Black noddies form monogamous pair bonds that are long-lasting. In one study 86% of mated pairs remained together through mating seasons. Pairs tend to be made up of birds of similar ages. Courtship behaviors include flying together and a high-flight display in which birds ascend together and then glide at a steep angle back to sea level. Males attract females to a nest site with a "bridling" display - a rhythmic backwards and forwards movement of the head paired with opening and closing of the bill - followed by a "nodding" display in which birds nod their heads forward. Pairs avoid antagonism through the use of the a foot-looking display, where they suddenly look down as if to inspect their feet for several seconds, and gaping displays, where they hold their bills open and pointing downwards to display the colorful tongue and mouth.
Mating System: monogamous
Black noddy pairs stay together throughout the year or come together approximately 2 months before egg-laying. They build or reinforce large, untidy nests in trees (from less than 1 meter to over 20 meters tall) or on cliff ledges or sea caves. Nest sites seem to be selected mainly for their proximity to the breeding colony and even unsuitable nest sites are occupied if they are near other nesting pairs. Nests in trees may be mainly built on the leeward side of the tree for protection against wind. Males collect nesting material and females construct nests. Black noddies defecate at nests, helping to hold nest materials together and enlarging cliff ledges. The timing of breeding varies regionally. In some areas the breeding season is short and regular, in other areas breeding is irregular, and in some areas breeding may occur throughout the year. Within colony islands, the timing of breeding can vary annually as well. On Ascension Island birds breed at 8 to 10 month intervals, so the timing of the breeding season is earlier each year. Some populations have 2 clutches per year, 5 months apart. The timing of breeding may be most influenced by the availability of prey species.
Black noddies lay 1 egg per clutch. Two egg nests are sometimes observed, but these are thought to be eggs that have rolled or fallen from adjacent nests. Eggs are large (23.7 to 25.2 g), oval, and buffy marked with spots and streaks of reddish brown. If an egg fails or is lost, a replacement egg is laid. Black noddies may even lay replacement eggs after the loss of nearly fledged young. Incubation begins immediately after egg-laying and lasts for about 34 days. Both males and females incubate the eggs, leaving for only about a minute at a time. In cold weather they sit on the egg and in hot conditions they may wet their ventral feathers to help cool the egg. Young fledge in 39 to 52 days, depending on the availability of prey. Development may be prolonged by periods of low prey availability. Although weight gain and morphological development slows during such periods, this does not seem to result in juvenile mortality. This may be an adaptation to unpredictable resources. Fledglings remain near their parents for up to 17 weeks after fledging, although they roost with other juveniles during that time. Black noddies may breed as early as 2 years old, although 3 years is more typical.
In artificially enlarged broods, black noddy parents were able to successfully compensate for the nutritional demands of additional young. Enlarged broods did not apparently adversely impact nestling development or survival. However, the nutritional stress associated with enlarged broods resulted in slowed wing and feather development. Broods with differences in ages of the nestlings, however, experienced more competition between nestlings for food, with younger nestlings not able to compete as well as older nestlings.
Breeding interval: Black noddies can breed from every 5 months to once yearly. A maximum of 3 clutches per year has been estimated, although 1 successful clutch per year is typical.
Breeding season: Breeding season in black noddies varies regionally and may depend on the peak seasonal availability of prey. Some populations breed throughout the year, others have a strongly seasonal pattern of breeding.
Range eggs per season: 1 (high) .
Average eggs per season: 1.
Average time to hatching: 34 days.
Range fledging age: 39 to 52 days.
Range time to independence: 116 to 171 days.
Range age at sexual or reproductive maturity (female): 2 (low) years.
Average age at sexual or reproductive maturity (female): 3 years.
Range age at sexual or reproductive maturity (male): 2 (low) years.
Average age at sexual or reproductive maturity (male): 3 years.
Key Reproductive Features: seasonal breeding ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate)
Males and females incubate, feed, and protect their young. Incubating parents are reluctant to leave the nest when the other parent comes to relieve them. One parent may physically push the other off the nest. Allopreening or feeding behaviors may accompany one parent replacing the other at the nest during incubation. Chicks hatch without help from parents. Young black noddies are semiprecocial; they have downy feathers in the same color pattern as the adult and remain in the nest until they fledge. Hatchlings are brooded and fed by regurgitation by both parents. Chicks are fed about every 1 to 2 hours when young and about every 11 hours when closer to fledging. Young black noddies place their bills in their parent's open mouth and then rapidly open and close their bills to stimulate regurgitation. Adult mass is attained at about 3 weeks after hatching. Hatchlings lose weight in the last week before they fledge but still typically fledge at masses greater than or equal to adult mass. Hatchlings that fall from nests are typically abandoned, although some older hatchlings are fed by their parents on the ground. Adults do not feed hatchlings that aren't recognized as their own. Adults continue to feed young up to 17 weeks after fledging.
Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)
- Congdon, B. 1990. Brood Enlargement and Post-Natal Development in the Black Noddy Anous minutus. Emu, 90: 241-247.
- Gauger, V. 1999. Black noddy (Anous minutus). Pp. 1-32 in A Poole, F Gill, eds. The Birds of North America, Vol. 412. Philadelphia: The Birds of North America, Inc..
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