roost sites (Grubb et al , Buehler et al , Watts and Mojica ), roosts have typically been both perceived and managed as stand‐alone resources (Becker , U.S.…”

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confidence: 99%

Structure and resilience of bald eagle roost networks

Watts

Dyer

2018

Wildl. Soc. Bull.

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The recognition that communal roosts are important elements within the life cycle of bald eagles (Haliaeetus leucocephalus) led to their protection under the "disturb" clause of the Bald and Golden Eagle Protection Act. The regular roost-switching movements of bald eagles imply that roosts are part of an interactive network where roosts represent nodes linked by birds moving between them. Network analysis holds promise for informing management decisions by assessing the effect of roost removal on the resilience of the broader network. We tracked nonbreeding bald eagles (n ¼ 56) within the upper Chesapeake Bay (2008)(2009)(2010)(2011)(2012)(2013), USA, to evaluate roost characteristics and network structure. We used midnight locations (n ¼ 14,464) to assess the use of communal roosts (n ¼ 212) and movement of birds among roosts (n ¼ 2,634) on successive roost nights to evaluate the pattern and strength of connections. We performed a sensitivity analysis to assess the response of the roost network to roost loss. Structure of the roost network approximated that of a scale-free network where the distribution of connections follows a power law of the form P(k) ¼ Ak Àg and g ¼ 1.1. Unlike random networks, connections within scale-free networks are concentrated within a few highly connected nodes (hubs). These hub roosts serve as bridges between large numbers of other roosts, have the shortest travel times to other roosts and greatest overall influence on network functioning. The effect of roost removal on overall network function was directly proportional to the connectivity of the roost being removed. The targeted removal of the majority (>90%) of roosts had very little effect on the network. Network sensitivity was high in response to the loss of roosts within the highest 10% of connectivity. This small (n ¼ 18) subset of roosts makes a disproportionate contribution to network function and the protection of these roosts should be a stated management objective with high priority. Network analysis represents a powerful tool with the potential to inform management decisions. Ó 2018 The Wildlife Society.

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Characteristics of Bald Eagle Communal Roosts in the Klamath Basin, Oregon and California

Cited by 15 publications

References 5 publications

Use of Satellite Transmitters to Delineate Bald Eagle Communal Roosts within the Upper Chesapeake Bay

Use of Satellite Transmitters to Delineate Bald Eagle Communal Roosts within the Upper Chesapeake Bay

Klickitat Cogeneration Project : Final Environmental Assessment.

Structure and resilience of bald eagle roost networks

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