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Do you remember in school when your teacher told you “I before E except after C”? Telling the difference between eagles and falcons can be a lot like that. While there are some generally accepted rules, there are also a large number of exceptions.
Just last week, I saw the impressive Black hawk-eagle perched on a tall bare branch in our garden. It was a sight that prompted much photography from everyone on our street. But even though it is a huge bird (66 cm), it took us a bit of time flipping through our books to identify it.
I decided for this article to take a look at all 112 species of falcons and eagles, focusing on specific traits that would help with identification. I tabulated the results in a spreadsheet and analyzed the results. It probably goes without saying that my husband was on housework duty that day!
So, let’s take a look at all the fascinating differences and similarities between eagles and falcons. I hope that this will help you with your future birding, and I promise to make it much more fun than a spreadsheet!
Falcons vs. Eagles Quick Facts
Taxonomy: Falcons are memebers of order Falconiformes, whereas eagles are Accipitriformes.
Size: Falcons measure 20-65cm, whereas eagles measure 40-100cms
Beaks: Falcons have tomial teeth, whereas eagles have large smooth hooked beaks
Wings: Falcons have pointy wings, whereas eagles have rounded wings
Hunting: Falcons hunt in flight, whereas eagles hunt on the ground (sort of)
Diet: Falcons eat insects and birds, whereas eagles eat mammals, reptiles, and fish
Flying: Falcons are known for their agility, whereas eagles are known for soaring (sort of)
Evolution and Taxonomy
Falcons include 30 species of falcons, kestrels, and hobbys. They also include 25 species of caracaras, forest falcons, falconets, and pygmy falcons. Eagles include 57 species split into 20 different genera.
Until 2008, both Falcons and Eagles were placed within the same order of predatory birds known as Falconiformes. Through continuing DNA and phylogenetic studies, it has been discovered that falcons and eagles are not at all closely related. They diverged approximately 57 million years ago. Today, birds known as falcons, kestrels, hobbys, caracaras, and forest falcons fall under Falconiformes. Eagles, hawks, kites, and allies are referred to as the order of Accipitriformes.
In practical terms, this means that Falcons are more closely related to Parrots than they are to Eagles. It is a clear example of convergent evolution where species develop similar physical characteristics and behaviors in response to similar environmental pressures.
While that’s all extremely interesting, it doesn’t really help birders, when trying to tell the difference between them. So, how should we proceed? First, I will take a look at Typical Falcons (genus falco) and True Eagles to examine the differences. Then, we’ll take a look at some of the remaining genera to discover the most significant outliers.
Eagle vs. Falcon Appearance
All Falcon species from the genus falco have teeth! Ok, not exactly teeth. They are called tomial teeth, which are sharp protrusions on the edge of the upper mandible. Falcons use these protrusions to stab and grab their prey. There are some species of falcon that use their talons to stun prey- like a swift sucker punch- but almost all will use their beaks to make the final kill.
Eagles, on the other hand, have broad, robust beaks with a smooth upper mandible that is dramatically hooked. Eagles tend to kill their prey using their talons instead of their beaks. Although tomial teeth can be found in some kites, goshawks, and sparrowhawks, no eagles display this feature.
Typical Falcons are generally smaller than Eagles. The smallest eagle is the Nicobar serpent eagle at 40 cm in length. The Philippine and Harpy Eagles reach lengths of up to 100 cm. Typical Falcons range in size from the African hobby (20 cm) to the Gyrafalcon (65 cm).
As you can probably tell, this leaves a certain amount of overlap in size. I don’t usually like mentioning relative size when it comes to birding. A falcon is pretty unlikely to stay still while you climb up a tree with some measuring tape! But let’s try and simplify the information.
If you are looking at a large bird of prey between 40 and 65 cm long, your location may help you to figure it out. In the Americas, Africa, and Eurasia, there are seven large species of falcon. If you memorize the other characteristics of these large falcons, you will be better equipped to identify the bird based on a process of elimination.
If you are in Australia or New Zealand, unfortunately for you, all the species of falcon are large (45-57 cm). So what else can we use to make an identification?
Wings, Legs, and Tails
With very few exceptions, falcons have long, thin, pointed wings. The only typical falcon with rounded wings is the Mauritius Kestrel, located in Africa. Eagle wings are broad and rounded. When in flight, you can see the feathers at the tips of the wings are splayed out like a fan.
A rare and fascinating attribute of eagles is the lower legs (known as tarsi). In all “true eagle” species, the lower part of the leg is feathered to the foot. Hence, they are sometimes referred to as “booted eagles.” If you see a raptor with feathered tarsi (unless it is an owl), it is almost certainly an eagle. It was previously thought to be a cold weather adaptation, but tropical eagles also have this feature. Other birds with this rare attribute are some species of hummingbird, swallow and finch.
As for tails, falcons have long, thin tails that are aerodynamic in appearance. Eagles have shorter, broader, more wedge-shaped tails. Hawk-eagles of the genus spizaetus tend to have longer tails than other eagles- but the feathered tarsi gives them away.
Eagle vs. Falcon Behavior
As briefly discussed before, falcons and eagles display different hunting behaviors. For the most part, eagles capture and kill prey using their large, powerful talons. Falcons kill with their beaks.
