A Comparison of Certain North American Birds to the Thunderbird
by Willie Shughart

Five of the largest birds to occur in the contiguous United States and southern Canada were examined in comparison to the exceptionally large birds known as “Thunderbirds” reported throughout this area. These species were the Great Blue Heron, Ardea herodias; the Golden Eagle, Aquila chrysaetos; the Magnificent Frigatebird, Fregata magnificens; the American White Pelican, Pelecanus erythrorhynchos; and the Brown Pelican, Pelecanus occidentalis. In examining special cases of the thunderbird, other species are also compared. These species were selected for size, color and form, hence some other large species are excluded, including swans, cranes and albatrosses. Here we show that a number of sightings of the Thunderbird may be misidentifications of large, rare, or vagrant birds which are otherwise well-known to science.

Thunderbird sightings were taken mainly from Hall’s (1994) collection. Sightings from recent times only (the 19th century and later) were examined. Amerindian legends and folktales were not examined, as no definite firsthand accounts could be identified. A general description of the Thunderbird (personal observation, based on sightings in Hall, 1994 and other sources) would be that of a huge, vulturine or raptor-like bird, often with a long beak, often with a featherless head, and occasionally with long legs which trail behind in flight, invariably dark-colored, often with white markings around the neck or collar. Measurements vary, but usually fall within a body length of 1.2-1.8 m (4-6 ft) and a wingspread between 2.4 and 6 m (8-20 ft), with extreme cases (Hall 1994), surely significant exaggerations, placing the wingspread at more than twice the usual upper limit. Supposedly, the bird is often predatory in nature, at times making attempts at capturing children and medium- to large-sized mammals (Hall 1994).

The Great Blue Heron (Ardea herodias) is the largest heron to occur in North America (Terres 1991), and one of the largest waterbirds. Its wingspread may reach 2.1 m (7 ft, or 84 in); it can stand 1.2 m (4 ft) in height (Terres 1991). While no particular sightings examined could be ascribed to the Great Blue Heron, its large size, dark coloration, long beak and long, trailing legs (all characteristic of the thunderbird [Hall 1994]), make it a potential candidate in some sightings. However, it is also a fairly common bird throughout its range, which includes most of the United States and southern Canada (Terres 1991), and might well be familiar to most people who would have such sightings.

The Golden Eagle (Aquila chrysaetos), on the other hand, is more likely to be responsible in more Thunderbird sightings, and certainly has been in several cases. It is the largest eagle to occur regularly in the contiguous United States (Terres 1991), averaging slightly larger than the Bald Eagle (Haliaeetus leucocephalus), which is not considered as a candidate here due to its extremely recognizable appearance. It reaches a maximum wingspan of about 2.3 m (7.5 ft) and body length of 96 cm (38 in).

Thunderbirds are often noted to carry off animals of considerable size (Hall 1994), a feat which of all North American predatory birds, the Golden Eagle is probably most adept at. One sighting, according to Hall (1994), involved a large bird snatching up, and later releasing, a Beagle puppy weighing 2.3 kg (5 lbs), in Rabbit Hash, Kentucky, in 1977. As Palmer (1988) notes that the maximum weight that a Golden Eagle can carry is disputed, but is probably at least 2.3 kg (5 lbs) and perhaps as great as 3.2 kg (7 lbs), it is quite possible that an eagle could have been responsible for this act. In cases where children and large mammals are attacked by “giant” birds, the Golden Eagle may be responsible as well. Palmer (1988) mentions that these eagles, especially juveniles, may make attacks on animals much larger than they could actually capture, and Terres (1991) reports rare killings of animals as large as adult deer. On the other hand, there are cases such as the Lawndale, Illinois Incident (Hall 1994), when a ten-year-old boy weighing 30 kg (65 lbs) was mobbed by two large birds. If indeed, as reported, the boy was lifted as much as 60 cm (2 ft) above the ground (Hall 1994), then the Golden Eagle could not have been responsible. See further discussion of this incident below.

Another incident taking place in Kentucky, this time in 1870 (Hall 1994) is also likely to have been a Golden Eagle. According to a contemporary newspaper article reprinted in Hall (1994), a large, black bird was captured with a wingspan of 2.1 m (7 ft) was captured. It was described as eagle-like, though because of its color, it was considered to be unusual, and not even an eagle at all. However, melanism is now known to occur in Golden Eagles (Palmer 1988).

The Magnificent Frigatebird (Fregata magnificens) is a huge, black seabird attaining a wingspan of 2.4 m (8 ft) and body length of close to 1 m (3.5 ft) (Terres 1991). Its wings are narrower than is generally reported in thunderbird sightings; on the other hand, its trailing, forked tail might be mistaken for long legs in some cases. It rarely finds its way inland, as an accidental (Terres 1991). However, like the Great Blue Heron (Ardea herodias), no particular Thunderbird sightings can be ascribed to it.

