Bird Species Spotlight: Black Skimmer

The black skimmer is an instantly recognized bird that is best known for its remarkable beak, and its black and white underpants. These skimmers have long, deep, and flattened blade-like mandibles. The upper mandible is shorter than the lower mandible and all skimmers have short legs with webbed toes.

Black skimmers live in large colonies in coastal waters which are usually free from open waves, but will sometimes flock together and feed along a beach shoreline. Their habitats include bays, estuaries, creeks, inlets and tidal pools. They can live for up to 20 years and start breeding from 1 to 3 years of age. Their beaks and necks are relatively long in order to maintain their body position above the water’s surface while skimming for prey. They usually feed on fish, insects, crustaceans, and mollusks. The edges of the beak are knifelike to allow the bird to grasp slippery prey. They also have very strong neck muscles which allows them to pull their prey from out of the surface of the water.

Skimming for fish © Jake Jacoby

Black Skimmer with fish © Jake Jacoby

Black skimmers are active throughout the day, but are mainly crepuscular (most active at dawn and dusk). Black Skimmers have large vertically-oriented pupils like cats, which are unique in the bird world. They are able to narrow their pupils into slits when skimming the water which allows them protection from the sun and reduces the glare on the water.

Black skimmers fly close to the water surface. They keep their beaks open while the lower mandible is submerged into the water to detect prey by a sense of touch. When the lower bill senses a fish, the upper bill snaps shut instantly. While they spend most of their life close to the water, they do not swim.

On landing approach, flaps up © Jake Jacoby

Black skimmers are monogamous and highly social. They are closely related to terns, including Least Terns. When resting in the sand, they will often lay flat and put their entire body, including head and bill, on the sand, probably to keep cool and to give their neck muscles a break from supporting their long beaks.

Black skimmers breed in loose groups on sandbanks and sandy beaches. Both adults take turns scraping a nesting site in the sand, by using an exaggerated posture to kick sand behind them with alternating foot strokes. They then rotate in their scrape to create a saucer-shaped depression. This depression only takes a few moments to create and the males do more scraping then the females. These nesting sites are often among tern nesting colonies which can provide benefits as terns will aggressively attack gulls and mammals that prey on eggs and chicks.

Females lay two to five eggs which are incubated by both parents (in fact, the males even have brood patches). The chicks are born with their mandibles the same length but the lower mandible starts to grow longer when the chicks fledge. The chicks leave the nest as soon as they hatch and lie inconspicuously in the nest depression where they are shaded from high temperatures by their parents. Both parents feed the chicks exclusively during the day.

Adult © Jake Jacoby

Juvenile © Jake Jacoby

Crows are the primary natural predator of black skimmers. Other predators include dogs, cats, gulls, and rats. These predators will feed on eggs and chicks. However, the birds have natural adaptations to help them protect their chicks and eggs from the predators because they tend to forage at dawn and dusk. This way, one parent can always remain on top of their eggs or chicks during the day and shield them from predators.

I took all the above photographs along the beaches of Fort de Soto State Park at the southern end of Pinellas County, Florida.