Rationale: Bald Eagles and Ospreys can share similar ecological landscapes and compete for food in the same geolocation area (see as example in iNaturalist - as example,
https://www.inaturalist.org/observations/119976509#activity_comment_c352dda5-d2ff-4588-81d0-f871575e96f4.
Wheeler (2018) provides a relevant description of nesting behaviors and preferred settings in the guidebook, “Birds of Prey of the West.”
However, some observations may show a nest unoccupied, or the image is blurred, or at a distance too far to clearly separate the two species, I will often support the ID suggested based on geolocation (e.g., near body of water {river, lake, bay, ocean}, previous observations in the same proximity, and take into account, the nesting behavior and dynamics of the Osprey vs. the Bald Eagle.
As it relates to a nest unoccupied, or where the actual species is not visible in the image, I consider nesting behavior and structure and typical patterns and outcomes. For example, Bald Eagle nesting structure (see as indicated here,
https://www.inaturalist.org/observations/75725511
Vs. Osprey (see as indicated here
https://www.inaturalist.org/observations/115510491
And then see again here
https://www.inaturalist.org/observations/124958811
For example, Henny and Anthony (ed. B. G. Pendleton,1987, Bald Eagle and Osprey) noted that , “Nesting ospreys appear more tolerant than nesting bald eagles of man and his disturbance; thus, more restrictions are required at bald eagle nest sites.”
Or relevant here: Ospreys (Pandion haliaetus) and Bald Eagles (Haliaeetus leucocephalus) share similar breeding habitat in the Chesapeake Bay area and elsewhere. The nests of these species are similar in size and appearance. Ospreys typically build large stick nests in dead trees or on man-made structures (C.J. Henny et al. 1974, Chesapeake Sci. 15:125-133; A.F. Poole 1989, Ospreys: a natural and unnatural history, Cambridge Univ. Press, NY), while Bald Eagles usually build larger nests in live trees (P.B. Wood et al. 1989, J. Wildl. Manage. 53:441-449; Maryland Dept. of Natural Resources, unpubl. data). Osprey nests are usually placed in the open at the top of dead trees or structures, while Bald Eagle nests are usually beneath the tree canopy obscured from view. Both select nest sites close to large bodies of water or wetlands (J.M. Andrew and J.A. Mosher 1982, J. Wildl. Manage. 46:383-390; Poole 1989). See also: Henny, C. J. (1983). Distribution and abundance of nesting ospreys in the United States. Biology and management of bald eagles and ospreys, 175-186.
While it is possible to for a Bald Eagle to nest successfully on an Osprey platform, (see: Larry Rymon, Ed Henckel, and Judy Henckel "BALD EAGLES NEST SUCCESSFULLY ON OSPREY PLATFORM," Journal of Raptor Research 40(4), 306-307, (1 December 2006). https://doi.org/10.3356/0892-1016(2006)40[306:BENSOO]2.0.CO;2), and therefore taken that into account, I have also tried to weigh in other factors (as noted above) to help determine a reasoned ID determination, including previous observations that have been research graded (as example, a previous observation with research grade,
https://www.inaturalist.org/observations/83711760
and then matched to a more recent observation in similar location, such as
https://www.inaturalist.org/observations/124960760