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The order Psittaciformes is one of the most prevalent groups in the illegal wildlife trade. Efforts to understand this threat have focused on describing the elements of the trade itself: actors, extraction rates, and routes. However, the development of policy-oriented interventions also requires an understanding of how research aims and actions are distributed across the trade chain, regions, and species. We used an action-based approach to review documents published on illegal Psittaciformes trade at a global scale to analyze patterns in research aims and actions. Research increased exponentially in recent decades, recording 165 species from 46 genera, with an over representation of American and Australasian genera. Most of the research provided basic knowledge for the intermediary side of the trade chain. Aims such as the identification of network actors, zoonosis control, and aiding physical detection had numerous but scarcely cited documents (low growth rate), while behavior change had the highest growth rate. The Americas had the highest diversity of research aims, contributing with basic knowledge, implementation, and monitoring across the whole trade chain. Better understanding of the supply side dynamics in local markets, actor typology, and actor interactions are needed. Protecting areas, livelihood incentives, and legal substitutes are actions under-explored in parrots, while behavior change is emerging.

Estimating abundance and population size is essential for many ecological and conservation studies of parrots. Achieving these goals requires methods that yield reliable estimates, but parrot traits can make them difficult to detect, count, and capture. We review established and emergent sampling and analytical methods used to estimate parrot abundance and population size, focusing on their assumptions, requirements, and limitations. Roost surveys are cost-effective if all roost locations in a region are known and stable, which is uncommon. Capture-recapture methods incorporate detection probability, but capturing, marking and resighting parrots can be difficult. Distance sampling estimates detection probability and surveys multiple species simultaneously, but is sensitive to the spatial distribution of individuals and excludes birds in flight. Roadside transects can cover large areas and survey multiple species, but habitats near roads may differ from the surrounding areas, biasing abundance estimates. Occupancy surveys and hierarchical models usually require spatially and temporally replicated datasets. Both allow estimation of detection probability; the former dispenses with count data, while the latter is a versatile set of methods that can incorporate multiple processes influencing detection and abundance. Finally, passive acoustic surveys can sample multiple species simultaneously, but identification of vocalisations can be difficult and time-consuming.

Estimating abundance and population size is essential for many ecological and conservation studies of parrots. Achieving these goals requires methods that yield reliable estimates, but parrot traits can make them difficult to detect, count, and capture. We review established and emergent sampling and analytical methods used to estimate parrot abundance and population size, focusing on their assumptions, requirements, and limitations. Roost surveys are cost-effective if all roost locations in a region are known and stable, which is uncommon. Capture-recapture methods incorporate detection probability, but capturing, marking and resighting parrots can be difficult. Distance sampling estimates detection probability and surveys multiple species simultaneously, but is sensitive to the spatial distribution of individuals and excludes birds in flight. Roadside transects can cover large areas and survey multiple species, but habitats near roads may differ from the surrounding areas, biasing abundance estimates. Occupancy surveys and hierarchical models usually require spatially and temporally replicated datasets. Both allow estimation of detection probability; the former dispenses with count data, while the latter is a versatile set of methods that can incorporate multiple processes influencing detection and abundance. Finally, passive acoustic surveys can sample multiple species simultaneously, but identification of vocalisations can be difficult and time-consuming.