Peregrine Falcon vs Prairie Falcon
- Zach (Head Flocker)
- 3 days ago
- 7 min read
Just because you can identify the Millennium Falcon does not mean you are prepared to identify all other falcons. In fact, I would guess you are woefully unprepared.
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Quick Tip
Spotting falcons is tough, so I recommend using a spotting scope to scan the places falcons frequent for better chances to spot your target species.
Understanding key differences between falcons
The Peregrine Falcon is a large, dark raptor found across much of North America, and the Prairie Falcon is a large, brown raptor found from the Great Plains west to the Pacific Coast. Those along the Atlantic Coast may not regularly need to separate these two species, but knowing the quick tricks for separating the Peregrine and Prairie Falcon will help when traveling west or when a vagrant Prairie Falcon shows up in your area!
I will focus on four quick features to identify both falcon species: head, armpit, back and body, and tail. Additionally, it is critical to understand that while size helps separate Prairie and Peregrine Falcons from Merlins and American Kestrels, there is far too much overlap in length and wingspan to safely separate the Prairie from the Peregrine. Simply, do not rely upon size when identifying these two species in areas where their ranges overlap.
Following the four identification features, you will find updated range maps for these species. As the Peregrine Falcon continues to recover in some regions on the continent, its range has changed. See those changes reflected in the maps below. Now, jump into falcon ID!
You will need a fast focus to capture these fast birds!
1. Identifying Features of the Head
All falcons have distinctive facial features, usually including a conspicuous mustache of varying size and color and a "plumage helmet," which is the darker coloration that extends from the back onto the face.
Helmet - The Peregrine Falcon's "helmet" is usually darker and more extensive than what is seen on Prairie Falcons. Some immature and pale Peregrine Falcons can have restricted helmets that appear much more Prairie-like. Be careful with these birds, and combine other features for a confident identification.
Mustache - The mustache of the Prairie Falcon is usually more distinctly separate from the helmet when compared to the Peregrine Falcon. Note how the white between the mustache and the helmet reaches closer to the eye. As in the helmet, pale juvenile, immature, and adult Peregrines can be similar.
Eyebrow - Prairie Falcons have distinct pale to white "eyebrows" or superciliary stripes that run through the "helmet." This feature is lacking in Peregrine Falcons. However, some younger, pale birds will show a smaller eyebrow similar to a Prairie. If a bird is darker brown or gray but also shows an eyebrow, refer to the mustache field mark or other marks listed below.
Peregrine and Prairie Falcons possess unique facial features that aid in their identification, but careful attention to detail is essential for accurate identification. The darker and more extensive "helmet" of the Peregrine Falcon, along with its distinctly integrated mustache, contrasts with the more defined and separated mustache and distinct pale eyebrows of the Prairie Falcon. Observers should particularly note variations in head plumage among juvenile and immature birds, as these can complicate identification. By combining these key characteristics, you marvelous birdwatchers are a step ahead in falcon ID.
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2. Check the Armpit
Falcon wings are designed for one thing: speed. With long, pointed wings, falcons are built for fast flight and expedient dives. While the shape of both of these fast fliers is not the most helpful in identification, the plumage in the underside of each wing can be useful!
Armpits - When a large falcon flies over you, your eyes should focus as quickly as possible in a single location: the armpits. For in the armpit, truth is offered. (Truth=identification.) When a Peregrine Falcon flies overhead, you may not notice anything of note. BUT, when a Prairie Falcon buzzes your dome, its like the armpits of a gorilla have opened over your head. Why? Prairie Falcons have dark plumage in the armpits or axillaries. This field mark is surefire to help in identification of these raptors. Quick note: If the entire underwing is dark, this does not indicate a Prairie Falcon. The dark armpit will contrast with the rest of the wing.
Seeing the wings of a speeding falcon might seem an impossible task. But if you can manage it, the underwing plumage is a guarantee that does not need an extended warranty to back it up.
3. Back it Up to the Body
Speaking of backing it up, the coloration of the plumage on the back of these birds can offer a clue that does not require the work of a Sher-Lark Holmes to utilize. In most scenarios, Prairie Falcons will have back plumage that is a truer, paler brown than the Peregrine Falcon. Peregrines have more blues, grays, slates, and other darker colors as part of the base coloration. While colors can be tricky for some birders, back coloration should be used as supporting identification evidence when possible.
The back might be difficult for people who view colors as overly subjective, but the breast and belly feathers are less subjective in these falcons. The Prairie Falcon shows FAR more white in the breast and belly, with more vertical, teardrop-esque streakings. The Peregrine Falcon, contrastingly, is much darker in the underparts, with DISTINCT horizontal, barring. Both patterns in the bellies of these species follow the coloration of their back, with Prairies having a more true brown cast to their streaks, and Peregrines possessing a darker cast to their barring.
The body of these falcons are tubular masses of flying death. At least to their prey species. But to birders, the bodies possess helpful field marks to be used in rapid identification. Why rapid? Because falcons do not do anything slowly.
4. Examining the Tail
In flight, the armpits are the field mark to look for. If you are still uncertain or lacking confidence in your identification, the tail can be a final resort.
The shape and pattern of the tails of these two species are subtly different, making them a less helpful field mark. Unfortunately, I already begain writing this section, so I will share what I can. First, in shape and length, the Prairie Falcon tail appears longer and more narrow than most Peregrine Falcons. This is less useful if the tail is flared, but when folded, it usually holds true. The tail pattern is also different, with the Peregrine Falcon's tail having a thick, dark band at the tip (in the underside). The underside of the Prairie's tail is less boldy marked, is more pale, and it lacks the thick band at the tip.
The tails are not my favorite field mark to teach for falcon species separation, but I cannot deny they have their use. Take this field mark and apply it cautiously in combination with the better field marks I provided above.
Range of the Peregrine Falcon
Range of the Prairie Falcon
Spotting a falcon in the field
Falcons are not always the easiest raptors to see in the field (except for kestrels). Being in appropriate habitat is not always enough to spot these species. So, how can you increase your chances? Visit known nesting habitats (cliffs, buildings, etc) and view from an ethical distance (I use this spotting scope). During the nesting season, falcons will visit their nesting sites frequently. So go to the places they would prefer to nest. During the winter, find these falcons's foods. Waterfowl, shorebirds, prairie birds, large songbird flocks, etc. These two species are bird hunters, so find their prey to increase your chances of getting eyes and lenses on their amazing hunting skills.
Faster than a speeding falcon
This guide hopefully provides insight for identifying Peregrine and Prairie Falcons. I have detailed key characteristics such as head features, wing armpits, body plumage, and tail differences. With the photos emphasizing these features, and utilizing updated range maps, I hope you adventurous bird lovers can continue developing your identification skills, especially with these two raptors.
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Photo Credits
Peregrine Falcons
Prairie Falcons
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