The kestrel, a widespread small raptor, is best recognized for its distinctive hunting method of hovering in mid-air. Common species, like the American or Eurasian kestrel, engage in pair bonding for reproduction, leading many to wonder about the permanence of these relationships. In avian biology, “mating for life” suggests a lifelong, exclusive partnership that persists across multiple breeding seasons. This article explores the specific nature of the kestrel’s pairing habits, detailing the duration of their bonds, formation, and separation factors.
The Kestrel Pair Bond: Monogamy Defined
Kestrels are typically categorized as socially monogamous birds, meaning a male and a female associate exclusively to raise a single brood. This commitment usually lasts for only one breeding season, classifying their behavior more accurately as serial monogamy. The pair bond forms in the spring, endures through nesting and the fledging of the young, and often dissolves by the autumn or winter.
True lifelong pairing is uncommon and depends largely on the species’ migratory habits and survival rates. For resident kestrel populations that remain in the same territory year-round, pairs sometimes stay together for successive seasons due to high site fidelity. This tendency to return to the exact same nesting location often facilitates a reunion with the previous year’s mate, provided both partners survived. Therefore, the permanence of the bond is generally an outcome of geography and longevity, rather than an inherent commitment.
Courtship and Mate Selection
The establishment of the seasonal pair bond begins with a distinct courtship period involving aerial displays and provisioning rituals. The male initiates the process by performing elaborate flights, including sequential dives and ascents accompanied by loud vocalizations. These energetic maneuvers advertise the male’s territory and his physical fitness to potential mates.
A significant part of mate selection centers on the male’s ability to provision food and secure a suitable nesting site. The male locates potential cavities, such as tree hollows or crevices, and leads the female to inspect them. The female often assesses the male’s capability as a provider through ritualized courtship feeding, where he presents her with captured prey, known as a nuptial gift. This display of hunting proficiency demonstrates his ability to support her during incubation and raising the young.
Shared Parental Duties
The pair bond achieves its purpose through a distinct division of labor once the eggs are laid. The female takes on the majority of the incubation duties, sitting on the clutch of four to five eggs for nearly all of the 26 to 32-day period. During this time, the male assumes the primary role of hunter, providing food for the female so she can maintain her energy reserves.
After the chicks hatch, parental responsibilities shift to accommodate the brood’s increasing nutritional demands. The female initially remains close to the nest to protect the young, while the male continues to provide the bulk of the food supply. As the nestlings mature, the female begins to join the male in hunting. Both parents share the duties of feeding the young until they fledge at about 28 to 31 days old, continuing to feed the juveniles outside the nest until they develop hunting skills for independence.
Factors That Break the Bond
The seasonal nature of the kestrel bond means its dissolution is a predictable event following the successful raising of the brood. The most common factor leading to separation is the onset of migration in species that do not remain year-round in their breeding territory. Individuals typically disperse for the winter, and this geographic separation prevents the maintenance of the pair bond.
Even in non-migratory populations, a lack of breeding success can prompt a separation, as one or both partners may seek a new mate the following year to improve reproductive output. The death of one partner, known as widowhood, breaks the bond and forces the surviving kestrel to find a new mate for the next breeding cycle. If a pair fails to return to the same territory the following spring, they are unlikely to reunite, leading both birds to establish new seasonal bonds.