In addition, the vast majority of typical falcons capture their prey while they are in flight. Either using a horizontal pursuit or diving and swooping from a perch. They also tend to eat “on the wing,” especially when consuming small insects. It looks a little bit like how flycatchers and hummingbirds swoop around for bugs.
There are only four species of typical falcon that capture the majority of their prey from the ground. These are the greater kestrel, grey kestrel, brown falcon, and grey falcon. These occur in Africa and Australia, respectively.
Eagles are often seen grabbing large prey directly from the ground and then carrying it off somewhere to tear it apart. If you see a bird of prey take off from your garden with one of your chickens- it is far more likely to be an eagle than a falcon. Although that doesn’t help the poor chicken.
There are some eagles, however, who do capture prey in flight. For the most part, they fall into the genus haliaeetus, known as “fish eagles” or “sea eagles.” This includes the famous bald eagle and nine other species. This is easy to remember because it would be quite impossible to hunt for fish on the ground!
Flight Pattern and Speed
Likely due to the differences in hunting behavior and diet, falcons and eagles can also be distinguished from each other by flight pattern. Sort of. Eagles are known for soaring high up in the sky. Circling and gliding, while using their incredible eyesight to look for prey.
Falcons are known for their impressive agility. They will typically exhibit diving and swooping behavior more often than soaring or gliding. When flapping their wings, eagles will exhibit slow and steady flaps. Whereas falcons tend to beat their wings much more quickly and change direction more often. Of course, there are exceptions.
Almost all kestrels are keen on gliding and soaring. Particularly the nankeen kestrel from Australia, which is famous for using thermal air pockets to hover almost stationary above fields. All species of kestrel are smaller than eagles, so you can usually identify them this way.
Another birder told me years ago that falcons can also be identified through their impressive speed. This isn’t entirely true. The peregrine falcon is the fastest living animal on earth. It can dive up to 200 mph (320km). But then again, this speed has also been clocked for the fastest eagle, the golden eagle. Not super helpful, but it’s still really impressive!
The Exceptions that Prove the Rules
Aside from typical falcons, there are several species of falcons that do not adhere to the above “rules.” The most obvious are forest falcons and caracaras. Both of these groups of falcons lack the tomial teeth of other falcons. Additionally, they have rounded eagle or hawk-like wings. Last but not least, they are often seen hunting for prey on the ground.
So, how do we tell them apart?
Unlike eagles, forest falcons (as the name suggests) prefer dense forest environments. You are very unlikely to spot a forest falcon in an open field. They also have impressively long tails and legs- unlike most eagles.
Caracaras enjoy open areas, unlike most falcons. The reason for this is that caracaras like eating dead things. Eagles such as the bald eagle and golden eagle have been known to eat carrion in times of stress. But for caracaras, dead animals form the main part of their diet. You are likely to find them along roadsides and in pastures.
Among the birds that we commonly refer to as eagles, there are four unofficial groups. True Eagles, Sea Eagles, Serpent Eagles, and Harpy Eagles. Most of the species follow the rules that we have previously discussed. But again, there are some outliers. Serpent eagles, for example, tend to have unfeathered tarsi- such as the crested serpent eagle. Harpy eagles also have a strikingly different appearance- with large head crests and overall enormous size. Although, if you are lucky enough to see a harpy eagle, it’s pretty unlikely that you would confuse it with a falcon!
Answer: Falconry is the practice of hunting small animals such as rabbits and squirrels using trained birds of prey. Although the peregrine falcon and merlin falcon are used in falconry- the most common species are hawks and eagles. If falconry is of interest to you, some species that are particularly suited to the task include:
• Harris’ Hawk
• The Northern Goshawk
• Red-tailed Hawk
• Australasian Harrier
Answer: Ok, this was not an article about Kites. But I’ll bet a few of you out there are thinking- wait a minute. What about the Double-toothed kite? There are certainly some species of kites that can be easily confused with falcons. Perhaps this is a project for another day, but broadly speaking, kites can be differentiated from both eagles and falcons by the following characteristics:
Flight: Agile gliding with backwardly angled wings
Hunting: Open areas and scavenging of carrion and garbage
Answer: Both falcons and eagles are cosmopolitan birds that can be found the world over. However, the highest concentration of species is in the Americas, Africa, and Australasia. For spotting eagles, you need to be scoping out undisturbed habitats of forests, waterways, and open woodlands. Falcons are generally less bothered by human activity than eagles, so as long as there is a good food supply and a few good trees- falcons could be around.
At the end of the day, telling the difference between falcons and eagles is a lot to do with their behavior and a bit to do with your birder instinct. What was fascinating to me about this research project was how distantly related they are. For example, 57 million years ago, the ancestors of whales looked like deer. But in that same time frame, we have two very distinct types of birds that can be difficult to tell apart. It is complicated, but I hope that this has helped in some small way.
- Bird Watching USA
- Ornis Hungarica
- The Specialization of Raptor Beaks
- Raptors of the World
- Birdlife International
- The Birds of Costa Rica
- An Illustrated Field Guide to the Birds of Costa Rica
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