The American White Pelican (Pelecanus erythrorhynchos) and the Brown Pelican (P. occidentalis), will be considered together. Again, there are no Thunderbird sightings which can be identified as either of these birds with any certainty, however, there are many similarities between these two birds and the typical Thunderbird description. The American White Pelican is the larger of the two, and indeed is North America’s second-largest bird (personal observation). Its wingspan may be as great as 2.9 m (9.5 ft), with a body length of 1.8 m, or 5.8 ft (Terres 1991). The Brown Pelican is somewhat smaller, reaching a 2.3 m (7.5 ft) wingspan and 1.4 m (4.5 ft) body length (Terres 1991). Both have black flight feathers, though the American White Pelican is otherwise totally white, whereas the Brown Pelican, like the Thunderbird, is dark overall (other than white and yellow markings on the head), and has a predominantly white neck. From below, either species might look like a large, bald-headed, vulture- or eagle-shaped bird (personal observation). As the head is tucked in during flight, only the bare, flesh-colored beak is visible beyond the curve of the neck. A bird with the coloration of the Brown and the size of the American White Pelican would be an ideal candidate for many sightings of a Thunderbird in flight, provided it did not exhibit predatory behavior (as pelicans feed only on fish and crustaceans [Terres 1991]).

Interestingly, an American White Pelican × Brown Pelican hybrid has been recorded (Terres 1991). While descriptions of its appearance could not be found, nor information regarding whether this hybrid was fertile, it is possible that instances of hybridization such as this zoo hybrid could occur in the wild (personal speculation), as the breeding range of the American White Pelican is occasionally overlapped by stragglers of the Brown species (personal observation based on Palmer, 1976). Such a rare hybrid could be responsible for a number of Midwestern Thunderbird sightings, and is also more likely than the California Condor (Gymnogyps californianus) which is rare and has an extremely limited range (Terres 1991). The American White Pelican, on the other hand, may disperse over much of the United States after breeding (Palmer 1988).

To conclude, and to further illustrate how misidentification of known species may occur, and has occurred in some cases, two further Thunderbird cases will be examined which seem to have involved known species which have not been discussed earlier in the text.

Firstly, the Lawndale Incident, as mentioned above, and the sightings in nearby towns of Illinois, described two large birds, one significantly smaller than the other (Hall 1994). The larger bird was described much as an Old World stork would be (personal observation) – vulture-like, heavy-billed, bald-headed, and long-legged. That these incidents coincided with the escape of a Marabou Stork (Leptoptilos crumeniferus), an African species, from a nearby zoo according to Hall (1994), is indication that an Old World stork may indeed have been the bird in question, especially when the reported sizes of the larger bird and the size of the Marabou Stork match almost exactly (personal observation). The smaller bird may have been a large native species which for some reason accompanied the stork from time to time (some sightings, indeed, involved only the larger bird [Hall 1994]). While the Marabou Stork would be incapable of lifting a child as much as any native North American bird, it is possible that no physical lifting took place, and that this was merely a mistaken impression or exaggeration. At any rate, the Marabou Stork has been known to attack and kill children when provoked (Hancock, Kushlan and Kahl 1992), so such an attack would not be unprecedented.

The second case is that of a supposedly massive bird killed in Mound City, Illinois, in 1868 (Hall 1994). According to the newspaper report of this incident, reprinted in Hall (1994), this bird was larger than an ostrich and weighed 47 kg (104 lbs), with a wingspan of 4.6 m (15 ft). It was described as having black wings and a red head, and was otherwise snowy white. It had a yellow bill and “pea-green” legs. Aside from its massive size, this bird would appear to be a Whooping Crane (Grus americana) (personal observation). Though its measurements would have to have been doubled, and its weight multiplied by six, and although the wings of the Whooping Crane are black only at the ends, if this bird ever existed (which is somewhat doubtful, as the entire account seems rather embellished) then it was probably a Whooping Crane.

While in many cases Thunderbird sightings cannot be ascribed to known species with any confidence, in some cases it is likely that it was a known, rather than an unknown, species at work. Even the largest of North American birds would have to be significantly exaggerated to come close to some Thunderbird sizes reported; however, this may happen, as the sizes of birds, especially in flight, may be difficult to estimate. Whether there is an unknown large bird species which may occur in North America cannot be determined; however, it is certainly not the only species called by the name “Thunderbird”.
Works Cited:

Hall, Mark A. 1994. Thunderbirds- The Living Legend!. Mark A. Hall Publications, Wilmington, NC.

Hancock, James A., James A. Kushlan, and M Philip Kahl. 1992. Storks, Ibises and Spoonbills of the World. Academic Press, San Diego, CA.

Palmer, Ralph S. (ed.). 1976. Handbook of North American Birds volume 1: Loons through Flamingos. Yale University Press, New Haven and London.

———. 1988. Handbook of North American Birds volume 5. Yale University Press, New Haven and London.

Terres, John K. The Audubon Society Encyclopedia of North American Birds. Wings Books, New York, NY and Avenel, NJ.