Birds diurnal

Common Tern

Sterna hirundo

Known as the 'Sea Swallow' for its elegant flight and forked tail, the Common Tern is a master of the plunge-dive. Watch as these spirited migrants transform coastlines and lakeshores into bustling, vocal colonies each summer.

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Quick Identification

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Size

Length: 12-14 in (31-35 cm); Wingspan: 30-39 in (77-98 cm); Weight: 3.9-5.1 oz (110-145 g)

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Colors

Pale grey upperparts and white underparts; jet-black cap; bright orange-red legs; red bill with a distinct black tip.

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Key Features

Deeply forked 'swallow-like' tail
Jet-black cap covering the crown and nape
Bright red bill with a sharp black tip
Long, narrow pointed wings with dark outer primaries

When You’ll See Them

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Activity pattern diurnal

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Peak hours 6-9 AM and 4-7 PM, following the movement of baitfish toward the surface

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Season April-September

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Diet Primarily a piscivore, the Common Tern eats small forage fish like sand eels, herring, and smelt. They also occasionally hawk for insects over marshes or water surfaces.

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Habitat Coastal beaches, rocky islands, salt marshes, and large inland lakes or river systems with gravelly shorelines.

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Behavior

Common Terns are often referred to as 'sea swallows' due to their graceful, buoyant flight and deeply forked tails. They are highly social birds that nest in noisy, energetic colonies, often on islands or secluded beaches. You’ll frequently see them hovering over water before performing a dramatic vertical plunge-dive to snatch small fish. Their social structure is complex; during the breeding season, males perform elaborate 'fish flights,' carrying a silvery prize in their beak to impress and court a mate.

While elegant in flight, these birds are famously feisty when it comes to defending their territory. If a predator—or an unsuspecting human—gets too close to their nesting site, the colony will rise up as one, dive-bombing the intruder with sharp cries and occasionally striking with their bills. This aggressive defense actually benefits other bird species, which often nest near terns to take advantage of the 'security umbrella' they provide against crows and gulls.

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Camera Tips

To capture high-quality footage of Common Terns, focus your camera placement on 'loafing' spots rather than foraging areas. These birds spend a significant amount of time resting and preening on dock pilings, floating logs, or shoreline rocks. If you have a lakeside or coastal property, setting up a camera on a tripod at a low angle facing a popular resting spot will provide the best results. Ensure the camera is positioned with the sun behind it; terns have bright white plumage that is easily 'blown out' (losing all detail) in harsh, direct light or high-contrast settings. If your camera allows for exposure compensation, set it to -0.5 or -1.0 to preserve the delicate texture of their feathers.

Because Common Terns are incredibly fast, you need a camera with a high-speed trigger and a fast shutter speed. In a backyard setting near water, you can encourage them to land in front of your camera by providing a stable, elevated perch, such as a dedicated wooden 'tern platform' or even a clean, flat-topped fence post near the water's edge. They prefer perches with a clear, 360-degree view of their surroundings to stay alert for predators like hawks or gulls. Avoid using food as bait, as they are strictly live-prey hunters, but providing the ideal vantage point is often lure enough.

During the peak of the breeding season in June and July, try to position cameras near the edges of known nesting areas (while respecting all local wildlife laws and staying outside of protected zones). You may capture incredible behavioral shots of 'fish-passing,' where a parent brings a small fish back to a fledging chick. For these shots, use a 'burst' or 'photo-mode' setting rather than video to capture the split-second interactions and the beautiful transparency of their wing feathers. If your camera has an AI-subject detection mode, ensure 'Bird' is selected, as their rapid movements can sometimes trick standard motion sensors.

Similar Species

Species that look similar or are commonly confused with Common Tern.

Arctic Tern

Features a shorter, all-red bill and shorter legs; also has more translucent primary feathers when seen from below.

Forster's Tern

The bill is more orange than red, and the wings are silvery-white without the dark wedge-shaped tips seen on the Common Tern.

Roseate Tern

Much paler overall with a very long tail; the bill is mostly black during the peak of the breeding season.

Frequently Asked Questions

Common Terns are strictly diurnal and are most active during daylight hours. Their peak activity occurs in the early morning and late afternoon when schools of small fish move closer to the water's surface, making them easier to catch via plunge-diving.

Common Terns won't visit bird feeders since they only eat live-caught fish. However, if you live on the water, you can attract them by providing flat resting areas like dock pilings, floating platforms, or ensuring shoreline rocks remain undisturbed for 'loafing.'

Their diet consists almost entirely of small fish, usually between 1 to 4 inches long. They favor species like sand eels, smelt, and herring. Occasionally, they will supplement their diet by catching large insects in mid-air over wetlands.

They are common in suburban areas only if those areas are adjacent to large bodies of water, such as coastal towns, the Great Lakes, or large reservoirs. They are frequently seen around marinas and public beaches during the summer months.

The easiest way is the bill: breeding Common Terns have a red bill with a black tip, while Arctic Terns usually have a solid red bill. Common Terns also have longer legs and slightly darker grey plumage on their underparts compared to the Arctic Tern.

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