Southeastern American Kestrel in Louisiana
The American Kestrel (Falco sparverius) is the smallest member of the family Falconidae in North America. The American Kestrel can be identified by two distinct black streaks on each side of the head that contrast with the white throat and cheeks, and by a blue-gray patch encircling a rufous-colored spot on the top of the head. The males have a prominent rufous coloration on the back and tail. The Southeastern American Kestrel (F.s. paulus), which is one of two subspecies that occurs in the United States, is a local resident of Louisiana. It is approximately the size of a robin, and the female is larger than the male. The Southeastern American Kestrel (SAK) is often seen during the winter months in Louisiana perched on telephone lines located along fields and pastures.
The resident SAK is often confused during the winter with the migratory subspecies F.s. sparverius, although the resident species is smaller. The mean body mass of the SAK is approximately 22 percent lower in males and 26 percent lower in females, as compared to the migratory subspecies. It is very difficult to distinguish the two subspecies in the field. F.s. sparverius may look chunkier, but it takes someone who has spent long hours in the field watching kestrels to determine the difference between the two subspecies.
SAKs form strong pair bonds that tend to remain permanent. Displaying high site fidelity, pairs often remain on or near their nesting territories. SAK territories can range in size from 300 to 700 acres. In Louisiana, the SAK prefers open, park-like pine forest and open areas with scattered mature trees, which are needed for perch and nest sites. It is important that forest stands do not have a dense understory. The SAK prefers the same type of habitat preferred by the endangered Red-cockaded Woodpecker (RCW).
The SAK begins breeding courtship in late winter. The courtship includes aerial displays in which the male performs dives and a flutter-glide to advertise to the female. The SAK nests in cavities located in snags or living trees, usually excavated by woodpeckers. The Pileated Woodpecker often plays on important role in creating cavities suitable for nesting SAKs by enlarging the cavities of smaller woodpecker species. The SAK will also use nest boxes, when they are placed in suitable habitat. On Fort Polk, we usually find our first eggs in early April, and a full clutch usually consists of four to five eggs. The incubation period lasts 29 to 30 days. The young will fledge around the age of 30 days. The adults and young will forage together until dispersal, which occurs in the fall.
The SAK hunts from a perch, on the wing, and hovering. It is a generalized predator, feedings on rodents, insects, reptiles, amphibians, and small birds. The favorite food items on Fort Polk are lizards, including anoles, fence lizards, and skinks.
The U.S. Fish and Wildlife Service formerly considered the SAK a candidate subspecies for listing as threatened or endangered. It is no longer being considered a candidate for listing, but is considered a species of concern. The SAK is listed as threatened in Florida by the state’s game and fish commission. The SAK is a nonmigratory resident of the gulf coast states, now very rare over much of its former range. Current range includes east Texas, Florida, Louisiana, and the southern portions of the states of Mississippi, Alabama, South Carolina, and Georgia. The ranges of the two subspecies overlap during the winter.
Habitat loss is the main factor in the population decline of SAK in parts of its range. Industrial forest lands provide open areas important for the SAK, but they do not provide mature trees for nests sites. When the timber matures, the timber stand is usually too dense to be suitable for the SAK. Lack of prescribed fire is also detrimental to the SAK, because it prefers open, park-like forest stands kept open by regular prescribed burning. Prescribed burning and placing nest boxes in suitable habitat are the quick and feasible ways to improve SAK habitat.
Contributed by: Kenneth Moore
Also by Kenneth Moore: Southeastern Kestrel Management on Fort Polk