European bee-eaters are monogamous and will generally stay together from year to year if both survive. Courtship feeding has been observed of some male European bee-eaters, where the male will bring food to the female a couple days before, during, and after egg laying. Roughly 20% of nesting pairs have 1 to 4 helpers that exhibit cooperative breeding, where a non-breeding male, likely a close relative, will assist the nesting pair by sitting on the nest and catching prey for young.
Mating System: monogamous ; cooperative breeder
In central Europe, most European bee-eaters return to their breeding range in late April or early May. They will mate in May and dig out burrows around 1 m deep in sand pits or steep river banks. Females lay 4 to 7 eggs in late May to early June. They are laid in 2 day intervals and incubated 3 to 4 weeks before hatching asynchronously. Before young fledge asynchronously at around 4 weeks of age they undergo weight loss to reduce their weight closer to that of an adult. Asynchronous Hatching and fledging is thought to help offset sibling rivalry and allow better care of young with a variable food source like flying insects. Juveniles become independent at 1 to 2 months of age. Sexual maturity is reached within the first year, though juveniles are not always successful at breeding in their first year. Juveniles may come back to the same colonies and nest near relatives such as parents or siblings. These juveniles may become family helpers if they fail to nest.
They are either solitary or colonial nesters. One study found a negative effect on nest success with increasing colony size. Isolated pairs with equal clutch size had a higher rate of nesting success. It is thought that colonial breeding could still be worthwhile if it increases adult survival.
Breeding interval: European bee-eaters breed once yearly.
Breeding season: European bee-eaters breed between May and June.
Range eggs per season: 4 to 7.
Average eggs per season: 5.
Range time to hatching: 3 to 4 weeks.
Range fledging age: 28 to 32 days.
Range time to independence: 1 to 2 months.
Average age at sexual or reproductive maturity (female): 1 years.
Average age at sexual or reproductive maturity (male): 1 years.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)
Both male and female European bee-eaters participate in excavating the underground nesting burrow. After the eggs are laid, the pair shares incubation responsibilities. Chicks are born altricial, without feathers and eyes closed, and rely on significant parental care for survival. The male "helper" will also share incubation and feeding duties, but is not as reliable as the breeding pair. Both parents provide food and protection for young until fledging. Some male European bee-eaters will continue to feed the female for several days during and after egg laying.
European bee-eaters exhibit very specific feeding behaviors that are difficult for young birds to learn. Breeding pairs will continue to feed fledglings until the young learn the skills to successfully forage for themselves.
Parental Investment: altricial ; male parental care ; female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Male, Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female); post-independence association with parents; extended period of juvenile learning
- Avery, M., J. Krebs, A. Houston. 1988. Economics of courtship-feeding in the European bee-eater (Merops apiaster). Behavioral Ecology and Sociobiology, 23/2: 61-67.
- Hoi, H., C. Hoi, J. Kistofik, A. Darolava. 2002. Reproductive success decreases with colony size in the European bee-eater. Ethology Ecology & Evolution, 14: 99-110.
- Horváth, G., M. Fischer, T. Szekely. 1992. The delivery of surplus prey to the nest by a pair of bee-eaters (Merops apiaster). Ornis Hung, 2: 11-16.
- Lessells, C., M. Avery, J. Krebs. 1994. Nonrandom dispersal of kin: why do European bee-eater (Merops apiaster) brothers nest close together?. Behavior Ecology, 5: 105-113.
- Lessells, C., M. Avery. 1989. Hatching Asynchrony in European Bee-eaters Merops apiaster. Journal of Animal Ecology, 58/3: 815-835.
- Lessells, C., G. Ovenden. 1989. Heritability of Wing Length and Weight in European Bee-Eaters (Merops apiaster). The Condor, 91/1: 210-214.