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(Wrege & Emlen 1994)
Choose one of the two rainy seasons each year for breeding
Females consider the family structure of a potential mate when choosing a partner.
- In a 5-year study of mate choice in Kenya, females preferred males with a large, genetically close family of helper- birds that could aid the pair in rearing their young.
- The advantage to the female's breeding success of a male with a "good family" is so great that a female may skip a breeding cycle rather than choose a mate of poor social quality.
Courtship interactions occur at the roosting colony and on the feeding territory.
Courtship is lengthy - often 6 to 8 weeks
At the start of courtship both birds are excluded by their families; as they form a pair-bond, the female usually becomes accepted into the male's family group.
After mating, males spend most of day guarding female from other males.
Monogamous, cooperative breeders, living in colonies. (Emlen 1990)
Breeding success in this species strongly influenced by family structure. (Wrege & Emlen 1994)
Females typically leave their birth group to join the family of the male (patrilocal)
- Loose ties are maintained with birth group; may leave mate, if not nesting, to return home and help with nesting of a genetic parent; return to mate when task is completed. (Emlen & Wrege 1988)
- "In-laws" usually are nesting and roosting nearby. (Emlen 1990)
Many individuals of both sexes play a role as a helper at the nest. (Emlen 1990, 1991))
- They differ from other colonial birds who typically play the helper role only when young, before achieving breeding status.
- Helper birds help their close genetic relatives.
- May switch several times between breeder and helper roles.
- Some 60% of breeding pairs have 1-5 helpers. (Fry 2001)
- Nests with helping birds have much more twice as much reproductive success.
- Helper birds associate with a single nest and assist in all phases of the nesting activity.
- Excavate tunnel
- Defend nest
- Bringing food to the breeding female
- Incubating eggs
- Feeding nestlings
- Caring for fledglings after they leave nest
Gestation & Birth
Nesting (Emlen 1990) (Fry 1984, 1992)
- Nests only dug into perpendicular cliffs.
- Usually 10-20 active nests but up to 150 nests with 450 birds.
- Highly variable level of nesting success; often not successful.
- Many nests abandoned early (but males or females may go on to be a helper at another nest).
- Chicks in many nests starve; with helper birds assisting the parents, less starvation.
- Helper birds assist in excavating and defending the nesting chamber, incubating the eggs, feeding and caring for young.
- Helpers are dedicated to one nest for the nesting season.
- If nesting effort fails, helpers plus the parents may redirect their efforts to helping another related bird pair's nesting effort.
- Benefit of helpers' work is great: each helper accounts for an average of 0.44 additional offspring; the more helpers, the better the results.
- Nest sites not necessarily chosen next to other clan members (clan members share foraging territory, not nesting area).
- One bee-eater studied (M. orientalis) could judge the line of sight of a predator and not enter the nest burrow when the predator could see the nest. (Watve et al 2002)
- Incubation period: 20-21 days
- Female spends most of day (94% of time) in nest to prevent other females from parasitizing nest (she removes all foreign eggs before laying own eggs).
- About 7% of all eggs in colony are laid in another female's nest, by either another bee-eater or other bird species.
Eggs (Fry 1984)
- Clutch size: 2-5 eggs; nests with helpers have the most eggs.
- Incubation: Female parent spends more time inside nest cavity than male parent.
- Brooding: Parents allow other members of its clan to visit the nest.
- Chicks altricial (blind and naked when born).
- Chicks weigh an average of 4.8 g (1.7oz)
- Male parent may spend more time than females in caring for nestlings. (Fry 1984)
- Growth rates of nestlings flexible, depending on food availability. (Fry 2001)
- In this species, nestling mortality is high - 48% of all hatchlings die of starvation. (Emlen et al 1991)
- Feather growth completed at 25 days (for well-fed chicks). (Emlen et al 1991)
- Fledging at about 29 days for well-fed chicks in a study in Kenya by Emlen et al (1991)
- Some chicks delayed fledging to as much 42 days.
- Low food availability meant more days of delayed development.
- Chicks born last were more likely to have delayed development, due to facing more competition for food.
- Chick in nests with helpers (in addition to parents) had less delayed development.
- Fledglings average 22% heavier than average adults' weight.(Elston 2007)
- Both parents tended young in nest chamber equally. (Fry 1984)
- Adult plumage at 6 months.
- Young remain with parental group till about 9 months, then may pair into other social groups. (Emlen et al 1991)
- Around 7 years in managed care
In the wild
(Fry 1984) (Wrege & Emlen 1991)
Aside from flooding and cliff collapse deaths, 48% of nestlings die of starvation.
Predation on eggs and young only a minor cause of mortality
- Nest parasitizing Honeyguide birds (Family Indicatoridae) kill embryos by pecking the egg; their young kill nest mates with sharp beak-hooks.
- Predators on nests in Lake Nakuru National Park, Kenya: snakes, mongooses, swifts
Collapse of undercut cliff faces along a river are common; often considerable or total loss of colony's eggs and young.
Cliff faces may be flooded with rising river waters, resulting in a loss of eggs and young.
White-fronted Bee-eater Call
Emlen (1990, 1991)
Emlen & Wrege (1988, 1991)
Emlen et al (1991)
Wrege & Emlen (1991, 1994)
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