A European Bee-eater can eat 250 honeybees a day, but that’s fewer than 1 percent of honeybees in any area, so bee-eaters don’t harm hives.
In southeast Spain, a study found that each bee-eater consumed about 1,333 honeybees during its stay in the Murcia region. The regeneration capacity of an individual hive is 36,000 to 45,000 honeybees per month from April to July. “Under normal circumstances, the effect of bee-eater predation on local apiaries appears negligible,” researchers from the University of Murcia reported in the Journal of Apicultural Research.
The availability of bees and other large flying insects is intimately tied to favorable weather conditions, especially warm, dry days with long hours of sunshine. German and Swiss researchers said good weather creates a “cascade effect” — more flying insects improves higher breeding success during reproductive periods (May and June in Europe, April to June in northwest Africa, June ad July in Uzbekistan, and October and November in South Africa). Parent birds continue to feed offspring for a couple months after they fledge.
European Bee-eaters have expanded their range northward through Europe as temperatures have risen. However, those birds “might be especially susceptible to regional changes in weather and climate conditions,” researchers wrote in the Journal of Ornithology.
Something other than bird predation is causing the mysterious honeybee illness called Colony Collapse Disorder (CCD). It’s also called Honey Bee Colony Depopulation Syndrome. Worker bees disappear from a hive and the queen and nurse bees face an uphill battle to replace them.
Bee-eaters and bee colony health
The cause or causes of CCD are not fully understood. Pesticides and viruses, such as Israeli Acute Paralysis Virus and Deformed Wing Virus, have been suspects. However, many microbiologists are focusing on a digestive-system parasite of Asiatic Honeybees called Nosema ceranae.
In about 2007, the Nosema parasite did something unexpected. It acquired the ability to infect Western Honeybees (also called European Honeybees). Soon, a fast moving wave of collapse disorder rapidly spread worldwide.
European Bee-eaters & parasites
On the good side, bee-eaters may actually help infected hives by removing the sickest, slowest-flying worker bees. (The Nosema parasite doesn’t make the birds sick.) Across southern Europe and nearby parts of Asia and Africa, European Bee-eaters bang their prey against a tree limb or other hard surface to remove the stingers before ingesting them.
To cope with their prey’s indigestible exoskeleton, bee-eaters regurgitate a moist pellet of bee leftovers every few hours. Viable Nosema spores have been found in pellets regurgitated by bee-eaters in every location tested in Spain, Central Europe, central Africa and central Asia.
When bee-eaters in, say, Spain, migrate, they seek new honeybee cafeterias. Unfortunately, the birds may also bring the bee parasite with them.
“Bee-eaters frequently stop and perch on bee-hives and they commonly expel pellets on hives,” Professor Francisco Valera Hernández, a scientist at Estación Experimental de Zonas Áridas in Spain, said in an email to Top Birding Tours. “In this way, contaminated pellets containing viable spores are very near healthy bees.”
Honeybee health problems
Some European apiaries that were treated to destroy the Nosema parasite became healthy again. However, Hernández and other scientists say it is unlikely that the Nosema parasite is responsible for all forms of CCD in all locations. In fact, the parasite is occasionally found in healthy hives.
In honeybee colonies dying of CCD, many also contain strains of the Invertebrate Iridescent Virus. What, if any role pesticides may play is not known.
All 24 species of bee-eaters live in Europe, Asia, Africa, Australia and many island. Some species are migratory, including the European Bee-eater. Bee-eaters that nest in Spain and France migrate to northwest Africa to spend the winter, crossing the Strait of Gibraltar.
Pesticide use on their breeding and wintering grounds is the main threat to bee-eaters and the insect communities they rely upon.
In North America, other bee-eating groups of birds may also play a role in spreading CCD. Ants also suffer from a colony collapse disorder called Lomechusamania. Better understanding of all insect diseases may shed light on CCD in all insects. Hernández said more research funding is most urgently needed to rigorously study colony collapse disorders, particularly among honeybees.