Evaluating the impact of reinforcement efforts on imperiled species: The North African houbara bustard

Population reinforcement can be an effective strategy for stabilizing declining populations. However, assessing reinforcement success requires comprehensive information on the demography of both wild-born and released individuals. Here, we evaluate the population reinforcement of North African houbara bustards ( Chlamydotis undulata undulata ) in eastern Morocco. Using long-term intensive monitoring data, we developed a coupled integrated population model (IPM) and population viability analysis (PVA) to evaluate the efficacy of reinforcement and predict population responses to alternative conservation strategies. Combining point counts, individual tracking, and breeding data from thousands of houbara, we modeled demographic rates and abundances based on origin (captive-bred and wild-born), age, and sex-specific classes. We then predicted population responses to changes in demographic rates and numbers released. We provide the first estimates of wild houbara abundance, indicating a sharp decline since 2011 and a total population consisting mainly of captive-bred individuals. Projections indicate continued releases combined with substantial increases in survival and productivity are needed to support a viable population of wild houbara. Previous analyses of independent data sets highlighted the positive demographic contributions of released birds and success of reinforcement given high houbara numbers. However, our integrated demographic assessment revealed that the wild population has and will continue to decline, despite high houbara abundance. Our work highlights the need to establish targeted monitoring and modeling plans to ensure reinforcement programs are performing with the intended consequences.