Fighting bees leads to an increase in the Lear’s macaw population
The world needs honey bees. Aside from their key ecological role, they are responsible for the pollination of almost 85% of all food crops for humans and provide us with several useful products, with honey at the top of the list.
But what about Africanized bees? These are the infamous aggressive “killer bees”, descendants of the African honeybees introduced to South America in 1956, which quickly spread over most of South and Central America and arrived in the US in the 1990s. While specific management techniques do not seem to have a significant impact on honey production or beekeepers’ investments, at least in the US, they can have serious effects on native wildlife. In South and Central America, Africanized bees often occupy holes suitable for endangered native species of cave breeders, and the possible negative effects of this competition are worrying.
The Lear’s Macaw is an endangered species endemic to Northern Bahia, Brazil, that nests in cliff caves that are often invaded by Africanized bees. Native to the tropical dry forest and scrub of the arid Caatinga zone, the Lear’s Macaw has a very limited geographic distribution and is threatened by the continued deterioration of its habitat and food supply, the theft of wild chicks from nests for trade and occasional persecution Farmers foraging in maize crops.
Lear’s Macaw classified as Endangered (Joao Quental / Flickr)
Lear’s Macaws nest on cliffs in two traditional locations, but have recently colonized at least two other locations – this expansion is most likely related to the continued increase in the wild population, which reached 1,694 individuals in 2018, largely due to efforts made since 2006 with more than $ 480,000 in support from Loro Parque Fundación (LPF) to better understand their environmental needs while implementing conservation measures for their immediate recovery and long-term safety.
Although the species is improving, the species’ situation is still precarious, not only because of their very limited breeding areas, but also because of Dr. Erica Pacífico that only about 20% of the individuals are reproductively active in a breeding season. With climbing gear and courage, Erica has spent years climbing and abseiling the cliffs to study the species’ breeding biology.
She found that Africanized bees gradually occupied more and more burrows in the breeding cliffs. Not only do the bees exclude the macaws from suitable nesting holes, but they also prevent bee colonies that are near active macaw nests from preventing safe access to surveillance. In one count, more than 100 bee nests were recorded on the nesting cliffs – the number of nests of the Lear’s macaw in two areas is ten times as large. The bee-occupied burrows were significantly higher on the cliffs than those of macaws, possibly forcing the macaws to breed in lower, more accessible burrows.
The Lear’s Macaw nests in caves on inaccessible cliffs (Juan Cornejo).
Therefore, measures have been taken to evaluate the effectiveness of the so-called “push-pull” method of removing the bees. Bee control expert Dr. Caroline Efstathion, founder of the Florida-based Avian Preservation and Education Conservancy (APEC), advocated this method using a safe permethrin repellent to push the bees out of their nesting holes while drawing the bees close to trap boxes with an attractant pheromone as a bait, the installed on a lower level. The LPF previously supported Caroline’s work with this method to reduce the colonization of nest boxes for endangered Cape parrots in South Africa by bees.
The bee nests in cavities on the macaw nesting cliffs were treated with permethrin by firing a crossbow bolt, which spread the repellent on impact. Whenever possible, the comb was removed from the den and a lower toxicity insecticide (fipronil, used to control fleas in domestic animals) was applied to prevent bees from colonizing again. Despite the experimental nature of the work, the results were very encouraging. None of the untreated caves were occupied by nesting Lear’s macaws, but 15% of the treated caves were occupied within two years of treatment. Treated caves occupied by macaws were significantly higher on the cliffs than the unoccupied ones. A subsequent study of the macaw brood population showed that bee nest management contributed 71% to the increase in the brood population.
An Africanized bee nest high on a Lear’s Macaw breeding ledge (Loro Parque Fundación)
An intensive and ongoing eradication program is recommended to encourage the expansion of the macaw population into historic areas, but long-term success will depend on the participation of local people. It is common in this region for people to collect wild honey and build stick ladders on the cliffs to reach the higher bee nests. This brings the foragers close to macaw nests in some cases, with the risk of poaching chicks for convenience. However, part of the ongoing work is to provide interested farmers with beehives, personal protective equipment and instructions on how to conserve colonies for honey production. This gives them a new sustainable source of income and an incentive not to cut trees or climb cliffs to extract honey, thus helping to keep poachers out of the area.
Pacífico E, Efstathion C, Filadelfo T, Dénes F, Gilardi J and Tella, J. 2020. Experimental removal of invasive Africanized honey bees increased the breeding population of the endangered Lear’s macaw. Science of Pest Management. DOI: 10.1002 / ps.5972