The Bank Swallow is a small, slender song bird. In its typical adult appearance, the bird is white on the underneath and brown on top of its feather coat, with a dark band running across and extending all the way down to the middle of its chest. It has a small bill and supports long wings of about 25-29 cm which help it during flight. They are usually 12-14 cm in length, and weigh around 10-19 grams. Traditionally, Bank Swallows nest in colonies along the streamside banks of North America, but they can also be found across Europe and Asia. The British name for Bank Swallows is Sand Martin and is commonly used across Britain; other Spanish and French names for the bird are also commonly used in the respective countries.
Bank Swallow Habitat
Since they live in low areas mostly around rivers, streams, ocean coasts or reservoirs, the territories they are found in are vertical cliffs or banks. Here they nest in colonies which include up to 20,000 nests. In the past, Bank Swallow bird was commonly found around natural bluffs or on the streamside. However, with the seemingly increased eroding, the Bank Swallows have re-located their colonies to more man-made sites like quarries made out of sand or gravel, or road cuts. These locations offer the same support as a vertical cliff and allow for stability of their nests. As you can see in bank swallow pictures, these nests are very carefully made and placed. Each nest is made in such a way that it forms a chamber. The male member uses his small, cone shaped bill along with feet and wings to dig burrows which are perpendicular to the ground level and go about 25 inches into the side of the banks. These burrows eventually lead to the nest chamber, as the male widens them upwards and from both sides in such a way that constant temperatures can be maintained inside the burrow. Then the female member builds the nest by constructing a mat of straw, grasses, leaves, or rootlets that she collects from around the banks. This mat is 1 inch thick and 5 inches in diameter to offer support and firmness.
Bank Swallow Breeding Style
Since the Bank Swallows make nests in large colonies, they do it around fairly loose soils so that it is easy to burrow in. Similarly, these areas are located near water bodies so that there is vertical space for the birds to fly. It is one of the interesting bank swallow facts that every individual chooses a colony first, then a nest location within that colony area. Interestingly, it is the male that digs the burrow before it has a mate. It is only then that a female hovers itself over the burrow she chooses and then mates with the male in that nest site. The Bank Swallows carefully choose a location that is in the upper third part of the bank so that few ground predators can attack them. They mostly eat insects like bees, wasps, ants, butterflies or moths. Since they live near water, it is easy for the Bank Swallows to catch food. They fly at a height of about 50 ft above open water or ground and catch insects, and then feed either singly or with large groups from their colonies.
Distinctive Behavioral Patterns
Bank Swallows have a set of distinctive behavior that instantly distinguishes them from other such bird species. These include the seemingly different pattern of flying with shallow, fluttery wing beats. They glide for 2 seconds but have a less twisty and straighter flight than other Swallows. Bank Swallows are extremely social; this can be seen clearly from their large colonies also. They are rarely ever alone and have developed complex social behaviors. During the extreme cold weather, they are seen huddling with one another and even with other Swallows. However, they also commonly fight with one another for nest locations, mates, or nest materials.
Bank Swallow Life Threats
Despite their small size, Bank Swallows are very interesting birds. They are present in a fairly large and stable number and despite the fact that monitoring them isn’t very easy; there are no evident threats to their survival and population. This doesn’t mean that there aren’t any factors which might cause a decrease in their number. These factors generally include changes in their nesting, like erosion, floods, road building projects that remove banks or make them less steep and unsuitable for Bank Swallows. Since they are found together in their colonies in large numbers, any harm caused to Bank Swallows brings large scale destruction for their population.