History of Ornithology: The Osprey

tl;dr: My first post about the history of ornithology (fulfilling the “Kestrels” half o my blog name) discusses the osprey and how various naturalists perceived it. It’s a rather messy story.

Note: As is evident from the opening lines, I wrote this around the time the Seattle Seahawks defeated the Denver Broncos in the Super Bowl. I wasn’t ready to relaunch my blog yet though, so I set it aside for a later time. It feels somewhat unfinished but whatever, it’s out there now!

Given the recent victory of the Seattle Seahawks in the Super Bowl, I thought I would take the time to write about one of my favorite birds: the osprey, or “sea hawk.” Despite the name, the osprey is not actually a hawk, nor is it an eagle. Neither name is “scientific,” but differences have been maintained anyway, and there really is no way an osprey is a hawk. In fact, the osprey is the single species in its family, Pandionidae. Its lineage diverged from the eagles/hawks around 48 million years ago (source: timetree.org), making it more different from an eagle/hawk than you and an orangutan. But of course, this is with the benefit of modern genomic sequencing. These differences had to be established based on physical characteristics, and in the early modern period, as I will discuss, naturalists really had no idea what the bird they were looking at was.

Linnaeus himself provided a brief description of the osprey, or as he named it, Falco haliaeetus. Linnaeus's description of the Osprey.

I don’t know any Latin whatsoever, so I had to make due with Google Translate. (I know, I know!) From what I can tell, the first line describes that the bird has waxy blue feet, a dark upper body, and is white underneath with a whitish head. Following the references to other naturalists (Aldrovandi and Willughby discussed below), he notes that it lives in Europe, on the ground amongst the reeds(?), where it feeds on large fish and ducks. Its left foot is webbed, apparently. Then he mentions the brown stripe around the eyes that go up the side of the neck and connect to the wings.

The physical description seems pretty good (except the feet), but ospreys do not live on the ground, but in large nests in trees.

Francis Willughby, a mid-17th century English naturalist and friend of John Ray, also identified and discussed the osprey. Before the age of photographs, he had to establish whether the bird he was writing about was the same bird other naturalists, such as Linnaeus and Aldrovandus, had studied. And worse than that, if you look at the images he provides, the bird clearly does not look at all like an osprey, so it was a rather confused affair.

Given Aldrovandus’s description of the bird, his “Ossifrage,” Willughby decided that it was the same as the English “Bald Buzzard.” A fisherman, Leonard Baltner, called it the “Fisch-Adler,” or “Fish-Eagle.” But Willughby wasn’t sure it should be called an eagle, because it was too small; the difference between a hawk/buzzard and an eagle was only one of size at this time. But if I’m reading him correctly (at the top of the page), because that distinction is somewhat arbitrary, he doesn’t seem to care much about dissolving it, due to him continuing to call it the “sea eagle.” (This 1901 article about the osprey provides a more in-depth account of the bird’s various names and their possible sources.)

Following a lengthy physical description, Willughby related some of the fanciful stories regarding the birds. For example, as Linnaeus alluded to, some people thought the osprey has two different feet: one is webbed, one is not. He called this “fabulous” and that “even the best Naturalists have been deceived.” He decided that because no credible person he knew confirmed the story, it was false, even if the “Vulgar” are so easily persuaded as to its truth.

A second story is with regard to “Oyl of Osprey.”

Not less fabulous is that which is reported of the oyl or fat which this bird hath in her rump, and which hanging in the air, she lets fall drop by drop into the water; by the force whereof the Fishes being stupefied, and as it were Planet-strucken, become destitute of all motion, and so suffer themselves without difficulty to be taken; though some are so vain as to put Oyl of Osprey into their receipts or prescriptions for taking Fishes, by the smell whereof the Fishes being allured, rather than stupefied by its narcotic virtue, yield themselves to be handled and taken out of the water by such as have their hands anointed with it. Doubtless he that can get the Oyl of such an Osprey as they talk of may work wonders with it.

But apparently this Oyl did not work.

Willughby’s book includes some illustrations of an osprey (as both the sea eagle and as the bald buzzard). They’re pretty terrible.


From Willughby’s Ornithology (1678). Source: Smithsonian Libraries via the Biodiversity Heritage Library, http://biodiversitylibrary.org/page/41442248 and http://biodiversitylibrary.org/page/41442258.

John Ray, who translated and published Willughby’s ornithology from Latin, also denied the foot story. His account discussed even more names for the bird, but he didn’t add much information. He did bring up several anecdotes about his experiences with them, including taking some osprey eggs out of a nest, but he failed (unsurprisingly) in taking the large nest itself.


From John Ray’s L’histoire naturelle (ed. published in 1767). Source: Biodiversity Heritage Library,

Ray said there is an “ancient opinion” regarding the relationship between parents and offspring (pp. 5-6). Apparently, if parents abandon their young, other osprey take responsibility for raising the orphans. But when these chicks become adults, they “devour” their foster parents. From what little I know of this period, I suspect this story was used in the “emblems” Renaissance natural historians employed to draw stories and morals from the animals they discussed. But I’d have to do more digging.

Like Willughby, the associated image of the osprey looks nothing like the bird. The wings look better this time though. But Ray clearly has experience with them, so I just don’t know how to reconcile the problem. I find it so strange: the osprey’s defining feature when it comes to color pattern is the brown eye-band, but these images all fail to capture that.

** About 100 years later (1731), the earliest accurate depiction of an osprey is Mark Catseby‘s 1731 Natural History of Carolina, Florida, and the Bahama Islands. In his physical description of the bird, which he calls the “fishing hawk”/Accipiter  piscatorius, he notes that “the Feathers of the Thighs are short, and adhere close to them, contrary to others of the Hawk kind; which Nature seems to have designed for their more easy penetrating the water.” I think this is indeed a unique feature of the ospreys; whether or not it was “designed” for this reason, I am unsure.

Catesby's osprey. 1731. Source: Biodiversity Heritage Library, http://biodiversitylibrary.org/page/40753123.

Catesby’s osprey. 1731. Source: Biodiversity Heritage Library, http://biodiversitylibrary.org/page/40753123.

Additionally, Catesby discusses of the bird’s interactions with the bald eagle, which Benjamin Franklin notes in his rejection of the bald eagle as the U.S.’s choice as a national symbol. Catesby writes,

Their manner of fishing is … to precipitate into it with prodigious swiftness; where it remains for some minutes, and seldom rises without a fish; which the Bald Eagle (which is generally on the watch) no sooner spies, but at him furiously he flies: the Hawk mounts, screaming out, but the Eagle always soares above him, and compels the Hawk to let it fall; which the Eagle seldom fails of catching, before it reaches the Water. It is remarkable, that whenever the Hawk catches a Fish, he calls, as if it were, for the Eagle; who always obeys the call, if within hearing.

I am not sure whether this is a common occurrence, but it does happen, as can be seen in this video. And this video:


By the mid-1800s, the depicion of the osprey was well-established. See: John James Audubon.


Addendum (2014/8/25): I recently came across Mark Catesby’s Natural History of Carolina, Florida, and the Bahama Islands. I have incorporated his work into this blog post, surrounded by the double asterisks.

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