Experimental removal of invasive Africanized honey bees increased breeding population size of the endangered Lear's macaw.

BACKGROUND: Invasive Africanized honey bees potentially compete with cavity-nesting birds in South America. However, the impacts of this competition and its conservation consequences to threatened species are poorly known. We quantified the presence of these bees and assessed their competition for cliff cavities used by nesting Lear's macaws Anodorhynchus leari, a globally endangered parrot endemic to the Caatinga biome of Brazil. We treated beehives with permethrin by shooting them with a crossbow bolt that distributed the compound upon impact. When feasible, we removed the comb and applied an insecticide (fipronil) to deter bee recolonization. We subsequently surveyed the macaw breeding population to verify whether our treatment allowed for nest recruitment in cavities previously occupied by bees. RESULTS: We recorded > 100 beehives in the nesting cliffs. Hives outnumbered macaw nests tenfold in two areas recently recolonized by macaws. Cavities occupied by bees were significantly higher than those occupied by macaws, suggesting that macaws may be forced to breed in lower cavities. None of the untreated cavities (n = 50) were occupied by nesting macaws, whereas 15% of treated cavities (n = 52) were occupied within 2 years post treatment. Treated cavities occupied by macaws were significantly higher than those not occupied. Hive management increased macaw breeding population by 71% of the macaw breeding population increase. CONCLUSION: Experimental hive treatments were effective in restoring nesting resources lost due to bee infestation. An intensive and continued eradication program is recommended to enhance macaw habitat restoration, facilitating its expansion into historical areas. © 2020 Society of Chemical Industry.

Reproductive parameters in the critically endangered Blue-throated Macaw: limits to the recovery of a parrot under intensive management.

Rediscovered in the wild twenty years ago, the breeding biology of wild Blue-throated Macaws remains largely unexplored, yet is essential to its effective conservation and recovery. Here, we analyse reproductive parameters in an intensively managed wild population of Blue-throated Macaws, providing the first data on the breeding biology of this critically endangered species. During the six-year study period, 2007-2012, the number of active breeding pairs either remained constant or decreased, depending on the site, and no new breeding pairs were discovered despite extensive searching. We documented nesting attempts in natural cavities in dead palms or live hardwoods, and artificial nest boxes. Egg-laying was concentrated during the end of dry season and the beginning of the wet season, August through December. Hatching failure was the greatest cause of egg losses. Half of the breeding attempts of Blue-throated Macaws produced at least one fledging, on average two, after a 85 days nestling period. An average of 4.3 nestlings per year fledged from all known wild nests combined. Each pair lost roughly 65% of its initial reproductive investment at each nesting attempt. In most successful nesting attempts of individualized pairs, a new nesting attempt was not detected the following year. All monitored breeding pairs showed high nest site fidelity, reusing hardwood-tree cavities and nest boxes. Our findings will aid conservation efforts by refining current actions and prompting new approaches towards the conservation and recovery of the Blue-throated Macaw.

Parrots eat nutritious foods despite toxins.

BACKGROUND: Generalist herbivores are challenged not only by the low nitrogen and high indigestibility of their plant foods, but also by physical and chemical defenses of plants. This study investigated the foods of wild parrots in the Peruvian Amazon and asked whether these foods contain dietary components that are limiting for generalist herbivores (protein, lipids, minerals) and in what quantity; whether parrots chose foods based on nutrient content; and whether parrots avoid plants that are chemically defended. METHODOLOGY/PRINCIPAL FINDINGS: We made 224 field observations of free-ranging parrots of 17 species in 8 genera foraging on 102 species of trees in an undisturbed tropical rainforest, in two dry seasons (July-August 1992-1993) and one wet season (January-February1994). We performed laboratory analyses of parts of plants eaten and not eaten by parrots and brine shrimp assays of toxicity as a proxy for vertebrates. Parrots ate seeds, fruits, flowers, leaves, bark, and insect larvae, but up to 70% of their diet comprised seeds of many species of tropical trees, in various stages of ripeness. Plant parts eaten by parrots were rich in protein, lipid, and essential minerals, as well as potentially toxic chemicals. Seeds were higher than other plant materials in protein and lipid and lower in fiber. Large macaws of three species ate foods higher in protein and lipids and lower in fiber compared to plant parts available but not eaten. Macaws ate foods that were lower in phenolic compounds than foods they avoided. Nevertheless, foods eaten by macaws contained measurable levels of toxicity. Macaws did not appear to make dietary selections based on mineral content. CONCLUSIONS/SIGNIFICANCE: Parrots represent a remarkable example of a generalist herbivore that consumes seeds destructively despite plant chemical defenses. With the ability to eat toxic foods, rainforest-dwelling parrots exploited a diversity of nutritious foods, even in the dry season when food was scarce for other frugivores and granivores.