American Kestrel vs. Merlin: Two Tiny Falcons, Unmasked

Many bird enthusiasts stumble upon a small falcon and find themselves scratching their heads, wondering if it is an ‘American Kestrel or a Merlin?’ Today, we clear the confusion and equip you with the tools to confidently identify these two tiny raptors.

American Kestrel vs. Merlin: Plumage characteristics

Merlin: The male has the entire back and wings slate-gray. The tail is dark with gray to pale gray bands. The underparts have dark streaking. The female has as darker nearly blackish upperparts and similar streaking as the male in the underparts. Both sexes have a pale eyebrow and faint “mustache” stripes. The Merlin’s plumage is more variable than that of the Kestrel but revolves around similar pattern on the upperparts and underparts.

Feature	American Kestrel	Merlin
Upperparts:	Male: Rich rusty brown back with black barring, transitioning to gray-blue wings. The tail is orange-brown with a broad black terminal band. Female: All the upperparts and the tail are rusty brown with black barring. It has a terminal black band in the tail but is narrow.	Male: Slate-gray back and wings. Dark tail with gray bands. The underparts are heavily streaked with dark-gray. Female: Dark to blackish back and wings. It may show some “scaly” pattern depending on age. Underparts heavily streaked with dark-gray. Tail similar as the male’s. It has a variable plumage.
Underparts:	Male: Buff to pale orange underparts with streaks and bold black dots concentrated on the chest and sides. Variable. Female: Pale to buff with heavy brown to graying brown streaking. Also variable.	Male: Heavily streaked but variable. Some forms have brown streaking while others dark streaking. Yet others have a combination of both. Female: The streaking in the underparts is generally darker and less variable than in the males.
Head Markings:	Key Feature: Boldly patterned head with two prominent black stripes on the sides of the head.	Faint “mustache” stripes, but variable. Somo individuals have an obvious stripe on the cheek while it is nearly absent in others.
Head Color:	The top of the head is bluish-gray with a warm orange-brown center of the crown in some forma or all bluish-gray in others.	Dark slate-gray top of the head (crown) with a variable pale eyebrow. Dark Merlins of the Northwest have black heads and no pale eyebrow.
Tail:	Both sexes have a long and narrow tail. The male has an orange-brown tail with a bold black terminal band. The female American Kestrel has a rusty-brown tail with black barring. The black terminal band varies in thickness.	In both sexes, the tail is proportionally shorter, dark with multiple gray bands that vary in thickness, apparently with age.
Seasonal Variations:	Males show brighter plumage, especially on the back and underparts, during breeding season.	Both sexes show brighter fresh plumages during the onset of the breeding season. The three forms found in the continental United States show plumage variations.

Size and Shape Showdown: American Kestrel vs. Merlin

Unveiling the differences between these two falcons starts with dissecting their physical characteristics. Let’s take a close-up look at their size, shape, and wing design:

Feature	American Kestrel	Merlin
Overall Size:	Smaller, more delicate and slender, resembling a large (long-tailed) robin. Weight: 4.1 oz Wingspan: 22″	Slightly larger and stockier, larger than a blue jay in size. Think of a miniature Peregrine Falcon. Weight: 6.5 oz Wingspan: 24 “
Tail Length:	Long and relatively narrow, often held slightly spread during flight.	Shorter and broader, often folded tightly.
Body Proportions:	Head appears small and rounded in proportion to the body.	Larger head relative to the body.

Flight style and function: Kestrel vs. Merlin 

The flight pattern and function is as distinctive feature that separates the American Kestrel from a Merlin.

• American Kestrel: Hunts its prey using a sit-and-wait technique. They sit on a perch or any vantage point above the ground to scan the ground for prey. When perches are not available, kestrels hover to spot their prey on the ground.

When hunting, kestrels either drop from a perch to swoop down on prey or hover and then drop to the ground to capture prey. However, during normal flight they can perform opportunistic dives on insects or small animals.

When an American Kestrel is seen flying, it is likely that it is going from one place or perch to another not hunting.

• Merlin: Hunts primarily birds with aerial chases. Merlins do all their hunting in midair. This means that they require a fast and direct flight to be able to ambush and out run-fly their prey.

Feature	American Kestrel	Merlin
Flight Patterns:	More leisurely and undulating flight, often hovering extensively and scanning for prey below.	Swift and direct flight, characterized by bursts of speed, agile turns, and low dives.
Wing Beats:	Shallow and deliberate wing beats, creating a graceful, buoyant appearance.	Fast and powerful wing beats, capable of sudden changes in direction and explosive acceleration.
Wing shape:	Long, narrow wings with slightly rounded tips. These details can be difficult to see in the field.	Broader wings with sharper, more tapered tips, offering greater airspeed and maneuverability.
Hovering:	Masterful hoverer, remaining virtually stationary while searching for prey.	Limited hovering ability, primarily used for brief pauses during hunts.
Hunting Style:	Opportunistic ambush predator, often hovering or perching before diving on insects, lizards, small birds, and rodents.	High-speed pursuit predator, chasing down birds in midair with incredible agility and accuracy.
Prey Preference:	Primarily insects, supplemented by lizards, small mammals, and occasionally small birds.	Primarily small to medium-sized birds, including songbirds, sparrows, and doves.

