If you’ve ever questioned the identity of the small falcon that just zipped passed the migration site, you may have been left wondering whether you had an American Kestrel or a Merlin. The differences between these two falcons can seem subtle at first but the differences become more pronounced after even just a quick study of their shape and cadence in flight. Add to that distinct behavioral differences to the equation for these two species and confidence builds quickly.
American Kestrels are small thin falcons with wings that look like banana peels attached to their body. The thin, dainty impression of this bird is the first thing noticed when graced with their presence. When soaring they hold their wings mostly flat, straight out from their bodies and they remain perpendicular to the body instead of the more expected swept back falcon appearance. They make tight circles as they gain altitude fast. They are buoyant and animated in flight often rising and lowering while soaring, flapping and gliding; especially when any kind of wind is present. When gliding, their wings are held slightly bowed downward and the more classic swept back shape appears. Their glides often end with them losing speed quickly, forcing them to flap and correct themselves.
The Kestrel’s wing beat is light, fluttery and looks like they are spending a lot of time getting from point a to point b. They will also flap and glide in direct flight, similar to Sharp-shinned Hawks but unlike the active Merlin.
Where American Kestrels feel thin and dainty, Merlins feel stockier and heavier. They llook like Kestrels on steroids and are masters of speed. Where Kestrels seems light and delicate in flight, Merlins command their space and fly through it like they are late for a date. If seen soaring, consider yourself lucky as these falcons rarely soar. While in a soar, they show pointed falcon-like wings, held flat or slightly angled downward, however, their stocky build shines through. Their wings are especially heavy near the base before tapering to sharp points. A Merlin’s tail shares the heavier look and is sharply squared at the end. When gliding their wings are angled down and they hold their speed throughout.
When flapping, it’s fast, rhythmic, powerful and sometimes feels like it never ends. If you have a falcon in your bins, the bird is low and suddenly drops out of view, consider a Merlin. They hug tree lines and shorelines, sometimes rocketing by only to be noticed at the last minute, if at all.
While these two raptors both have classic falcon wings, there are some key things to look for to distinguish the two. With Merlins, it’s all about noticing a heavier, stockier build, including the wings and tail. They are especially hefty in the wings from the body to the wrists before the wings taper to points. Kestrels on the other hand, appear thinner more delicate and longer winged; in fact, everything about the Kestrel is thinner all around. Because both birds hold their wings slightly drooped in a soar, one needs to look for other pieces of the puzzle to differentiate the two but behaviorally, Kestrels will soar infinitely more often than Merlins, so this is an important factor to consider.
Be sure to pay attention to other clues related to flight behavior. Kestrels rise and lower in altitude, both while flapping and gliding. In active flight, the Merlin flaps more often and is more active overall. The wing beat of the Merlin is fast, at a constant even rate and it seems like it never ends. They have a direct line of flight and rocket through it. The Kestrel often flaps and glides in an alternating fashion, similar to Accipiters like Sharp-shinned Hawks. They are more buoyant and move around a lot in their space.
Behavioral traits to look for:
- Both of these falcons will actively hunt in flight, even during migration but Merlins tend to do it more often
- Merlins seem to prefer their space and will scream and go after any other bird occupying where they want to be, even birds as large as Eagles
- Kestrels are typically seen well before getting close to a migration count site and also tend to be higher in the sky, while Merlins are most often low, hugging tree lines and beaches
- The speed and timing of Merlins is extremely fast and usually found with little time to study them as they rocket by migration sites
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