Source and Additional Information

Animal Diversity Web
 
Mithil Pandhi
Some rights reserved

Black skimmers are a social species. They form colonies that consist of an aggregation of flocks containing both young and old birds. In colonies, males and females form pairs. Colony size can vary between a small number of pairs to several thousand pairs, but when colonies are large the birds tend to nest in clusters of less than 50 pairs. There is no social hierarchy but black skimmers tend to be highly territorial and defend their nest sites. The distance between nests is usually 95 cm, but when space is available nests can be up to 400 cm from the nearest neighboring nest. Individuals communicate with one another both vocally and through posturing displays. Black skimmers exhibit aggressive behaviors such as barking and posturing to defend a territory. They also engage in active and passive anti-predator behavior. Their unique foraging behavior is interesting and distinguishes them from other birds as they skim above the water with the long, lower mandible extended into the water to search for prey. They are successful nocturnal foragers but are also active during the day and at dusk and dawn. Black skimmers clean themselves regularly. They bathe in freshwater and exhibit preening behavior. When sleeping, they tuck their heads into the feathers on their back. (Burger and Gochfeld, 1990; Gochfeld and Burger, 1994)

Home Range

Black skimmers forage between 5.2 to 8 km from colony sites. (Burger and Gochfeld, 1990)

Communication and Perception

Source and Additional Information

Animal Diversity Web
 
Mithil Pandhi
Some rights reserved

Black skimmers communicate with each other by both vocalization and displays. Their bark has been commonly described as a low-frequency bark like that of a dog. They bark as an anti-predator response, to warn their neighbors of potential danger, and also give a low-frequency bark to display aggression when neighbors intrude on their territory. The barks of males are of a lower frequency than those of females. Typical barking calls have a high frequency of approximately 6 kHz and the longest of these barks can last about 0.5 sec.

These barks are often accompanied by head tosses and an aggressive upright posture. A head toss occurs when black skimmers quickly raise and lower the head and bill. In an aggressive upright posture, black skimmers extend their legs, body, and neck and hold the carpals away from the body. They may also open their bill without making noise.

Another aggressive posture is the low oblique. This posture may follow the upright aggressive posture but is less intense. It is often accompanied by head tosses and soft barks. In the low oblique posture they tilt the body down and extend the tail and wings upward.

To avoid aggression when moving through a colony black skimmers walk with the bill held upright.

When selecting a nesting location, males and females communicate by kicking sand to establish a scrape at that particular spot. This method of communication also allows their neighbors to know where the nest will be made. Black skimmers communicate vocally most often when they are in their own territories. (Burger and Gochfeld, 1990; Gochfeld and Burger, 1994)

The tactile senses of black skimmers are important in their foraging behavior. When skimming over the water at night, they use their lower mandibles to make contact with fish and other marine prey before catching them. Their vertical pupils may help their vision during nocturnal feeding or protect their retinas. (Burger and Gochfeld, 1990; Gochfeld and Burger, 1994)