Miguel Ángel Cruz Nieto’s scientific contributions

The thick-billed parrot (Rhynchopsitta pachyrhyncha) inhabits highland pine forests in the Sierra Madre Occidental ranges of northwestern Mexico. Their populations have declined significantly due to habitat loss, illegal hunting and increasing predation. Despite their ecological and cultural importance and increasingly endangered status, the species is highly data deficient. Our study aimed to inform and enhance conservation management strategies for thick-billed parrots with information on their spatial ecology, habitat use, and migratory behaviors. We deployed biotelemetry devices to conduct the first tracking study of wild parrots. Our study revealed that thick-billed parrots are obligate migrators, departing their breeding habitats around October and returning from southern habitats around April. We also identified previously unknown overwintering sites and migratory stopover locations, as well as a new nesting site. The parrots exhibited high spatial variability in range shifting behavior, but all tracked parrots exhibited range shifts during migration, with durations of 3 to 181 days and distances of 173 to 765 km. They traveled in close social groups and migratory routes primarily followed high-elevation forests. Home range analysis indicated smaller breeding site ranges and larger overwintering ranges, possibly reflecting nesting constraints and winter food resource dispersion. Less than 20 % of parrot habitats have formal regulatory protections. Conservation management efforts must focus on increasing protections for nesting areas, overwintering habitats, and migratory stopover sites. As climate change exacerbates regional threats, integrated management plans involving local stakeholders are essential for the parrots' survival and the preservation of their old-growth forest habitats.

by analyzing 358 pellets, identifying 850 prey items. Invertebrates constituted 90% of prey items, which mostly included insects (85%); beetles were the most common insects found in pellets (70%). Vertebrates made up 84% of consumed weight, of which 83% were mammals. Most of the mammals were cricetid rodents (41%). Niche breadth based on the numerical and weight percentage confirmed the Burrowing Owl as a generalist species with mean values per year ranging between 0.65 and 0.82. Additionally, there was a strong association between the weight of rodent species in winter. This association was mainly driven by changes in composition and frequency of these prey species during the second winter, probably caused by high annual rainfall. The second season also showed a statistically significant narrower niche (Ro = 0.96) and the smallest overlap (0.45 vs. 0.76) among the three winters.

We report on what appear to be increasing predation events on nesting Thick-billed Parrots Rhychopsitta pachyrhyncha. Thick-billed Parrots are classified as 'Endangered' and their seasonal breeding range is restricted to increasingly fragmented and degraded high elevation mixed conifer forest habitat within the Sierra Madre Occidental region of northwestern Mexico. Predation of established breeding pairs has recently contributed to the ongoing decline of Thick-billed Parrot populations by removing mature birds with high reproductive value, which has associated consequences for future recruitment. We observed increasing predation events on nesting Thick-billed Parrots by bobcats Lynx rufus accompanied by kittens throughout the 2018-2019 breeding seasons , and we speculate that recent reductions in bobcat habitat have pushed them into new ranges where they are supplementing their diet with nontraditional prey items.