Kestrel vs. Merlin: calls and screeches

Falcons are not songsters by any means. But familiarizing yourself with their calls and screeches you’ll add another layer to your understanding of these birds.

Falcon vocalizations can vary depending on context and individual bird. Pay attention to the pitch, tone, and repetition of calls for a clear identification.

Kestrel vs. Merlin Habitats

Both the American Kestrel and Merlin share similar habitat. They both favor open habitats with short vegetation, ideal for scanning and hunting prey. However, Merlins exhibit a greater dependence on this habitat on a larger scale, as they require it for pursuing and catching prey in the air.

On the other hand, Kestrels are stationary hunters, display greater adaptability, and can thrive in relatively smaller open spaces.

• The range of these small falcons overlap across much of North America. But merlins generally occupy more northerly and pristine landscapes.

Feature	American Kestrel	Merlin
Preferred Habitats:	Open fields, meadows, grasslands, agricultural lands, edges of woodlands and forests.	Open tundras, taiga forests, coastal marshes, grasslands, farmland, and mountain meadows.
Geographical Range:	Breeds across North America, from Alaska, Canada to Mexico. Winters from just below the border of Canada to Mexico and Central America.	Breeds across Northern North America, mostly in Alaska, most of Canada, and only parts of the US. Winters in coastal areas of the far northeast and northwest, most of the US below Canada, and southern US down to northern South America.
Areas of Overlap:	Most of North America, especially open landscapes like farmland and prairies.	Overlaps with Kestrel throughout its breeding range, but tends to favor more northern and open habitats.
Habitat Specificity:	Adaptable to various open areas, able to utilize human-modified landscapes.	Prefers wilder, untouched habitats with abundant open spaces and prey availability.

Conclusions and field tips for spotting Kestrels and Merlins

So you’ve spotted a small falcon flying overhead, but is it a “Kestrel or Merlin?” Here are some field-tested tips to help you identify the bird like a pro:

Size and Shape:

• Kestrel: Think larger than a robin-sized, slender and graceful with long tail and narrow wings.
• Merlin: Think mourning dove build, or miniature Peregrine Falcon, stockier and more compact with broader and pointier wings.

Plumage:

• Kestrel: Look for a rusty back, blue-gray wings, pale underparts with bold black dots and streaks, and patterned head.
• Merlin: Darker slate-gray back, bold dark or dark-brown streaks underneath, and faint “mustache”.

Flight and Hunting:

• Kestrel: Observe leisurely, buoyant flight with frequent hovering and undulating wing beats. Look for a bird perched on branches, utility poles or wire scanning the ground below for insects or small animals. Listen for the typical calls.
• Merlin: Look for swift and direct flight with bursts of speed and agile turns, chases after birds in the air. Listen for its long calls.

Lighting and Distance:

• Low light or distance: Focus on overall size, body proportions, and flight style. Kestrels often appear lighter and more delicate, while Merlins hold their wings flat and fly more decisively.
• Good lighting and close proximity: Pay attention to plumage details like streaking patterns, facial markings, and body shape. The kestrel’s rusty back and patterned head are key giveaways, while the Merlin’s “slate-gray back” and darker tones stand out.

Bonus Tips:

• Check the tail: Kestrels have long, orange/rusty narrow tails, while Merlins have shorter, broader dark tails with multiple gray bands.
• Consider the context: Merlins tend to favor wilder, northern habitats, while Kestrels are more tolerant of human-modified landscapes.
• Consult field guides and birding apps: Visual aids and detailed descriptions can help solidify your identification.

But remember, this is just the beginning of your falcon fascination! With practice, you’ll transform from spectator to avian detective. So, keep your eyes scanning the skies, your ears tuned for their calls, and your heart open to the wonder of these magnificent predators.

Ready to take your identification skills to the next level? Check out these resources for further exploration:

• Online field guides and bird photography websites. Immerse yourself in detailed descriptions and stunning visuals.
• Local birding groups and events. Connect with fellow bird enthusiasts and swap birding tales.
• Volunteer for conservation initiatives. Contribute to protecting these falcons and their habitats.

And finally, share your own spotting experiences! Leave a comment below and tell us about your encounters with these small raptors.

References

• Johnsgard, P. 1990. Hawks, Eagles, and Falcons of North America. United States: Smithsonian Institution.
• Smallwood, J. A. and D. M. Bird (2020). American Kestrel (Falco sparverius), version 1.0. In Birds of the World (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA.

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