The use of foster parents has great potential to help the recovery of highly endangered bird species. However, few studies have shown how to successfully use these techniques in wild populations. Scarlet Macaws (Ara macao macao) in Perú hatch 2–4 chicks per nest but about 24% of all chicks die of starvation and on average just 1.4 of them fledge per successful nest. In this study we develop and test new techniques to increase survival of wild Scarlet Macaw chicks by reducing chick starvation. We hypothesized that using foster parents would increase the survival of chicks at risk of starvation and increase overall reproductive success. Our results show that all relocated macaw chicks were successfully accepted by their foster parents (n = 28 chicks over 3 consecutive breeding seasons) and 89% of the relocated chicks fledged. Overall, we increased fledging success per available nest from 17% (2000 to 2016 average) to 25% (2017 to 2019) and decreased chick death by starvation from 19% to 4%. These findings show that the macaw foster parents technique and post relocation supplemental feeding provide a promising management tool to aid wild parrot population recovery in areas with low reproductive success.

Avian brood reduction was initially thought to be driven by insufficient food supply. Now it is more commonly considered a consequence of asynchronous hatching and resulting siblicide, direct filial infanticide (where parents kill specific chicks) or indirect filial infanticide (where parents starve specific chicks). In psittacines, brood reduction has been reported, but the mechanisms and causes remain unexplored. In this paper, we test the hypotheses that Scarlet Macaw chick starvation is driven by (1) sibling aggression, (2) food scarcity, and (3) parental food allocation based on (a) chick hatch weight and (b) chick age differences. We documented wild Scarlet Macaw behavior in lowland Peru in 37 nests over 19 seasons using morphological measurements and nest videos. Chick starvation was the leading cause of chick mortality (27% of all second-hatched chicks starve, and nearly all third- and fourth-hatched chicks starve). We found no evidence that starvation was caused by (1) sibling conflicts or (2) food availability. We did find parental food distribution favors first-hatched chicks, with larger age differences increasing the chances of second chick starvation. This study offers insights into brood reduction among Neotropical cavity-nesting birds and enhances our capacity to develop scientifically informed management strategies to support endangered psittacines.

Illegal wildlife trade exerts severe pressure on wild parrot populations, and confiscated parrots often end up in rescue centers where they are rehabilitated for release. However, parrots kept in captivity often develop potentially maladaptive behaviors, including attraction to humans. This behavior can increase the risk of recapture. We modified and tested a previously published human aversion training (HAT) protocol designed to reduce human attraction in confiscated Amazona parrots. The HAT consisted of observers either on the ground or on a ladder, offering food to a single individual and then feigning capture of birds that approached or failed to move away from the observer. Twelve Yellow-naped Amazons (Amazona auropalliata) underwent 36 sessions of HAT over a 14-week period. Ten additional birds were held without training as a control. All birds were evaluated through food offer tests (FOTs) before, during, and after the experiment (FOT scores ranged from 1 when the bird approached the observer to 6 when the bird flew away). Over the training period, both groups showed increased aversion to people. However, contrary to our predictions, aversion scores were not higher for the group given aversion training. Aversion training also did not have a strong impact on fate post-release: within a month of release, 40% of the 22 birds were recaptured in a nearby village, including 4 treatment and 5 control birds. Overall, these results suggest that holding these birds in monospecific groups increased aversion to humans. However, the intense training aversion protocol did not further increase the fear of humans in these Amazona parrots, many of which may have been pets for years before entering the program. This study suggests that rehabilitation and release projects should regularly evaluate the impacts of their training programs and improve or eliminate costly protocols that do not achieve stated objectives.

Incubation is a fundamental component of avian reproductive biology. One element of avian incubation, egg turning, is nearly universal among avian taxa and is vital for optimal embryonic development, hatch success, and chick quality. Despite its importance, egg turning behaviors are poorly understood. Egg turn parameters, such as rate and angle, are subject to wide variation among and within taxa and may vary over the incubation period. In this study, we used data loggers in artificial eggs to measure the rate and angle of egg turns from wild Scarlet Macaw ( Ara macao macao ) hens nesting within artificial cavities in southeast Peru. Our results from four of these hens indicate that egg turn rates averaged 11.5 turns h ⁻¹ , turn angles averaged 42.2° turn ⁻¹ , and these parameters varied significantly among hens. Egg turn rates were dynamic over the incubation period, peaking during the middle third of incubation, whereas egg turn angles increased linearly over the incubation period. Comparison with the literature suggests that the highly altricial Scarlet Macaws turned their eggs at a higher rate than the more precocial taxa studied with similar methods. Our study is the first to characterize the egg turn parameters of any wild parrot using data loggers and may prove useful for discerning larger taxonomic patterns in incubation. We found wild Scarlet Macaw egg turn rates to be much higher than published recommendations for the artificial incubation of parrot eggs, suggesting this work could be used to inform captive breeding and other conservation techniques.