Food

The Black-naped Tern (Sterna sumatrana) is primarily a piscivorous bird, meaning its diet mainly consists of fish. These elegant seabirds hunt for small fish, crustaceans, and squid along coastal waters and over open seas. Their foraging behavior is characterized by plunge-diving from the air or skimming the water's surface to catch prey. Black-naped Terns have keen eyesight and excellent aerial agility, allowing them to spot and capture prey with remarkable precision.

Fish make up the bulk of the Black-naped Tern's diet, with small species such as anchovies, herring, and sardines being preferred prey items. These fish are often found in large schools near the water's surface, making them easily accessible to terns as they dive or skim for food. Additionally, terns may target small crustaceans such as shrimp and krill, as well as cephalopods like squid, which are abundant in coastal and offshore habitats.

The foraging behavior of Black-naped Terns is influenced by environmental factors such as tide cycles, water temperature, and prey availability. Terns are opportunistic feeders, adjusting their hunting strategies based on changing conditions. Terns may also follow fishing vessels or feeding aggregations of other seabirds to scavenge for food scraps or steal prey.

During the breeding season, Black-naped Terns must ensure an adequate supply of food to sustain themselves and their chicks.

Both parents participate in feeding the young, bringing back small fish and other prey items to the nest. The provisioning rate may increase as the chicks grow and require more food to fuel their rapid growth and development. Adequate food resources are essential for the reproductive success of tern colonies, as food shortages can lead to reduced chick survival rates and lower breeding success.

Black-naped Terns may face competition for food resources from other seabird species, including gulls, pelicans, and other terns. Competition can be particularly intense in areas where prey is limited or concentrated, leading to aggressive interactions between birds vying for the same food source. Terns may also engage in kleptoparasitism, stealing food from other birds through aggressive behavior or by scavenging on food scraps left behind by other predators.

In addition to fish and squid, Black-naped Terns may supplement their diet with other prey items such as insects, small crustaceans, and even terrestrial vertebrates like lizards or small mammals. These additional food sources may be consumed opportunistically when fish are scarce or during periods of fasting, such as during migration or inclement weather. Terns are adaptable feeders, capable of exploiting a wide range of food resources to meet their energetic needs.

Overall, the food of Black-naped Terns consists primarily of small fish and squid, supplemented by crustaceans, insects, and other prey items as available. Their foraging behavior is characterized by plunge-diving, skimming, and opportunistic feeding strategies, allowing them to efficiently capture prey in a variety of marine habitats. Studying the food habits of Black-naped Terns provides valuable insights into their ecology, behavior, and interactions with other species within their marine ecosystems.