Semipalmated plovers are socially monogamous birds during their breeding season. They pair up on their breeding grounds. Males arrive at their potential nesting sites and perform a fluttering courtship flight, which is accompanied by courtship display calls. This distinctive, slow-flap, deep wing-beat flight takes place at more than 50 meters above the ground and serves to delineate the boundaries of the male’s territory as well as to attract females. On the ground, the male then spreads and depresses his tail feathers, slightly opens his wings, and puffs his feathers while continuously calling.
Once the female has chosen a male’s territory, the male follows the female, appearing to defend her and the territory. The male displays threatening behavior to other male birds by moving toward them with his head down, and wings held slightly out from his body. The male meets the female with somewhat aggressive behavior, in which he chases her with his tail cocked and fanned while making a "chuttering" vocalization. This aggressive behavior declines as the courtship proceeds. The male makes scrapes on the ground with his feet, and the female will assist. While sitting in this new scrape, the female may also perform a tail-fanning display, indicating her decision to choose her mate and his nesting territory.
Copulation then usually occurs after the female’s tail display. The male swings his leg onto the female’s crouched back, the female raises her tail, and the cloacae touch. After copulation, both male and female peck at the ground or preen. It is usually within this scrape that the nest is built. Both sexes incubate and care for the chicks. The pair remains together until the nest is lost or the chick dies; it has been shown that pairs also stay together in subsequent seasons.
The male assures the paternity of his offspring and the monogamy of his paired mate in several ways. When he is not mating with his female he guards her by physically attacking her, which is presumably meant to discourage her from cheating with other males. This is more commonly seen in areas where there is a high likelihood of potential extra-pair partners. Physical attacks may make it more costly for the female to reject a mate's copulation, and may also be used to expel an uncooperative female from a defended territory to vacate space for other potential females.
Mating System: monogamous
Semipalmated plovers are socially monogamous birds that breed seasonally from May to August. The male arrives before the female to the mating grounds and establishes the nesting territory. The male chooses a patch of dry ground, usually on sandy or gravely substrates with relatively sparse vegetation. Then the male scrapes the boundaries of the nest on the ground with his feet, and lines the nest with material collected nearby, such as leaves and pebbles. When the female arrives to the mating grounds, the male courts her with a slow-flapping, butterfly-like flight.
Once copulation has occurred, the females begin laying their eggs, with the clutch completed within 5 days. There is an interval of 24 to 30 hours between the laying of each egg, with a complete clutch usually contains 4 eggs. For the next 23 to 25 days, both male and female equally contribute to the incubation of the eggs.
The eggs are smooth, glossy, and short with a pear-like shape. They are between 32.4 and 33.1 mm long, and 22.8 to 24.1 mm in width. The average mass of the egg ranges from 8.7 to 9.4 grams. The colors range from light brown to pale, olive buff, with small blotches of black to brownish black. Some eggs are blotched with chestnut brown or sepia color, with a few underlying spots of pale gray.
Hatching of the full clutch can last from 2 to 5 days. Once the chick has broken through the shell, it usually completes its hatching within 12 hours, but can take up to 4 days. Chicks weigh an average 6.6 grams upon hatching. The male takes the hatched chicks a short distance away from the nest in order to brood and feed them, while the mother continues to incubate the unhatched eggs of the nest. Semipalmated plover chicks are precocial and can walk and feed within hours after hatching, but are brooded by their parents up to their fifth day of age. About 15 days after the eggs hatch, the mother abandons her mate and brood, leaving the father as the sole guardian of the nest.
The chicks fully fledge between 22 to 30 days after they have hatched. Semipalmated plovers become sexually mature when they are 2 to 3 years old, and continue to breed yearly after their first breeding experience.
Breeding interval: Semipalmated plovers breed once once every year.
Breeding season: Breeding occurs from early May to late August
Range eggs per season: 2 to 5.
Average eggs per season: 4.
Range time to hatching: 24 to 25 days.
Range birth mass: 5.0 to 8.1 g.
Average birth mass: 6.64 g.
Range fledging age: 22 to 30 days.
Range time to independence: 5 to 15 days.
Range age at sexual or reproductive maturity (female): 2 to 3 years.
Range age at sexual or reproductive maturity (male): 2 to 3 years.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)
Prior to copulation on the breeding grounds, adult males invest time and energy in finding a suitable site for establishing their nests. Nest site selection plays a very important role on the reproductive success and survival of the offspring. Birds who select nest sites with more pebbles, less vegetative cover, and a smaller percentage of bare mud have greater hatching success than birds who select other kinds of nest sites.
Once the nest is built and eggs have been laid, males appear to be in attendance most of the time, while females are foraging nearby. Once the clutch is completed, males and females equally attend the nest and incubate throughout the day. The males usually incubate during the darkest hours, and switch off with the females every 2 to 5 hours throughout incubation. The incubation period lasts between 23 to 25 days
When the eggs are hatched, the parents brood the chicks immediately. The chicks are precocial and able to find their own food. Young may be led to nearby water areas to feed. When the chicks are about 3 days old, males and females continue to switch off attending the nest but the non-attending adult flies further away. Females abandon their mates and nests 15 days after the eggs have hatched and leave the males as the sole guardians of the brood. As the chicks get older, the adults spend greater amounts of time foraging, and males often leave the nest unattended in order to pursue invading species. The young fledge about 22 to 30 days after they hatch, but the father generally departs before this stage. Juveniles usually flock together before they migrate during the fall.
Parental Investment: precocial ; male parental care ; female parental care ; pre-fertilization (Provisioning, Protecting: Male, Female); pre-hatching/birth (Provisioning: Male, Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Protecting: Male)