| Sea eagle | |
|---|---|
 | |
| Bald eagle (Haliaeetus leucocephalus) | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Accipitriformes |
| Family: | Accipitridae |
| Subfamily: | Haliaeetinae Savigny, 1809 |
| Genera | |
See text | |
Asea eagle orfish eagle (also callederne orern, mostly in reference to the white-tailed eagle) is any of thebirds of prey belonging to thesubfamilyHaliaeetinae[2][disputed –discuss] of the bird of prey familyAccipitridae. Ten extant species of sea eagles are known.
The subfamily has a significant "reach", with a scholarly article in 2005 reporting that they were "found inriverine andcoastal habitat[s] throughout the world". However,Haliaeetinae inhabited areas have experienced particular threats given the context ofhuman impacts on the environment.[3]
The genusHaliaeetus was introduced in 1809 by French naturalistMarie Jules César Savigny in his chapter on birds in theDescription de l'Égypte.[4][5] In 2005, Haliaeetus was found to beparaphyletic after molecular study was performed; that genus was found to subsumeIcthyophaga with the species within it diverging into temperate and tropical groups. Subsequently, the two species ofIcthyophaga were accordingly moved withinHaliaeetus, within the tropical group.[3]
However, an academic paper published in 2024 based on a densely sampledmolecular phylogenetic study of the Accipitridae by Therese Catanach and collaborators foundIcthyophaga to be distinct enough to be their own genus fromHaliaeetus.[6] This resulted inFrank Gill,Pamela C. Rasmussen and David Donsker on behalf of theInternational Ornithological Committee (IOC) resurrectingIcthyophaga, and also moving the more tropical members ofHaliaeetus into a now-expandedIcthyophaga.[7]
| Image | Genus | Living species |
|---|---|---|
 | HaliaeetusSavigny, 1809 |
|
 | Icthyophaga(Lesson, 1843) |
|
Haliaeetus is possibly one of the oldest genera of living birds, remainingextant until today. Adistal lefttarsometatarsus (DPC 1652) recovered from earlyOligocenedeposits of Fayyum,Egypt (Jebel Qatrani Formation, about 33 million years ago (Mya)) is similar in general pattern and some details to that of a modern sea eagle.[8] The genus was present in the middleMiocene (12–16 Mya) with certainty.[9]
The point of origin of the sea- and fishing eagles is probably in the general area of theBay of Bengal. During theEocene/Oligocene, as theIndian subcontinent slowly collided withEurasia, the region was a vast expanse of fairly shallow ocean; the initial sea eagledivergence seems to have resulted in the fourtropical (andSouthern Hemispheresubtropical) species living around theIndian Ocean today. TheCentral Asian Pallas's sea eagle's relationships to the othertaxa is more obscure; it seems closer to the threeHolarctic species which evolved later and may be an early offshoot of this northward expansion; it does not have the hefty yellow bill of the northern forms, retaining a smaller, darker beak like the tropical species.[10]
A prehistoric (i.e. extinct before1500) form from Maui in the Hawaiian Islands may represent a species or subspecies within this clade.[citation needed]
The rate ofmolecular evolution inHaliaeetus is fairly slow, as is to be expected in long-lived birds which take years to successfully reproduce. In themtDNAcytochromeb gene, amutation rate of 0.5–0.7% per million years (if assuming an Early Miocene divergence) or maybe as little as 0.25–0.3% per million years (for a Late Eocene divergence) has been shown.[10]
The relationships to other genera in the family Accipitridae are less clear; they have long been considered closer to the genusMilvus (kites) than to the true eagles in the genusAquila on the basis of their morphology and display behaviour;[11][12] more recent genetic evidence agrees with this, but points to their being related to the genusButeo (buzzards/hawks), as well, a relationship not previously thought close.[10]
Sea eagles vary in size, fromSanford's sea eagle, averaging 2–2.7 kilograms (4.4–6.0 lb), toSteller's sea eagle, weighing up to 9 kg (20 lb).[11] At up to 6.9 kg (15 lb 3 oz), thewhite-tailed eagle is the largest eagle in Europe.Bald eagles can weigh up to 6.3 kg (13 lb 14 oz), making them the largest eagle native to North America. There are exceptional records of even heavier individuals in both the white-tailed and bald eagles, although not surpassing the largest Steller's sea eagles. Thewhite-bellied sea eagle can weigh up to 4.5 kg (9 lb 15 oz).[11] They are generally overall brown (from rich brown to dull grey-brown), often with white to the head, tail or underparts. Some of the species have an all-yellow beak as adults, which is unusual among eagles.[11] The tail is entirely white in adultHaliaeetus species except for Sanford's, white-bellied, and Pallas's. Threespecies pairs exist: white-tailed and bald eagles, Sanford's and white-bellied sea eagles, and the African and Madagascar fish eagles,[10] each of these consists of a white- and a tan-headed species.
Their diets consist mainly of fish, aquatic birds, and small mammals. Nests are typically very large and positioned in a tree, but sometimes on a cliff.[11]
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TheHaliaeetinae subfamily is an especially threatened collection of creatures within the broaderAccipitridae species, according to the academic journalMolecular Phylogenetics and Evolution, given the "anthropogenic factors" involved. The publication reported in 2005 that prior trends had meant that sea eagles could be "found in riverine and coastal habitat[s] throughout the world". In terms of international scientific campaigns, theConvention on International Trade in Endangered Species (CITES) protects all entities in the broader species, including sea eagles.[3]
