American Kestrels, the smallest falcons in North America, are known for their striking colors and hunting style. They are often seen perched on wires or hovering over fields. A common question about these adaptable raptors is whether they form lifelong pair bonds. This article explores their breeding strategies and the environmental influences shaping their family dynamics.
Kestrel Mating Behavior
Kestrels exhibit seasonal monogamy, forming a pair bond for a single breeding season. Successful pairs may re-pair in subsequent seasons if both individuals survive and return to the same breeding territory. In sedentary populations, pairs sometimes remain together and utilize the same nesting cavity for multiple years. For migratory populations, whether pairs mate for life is less clear.
The breeding season for American Kestrels in North America spans from March through July, varying with latitude. Prior to egg-laying, kestrels engage in courtship rituals. Males perform aerial displays, including climbs and dives, often with “klee-klee-klee” calls. Males also attract females to nesting cavities and offer food.
Once a pair forms, mating occurs. The active breeding period, from egg-laying to chicks leaving the nest, lasts 55 to 60 days. Females primarily handle incubation, while males provide food and occasionally take turns on the eggs.
Factors Influencing Pair Bonds
While kestrels may re-pair for consecutive seasons, several factors can influence the duration of their pair bonds and lead to changes in partners. One significant reason for bond dissolution is unsuccessful breeding. Pairs that experience failed nests or do not fledge young during a season are more likely to split and seek new mates.
The short lifespan of kestrels, typically less than five years, limits the opportunity for long-term pair bonds. Kestrels often show strong fidelity to their nesting territories, returning to the same area annually. However, this territory fidelity does not always translate to mate fidelity.
Mate changes are common, even when the previous partner is alive and present. Switching mates does not consistently lead to improved nesting success. For migratory populations, re-pairing chances are reduced because individuals may migrate separately, with males often returning before females.
Older birds tend to have higher reproductive success, and pairs with older males often show greater breeding success. Longer-lasting pair bonds can positively influence reproductive success, indicating a benefit to mate familiarity and coordination.