The Merlin (Falco columbarius) is a small, compact falcon distributed across the Northern Hemisphere. This swift and agile raptor is built for speed and maneuverability. The Merlin is a specialized avian predator, relying on the capture of other birds. Understanding its diet requires an examination of the specific types of prey it targets, the unique methods it uses to hunt them, and how its menu shifts based on location and season.
The Main Diet: Small Birds
Merlins are highly adapted to hunting small- to medium-sized birds, which form the staple of their diet year-round. These falcons are aerial hunters, typically capturing their feathered prey in mid-air rather than on the ground. They concentrate on passerines and other songbirds.
The prey species a Merlin targets is frequently the most abundant and vulnerable bird in its immediate environment. Common examples include Horned Larks on open plains, various species of finches, and the ubiquitous House Sparrow in urban and suburban settings. Along coastal areas, they regularly prey upon small shorebirds like sandpipers and Dunlin during migration and wintering periods. The success of the Merlin is directly tied to its ability to match the speed and agility of its flying quarry.
They frequently take locally abundant species, such as Meadow Pipits on moorlands or Bohemian Waxwings in northern regions. Merlins essentially act as opportunistic avian specialists, exploiting whichever small bird population is easiest to catch at any given time.
Supplemental Prey and Opportunistic Feeding
While their diet is dominated by birds, Merlins are opportunistic hunters when avian targets are scarce or when energy demands are high. These secondary food sources are important for ensuring survival during non-breeding periods or for supplementing the nutritional needs of growing nestlings. Large insects constitute a major part of this supplemental diet, especially during the summer months.
Dragonflies are a common insect prey item, often captured and consumed by the Merlin while still in flight. They also take moths, grasshoppers, and beetles, usually catching them close to the ground or in low flight. Less frequently, Merlins prey on small mammals, such as voles, shrews, or even bats, often taken near cave openings or on the ground.
Reptiles and amphibians are occasionally incorporated into the diet. These non-avian items collectively make up a small portion of the overall diet but are important for flexibility and survival.
Merlin Hunting and Capture Techniques
The hunting style of the Merlin is characterized by high-speed, sustained pursuit rather than the high-altitude dive used by larger falcons like the Peregrine. They rely on surprise, agility, and relentless chase to secure their meals. A common technique involves the Merlin flying fast and low, often skimming just a meter or less above the ground or water, using topography and vegetation for cover.
This low-level flight allows them to appear suddenly, catching flocks of small birds completely by surprise. Once a target is selected, the Merlin engages in a rapid, horizontal chase, following the prey’s evasive maneuvers until the smaller bird is exhausted or miscalculates. The capture generally occurs in the air, with the falcon seizing the prey with its specialized talons.
Merlins have also been observed hunting cooperatively, particularly when targeting large, dense flocks of birds. One falcon may fly in to flush and confuse the flock, while the other capitalizes on the resulting disarray to isolate and capture a bird. After a successful capture, the Merlin often carries its prey to a specific location, known as a plucking post, where it removes the feathers before consumption. They also cache excess food near the nest during the breeding season.
How Diet Varies by Season and Region
The Merlin’s diet is highly flexible and changes significantly based on the availability of prey, which is determined by both the season and the geographical location. During the breeding season in the northern boreal forests, the diet is almost exclusively small birds. Later in the summer, the menu often shifts to include an abundance of juvenile passerines, which are easier targets than experienced adult birds.
Merlins living near coastlines frequently target migratory shorebirds and waterfowl, which are numerous and vulnerable in that habitat. Conversely, Merlins that have adapted to urban environments rely heavily on introduced species like the House Sparrow and European Starling, which provide a consistent, localized food source.
During migration, they often follow and target large movements of other migratory birds. In non-breeding periods, when the energy expenditure of hunting small, agile birds is less critical, the proportion of insects and small mammals in the diet increases, serving as an important caloric buffer.